MONTHLY TECHNICAL REVIEW (TECHNICAL & SCIENTIFIC ARTICLES ON MEASURING INSTRUMENTS)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80T00246A041600360001-0
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 40
• Document Creation Date: December 22, 2016
• Document Release Date: May 14, 2010
• Sequence Number: 1
• Publication Date: April 14, 1958
• Content Type: REPORT

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CENTRAL INTELLIGENCE AG
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COUNTRY Bast G.nnasy
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INFO.
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Work. Troptow on measur s rumen ss containing too
articles.
scien
G snts The pamphlet is not classified when detaahod tram the 25X1
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14 APh IN
a pamphlet issued by V$B Kektro-ApparaU-
hnioal and
tific
L-JAEC
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i d
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oiflWy jchnicai Re%hiew
MEI$ JRiNG I M:0 RUiMENTS
D
for a ,
ependable control of technical
o ``
p~3tions.
'tric measuring instruments for switch
~oa Os.
Portab!e service instruments.
Recording instruments.
electric miniature measuring instruments.
High frequency measuring instruments
and thermal transformers.
,,Oh
I B' ELEy(TIR?APPARATE?WERKE BERLIN?TREPTBW
V E B V E P. L A G T E C H N I K B E R_ I N 10 / 1957
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Agfacolor-kine-film
Kine-film black-and-white 35 and 16 mm
Roentgen- and technical films
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Amateur-film black-and-white and coloured
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VEB BUROMASCHINENWERK RHEINMETALL SOMMERDA/THUR.
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Pare
The Key ................................. 233
Experimental Determination of the Lines of
Constant Speed in the Field of Hydrodyna-
mic Guide Grids by Means of Soap Skin
Models ......................... Pascher 235
A Simple Geometric Construction to Replace the
Adiabatic Ellipse in the Construction of Mach
Lines .................... Schieferdecker 241
Thickness Measurements of Oil Films
Dierichs/Gabbert 242
A New Method to Measure Non-linear Distor-
tions ........................... Henkler 247
The State of Cable Engineering in the Light of
the New VDE-Regulations ....... Doerfel 250
The Length of the Transition Are in Road
Building .................. Christfreund 255
Instrumentenkunde der Vermessungstechnik
(Theory of Surveying Instruments) ....... 259
On the Separation of Solid Particles from Li-
quids by Hydro-Cyclones ................ Lindner
The Development of Hi h-Speed Low Weight
Turbo-Compressors in the Lerman Demo-
cratic Republic ......................... Christof
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Subscription to
"Monthly Technical Review"
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Published by: VEB Verlag Technik,
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Monthly Technical 1te,l,W
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Published under Licence-No. 2132 of the German Democratic
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oiiltily Tchnical Review
Volume 1, Ao. 10 Berlin December 1957
THE KEY
llachine building is rightly called the heart of a country's economy: all other branches of industry depend on
it for their further development. The sooner the machine building industry of the German Democratic Republic
succeeds in developing and producing machines and aggregates of still higher perfection, the sooner all other in-
dustries rcill be able to satisfy the requirements of this and other countries.
Great Tasks
The main tasks set for the industry of the GDR by the Second Fite-Year Plan are the rapid development of
energy production, the raising of soft coal mining, greater output of building materials, and the development of
some branches of the chemical industries. All this means higher demands on our machine building industry. In
addition, there is a constantly increasing demand for complex machines required by the fast growing sector of our
socialist agriculture. (see, e. g., Steffen, The Tool-Carrier RS 09, pp. 251 and 2.58 of this volume).
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Gig.
,Spur grew I)! IIder (petrerutit~q tueNioJ)
t .il mttiiurhver.~ I'ti1 GrofGheh-
ttmsehiaeohaC Ot'loher". Berlin-
Great Icnnnplishments
Our machine building enterprises are working arduously to further the production of highclass machines.
Only a short time ago the wire rope spinning machine .18 1)VRI 1000 was completed by VER Schwernasehinenball
Ernst 1'hiilmann, Magdeburg. With a total u-eight of 370 t and an overall length of 65 m, it is the largest machine
of its kind built up till note.
Out of the large group of well-known trade marks only WM W may be mentioned. These three letters signify
top products of our peoplt:s'-owned machine tool building industry; many- of these have become known on the world
market. in our previous issues we have acquainted i ionthly Technical Review readers with some of these machines
(see Vol. I No. 1 , pp. 3- 7, New Developments in the Lathe Building Industry at the Technical Fair Leipzig
19,37; pp. 8 - 10, Haupt, Vacuum Forming of Thermo-Plastics; No. 2, pp. 27 - 32, Willeke, Gauge-Controlled
Grinding ilachines; No. 3, pp. 55-58, Masthoff, Planing Machines: No. -1, pp. 81 -80, Schroder, Trends in
the Development of Gear Cutting Machines).
't'hose who know the quality and the capacity of the machines built in the German Democratic Republic will
ask themselves hot(- such top-performances were possible.
llany Years of Production-Experience.
The above-mentioned lVMIV enterprise in 1Tagdeburg has begun to build rope spinning machines as far back
as 1892. There is no doubt that this decade-long experience has its beneficial effects on the capacity and reliability
of these aggregates.
Raising a New Generation of Technicians
There are 21 specialized Colleges with 13200 enrolled students alone in the field of machine building in the
German Democratic Republic. In addition, roughly 15000 internal and 3000 external students are trained in the
technical sciences in our Technical Colleges and Universities.
Generous Support of Technical Research
Large sums are put yearly at the disposal of our research workers by the People's Government. In extensive
research program is being carried through in the industrial and scientific research laboratories, among them the
Institutes of the Technical University at Dresden, staffed with a large number of highly qualified experts working in
close connection with the industry; (ice have reported for instance about the tasks and work of the Central Institute
of Welding Technique, Halle (Sanle), in the contribution by Dr.Gilde, Welding in the German Democratic Republic,
Vol. 1, No. 7, pp. 149 - 152).
We should like to remind our readers of the series of reports about the results of the research work carried out
in the Institute for Applied Vitriol Dynamics of the Technical University, Dresden (Director: Prof. Dr.-Ing.
IV. Albring). (Cf. also: Pascher, Experimental Determination of the Lines of Constant Speed in the Field of
ilydrodynrnnicGuide Grids by Means of Soap Skin Models, pp. 235 210, this issue).
Cooperation between Technicians and Scientists
The hammer der Technik, the organization of engineering scientists and technicians, has contributed largely
toward technical advancement during the ten years of its existence. The results of the group Machine Building are
mnong the most important ones.
The key
Thus, the acknowledged quality of the GDIi machine building has many causes. Workers, engineers, and scien-
tists of our people's-owned enterprises will not cease in their efforts to consolidate this fame and to produce still
better and more perfect machines in the future.
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Experimental Determination of the Lines of Constant Speed in the
Field of Hydrodynamic Guide Grids by Means of Soap
Skin Models
Communication from the Institute for Applied Fluid Dynamics of the Technical University Dresden -
Director: Prof. Dr.-Ing. W. Albring
The calculation of potential flora through strongly deflecting guide grids is difficult and time consuming. An op-
tical method based on the soap skin-flora analogy has been developed for rapid determination of lines of constant
speed. It is possible to photograph the soap skin with a comparatively simple camera in such a way that the photo-
graph will shot(- directly the lines of constant speed. These photos will facilitate the selection of advantageous shapes
of profiles.
Contents
1.
Introduction
4.
Test results
2.
The soap skin analogy
5.
Summary
:3.
Evaluation of the skin shape
6.
Literature
1. Introduction
Guide grids for the deflection of flowing liquid or gas play
,lit important part in many technical applications. The capa-
city and efficiency of a machine or installation depends very
often on the quality of its guide grids. To determine the shape
of these grids by theoretical calculation is extremely difficult
and time consuming if a strong deflection of the flow is to be
obtained. It has therefore become the custom to design these
grids accordingto simple empirical rules which very often are
,) Paper read at the 1st Polytechnic Conference held at the T. U. Dresden
on .June 19th, 1956. Translation of the German publication in Maschinenbau-
teehnik Vol. 5 ( 1956) No. 12 pp. 662--667.
out-dated. The experience made with already constructed
grids is not sufficient to find the best profile in every new case.
The usual way of developing stream-line profiles is to in-
vestigate first the velocity distribution or the pressure distri-
bution of the potential flow, and to account for the influence
of viscosity by a subsequent correction based on boundary
layer theory. A rather good judgement about the suitability
of a given profile can however in most cases be given already
on the basis of the theoretical pressure distribution according
to potential theory. Yet for strongly deflecting grids it will be
difficult to calculate the potential flow, i. e., to adapt the
known solutions of the differential equation to the boundary
conditions of the grid.
A possibility to solve such problems in a convenient way
is given by using models. This means that another physical
phenomenon is used which complies with the same differential
The Soap Skin Analogy
Plane field of flow Soap skin
Flow function tlt Vertical coordinate z
I)ifferential equation Differential equation (for 1P --- 0)
(2[j . Ca2T v'Zz CJ~2z
i'r2dy2
axe + 7y2
(u.uttity
of flux
.-) t
Difference of height J z
velocity:
p~
dy
Inclination: az
e __ tauT(?')
do
Rigid wall. stream linei1o=const. Plane edge, line of height z =const.
Level from which the parallel Slanted straight edge piece with
flow with normal component angle of inclination T
It ? u', emerges
G -= 11
d.~
tan = K. tan
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equation. One only has to transpose the original boundary
conditions to the model. Furthermore the function appearing
as the solution should be capable of easy accurate evaluation.
2. The Soap Skin Model
I have used the soap skin model. The vertical coordinate z
of a stretched soap skin satisfies approximately the potential
equation . I z 0 if the skin is only slightly inclined against
the x-v-plane. The vertical coordinate z of a stretched soap
skin can thus be considered as corresponding to the flow func-
tion ?i, which complies with the same differential equation
Icy-0.
The analogy between soap skin and potential flow is ex-
plained in detail in Fig. 1. The differential equations are the
.ante in both cases. The difference of height between two points
on the soap skin corresponds to a certain amount of flow be-
twecu these points. The direction of flow in a given point
corresponds to a line of equal height through the correspond-
ing point of the skin. The inclination of the soap skin
corresponds to the flow velocity.
Each stream-line corresponds thus to a line of equal
height on the skin. Since the profile is also supposed to be a
stream-line, the corresponding line of equal height must be
enforced in the model. This is done by using in the model metal
sheet disks with sharp edges arranged parallel to the x-y-
plane. All other boundary conditions will be realized so far
away from the model proper that the conditions practically
will correspond to parallel flow. Straight frame parts will be
used there, the inclination tan q of which will be proportional
to the normal component of the flow vector.
A clear idea of the soap skin model may be gained by
drawing the field of the stream lines and then considering them
as lines of equal height.
Fig. 1 shows the flow through a grid of guide blades with
the stream lines clearly indicated. In front of and behind the
grid the stream lines are parallel; hence the corresponding soap
skin is plane and inclined correspondingly. Below this drawing
the angles of inclination have been drawn in a perspective
presentation. Tangens q .11 corresponds to the normal compo-
nent of the flow through the grid, which is the same in front
of and behind the grid. Tan q t, represents the velocity com-
ponent parallel to the grid, which will change with the passage
of the fluid through the grid. The difference of height .I z of
two neighbouring profiles fixes the quantity of flux between
them and must conform to the angle y tit.
Fig. 2 shows the apparatus by means of which we have
realized the boundary conditions of the grid. The models are
seen in the middle. From them to the frame the soap skin is
stretched. The sides of the frame are made of rubber and can
be adjusted to the desired angle. Of the skin only reflections
are seen, about which it will be said more further on.
Fig. 3 shows the same apparatus without the soap skin.
The adjusting devices are therefore better visible. The models
are bolted in a perforated ledge and can be turned round. With
this arrangement the grid division constant and the grading
angle of the series of models can easily be changed. Differences
in height are obtained by bolts of different length.
The whole frame is fastened to a basic plate which can be
slanted according to the grading of height of the guide grid.
The upper and the lower half of the frame can be slanted nor-
mally to this by micrometer screws. The inclination tan q 'C
can be read off directly from these screws; it corresponds to the
velocity component parallel to the guide grid. Both halves of
the frame can also be displaced parallel to each other. There
is furthermore a dish for the soap solution, fixed to the lower
side of the frame. The soap skin is produced by immersing, a
flexible strip of plastic material into the solution and drawing
it upwards over the frame. The skin must adhere immediately
to the models and the strip of plastic material must be pressed
well against the wall of the frame, especially when drawing it
off.
In order to represent in the model a certain condition of
flow, the models are first screwed on and adjusted. Now the
frame plate is turned into the direction of the models and is
adjusted to the desired inclination by the micrometer screws.
This inclination is calculated from the given grading of height
and the angle of inflow or outflow. Next the soap skin is drawn
and both parts of the frame are displaced parallel to each other
till the skin shows an equal image on all models and a stagna-
tion point appears at the rear edge, i. c., till the rear edge of
the model is even with the surrounding soap skin. This can
be judged best by sight.
It is impossible to comply with the stagnation point con-
dition so accurately that small differences between fl2 and /iy
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can be recognized and corrected. Yet the distribution of
velocity will be noticeably influenced by this inexactness only
in the immediate proximity of the rear edge. The frame will
therefore be adjusted to I12 on the outflow side and will be left
there.
The soap solution of water, natriumoleate, and glycerine,
prepared according to Boys [1], will produce skins which will
last 3-4 tests of about 2 minutes each.
Something must still be said about the errors of the soap
skin analogy. The soap skin analogy holds only approximately.
The differential equation of the soap skin coincides with the
potential equation only when the inclination y is small com-
dfferenhalequatmn of the flow function
d' V ' d' V
dr: dyt -
differrrlio/ epuo6an of fhe soap sk;
drt[4.(da-jdr dz d=td'Z[4.(dz_)I_ p tJ
dx (( dy J dx dy dxdy dy dx
afar `0 d,1I (ddy~]`dyo
pared to 1. Most, authors refer in this connection to an esti-
mation of error given by Griffith and Taylor, which we could
not obtain. According to this estimation angles of up to 30
degrees are permissible. Yet we have found that the values ca
measured by its are too high by 6-8 percent as compared to
the theoretical values given by the conservation of momentum.
This fault is caused by the approximation character of the
soap skin analogy and is a systematic deviation which how-
ever will limit the usability of the results
only insignificantly because the velocity
distribution will be maintained qualitatively.
In Fig. 4, equ. (2) the exact differential
equation of the soap skin is noted down. If
the system of coordinates is rotated in such
it way, that the x-axis becomes tangential
to a line of equal heights, we receive dz/dx = 0
and hence equ. (3), from which it can be
seen that the 2nd derivative along the line of
descend will always be higher in the x-y-di-
rection than normal to this. Both differential
quotients will be equal for potential surfaces.
The soap skin is therefore too strongly curved
normally to the contour, so that the angles
of inclination, and hence the velocities, will
come out too large on the suction side and
too low on the pressure side, if the boundary
conditions are correctly represented. For
2
(~- - 0,
small values of Iax~ 0 and (ey
3. Evaluation of the Skin Shape
The use of a model is only sensible if the model can he
evaluated comparatively easily. In previous investigations the
procedures used were either mechanical or optical. The optical
method has the advantage that the skin will not be influenced
by it. The stereoscopic evaluation, for example, belongs to
this class, but in this case the skin must first be made visible
\
xa
91-lrorctg 'I- - arctgz
o ]
e~~xeyZ02- ]z
Z, Zo . xaz i Z02 - 0
as otherwise it will not be seen on a photograph. It is better
to take advantage of the skill's capacity for reflection and to
measure its angle of inclination in certain places [7]. One can
dispense with the graphic differentiation of the field of flow
when measuring the angle of inclination because when in-
vestigating a field of flow one will be interested not in the
numerical values of the flow function but practically only in
the velocities, which are proportional to the angle of inclination.
t ig. 6. Test stand diagram
A model - B soap skin - C cmrcaro mirror - D .spherical shell - 11 sourer (!flight. corresponds to
e;'e. -- con.st. (white ring on black background) - F camera - G frame for soap skin - F: inter-
section of the rays falling on the objective of the cmnera - K path of a light rov
equ. (2) will be transformed into equ. (1). For reasons of com-
parison we have drawn in Fig. 4 the axial section of the flow
function and the soap skin function of a potential whirl. By
means of these functions we have also verified the errors
numerically and here found the expected values.
A simple measuring arrangement for measuring the angles
of inclination can be seen in Fig. 5. The skin is observed verti-
cally from above (A), and when the image of a light source can
be seen at zero the angle of inclination of the skin at that point
will just be t1 = t/2 arc tan x0/z0. we have also written down the
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angle of inclination for the case that the point observed does
not lie vertically below the eye [equ. (4)]. The variation of q
at constant source of light is an error of first order. In order to
keep it reduced to acceptable dimensions a distance of 5
meters should be used for an image field of 5 mm, or else the
rays should be made parallel. It is also possible to correct the
error approximately. In order to do so we have calculated the
measured angle in a general way [equ. (4)] and have placed the
derivative d q ; d x = 0 at x = 0. Then the measured angle will
be an extremum in this point and the error will be compen-
sated in the first approximation.
9s can be seen from equ. (5), zl must always be negative.
This can be realized by using a large lens or a concave mirror.
All rays which seem to cone from the same point beyond the
soap skin are collected by these devices and then directed
towards the eye or the photographic objective. The main
advantage of this arrangement is the fact that now all points
on the soap skin can be obtained which are inclined by the
same angle q but are not necessarily located in the same plane.
In this case the source of light should be enlarged to the shape
Fig. 9u and 6. Plrn ore o/ i. uehrs for /loin nro~md a cylinder
uJ 'P-o ret in, l c,, e.. b} s[eu.ureI n1n'C
of a closed luminous ring. Changing the optic adjustment is
not necessary. If the source of light is now reflected by all
points inclined by (f, the image formed by reflection will be an
isocline (line of equal inclination) of the soap akin, or an iso-
tache (line of equal velocity) of the analogue field of flow. In
order to find out the position of other possible sources of light
that would also produce isotaches with the same optic arrange-
ment we put z, - 2 R const and obtain the. vertex cgua-
tion of a circle for the relation between z0 and x? equ. (5). The
ring-shaped sources of light are therefore all located on the
surface of a sphere formed by rotating the first circle about the
z-axis.
Fig. 6 shows the diagram of the. test stand constructed in
this way, with the path of a light ray drawn in. The camera
points through the skin to the concave mirror. In order to
reduce aberrations the angle between camera normal and
mirror normal should be as small as possible. This angle gives
rise to astigmatic errors which will grow with the sgare of the
angle. The test stand was constructed with a spherical mirror
of 300 mm radius and operates with an accuracy of about I
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ZMEMENEW
percent of the quantity to be measured (i. e., tan (/ ) when the
diameter of the image field is 100 mm. Directly at the model
the error is somewhat smaller. As no sources of light can be
located at the place of the mirror the smallest measurable angle
of inclination is 5 degrees. Figs. 7 and 8 show two views of the
ready test stand; the arrangement of the mirror and of the ring-
shaped light sources can be seen clearly in Fig. 7. The sources
of light are white rings on the otherwise black concave side
of spherical shell illuminated by two 200 NX` lamps. The indi-
vidual rings are numbered in mirror writing so that these
numbers are seen correctly in the mirror, thus facilitating the
evaluation. The model as well as the holding and adjusting
devices for the concave mirror can be seen in Fig. 8.
0,5
4. Test Result.
The photograph of the model of a circulation-free flow
around a cylinder is shown in Fig. 9 to the right, while to the
left curves calculated from potential theory are drawn. A
comparison of both pictures will show clearly the applicability
of the model and the method used.
The surroundings of the stagnation points around which
the isotaches close in almost circular curves are typical. Siuti-
lar pictures result also at the nose of single and grid profiles.
A series of grid photographs corresponding to different
angles of influx are shown in Fig. 10. The variation of this
angle has a noticeable effect only at the front part of the pro-
file. The profile was developed by us by superimposing a
drop and a curved skeleton line. The disturbances on the sur-
face of the profile are caused by small faults in the sharpened
edge. The lines become a bit indistinct at the rear edge be-
cause the skin cannot represent the sharp changes of velo-
city immediately at the edge.
The velocity distribution on the pressure side is quite
Fig. 10a-d. Pictures f Lsotaehes of guide grid floe for different angles of injlu e,
i t - 0.53; its 30 degrees
- 155 degrees c ri0 - 115 degrees
b f'0 = 150 degrees d 10 = 110 degree,
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favourable. The flow is accelerated almost along the whole
stretch, so that there is no danger of the boundary layer be-
coming detached. The picture is not so favourable on the back-
side because there the flow is retarded already rather near the
front. The danger of boundary layer detachment would there-
fore exist. The course on either side of the retardation point
(at f(a 150 degrees) is comparatively favourable, the speed
being constant and the pressure increasing further on. This
region of retardation could be avoided by correcting the shape
of the profile.
AP
912 C3
't
profile Pa
Aa=>S5?tt,
f/,1=053 jr=30?
450 ? t`
,t
-
445? ~~
~
Ir~
t,
Fig. 12a (Sf ) arid b (right). Di.siribution if prrssure around a profile, at tuo dif-
trrent angles rf' irrflu.c aad numb- of division, established from pictures
of isotaches
An even distributiom of velocity on the suction side is of
special value for profiles destined for steam or gas turbines
because, the flow velocity will here often reach values com-
parable to the speed of sound. If there are any places with a
high velocity on the suction side, the speed of sound can easily
be surpassed. This would cause additional losses and an in-
creased danger of boundary layer detachment.
The photographs are evaluated on a ruled sheet of paper
as shown in Fig. 11. For each line of the photograph zl p/q was
calculated and the value found was marked on the sheet. The
photograph of isotaches is projected on square paper for pur-
poses of evaluation. The negative of the photograph can be
used for this purpose. Then the distance between the begin-
ning of each line and the front edge is measured and a point is
marked on the sheet at the point xli' on the corresponding
horizontal line. These points are then joined by a curve which
gives the distribution of pressure.
The result of such an evaluation is represented in Fig. 12.
It is the distribution of pressure for two profile grids of diffe-
rent divisions and different influx angles. The variation of the
influx angle makes little difference at these grids with small
divisions, the outflux remaining practically unchanged. We
want to point once more to the corner at On - 150 degrees in
the pressure distribution which indicates a fault of the profile
and which will become an underpressure point at a steeper
influx ([f0 < 150 degrees).
If it should be possible to compensate this corner, the drive-
up value of the grid and with it the number of divisions could
be increased without increasing the maximum speed.
5. Summary
We wish to summarize the main points of guide grid in-
vestigation by means of soap skin models. For the investi-
b)
tPo=15
5?
profile Vu
t/f'- 0
=30?
66 p
,
3
O o
945?
'
t
1
gation of the grid we need a set of very accurate models. Of
special importance are plain surfaces and smooth and sharp
edges. The flow function of the potential flow is represented
by these models in the test stand described above and lines
of equal speed are photographed. It is possible to vary influx
angle, grading angle, and division. The field of isotaches
allows to judge the qualities of the profile and indicates the
points at which the profile may still be improved. This proce-
dure is specially suited in cases where large differences of
velocity will appear, i. e., for large angles of deflection. It will
be the aim of further investigations with this apparatus to
determine the parameters of the most suitable grid shapes in
dependence on the angles of flow. TRA 87
Literature
111 Boys, C. V.: Seifenblasen. Leipzig 1913.
121 Quest, H.: Eine experimentelle Liisung des 'l'ore ionsproblems. Ing.-Archie
Vol. 4 (1933) p. 510.
131 Funke, II'.: Bestimmung des Auftricbes von Tragll iigeln mit Mille des
Prandtlsehen Memhrangleiehnisses. Dissertation Hannover 1938.
[41 Biezeno-Grarnmrl: Teehnische Dynamik. 2nd Edition Berlin 1955.
15, Bauerrfeld: Ubrr eine Erweiterung des Prandtlsehen Mein brangleichnisscs.
Ing.-Archiv Vol. 5 (1931) p. 69.
161 Thiel Photogrammetrisches Verfahren our Lbsung von Torsi onsaa Iga ben.
Ing.-Archiv Vol. 5( 1934) p. 417.
171 ReiehenWelter: Selbsttatige Ausmcssung on Seifenhautmodellen. Inge-Archiv
V.I. 7 (1936) p. 257.
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A Simple Geometric
Construction to Replace the Adiabatic Ellipse
in the Construction of Mach Lines
The behaviour of laminar plane supersonic flows can be
theoretically comprehended by the method of characteristics
due to Prandtl and Busemann [1].
For an ideal gas the characteristics in a polar diagram
M' (6) follow as congruent and reflected epicycloidal arcs
which result one from another by rotating' through the mul-
tiple of a fixed angle.
Here,
Me = c, a*, the critical velocity ratio (Mach number) at the
point observed, and
6 = the angle between the flow directions in two
successive points of the field of flow.
construction of the epicycloids can be applied with advantage.
Let us construct the Mach line through the point A,
(Fig. 1), of the solution characteristic. The circular are about
A with radius r (radius of the rolling circle k) intersects the
circle k1, on which the center of the rolling circle is moving, in
point B. KO intersects the base circle K in point P, the in-
stantaneous center of rotation of the two generating circles
(planes).
PA is perpendicular to the trajectory and in the direction
of the Mach line. Since the circle kl is supposed to be given
the construction merely consists in describing a circular are
and in drawing two straight lines.
Fig. 1. Construction of the Mach line as
normal to the solution epicycloid
M' (h) in the diagram of cha-
racteristics
Fig. 2. (ri hi) Instrument for drawing
normals in the diagram of eha_
racteristics
Particular importance attaches to the normal to the
characteristic in the point of solution. As Mach line, it connects
points of constant flow condition (constant velocity, pressure,
density, and temperature). The well-known text books of
fluid dynamics describe the determination of the Mach line
from the diagram of the characteristics by means of the adia-
batic ellipse. This determination, though theoretically correct,
is unpractical. The working with a template (adiabatic ellipse)
is not an exact construction in sense of classical geometry.
As the characteristics are epicycloidal arcs, the known normal
1) Communication from the Institute f,r Applied Fluid Dynamics of the
Technische Hochschule (Technical University), Dresden. Director: Prof. Dr.-Ing.
W. Albring. Translation of the German Publication in Maschinenbautechnik
Vol. 6 (1957) No. 3 p. 171.
For frequent application the construction illustrated in
Fig. 2 is recommended.
1
Let R=M*=1,r/R=- +1 i,
2 0X - 1 /I
and 0 being the origin of the diagram; then A P is the normal
to the solution curve and in the direction of the Mach line.
For x = 1.30 1.405 2
we have r/R = 0.8844 0.71814 0.3660.
Literature
[1] Sauer, R.: Einfuheung in die theoretische Gasdynamik. Springer-Verlag
1951, p. 40, pp. 64-66, pp. 119 etc.
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Thickness Measurements of Oil Films
Communication from the
Institute for Organic
Chemistry and the
Chemistry of Coal and Oil,
Bergakademie Freiberg
Director:
Prof. Dr. A. Dierichs
By Prof. Dr. A. DIERIcHs and H. GABBERT, Freiberg/Saxony 1)
It is possible to-day to determine the general structural characteristics of lubricants, by
chemical, physical, and electrophysical analyses, but it is still impossible to predict with cer-
tainty the lubricating properties by such analyses. In general, predictions of this type can be
made only on the basis of actual tests with the machines to be lubricated, particularly where
the lubricants are subjected to very high operating pressures.
After, in 1952, Ubbelohde [1] had introduced a new characteristic property called by him
"statische Tragfahigkeit" ("static bearing strength"), the Institute for Organic Chemistry and
the Chemistry of Coal and Oil at the Bergakademie Freiberg begun a series of investigations on
this subject.
Starting from the observation that mercury placed be-
tween two differently curved watch glasses can be expelled
from the zone of contact by sufficiently high static pressure
while this is impossible in the case of lubricating oils, Ubbe-
lohde was led to the conclusion that the molecular layers of an
oil film adhering to a surface within the range of the adsorptive
forces of such solid surfaces are able under pressure to adopt
the character of a solid substance and, accordingly, a definite,
measurable thickness. In contrast to all known mechanical
oil-testing methods, this definite thickness is measurable in
absolute units.
The measurement of the "static bearing strength", i. e.,
the determination of the thickness-pressure function, of an oil
film leads to index numbers of great practical importance
since it deals only with the layer of the lubricating agent re-
maining between the solid surfaces under pressure and thus
excludes the influence of hydrodynamical processes that com-
plicate the evaluation of other tests and measurements. The
ideal condition is approached in sleeve bearings rotating at
low speed within the range of limiting friction. The adhering
oil film between the two surfaces may then be considered a
protective layer preventing the creation of dry friction be-
tween the two metallic surfaces. From this it might be expected
that the lubricating capacity of an oil increases with the thick-
ness of this protective layer.
1. Determination of Thickness-Pressure Functions
The experimental determination of thickness-pressure
functions requires the following apparatuses:
1.1 Interference comparator
1.2 Pressure apparatus
1.3 Measuring plates.
1.1 The Interference Comparator
The interference comparator (Inko) designed and con-
structed by VEB Carl Zeiss Jena permits measurements to be
carried out with the monochromatic light of helium and kryp-
ton lines.
The Inko-apparatus consists of three main sections: the
monochromator, the interferometer, and the telescope. All
parts are rigidly connected with each other and are located
in a casing provided with suitable heat insulation.
') Translation of the German Publication in Kraftfahrzeugtechnik Vol. 7
(1957) No. 6 pp. 210-212 and No. 7 pp. 251-253.
The monochromator is composed of the helium or kryp-
ton tube, the condenser, the collimator with entry slit and
objective, and the dispersing prism. The interferometer con-
sists of two glass wedges, the reference mirror, and the object
plate, while the main parts of the telescope are the telescope
objective, the exit slit, and the eye-piece. The interference
pattern is made up of light and dark interference bands ob-
served through the telescope. Well-measurable interference
bands are produced only when all optical surfaces are highly
polished so that the surface roughness falls below 0.1,u.
1.11 Measuring Procedure
Using monochromatic light interference bands are pro-
duced on the surface of the object to be measured as well as
Fig. 1. Interference bands
on object and pres-
sure plate
on the object plate supporting the body. The telescope shows
two band systems side by side (Fig. 1), the distance between
two consecutive dark bands corresponding to half a wave
length A/2. The band displacement towards the left is now
estimated in units of 0. (According to Fig. 1, this value
amounts to 0.3). Since a single measurement would lead to
inaccurate results, the estimated values were determined
twice for all spectral lines used, i. e., for red, yellow, green,
blue-green, blue, and violet. Since measurements were only
carried out to heights of up to 25 mm, only spectral lines of
helium were used in these tests, i. e.,
Red
Yellow
Green
Blue-green
Blue
Violet
0.6678184 It
with I 0.5875649 y
wave lengths 0.5015702 p
0.4921955 It
0.4713168 p
0.4471501 p
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Evaluation was effected in accordance with the following
equation: -
X a.
L +n
2 2
1, the height of the object investigated,
x = the still unknown full number of wave lengths,
a./2 = the distance between the bands, and
it = the fraction of the band distance.
The calculations were carried out with the aid of tables and
light wave slide rules supplied by VEB Carl Zeiss Jena. The
results obtained were corrected so as to refer to the meteoro-
logical standard conditions - 760 mm Hg atmospheric pres-
sure - 10 mm Hg-vapour pressure at 20? C and NN. The
corrections for the changes of wave length induced by the in-
fluence of air pressure, temperature, and atmospheric humidity
were made according to the following formula:
c2 = - 0.36 (b - 760) + 0.93 (t - 20) + 0.05 (e - 10).
These corrections may become quite large. It is therefore
necessary to provide for thermostatic arrangements designed
to restrict temperature variations to within ? 1 ? C, at a room
temperature of + 20 ? C. This important provision was not
fulfilled in the work described in the publication cited above.
1.2 The Pressure Apparatus
The pressure apparatus employed by Ubbelohde is un-
known. The publication merely indicates that this apparatus
remained outside the testing apparatus proper. The pressure
apparatus developed for our investigations (Fig. 2) is a hy-
draulic pressure system in which the measuring plates sub-
jected to pressure are not removed from the apparatus but
remain in the Inko for measuring purposes. The apparatus
consists of the pressure cylinder equipped with two pressure
gauges for the measurement of pressures up to 4 kg/cm2 and
up to 15 kg/cm2, respectively. Within the cylinder, the pres-
sure piston 1 together with the damping piston 2 moves against
a glycerine filling. Rod 3, fastened in the damping piston,
connects the pistons with the pressure nut 4 which acts through
the pressure cone 5 on the pair of measuring plates 6. The
pressure is created from outside by tightening the knurled
pressure nut. The forces transmitted by the pressure cone act
exactly normal to the contact surface of the pressure plate in
order to avoid distortions of the measuring plates. The pres-
sure piston has an effective area of 12 sq. cm., while the con-
tact area of the measuring plates amounts to 6 sq. cm., re-
sulting in a transmission ratio for the contact areas of 1 : 2.
It is thus possible by manual actuation of the knurled pressure
nut to obtain effective pressures of up to 30 kp/sq. cm.
1.:3 Measuring Plates
The experiments without pressure were carried out with
glass measuring plates supplied by VEB Carl Zeiss Jena and
dimensioned similar to those used by Ubbelohde. Their contact
areas measured 7.61 sq. cm. The steel plates were produced
in our own workshops, with a contact area of 6.00 sq. cm. All
measuring plates were brightly polished by VEB Carl Zeiss.
The degree of surface roughness of the measuring and contact
surfaces remained below 0.1 h. The pressure plates were
finished plane-parallel to 0.2 ,ii, at a diameter of 55 mm, while
the plane-parallelity of the object plate need not be considered
since only one of its surfaces is required for the measurement.
The values stated have to be considered minimum values
for the degree of plane-parallelity and for the surface quality
of the plates. The glass plates have been made of Jena-glass,
Type FK 1, having a coefficient of linear expansion of 8.68 X
10-e. The steel plates consist of hardened tool steel with a
coefficient of linear expansion of 11.55 X 10--8. The press ur
plates are fitted with calottes (spherical indentations) for the
oil.
2. Experimental Investigations
2.1 Preparation of the Measuring Plates
The most important prerequisite for accurate determina-
tions is the exact measurement of the height of the pressure
plate. This height, He, represents a constant for each indi-
vidual pressure plate. Accurate measurements of He-values
require perfect cleaning of the measuring plates. If these plates
are not absolutely clean, it is impossible to effect perfect con-
tact between pressure and object plate, while if the state of
perfect cleanliness is attained the adherence of the plates to
each other is so strong that they cannot be separated mechani-
cally without damage. Cleaning of the measuring plates is
effected with pure carbon tetrachloride and trichlorethylene.
Other solvents have also been tried, of course, but had to be
rejected after lengthy tests.
Fig. 2
Pressure apparatus
After preliminary cleaning the measuring plates were
flushed with carbon tetrachloride and polished with a degreased
piece of leather, followed by a second flushing with trichlor-
ethylene. After complete evaporation of the solvent, the plates
are rubbed down with clean linen or nettle cloth. Fibre rem-
nants are brushed or picked off with a soft clean brush. The
degree of purity of the plates can be tested by breathing on
the surfaces before the second flushing treatment. If the uni-
form cloudiness induced by the condensing moisture of the
breath is interrupted by darker spots, this indicates surface
impurities which occur especially after previous measurements
of oil films. Cleaning of the plates must therefore be repeated
until the breathing film remains uniform over the whole sur-
face. Trichlorethylene proved most satisfactory in this respect.
The cleaning process described above was applied in the
same manner for glass and steel measuring plates, although
the last and final proof of perfect preparation of the plates
remains the attainment of perfect contact between the plates.
This contact must apply to the entire contact area of the
plates. The glass plates always exhibited isolated small cloudy
areas indicating spots of unevenness on the contact surface.
The control of the glass plates proved to be comparatively
easy on occount of the possibility of optical observation which
is impossible in the case of metal plates.
2.2 Contacting and Separation of Measuring Plates
Contacting of the measuring plates was carried out only
in the case of glass plates where the measurements of the oil
films were performed without pressure, while contact treat-
ment of steel plates was unnecessary on account of the forced
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contact of the measuring plates under the load of the pressure
apparatus. The reason for this difference in treatment is due
to the different properties of the materials, especially to the
strong tendency of steel to cold-welding. As pointed out by
Ubbelohde, contacting of glass plates requires considerable
experience in order to avoid erroneous measurements.
Glass plates are contacted by sliding the pressure plate on
to the object plate from the side and turning it around (on the
object plate) by slight pressure of the fingers. The circular
interference bands produced by this motion have to be uni-
form in colour and width about the central point of the pres-
sure plate. Very small pressure differences change the colour
and width of the interference bands. When a uniform distri-
bution of the bands has been obtained, the pressure on the
rotating top plate is increased. Every change in pressure in-
duces a corresponding change in the interference band system,
Fig. 3
Light-metal stomp
for the separation
of glass plates
i. e., the closer the plates approach each
other, the wider are the bands produced.
Shortly before attaining perfect con-
tact only the yellow bands remain vi-
sible, while complete disappearance of
the interference bands indicates uniform
contact of the plates over their entire
contact surface. The last visible air film
between the plates escapes rapidly at the
moment of complete contact, the con-
tacting plates remaining unclouded and
clearly transparent.
In this condition, the Ho-value of
the pressure plate is measured. If the
appearance of the interference bands
indicates one-sided contact of the plates,
the contacting process has to be repeated.
For this purpose it is necessary to separate
the adhering part of the pressure plate,
which requires considerable care and
attention in order to protect the glass
plates as they are easily damaged in the
dry condition.
Separation of tightly adhering plates
was effected by means of the light-metal
stamp shown in Fig. 3. This stamp was
heated to 80 ? C and placed on the pressure
plate, heating the latter and inducing a
small but sufficient thermic expansion
of the plate material to effect automatic separation of the
pressure plate from the object plate. This process is accom-
panied by the appearance of interference bands. As soon as
these bands have reached the outer edge of the pressure plate,
it can be lifted up without difficulty. The pressure plate must
never be lifted off by lateral displacement or rotation, since
this will usually lead to scratches in the contact areas.
2.3 Measuring of Thickness of Oil Films between Glass Plates
Measurements of the thickness of oil films were carried
out without additional measuring plate loads, the only pres-
sure exerted being the dead weight of the pressure plate itself.
The specific load on the contact surfaces then amounts to
2.6 g/sq. cm.
The Ho-value of the pressure plate was determined as
follows: - The primary measurement of the Ho-value (cha-
racteristic length) was carried out with an optimeter, against
a dimensionally similar slip gauge, to a degree of accuracy
of + 1.0 u. The pressure plate was then contacted with the
object plate and the pair of plates placed into the Inko. The
height of the pressure plate was measured after the tempera-
ture of the pair of plates had adapted itself to the room tem-
perature of the Inko.
We then estimated the displacement of the bands pro-
duced by the pressure plate in fractions of the band distance
for the six spectral colours of helium light (red, yellow, green,
blue-green, blue and violet), first in the order from red to violet
and then in the reverse order. Each of these colours possesses
its own wave length, which also introduced a change of the
band displacement in the two band systems. The fractions of
the band displacement of each colour read off by us were
averaged and translated into dimensions of length, the results
thus obtained then being subjected to the necessary correc-
tions.
According to the instructions for Inko-measurements,
the individual ,u-values should not deviate from their mean
value by more than ? 0.0251u. For an end measure gauge of
1Q00 mm, this gives a permissible error of ? 0.0025% of the
end measure length. If the same tolerances were permitted
in the case of thickness measurements of oil films, the per-
centage error would amount to ? 12.5% for an actual film
thickness of 0.2y. Deviations of this magnitude would make
any accurate classification of oils by thickness measurements
of oil films practically impossible. In the work here described
it was possible by very accurate measurements to keep the
error down to ? 2.5%.
When the measured Ho-value of a pressure plate has been
confirmed by control measurements, this value can be used
for all thickness measurements of oil films. It was found that
in spite of most careful finishing of the measuring plates differ-
ences in height along the periphery of the pressure plates
amounted up to 0.1 u, but these differences were eliminated
by keeping the position of the measuring plates towards each
other and in the Inko-apparatus accurately the same.
After attaining perfect contact between the glass plates,
the calotte was filled from the outside with the oil to be meas-
ured. The oil could be introduced between the two plates only
by lifting the pressure plate by means of the light-metal stamp
shown in Fig. 3. This stamp is fitted with a control thermo-
meter. It is initially heated to 110 ? C; after cooling down to
105 ? C it is quickly placed on the centre of the pressure plate
and left there until its temperature has dropped to 90 ? C. The
heating effect of the stamp induces a corresponding expansion
to the pressure plate, lifting it off the object plate. The inter-
ference rings again observed indicated that the contact be-
tween the plates was not entirely broken at all points. The
open spaces between the pressure and the object plate filled
up with oil at a decreasing speed. The decrease in speed is due
to the cooling of the pressure plate and to the corresponding
tendency of the plate to return into its original position. This
tendency is much enhanced by the fact mentioned above that
the pressure plate had not been completely separated from
the object plate in the first place, a ring of about 2 mm width
along the periphery of the pressure plate remaining in contact
with the object plate until they are finally separated by the
action of the oil introduced between the two plates. The entire
process was carried out in an exsiccator and lasted about three
hours, terminating with the wetting of the entire contact area
with oil. The appearance of the interference bands in the space
between the plates permits a clear observation of the filling
process. (In the case of unobstructed migration the oil pene-
trating into the opening between the plates spreads almost
circularly. If the spreading proceeds in a strongly oval manner,
it is advisable to repeat the cleaning of the plates in order to
avoid erroneous measurements.)
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We did not observe any emergence of oil from the con-
tact area to the outside, in contrast to Ubbelohde.
The thickness measurement of the oil film took place
20 hours later. This period has also been determined by ex-
periment: practical constancy of the conditions between the
plates was reached only after this period of time, the growth
of the thickness of the film then proceeding only at an ex-
tremely slow rate. Transport of the plates into the Inko was
carried out with all possible care in order to prevent any re-
lative movements tending to influence the oil between the
plates. After a waiting period of one hour the film thickness
was measured in the same manner as used for the determina-
tion of the HD-value, the latter being deducted from the value
determined, the difference representing the thickness of the
oil film.
It is possible, of course, that errors of measurement may
occur even if all the measuring instructions have been duly
observed. Such errors may be due to a difference in weight of
the pressure plates and a corresponding difference in the thick-
ness of the oil film over the entire contact area. The following
section of this publication will therefore contain only the re-
sults obtained with one and the same set of plates.
2.1 Results of the Pressure-less Measurement of Film Thick-
nesses on Glass Surfaces
The experiments described above were conducted with the
following lubricating oils: -
1. Mineral oil 1 (mixed-basic)
2. Mineral oil 2 (mixed-basic)
3. Synthetic oil 1
4. Synthetic oil 2
Mineral oil Synthetic oil
1 1 2 1 2
&o
0.910 0.925
0.872
0.893
Flp. o. T. (?C)
243 222
220
212
CT )q?
0.55 2.22
0.18
0.17
NZ
0.12 i 0.33
0.09
0.05
VZ
0.25 0.48 0.18
0.33
20
1.5040 1.5140 1.4815
not measured
co I, F1
12.51 13.61 12.31
11.64
V11
2.45 2.87 1.72
1.86
Table 1 gives the results of the analyses of the oils tested.
The film thicknesses of the oils mentioned were measured after
a waiting period of 20 hours at room temperatures of 20? C
1 ? C yielding the following results:
1.
Mineral oil 1
Film thickness = 0.153,u
2.
Mineral oil 2
Film thickness = 0.123 0
3.
Synthetic oil 1
Film thickness = 0.094y
4.
Synthetic oil 2
Film thickness = 0.048 ,u
A comparison of the results obtained indicates that the films of
the mineral oils tested are thicker than the synthetic oil films. A
comparison of the viscosities of the oils tested, on the other
hand, does not offer any conclusions regarding possible con-
nections between viscosity and film thickness. The same
applies to possible connections between film thickness and
Conradson-test.
In order to determinate the influence of pressure on the
results of these measurements, tests were carried out with
steel plates.
2.5 Measurements with Steel Plates
The measuring plates were prepared by treatment with
solvents in the same manner as the glass measuring plates.
2.6 Determination of Pressure-Thickness Curves
Unlike glass plates, steel plates are not brought into close
contact by hand. In order to attain the condition of perfect
contact between the plates, required also for the determination
of the Ho value of the steel plates, these are mounted in the
pressure apparatus where they are subjected to a pressure of
about 16 kp/sq. cm. for one hour. When after this period of
compression the plates are removed from the pressure appa-
ratus, the plates are in complete contact with one another.
It was first attempted to carry out the Ho measurements
for steel plates in accordance with the directions issued by
VEB Carl Zeiss Jena, for the measurements of parallel end
gauges. According to these instructions, the steel pressure
plate has to be contacted with a glass object plate. These
attempts indicated, however, that in comparison with gauge
blocks the relatively large contact areas of the pressure plates
do not so easily make contact. After numerous vain attempts
to develop a satisfactory method for this purpose the only ob-
vious method to attain reproducible HD-values was to carry
out the measurements under increased pressure in the pressure
apparatus. In order to avoid destruction on the perfect con-
tact surfaces by cold-welding, the contacted plates were se-
parated thermically in accordance with the method employed
for glass plates, which proved to be absolutely free of cold-
welds.
The process was carried out as follows:
The cleaned steel plates were mounted on the pressure
apparatus, subjected to a pressure of 16 kp/sq. cm. and in-
stalled in the Inko. The measurement of the Ho-value took
place after a waiting period of one hour. After measuring the
H0-value, the plates were separated.
In most instances this work cannot be carried out with-
out soiling the measuring plates by finger impressions, re-
quiring a subsequent cleaning treatment. The contact sur-
faces of both plates are then wetted with the oil, leaving a
large excess of oil on the contact faces. In this condition the
measuring plates are placed into the desiccator. After 20 hours
of conditioning in the desiccator the plates are placed together
without removing the oil and fastened in the pressure appa-
ratus. The measuring plates are now subjected to the pressure
exerted by the pressure apparatus, usually to a pressure of
2 kp/sq. cm. The aggregate is finally placed into the Inko
under this pressure.
Measurements are commenced after one hour of condi-
tioning, the temperature adjustment being controlled by a
special thermometer fitted at the Inko. After readings of the
band systems have been taken a preliminary evaluation of the
values obtained is made so as to determine whether, and to
what a degree, the u-values determined remain within the
permissible range of errors. If this is not the case, the readings
have to be repeated. If the permissible range of errors has not
been exceeded, the pressure apparatus is removed from the
Inko only for the adjustment of the next higher pressure stage
and for immediate replacement. This process is repeated until
the maximum testing pressure has been attained.
In the experiments under discussion the pressures were
always increased by steps of 1.0 kp/sq. cm. After reaching
a certain pressure value characteristic for the particular type
of oil, the thickness of the oil film did not decrease by any
measureable amount. Measurements of film thicknesses at
decreasing loads could not be carried out on account for the
fact that it proved impossible to adjust the pressure stages so
as to correspond to the increasing pressure stages.
If the values determined by the measurements at the
various pressure stages are plotted the graph shows a charac-
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Q3
31
0.4
Oiese/oil
Fig. 4.
Measurement of film thickness of a
Diesel oil and a white oil
Characteristic data
white oil
d,o 0.879
Fip. o. T. ?C 208
CC % 0.013
NZ 0
VZ 0
V,oE 16.52
V6,'E 3.65
VP 2.18
Diesel oil
d.o 0.852
whi/heoil Fop. P. M. 65?C/728 mm Hg
Y
V._,o E 1.53
Vo'E 1.13
I i Elementary analysis: C = 86.60%
4 8 12 hg/cmt15 W = 13.04%
pressure on/he con/ce/faces S = 0.10%
teristic picture of the decrease of film thickness with increas-
ing pressure. The results of the experiments have been ar-
ranged according to the degree of viscosity as follows:
Fig. 4 shows the pressure thickness graph for a Diesel oil
and a white oil. Both oils yield definite minimum values and
give curves of rather different shape, the Diesel oil showing
a final film thickness almost twice as large as that of the white
oil in spite of its much lower viscosity.
SAE29
Boiling characteristics
acc. to ASTM ?C 189-321
Fig. 5.
Measurement of film thickness of an en-
gine lubricating oil SAE 20 and a steam
turbine oil
4 8 11 kurant 15
pressure on the con/act faces
Characteristic data
SAE 20
Turbine oil
d..o
0.893
0.900
Flp.o.T.?C
181
200
CT
0.33
0.56
NZ
0.12
0.01
VZ
0.34
0.04
V OE
19.87
20.00
Vsa E
4.19
4.17
VP
2.19
2.19
Fig. 5 shows the curves for two oils of low viscosity, a
straight engine lubricating oil of the SAE 20-group and a
steam turbine oil, the first one showing a considerably larger
film thickness. The results obtained with the four engine
lubricating oils are shown in Fig. 6.
r
synthetic 0Nr2
0 4 8 11 kp/mp 19
pressure on/he conlact faces
0 4 8 12 kp/rm? 16
pressure on the contact faces
Fig. 6. (on the 1sf) Measurement of film thickness of engine lubricating oils
Fig. 7. (on the rig if) Change of film thickness of the engine lubricating oil No. I
4 8 11 k9mt 16 0 4 8 12 kp/rm2 ffi
pressureen/hecon/ocl hcces pressure on/ho con/ocl faces
Fig. 8. (on the left) Measurement of film thickness of various phosphoric acid esters
Fig. 9. (on the right) Measurement of film thickness of the mineral oil No. I with
phosphoric acid esters
Fig. 6 also indicates the high degree of sensitivity of the
thickness measurements of films with regard to differences in
the oil proper, even if the differences are so small that they
cannot be detected by chemical analysis.
Fig. 7 shows the changes in the results of thickness meas-
urements of oil films due to traces of water.
Judging by the results obtained there can be no doubt
that the thickness of each of the oil films tends towards a
definite characteristic value with increasing pressure, although
the structures of the oils vary considerably as is indicated by
the Conradson-test which yielded very different values for the
various oils submitted to the tests.
However, the differences between the final values are so
small that no definite relation between these values and the
constitution of the oils could be discerned. We had expected
that the mineral oil No. 2 would give the thickest oil film. In
the case of the synthetic oils, exhibiting the same Conradson-
test results, the final film thicknesses are not nearly alike. The
fact that the final film thicknesses can be strongly influenced
by other factors is shown in Fig. 7, where small traces of
water in the oil induced a thickness difference of 0.052y.
Further measurements of film thicknesses were carried
out with oils containing certain chemical compounds added
for the purpose of increasing the pressure resistance of the
lubricating oils. The following three chemical compounds were
used: -
A. Thio-phosphoric acid ester of the normal fatty alcohols
C7-s,
B. Tricresyl phosphate,
C. Phosphoric acid ester of the normal fatty alcohols C7. 9.
Fig. 8 shows the results obtained. The curves do not tend
towards a definite value, as expected, but approach the H6-
value of the pressure plate. In spite of the fact that the chemi-
cal compounds selected for these tests were characterized by
strong dipole-moments, strongly adhering layers could not be
detected.
The addition A, which still permitted the formation of a
definite film thickness at a pressure of 16.4 kp/sq. cm., was
present in an amount of 1% by volume. This mixture was
used in order to determine the direction in which the film
thickness of the basic oil would change (Fig. 8, curve A).
The same basic oil was mixed with 3% by volume of the
compound C. The final film thickness determined is shown in
Fig. 8, curve C, while the measuring results for the two oil
mixtures are shown in Fig. 9. The measured values of the film
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a2
0 i 4 6 17 kg/ce 16
pressure on/he con/cc/faces
Fig. 10.
Measurement of film thickness of the
mineral oil No. I (curve D) after
measurement of the mixed oil C with
the some set of plates
They were therefore cleaned in accordance with the speci-
fications stated above, but the oils subsequently tested in
these plates yielded results entirely different from those ex-
pected.
Fig. 10 indicates this phenomenon. The set of plates used
only for the measuring of straight oils showed for mineral oil
No. 1 the characteristic curve with a final film thickness of
0.252,u. After the addition of chemical compounds according
to Fig. 9 we obtained the curve C. After cleaning the plates
they were again used for the measurement of basic oils with-
out additions, yielding the curve D. These peculiar phenomena
were noticed at all measurements of mixed oils, and the plates
could then be used for the testing of straight oils only after
regrinding and polishing them.
3. Conclusions
Our measurements were carried out with plates of very
little surface roughness, such as cannot be attained under
practical operating conditions. The final film thicknesses of
the liquids and oils between two even surfaces measured by
us did not exceed the value of 0.3 p. The remaining film will
therefore be unable to cover all the unevennesses encountered
under normal bearing conditions.
The present opinion that during initial movements of
sliding surfaces only the highest points of the uneven surfaces
remain in actual contact and that the pressures involved
therefore act only on a small part of the entire bearing sur-
face has not been disproved by the results of our experiments.
For this reason erosive corrosion must still be considered part
of boundary friction; chemical compounds with active con-
stituents (phosphoric acid-thiophosphoric acid), such as the
additions selected by us for our measurements, will accelerate
this process and thus help to form a more advantageous slid-
ing surface.
In view of the results of our measurements we therefore
believe that the final film thickness cannot be employed as a
characteristic parameter for the practical valuation of an oil.
TRA 93
thicknesses of the two oil mixtures lie so closely together that
they cannot be used for classification.
On the basis of previous measurements carried out se-
parately for the basic oils and the compounds mentioned, it
was to be expected that the final film thickness of the mix-
tures would become smaller. It was however a surprise to
find that these additions exerted such a strong effect. Accord-
ing to the theory that the lubricating properties of oils im-
prove with growing thickness of the film, these high-pressure
additions should have induced considerable deteriorations in
the lubricating properties of the basic oils, while practical
experience has shown that high-pressure additions actually
exert a protecting effect on the gliding surfaces of high-duty
lubricated bearings.
The results of the thickness measurements of the films
thus do not bear any relation to the behaviour of the oils under
practical operating conditions. As to our measurements with
mixtures, it was found that the surfaces of the measuring
plates had changed to such an extent that they had become
useless for further measurements, although there changes
could not be detected by the usual optical methods.
After measuring the alloyed oils it had been intended to
re-use the plates again for the measurement of straight oils.
By Dr.-Ing. O. HENKLER,
Institut fur Post- and Fern-
meldewesen, Berlin 1)
Literature
[1] Ubbelohde: Die ,statische Tragfahigkeit" der Schmierole and tine ,neue bl-
Kennzahl". Kolloidzeitschrift (1952) No. 2/3 pp. 120-140.
A New Method
to Measure Non-linear Distortions
The well-known harmonic-distortion method is not suited for the measurement of non-
linearity in high-grade low frequency or carrier frequency transmission. The frequently applied
differential tone method has the disadvantage of possessing only a limited selectivity and of
giving erroneous results due to the occurrence of modulation products with the same frequency,
and this becomes particularly significant in carrier frequency transmission. The present
paper suggests a new combination factor method to measure non-linear distortions in which
the above disadvantages are eliminated.
In communication by low-frequency and carrier trans-
mission, the non-linear distortions impair intelligibility and,
in addition, reduce the operating range. Therefore, in tele-
phony the spacing between the signal oscillation frequencies
and the noise voltages caused by non-linearities is required to
') From a paper read on October 2nd, 1956, at the Conference of Measu-
ring Technique and Automatization in Budapest. Translation of the German
Publication in Nachrichtentechnik Vol. 7 (1957) No. 4 pp. 145-147.
be above 6 Np at the ends of the transmission lines, and even
above 10 or 13 Np in case of some long-distance communi-
cation equipment. According to the present recommendations
of the CCI, the amplitudes of the harmonics appearing at the
output of communication equipment are used to characterize
and to measure non-linearity. This harmonic-distortion me-
thod, however, possesses the disadvantage that the harmonics
to be measured are often outside the transmission range
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(Fig. 1), and that the amplitudes of modulation products
within the transmission range, which may produce consider-
able distortions, escape measurement.
For instance, in a carrier-frequency amplifier for simul-
taneous amplification of the signal oscillations of 12 telephone
subscribers in the frequency range between 12 and 60 kc/s, the
square and cubic modulation products from several oscilla-
ki _ Aza
Aa
kJ A,..
Aa
Fig. I
Modulation products
at the output of the
object under test when
measuring by the
harmonic-distortion
method
tions of equal amplitude, such as appear at the amplifier out-
put, with the combination frequencies
wl - w2 = 45 - 14 = 31 kc/s and
wl - w2 + w3 = 45 - 25 + 17 = 37 kc/s
give distortions which are
larger in frequency as well
as amplitude than can be
determined by measuring
the harmonics with the fre-
quencies 2 wt = 90 kc/s and
3 wl = 135 kc/s at the out-
put of an amplifier with a
limited frequency band. The
two modulation products
mentioned, which lie with-
in the transmission range
and thus actually distort
the signal, have amplitudes
that are by 0.7 Np and 1.8
Np, respectively, greater
t ha n those of the harmonics
as may be seen from the
power series expansion of
the non-linear relation be-
tween amplifier output cur-
test
ogject
For this reason the differential tone method is often made
use of to measure non-linear distortion in carrier-frequency
equipment, i. e., the object to be tested is modulated with two
oscillations of equal amplitude and constant frequency band
d f (Fig. 2). Here, in order to characterize the non-linearity of
the object under test, the modulation products appearing at
the output with the frequency 0 - to, or 2 92 - co and S2 - 2 co,
are chosen and their amplitudes are compared with those
of the two test oscillations. In this method of measuring the
differential tone factor, the cubic distortion is not determined
directly, but only after an additional transposition into the
frequency range S2 - w of the test filter.
In this method, too, the modulation products characteri-
zing the non-linearity do not always lie within the transmission
range of the object under test. Furthermore, the differential
tone method has the disadvantage that the results may be
inaccurate or misleading including modulation products that
should not be used for the experimental determination of non-
linear distortion, but cannot be excluded if they lie near to the
oscillations to be measured and have a larger amplitude (e. g.
A,z_w > AQ_ 2 w), or even the same frequency.
Similar disadvantages may be found in another double-
tone method for measuring non-linearities, namely the modu-
lation factor method where the object under test is modulated
with two oscillations of different amplitudes.
In order to avoid these difficulties a new method to meas-
ure non-linear distortions is suggested in the following.
It is a modified difference tone method where the object
to be tested is likewise modulated with two measuring oscil-
lations of equal amplitude, though not with a constant fre-
quency separation but with an optimum separation to be
selected for each particular case. The properties of the non-
linear system are then characterized by a combination factor,
viz., the ratio between the amplitude of a certain modulation
product with a selected combination frequency that is present
at the output due to non-linearity on one hand and the am-
plitude of one of the two test oscillations on the other.
doable /ox wi/h sariable
frequencres and coarlont
i frequency separationdf
act 0]
a N 3 ~ryd
/a+(~ 2w),(2.Q w, 2(R-2w)-2w,2(2R-w)-2a,2a-2w
tuL ~u t~~ w (s2-2w)+R
2(J2 2w) 2Q,2w 2(22 w) (~_2w)+w
Fig. 2
Measurement of cubic distortion by
the differential tone m^thod
d -A2a--+Aa-2.
as +A~
A.?-A.
_AZ.,p-w A2 df
A.o+A~ Aa+Aw
(sa-2w)+s2-2(s2-w)
24f
lest Lille,-
ii
r-,Q, w, (s1-Zw)#(2.2-0
w#(2.2-w)
I-s2+(ZJZ-w)
III
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This combination factor method
is based upon an appropriate choice
of the frequencis for the two test os-
cillations (frequencies Q and w) and,
in addition, upon an appropriate
selection of square and cubic modu-
lation products within the transmission
range of the four-pole under test.
Since the expression for the com-
bination frequencies, when referred to
the frequency 0 of one of the test os-
cillations, i. e.,
~4Q+Pw
.- -/4,P=-oc...+00
depends only on the frequency ratio
CJ
Q of the test oscillations, it is possible
to select for the measurement of non-
II
?
/
/ \
\
'
I
1
I
I
1
I
J2+w
39
3Q-w
2.Qo2w
22+w
22
212-w
22-2w
2 J.
2+2w
2
J2-w
linearity those values of for which 2!pw
the combination frequencies have a
constant percentage frequency sepa-
ration (Fig. 3).
As an example, let us take an ob-
ject with a transmission range of 12
to 60 kc/s. Only one test filter is requi-
red. Its own transmission range can
be chosen more or less arbitrarily, but
let it be assumed in the present case to
i. e., near 60 kc/s. According to Fig. 3,
the modulation products with the
combination frequencies Q + 2 w,
2 Q - w, and 3 Sl will then be suited
for the measurement of the cubic
distortions, and that with a frequency
ratio of the two test oscillations as
indicated by Fig. 4.
In the given example, the fre-
quency separation between the mod-
ulation products to be used for the
determination of non-linearity and
the undesirable ones lies between 11%
and 50%. Hence a good compromise
can be obtained between the demand
for a large number of test oscillations
distributed over the entire trans-
mission range of the object under test
and the demand for a selectivity of
the test filter that can be economically
realized.
It might be mentioned that the
ratio of the amplitude of each modu-
lation product selected for this method
to the amplitude of the higher har-
monic used hitherto as a criterion of
non-linearity, can be determined in
a simple way from the general power
series expansion of the non-linear re-
lation between output current and
effective input voltage characterizing
the object under test. Therefore, this
method makes it possible to measure
the frequency-dependentnon-linearity
of a system with the aid of various
Fig. 3. Modulation products + 9 S? p `u as function of
f1 52
60
AV kHz
V 2
d2 *2w
.Qrw 2,2
3w 122-w 1?a.. Ja
of 3~q q~ At -0.B
2Q-w i i
LJj
107
2v0 kHz
5w _1,11
.Q + 2w
2'2w
22-w '712
S1-3w _ 32-2w-1.17
22-w 2d2-ru
2J2-w - 1,20
421,33
32
3.2 - 1,.50
2R
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frequencies distributed over the transmission range, which,
in addition, may belong to different modulation products
(Fig. 4). The combination factor method as described here,
possesses a further advantage - referred to the same
modulation products (e. g., with the frequency 2 Q - (o) -
it is more sensitive than the measurement of cubic distor-
tions by the method shown in Fig. 2 with an amplitude
of the interfering oscillation to be measured that is
reduced by double modulation. True, the new procedure has
the disadvantage that only relatively few points of the trans-
mission range are used, due to the economic restrictions on the
quality of the test filter. In practice, however, these points
will suffice for carrier-frequency equipment which, in general,
possesses a non-linearity that varies continuously with the
frequency. Apart from this, it is possible to determine the
distorting effect of non-linearities with the aid of noise vol-
tages which correspond better to the spectral distribution of
speech than but one or two representative sinusoidal oscil-
lations.
Such measuring methods which use noise voltage gene-
rators and noise voltage meters have long since proved useful
for the investigation of complete carrier systems because the
carrier frequency selection filters provided in these systems
may be utilized. Here, too, the novel graphical representation
of Fig. 3 can be used to advantage in order to determine the
modulation products [2].
Finally, for the testing of carrier-frequency four-poles
(such as modulators and amplifiers) not possessing any special
selection in their transmission range, measuring procedures
The publication of the new VDE2) Supplementary Regulations (Standards) for power cables, as well as the
new Material specification gives occasion to comment on construction and application of the various types of cable.
The State of Cable Engineering in the Light of the
New VDE-Regulations
In the field of power cables there is in the first place a
pronounced tendency for economizing on copper and lead,
i. e., more aluminium must be used as core and sheathing
material and more plastics as high-tension overhead line in-
sulation material for lead-uncovered high-tension cables. The
') Translation of the German Publication in Deutsche Elektroteehnik Vol. 11
(1957) No. 7 pp. 313-316.
?) VDE - Association of German Electrical Engineers.
have been suggested recently which filter out a "gap" from a
noise band and measure the noise voltage component con-
tained in such a gap [1], [4], this gap being shifted over the
carrier-frequency transmission range. For the time being,
however, no measuring equipment is known which would
allow to measure narrow or broad noise bands with a definitely
limited amplitude in gaps to be shifted over a carrier trans-
mission range with a sufficient accuracy and with means that
would be more economic than those of other well-known me-
thods for the measurement of non-linear distortions. Further-
more, the relation between the permissible power contents of
such limited noise bands and the admissible total LF-noise at
the end of the carrier voice communication line is not known,
nor is the relation between the noise of such limited bands and
the noise attenuation which is still generally used for the
characterization of non-linearity.
As long as such noise measuring methods have not given
any practically applicable results, the described combination
factor method should be recommended at least for the carrier-
frequency field where it can replace the less adequate methods
of harmonic-distortion or differential tones. TRA 98
Literature
[I] Darre, A.: Methoden our Messung nichtlinearer Verzerrungen im Tonfre-
quenzgebiet. Frequenz Vol. 9 (1955) No. 3/4.
[2] Henkler, 0.: Ermittlung storender Modulationsprodukte. Radio and Fern-
sehen (1956) No. 4.
[3] Henkler, 0.: t)ber die Nichtlinearitst von Tragerfrequenz-Verstarkern. Nach-
richtentechnik Vol. 6 (1956) pp. 455 and 456.
[4] Wolf, M. W.: Zur Untersuchung nichtlinearer Verzerrungen von Vierpolen
durch Signale -it kontinuierlichem Spektrum. J. d. techn. Physik (UdSSR)
Vol. 24 (1954) No. 11.
Second Five Year Plan demands that until 1960 the propor-
tion of copper to aluminium used in cable production should be
reduced to 33.5: 66.5 (Fig. 1). Furthermore, cable production
should increase to 200% and the production of aluminium
to 250%. The total export (which includes a considerable
share of cables) should be raised to 170%.
To the great number of cable designs already known still
further designs will be added because not all copper- and
Fig. 1. Objects of the Second Five Year Plan
ZOOM,
a)
b)
c)
d)
Copper and aluminium consumption
Cable production
Aluminium production
Export
Fig. 2. Survey concerning the permitted use of lead
shea!hings
I Indoor cables
E Underground cables
Three core cables
o Single-core cables
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lead-covered cable types can be replaced by copper- and lead-
uncovered cables. For particular cases, above all for the ex-
port, copper- and lead-covered cables have still to be produced.
Tables 1 and 2 and Fig. 2 give a survey in accordance with the
Material Specification No. 158, published on 12th November,
1946. In all other cases, the core material is aluminium and
the sheathing is aluminium or plastics. The cable types con-
cerned are by no means new, but for some types their range
of application has now been extended according to the VDE-
regulations 36.0255/2.57, 36.0270/2.57, 36.0271/2.57, and
36.0272/2.57.
1
Actuating cables
Control cables
3
Steering cables
Only up to 0.0093 sq.
4
Measuring cables
in. (6 mm')
5
Crane cables
6
Shaft cables
7
Cables for underground mines
8
Marine cables
9
River and deep sea cables
10
Cables for lubricating oil pumps')
I I
Cables laid in rooms with danger of explosion All cross-sections
12
Cables laid in work rooms of the chemical
industries')
') Of turbines, generators, or compressors.
2) If there is a danger of corrosion when using aluminium as core material
No.
Cable type
Tension
kV
Cross- Laying
section indoors underground
(mm')
I
Paper core cables
...1
120...400 + +
2
Paper core cables
3...10
6... 95 - +
3
Paper core cables
3...10
120...400 + +
1
Paper core cables
15...45
all') + +
o
Cables for mines
all
all
6
River cables
all
all
7
Deep sea cables
all
all
8
Cables contacting potash
salts
') From 185 mm' only as single-core cable.
') The cables may be fitted with lead sheathings, if this is in
with the relevant regulations in force for these cables.
Cable type
Characteristic
Abbreviations
Symbol)
(Examples)
Y
Cables having sprayed-on
plastics sheathing
NAYYBA
NAEYYBA
P
Cables having wound
plastics sheathing
NIAPB-R
}' (PR)
Cables having sprayed-on
plastics sheathing and
NAYuFY (PR)
NAHEYuFYBA
concentric central core
(PR)
P (BR)
Cables having wound
plastics sheathing and
NAPuFY(PR)
NAHEuFPBA
concentric central core
(PR)
Ka
Cables having aluminium
sheathing
NAKaBA
NAEKaBA
K
Cables having lead sheathing
The range of application of cables made of plastics has
been increased to 10 kV so that the well-known designs of the
metal-uncovered cables must be adapted to the requirements
of the higher tensions. In the new VDE-regulations mentioned
above the new state of cable engineering is already taken into
account.
Table 3 explains the symbols and abbreviations used for
the most important high-tension cable types (Y-, P-, Ka-, and
K-cables). Their range of application according to cross-sec-
tion and tension is shown in Table 4. Figs. 3 and 4 show the
basic design of the metal-uncovered cables without and with
concentric conductor, respectively.
The cables with insulation and sheathing made of sprayed
plastics are made with and without armouring. The cables
without armouring, however, are only allowed to be used in-
doors and only for tension as high as 1 kV. In place of the
omitted padding and armouring the NYY- and NAYY-cables
are constructed with reinforced sheathing made of plastics.
These unarmoured plastics cables are of nearly the same de-
sign as the plastics lines NYM. Nevertheless, the type NYY
is counted as "cable", because it is stronger dimensioned and,
consequently, admitted for higher tensions (Fig. 5). The lead-
less power cables are most frequently used as actuating cables,
viz.
NYY-cables with armouring for interiors, or
NKaB-cables with armouring for interiors, and
NKaB-cables without armouring for underground laying.
In case of plastics cables having large core cross-sections
it is advisable not to use the belted insulation Y-type, but the
YE-type (SL-cable or three-core cable with three lead sheath-
ings, one per core) (Fig. 6), because it consumes less plastics
material and has a greater flexibility. The fact that the cable
ends need not be fitted with sealed cable ends (Fig. 7) and that
differences of level do not matter, is generally considered by
the user as a particular advantage of the plastics cable.
Contrary to Y-cables, the P-cables (indoor cables having
reinforced plastics winding sheathing must always be with
armouring (abbreviation: NIAPB-R).
The PR-cables (underground and indoor cables admitted
on trial) having concentric conductors are fitted with a concen-
tric layer of flat or round aluminium wires which may be used
either as guard wires or, in case of three and a half- or four-
core cables, as centre core. These cables thus comprise only
three stranded main cores and one concentric centre core. As
a plastics sheathing is provided around the concentric core,
any special armouring or coating with asphalt may be omitted
(NAYuFY). In the first place, the use of concentric cores is
meant to offer a reliable shielding from contact, instead of the
unsafety involved with the provision of steel tape armouring
which is destroyed by rust in the course of time so that it can
no longer fulfil the important protective function.
Current Carrying Capacity of Underground Y-Cables
On this subject some remarks are necessary because very
often the relevant instructions contained in VDE 36.0271 are
not observed. As stated in Fig. 8, Y-cables carrying d. c. only
have a current carrying capacity of 50% of the VDE-table
values when laid underground. In case of d. c. and indoor in-
stallation the current carrying capacity can be based on the
full table values. The reduction of the current carrying capa-
city need not be considered for control and actuating Y-
cables, since then the power transmitted is so small that the
heat generated in the cables can be neglected for all practical
purposes.
Single-Core Cables with and without Armouring
By using single-core cables the current carrying capacity
and consequently the transmission capacity may be raised in
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Fig. 3. Metal-uncovered cables for tensions from 1-10 kV
without concentric central core
a) for dry and moist rooms
b) for indoor and underground laying
aa
mpregnoted
paper
rY
Concentric Core
P(PR) ~Y3-sheothingi
V.
-metaiized
(P(PR) isheathit EY(PR)
core
Y3
Fig. 4. Metal-uncovered cables for tens ions from l -10kV
with concentric central core
VD[ 38.0271/2.57 VDE 0.250/752
Inn0 Volt 500 Volt
Fig. 5. Technical comparison between plastics cable and
plastics wire
a) plastics cable
b) plastics wire
accordance with the informations of
the load tables VDE 0255/7.51 with-
out increasing the cross-section or
one may use a smaller core cross-
section for a given transmission ca-
pacity (Figs. 9 and 10). A disadvantage
of the single-core cables to be operated
by a. c. is that they must not be
fitted with steel tape armouring. In
such cases where an armouring is ab-
solutely necessary, the single-core
cables may be fitted with an open
steel wire armouring which offers me-
chanical protection not only in the
axial, but also in the transverse di-
rection.
When using single-core cables,
which in themselves are much thinner
than three-core cables, small cross-
sections should be avoided, because
thin cables easily kink and break in
case of careless laying. It is not prac-
tical to lay more than 820 ft. (250 m)
lengths of uuarmoured single-core
cables within a township, in which
case the minimum cross-section should
be 0.186 sq. in. (120 mm2). In case of
single-core cables having open steel
wire armouring the laying lengths
generally should not be more than
1312 ft. (400 m) in which case a
cross-section of 0.148 sq. in. (95 mm2)
should be considered as the lowest
limit (Fig. 11). Even when used as
neutral wire the single-core cable for
a. c. operation must have no closed
magnetizable armouring - hence also
no steel tape armouring - because the
50-cps-asymmetric current flowing in
the conductor would produce eddy
currents in the tape armouring. Mo-
reover, an excessively large inductive
drop of potential would occur.
Power cable
Y
Low-tension cable
Y Y
Indoor cable Underground cable
High-tension cable
Power Cables interfering with Communi-
cation Lines
For a long time it was customary to
observe a minimum distance of 12 in. (30
cm) between power and communication
cables, no matter whether the lines were
parallel or crossing each other (VDE 0101
? 18). In case of single-core cables arranged
side by side the communication cables were
~72
' mm
VI
"Y3.g7mm V3.7yDmm
Fig. 6. Plastics consumption of 6 kV-cables`
a) Belted insulation NA YYBA
3 x 0.2335 sq. in. (1S0mm2) - Y2 + Ys
=5.04 Ib/yd (2500 kg, cm)
b) Three-c, re cable NAEYYBA
3 x 0.2325 sq. in. (150 mm2) ? Y, -}- Y,
= 3.8302 lb/yd (1900 kg/km)
Fig. 7.
Plastics cable without
sealed cable end
laid zigzag above the three
power cables in order that
the power current induc-
tions mutually compensate
their effects on the com-
munication cables. Interfe-
rences have - as far as
known - not occurred in the
telecommunication system.
As far as the interests of
telecommunication are con-
cerned, the triangular ar-
rangement of the single-core
cables is the most favourable
one. The arrangement of the
cables side by side requires
their regular stranding,
similar to overhead lines.
This, however, is difficult
to realize if three operating
Y Y
Indoor cable Underground cable
Y Y Y
Y V' Y Y
max. 0.148
from 0.186 max. 0.148
sq. in.
sq. in. sq. in.
(95 mm2)
(120 mm2) (95 mms)
Y-cable K-cable
P-cable
Ka-cable
from. 0.186
sq. in.
(120 mm2)
3-10 kV 15-60 kV
3-60 kV
max. 0.148
from 0.186 1 all
sq. in.
sq. in. I cross-sections
cross-sections
(95 mm2)
(120 mm2)
Y-cable
K-cable
K-cible
P-cable
Ka-cable
t)
1)
_ =__LLLU1; Y-sheathing
Y(PR) 1
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Current carrying rapacity 100%
Overtemperature 35?C
Core temperature 55?C
100%
35?C
55?C
Kind of current
Current carrying capacity 100%
Overtemperature 350C
Core temperature 55?C
0 0"
m,
1,7
105
1951
1953
08
.55
20 40
DI
50 mm 0 20 40
Di --
Fig. 13
Permissible pressure or compound cables
PM' Di =PPb 26 Pb; PPb = 106.616/sc. in
(7.5 kg/cm')
PM = 15 ? 5 Pb; Di = 21 . 6 Ph;
Di
PM .; 10.098 lb,'s-. in (0.71 kg'cm'; h P6 l 1
Di 21
50%
9o c
29? C
Gel insula ion
cable
single core cable
p,
oo0
@@@
240mm2
240mm2
240mm2
J-100%
Jab. 115%
J Ob. 125%
240mm 2
185mm 2
150mm 2
J- 100 %
J ab. loo %
J ab. 100%
Thee x
-shealhin cabl
9 sin le core ale __~ single care cable
f--_^
C
J= 100%
NAHEKBA
core
lns0/ali/n -
- sheathing -
open f/ct or round
J ab. 120%,
NAHKA
30
35
105
115
1251
14
1,7
18
1
1,95
Fig. 8
Current carrying capa.
city of plastics cables
Fig. 9
Current carrying capa.
city of three-sheath and
single-core cables for
tension above 10 k V
Fig. 10
Current carrying capa.
city of belting insula-
tion and single-core
cables for tensions from
3-10kV
Fig. 11
Minimum cross-
sections of single-core
cables for laying:
a) within towns,
F= 0.186 sq. in.
(120 mm'),
I = 650 - 820 ft.
(200 - 250 m),
without armour-
ing;
b) outside of towns,
F = 0.148 sq. in.
(95 mm'), I - 985
- 1310 ft. (300-
400 m), with ar-
mouring
Fig. 12
Lead wall thicknesses of
compound cables
Vol. 1 , No. 10, December 195
cables and one reserve cable are arranged in this manner.
The telecommunication cables have become more sensitive
to inductive interference and therefore doubts have arisen
regarding the inductive effects of polyphase earths.
These doubts are even accentuated by the rigid neutral
point earthing now planned for high-tension lines, which will
make every earth connection a short-circuit. The Technical
Branch of Electrical Engineering of the Kammer der Technik,
District Great-Berlin, has resolved during its-meeting on the
28th February, 1957, to form a technical commitee for
preparing, in cooperation with technical experts at home
and abroad, new "Directives for Protecting Telecommuni-
cation Lines from the Danger of Interference by Three-
Phase Power Installations Working at 1 kV or more".
Lead Wall Thicknesses
The lead wall thicknesses corresponding to the GOST-
Standards 340-53 have been reduced in 1953 (Fig. 12). The
reduction of lead wall thicknesses is a tendency now existing
in nearly all countries, because the supply of lead has become
a bottle-neck everywhere. This reduction is of mechanical re-
levance for cable lines with differences in level, first of all for
shaft and mast cables. Since lead has a very low creep resist-
ance, the internal pressures produced by the drift of the im-
pregnation compounds towards the lower points of the cable
line may cause the danger of lead-sheath expansion and in the
end of bursting. As shown in Fig. 13, the maximum permis-
sible level difference is about 23 ft. (7 m) for lead-covered
cables using pure lead (VDE 0255/7.51), and only about 20 ft.
(6 m) for other lead-covered cables (VDE 36.0255/6.53). This
corresponds well to the specifications in GOST 340-53 which
e. g. provide for a maximum level difference of 16.4 ft. (5.0 m)
for 35 kV lead-covered cables with normal impregnation. In
case of alloy-lead sheathings the admissible level difference is
about 26 to 33 ft. (8-10 m). In case of greater level differences
the lead sheathing must be fitted with a compressive guard
bandage, and the insulation should only just comprise the
capillary-bound compound, i. e., the surplus should have run
off already in the factory after the impregnation process. By
way of compensation, the thickness of insulation in high-ten-
sion cables is a bit increased. With this basic design, shaft
cables of up to 1204 yd. (1100 m) have been manufactured
which have proved satisfactory in use. The same points of
view are involved with the so-called mast cables, if they are
laid higher than about 26 to 33 ft. (8-10 m). In this case the
effect of direct solar radiation has also to be taken into account.
A metal covering is, therefore, very suitable. It is profitable
to use a highly viscous adhesive compound for impregnating
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3x 120/70
3x 120
3x 120
QO, Do
sheathing
material
lead
lead
aluminium
crss-section
108m2
142mm2
112mm2
resistance
0,26.4/m
central care
412/km
sheathing
0.278/km
sheathing
Fig. 11
10 kV three-sheath flat cable
3 x 0.1085 sq. in. (70 mm2) Aldrey. Comparison
with a normal A aft cable shows a lead saving of
5.443lb/yd (2.7t/km). The total reduction in weight
amounts to 14 112 16 yd (7 t/km)
Fig. 16
Samples of aluminium-covered cables
a) four-core aluminium-covered cable
b) three-core aluminium covered cable
the dielectric of such cables in order to prevent or reduce
downward-drift. It should be stressed that high viscosity alone
is not sufficient and that the compound must also possess good
adhesion. In spite of all demands requiring cables for very
high masts, careful investigations have shown that in many
cases the sealed cable ends can be placed as low as 7-16 ft.
(2-5 m) instead of between 33 and 65.6 ft. (10-20 m). When
laying at greater heights one has to count with a 20% reduc-
tion in the current carrying capacity, and with a further re-
duction of 15% in case of outdoor temperatures reaching about
+ 86 ? F (+ 30 ? C). When using aluminium-covered cables
one may do without the compressive guard bandage, thanks
to the considerably higher strength of aluminium compared
to lead; however, all the other conditions mentioned above
hold good also for aluminium-covered cables.
A VDE-regulation concerning cables with little impreg-
nation is to be issued still this year by the Experts' Committee
on Cable and Wires of the Technical Branch of Electrical
Engineering of the Kammer der Technik.
The application of mast and shaft cables with dry insulation
(sprayed polyvinyl chloride insulation or wound insulation of
acetobutyrate foils, and the like, without or with gas pressure)
represents a further step of development. A particular design
of shaft cables is the flat three-core cable (Fig. 14), which, due
to its broad surface, considerably reduces the specific pressure
on the guide pulley so that a deformation of the cable cannot
occur.
Aluminium Sheathings as Centre Core
Although aluminium sheathings are thinner than lead
ones, their resistance is considerably lower than that of lead
sheathings, thanks to the relatively good conductivity of alu-
minium, and for this reason one aspires to employ aluminium
sheathings for the central core (Fig. 15). In case of larger cross-
sections it is profitable to provide multi-sheath cables with
aluminium sheathings instead of belted insulation cables, be-
cause the former possess a greater flexibility. In case of three
and a half- or four-core cables it is sufficient to use three-
sheath cables with the three aluminium sheathings connected
in parallel so that the total cross-section amply corresponds to
the usual centre core cross-section (Fig. 16). Detailed regula-
tions as o the conditions under which the aluminium sheath-
ings may be used as centre core are now being prepared by
the Experts' Committee 2 of the Technical Branch of Electrical
Engineering of the Kammer der Technik, and will soon be
published.
Summary
The new VDE-regulations 36.0255/2.57, 36.0270/2.57,
36.0271/2.57, and 36.0272/2.57 give information about im-
provements in cable design and their range of application. The
new technical directives of the Material Specification No. 158
concerning raw materials have been interpreted. Furthermore,
references have been made to further regulations of the Book
of Regulations of German Electrical Engineers (VDE) at
present in preparation, concerning cables with little impre-
gnation. TRA 103
We are special manufacturers of
measuring appliances
and controls,
adjusting members,
flow meters,
for automatization of thermic
processes
15
m rs ,l~ ~~}sip ~
- f1
VEB MESSGERATEWERK AUEDLINBURG
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? The Length of the Transition Arc in Road Building
To-day it is generally agreed that the ideal form of the
transition curve to be used in road building is the clothoid.
This result is based on the condition of uniform change of
curvature from R = oo to R = R8, constant driving speed,
and uniform turning of the steering wheel. From these con-
ditions one gets [6], [7]
H?L=C= a2,
L L
L2
L2
x - cos - - ? dL, v _ sin ? dL
2 a2 2 a2
li d
and for the clothoid with the parameter 1:
12 12
x = I cos 2- dl, y = I sin 2 dl
0 0
After expanding cosine and sine into a series and integrating
by terms one obtains:
1 vs
,A H=
25600 H3
1
dH= --- - q'.
1556,9
The length of the transition are is then fixed by the formula
deduced from the cubic parabola:
L2
dH ---- or
24.H
L = v24?H?AH
This deduction, however, involves an inconsistency; for if we
suppose that
50 ? v2
.f=q= 9. H
-,
the coefficient of friction f enters the basic equation
13
1e 113
L=v.g.
f
X =
1 -
+
.
40
3456 599040
as a variable, though it is a constant for each roadway in its
given condition. This means that in computing the length of
y
+
6
336
42240 9676800
the transition are the coefficient of friction takes the values
The displacement of the main curve for the inclusion of the
transition are becomes:
13 1 111
J h = +
24 2088 506880
In addition to its use as transition curve the clothoid is to be
regarded as a tracing element of the same value as the straight
line and the circular arc, because, by changing the value of the
parameter, one can construct any form of arc [4], [7]. It is not
likely, though, that the straight line and the circular are will
be fully replaced by the clothoid, since obviously it is impos-
sible to rebuild all the roads in this way; besides, other factors
such as aesthetics, economy, etc., also play a part [9], [10].
There still remains the question of how long the transition
arc should be made. As the clothoid is now tabulated for unit
parameter and for several other parameter values [6], [7], its
use no longer involves any difficulties.
The "Provisional Regulations for Road Building", RAL,
4th Edition 1942 [3] take as basis for the dimension of the
transition arcs the following formula which is due to Orley [2] :
L=vg .f
where
L -- length of the transition arc (m)
v = driving speed (m/s)
g terrestrial acceleration due to gravity (m/s2)
W -> jerky acceleration in the time unit (m/s3)
f = coefficient of friction between wheel and roadway.
As the driving speed v in a curve depends on the lateral
banking q, the radius H, and the coefficient of friction f, and
since the banking has been fixed in RAL to
50. v2
q - - - -
g?H
0.02 forq=2% 0.04 forq=4%
0.03 for q = 3% 0.08 for q = 8% etc.
while in reality the following values hold for a wet roadway
[1], [8]
mastic asphalt
f = 0.33
granite metalling
f = 0.25
concrete
f = 0.33
basalt metalling
f = 0.22
tar
f=0.31
The computation of the really necessary length of transition
arcs is to be based on the assumptions that
1. the driving speed is kept constant throughout the tran-
sition arc,
2. the jerk does not surpass a certain limit,
3. the coefficient of friction has a constant value.
According to Fig. 1 this gives the following condition of
equilibrium [5]
( g - c o s (1 )
V2
where z =- means the lateral acceleration.
H
Of this, the roadway takes up
(g ? cos x + z ? sin x) ? f,
so it remains the free lateral acceleration:
c=z?cos x-g?sin x.
Now the jerk tp (m/s3) is the rate of change of the lateral accel.
eration:
dc d
tp = -- = -- (z -cos c- g?sin a).
dt dt
1
cos x -- and sin 9 --
+ tang x yl + tan2x
d v2 g ? tan x
this gives y -- --- --- - - --
dt H V j_+ tang x vl -}- tang x
or, since tan x --- q, you have
1) Translation of the German Publication in Stralienteehnik, Vol. 5 (1957)
No. 7 pp. 82, and 83. Supplement to Bauplanung-Bautechnik Vol. 11 (1957)
d f V2
2 (/
it ~HV 1+
No. 7.
q
g?q
.
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As the slope should obey the law of curvature, qd (cross-section
like a one-sided lean-to) grows in proportion to the curvature
to qu (raised degree of bank in the curve), and even at the be-
ginning of the transition are there is a one-sided slant. Accord-
ing to Fig. 2 we have the relation
Ho q - qd Ho
H =9n=4d or q H (qa-qd)+qd-
Hence one obtains
d
Ydt
+~Ho(qu-qd) +
H z
(9ii - qd) + qd
g H
I / Ho z
+ H (qu - qd) + qdJ
or, since dt = dl - , it is
v
do d?v v2
dtdl r
V I Ho (qu
H
- qd) + qdl
Ho
g ( + qd
1I+LH(qu-qd)+gdlzI
According to equation (1) it is
V2
H (cos a -f- sin a)-g (sin a+f?cosa)=0,
0
and from this
v2 (cos a -f- sin a)
Ho = --- or as tan a = qu
g (sin a + f?cos a)
vz 1 -f?gi
Ho g (.f+qu
From this y ou get
-
H1/1 +I u
ka -J?Yul(qu-qd)+qd
V LH?g(.f+qu)
V2 qii)
g H g1(} + 9a) (qu - qd) + qd
11
vz (I +[ q6) ll
+ H,g (f+ qu) (gu - 4d) + 4d
y fd1=d(V)H_
vz (l- f?
)
9i
within the limits H = co to Ho = --
g (f + qu)
H- d ---} L --~
Fig. 2
After integration one obtains
1 2
v,L=v.grf 1iu + -9d-
1\ 1 -.f? qtt 1 ? qd2/
Thus, the length of the transition are is determined by:
Lv?g(fyl+quz + qd
tV ( I -.f?gil 1/ qdz
If you put qu and qd = 0, you get the Orley equation
L=v.g f
Y
On first sight, it seems to be odd that for decreasing f the
length of the transition arc should decrease; rather one would
expect that the length of the transition arc should increase for
a roadway that is more slippery. One can see, however, that
the formula is correct from the fact that for the limit f = 0
there is no possibility to build a transition arc.
As a lower limit one may take f = 0.25. The jerk q' still
admissible for driving motor vehicles can be taken as 0.5 m/s2.
while g = 9.81 m/s.
With these values one obtains
L = 4,905.v I I quz + 4 qd
l
I - 0,25 qu V 1 + qdz l
The limiting values are given by
1. qu=8% andgd=2%
2. qi: = 2% and qd = 2%.
With these values you get for L
1. L=5.415?v(m)
2. L = 5.229-v (m)
or with v = V 3 6 (km/h)
1. L = 1.503 V (m)
2. L = 1.45 V (m).
Thus, L = 1.5 V may be used as minimum length of the tran-
sition arc.
But we want to stress the fact that this is a minimum.
For aesthetic reasons one should always try to make the length
of the transition arc larger than 1.5 V.
Literature
[1] Weil: Ober die Reibungswerte zwischen Rad and Fahrbabn. Dissertation
Technische Hochschule Stuttgart (1934).
[2] Orley: Obergangsbogen bei StraBenkrummungen. Verlag Volk and Reich
(1937).
[3] Orley: Vorlaufige Richtlinien fur den Anshan von Landstralien. Verlag Volk
and Reich, 4th Edition (1942).
[4] Lorenz: Die Klothoide als Trassierungselemente. Verkehr and Technik
(1948) No. 9.
[5] Krebs: Der Vbergangsbogenim Stralenbau. Berechnung der Klothoide aus
der Fahrdynamik. Die Bautechnik (1950) p. 176; (1951) p. 207.
[6] Vesely, V.: Klotoida. Technicko - Vedecke Vydavatelstvi, Praha (1952).
[7] Kaspar, Schurba, Lorenz: Die Klothoide als Trassierungselement. Ferd.
Dummler Verlag, Bonn (1954).
[8] Boldizar, V.: Utepitestan. Tankonyvkiado, Budapest (1954).
[9] Hering, R.: Ist die Gerade als Trassierungselement notig? Stralle and Auto-
bahn (1955) No. 2.
[10] Albrecht: Ist die Gerade als Trassierungselement zum Aussterben verurteilt?
Stral3e and Autobahn (1955) No. 6. TRA 101
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The Tool-Carrier RS 09
Many years experience in tractor construction has proved
a great help to VEB Traktorenwerk Schonebeck in the de-
velopment of their new types and implements. In particular,
the new tool-carrier RS 09 seems to be well suited to solve a
major part of the problems involved in the mechanization of
agriculture.
The construction principle of the RS 09 is that of a con ?
bination of tractor and tools. That means that the design of
this tool-carrier is different from that of standard tractors. The
tool-carrier can also be used as a light tractor, but will be em-
ployed principally for soil cultivation (Fig. 1), harvesting
work, and for the preparation of the soil. Inasmuch as many
different operations are required for this type of work, the
tool-carrier must combine a high capacity with a great variety
of possible applications. Thanks to a number of technical in-
novations and improvements, this purpose was fully attained
with the RS 09.
The main components of the RS 09 are the driving axle,
the longitudinal girder, and the front axle. The operating
power is transmitted to the additional implements from the
driving axle, composed of engine- and gear-unit. The longi-
tudinal girder is designed for the attachment and for the trans-
port of these implements. The execution of driving manoeuvres
is left to the front axle. The condition for one-man operation
is given by the single-holm construction. An unobstructed
view and a favourable angle of survey over the additional im-
plements was obtained by other constructive improvements,
granting an unencumbered operation. The frame of the RS 09
is composed of a square-section girder and a front axle con-
sole. The telescope type front axle is suspended without
springs in the front axle console in a swinging way. The ground
clearance could be reduced from 480 mm to 240 mm by divid-
ing the axle shanks of the front axle, so that the vehicle,
thanks to its low centre of gravity, can be used also under the
most difficult conditions and on hilly grounds. Due to its air-
cooled Diesel engine the machine operates with a very high
efficiency. The engine is not located any more in front of the
gear-box, but is flanged-on behind the gear-box. This fact
alone grants four special advantages:
1. an increased tractional power due to a favourable location
of the centre of gravity;
2. an unobstructed view from the driver's seat;
3. easy accessibility of clutch and gear;
4. the construction of a self-contained driving axle.
The general use of this driving axle was made possible by
combining engine and gear into one unit. This construction
permits the development and application of new implements
suited to the requirements of widely different agricultural
operations. The intaken air is led through a cyclon with oil
bath filter so that the life expectance of the engine is not im-
paired even if the air contains a high percentage of dust. A
combined exhaust air filter and cyclon installation has been
planned as a further improvement, so that in future a nearly
dustfree operation will be obtained.
Console and front axle of the RS 09 are adjustable in the
driving direction. That means that the wheel distance can be
reduced from 2210 mm to 1760 mm. This will facilitate the
mounting of additional implements in front of the front axle.
Besides the possibilities of adjusting ground clearance and
wheel base, also the track gauge of the vehicle can be adjusted
within the range of 1250-1670 mm. It can thus be adjusted
to the different widths between rows. This fact is of special
importance when the tool-carrier is used for cultivation pur-
poses. The telescope pipe of the steering column and the
steering mechanism are built into the longitudinal girder and
the steering mechanism is fixed to the front axle console. In
this way the mounting of implements is made easier and a
higher safety against damage is obtained.
The divided steering rods between console and front axle,
as well as the telescope pipe axle, can be adjusted according to
the track gauge of the vehicle. The main part of the rear axle
is formed by the gear, which disposes of 2 X 4 = 8 foreward
and reverse speeds. Driving speeds between 0.9 and 15 km/h
can be obtained in two switching stages. A creeping speed of
0.59 km/h can be obtained in the first speed by throttling the
engine. In this way the speeds required for different operations
can be maintained.
Seat, steering column, and all control elements are mount-
ed on the gear-box. The changing levers are mounted on the
steering column and clearly marked. Axle cones and the
double countershaft are fastened to the driving wheel to the
right and to the left of the gear-box. The mechanical inner
jaw brake is located at the axle cone, in front of the counter-
shaft. There is a flange at the rear side of the gear, to which
the engine is attached. This is equipped with a driving clutch.
The connecting surface to the tenonshaft gear is formed by
the lower side of the gear. The rear tenonshaft is extended by
a counter-tenonshaft. Both front and rear tenonshafts can be
operated either by the engine or by the wheels. Both shafts
work independently of each other, so that there are 8 different
possibilities of gear-shifting. This means that any combination
of additional implements with suspension in front of, or be-
tween the axles, or behind the driving axle, can be used.
A further characteristic of the RS 09 is its great manoeu-
vreability. An almost pinpoint turning radius can be obtained
because of the individual wheel braking and the high turning
angle of the front wheels. Driver's seat, steering wheel, and
control elements can be reversed, so that it is possible to carry
out special operations in a direction opposite to the normal
driving direction, without the hazards usually connected with
driving backwards. The RS 09 can thus be considered a two-
way tractor. New ways of application may be derived from
this property, and it should be possible to develop new
implements specially adapted to certain tasks.
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The ado I it ioial implements provided
for this root-carrier are operated by a
hydraulic device built into the gear. The
output of this device is high enough to
operate several tools at the same time.
while sparing the physical .strength of
the operator. The pressure caused on the
soil by the tool-carrier is almost the In%y-
est possible, due to its light-weight con-
struction. This will help to avoid damage
to the cultures.
In the following a summate is given
of the technical data of the IIS 09:
h:ngine: I8 II. P. two-cylinder four -stroke
air-cooled Diesel engine (\ 'archalo,,-
ski licence construction).
Gear: Eight forward and nine reverse
speeds
Driving speed in kni h at 3110)) r. p. In.
of the engine:
Ist
speed
0.89
5th
speed
1.00
2nd
speed
1.33
(itIi
speed
5.95
3rd
speed
2.1-4
- tIt
speed
9.23
Ith
speed
3.32
8th
speed
11.86
Di-iv ing speed in kin h at 20110 r. p. it.
of the engine:
I sl
speed
4).59
it h
speed
2.66
2nd
speed
0.89
6th
speed
3.96
3rd
speed
I.43
-th
speed
6.15
Ith
speed
2.22.)
8th
speed
9.911
1'enonslui%t:
Front and rear according to DIN
9611 (29 31.9 8.'):
a) driven by the engine
n 5Io r. p. ut.
b) driven by the wheels 3.3 kit It
at n (10 r. p. nt.
\Iiximtnt output of the tenonshaft
15 II. P. at >Ifl r. p. nt. 2)) ntkg.
lyres:
Front : 6.01) - 10 \S Front
Hear: '.00 36 \S
'track gauge: :Adjustable to 1250. 1375,
151)1), and 16711 nun
1t heel base: Standard 2211) null. con-
tinuously' adjustable to I-61) mitt
I1 eight:
s.ith d,ird u t) 'p-s
rquipwrnt kg ~?quip,nent kg
total weight 98))
111911
a) front axle load 2222210
2 f0
b) rear axle load 760
850
Permissible total iseight
a) permissible service
load on front axle
11o11
b) permissible service load
on rear axle
2250
c) permissible total
service load
I Il))
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.Scat: Iicvcrsible for foreward and backward driving
.Steering: Steering system with a knuckle lever turn of 90
lirake.s: a) mechanical inner jaw driving brake, acting on the
differential
b) hand brake, acting also on the brake druin. Special
rods for manual operation
Ground rlenronce: Maximum 180 mm, adjustable to 240 inns
Trailirig, rail: Field type rail without springs
Ili druidic:
Cogwheel pump with built-on steering cylinder and work-
ing cylinders on either side.
Maxinniin capacily 28 Inl, adjustable from 10-28 1/m
Pressure 80 atm. (niaxinitin) 100 atm.)
Number of revolution n 1875 r. p. in.
. number of additional implements are being manu-
factured by our industry. Among then) are for instance:
reaping beams, change plows, fertilizer distributors, drilling
machines, ejector wheel cultivators, hoeing machines, multiple
Instrumentenkunde
der Vermessungstechnik
(Theory of Surveying Instruments)
'I'bis work meets the deniand for a reference-book about
up-to-date construction of geodetic instruments - a demand
all the more justified as great progress has been made during
the last 20 years. As will be seen by the title, the book has
been confined to the instruments of lower geodesy. There-
fore astronomic instruments, theodolites for high-class trian-
gulations, instruments for hydrostatic leveling, and electro-
optical range-finders have not been dealt with though the
latter are also used for lower geodesy" Likewise instruments
for indoor service (cartographic and drawing instruments,
planiuleters) have been omitted on purpose. The instruments
for lower geodesy to be used outdoors are thoroughly and
clearly discussed, the examples being chosen mainly from
instruments of Gerniaii and Swiss construction. The book
has the following Sections:
1. Fundamentals
2. Instruments for setting out and measuring horizontal
angles
:3. Instruments for measuring heights and differences in
height,
4. I)evi'es and illstrunients for range-finding
;i. Instruments for tachvn)etrv.
The first section deals with the fundamentals of op-
tical theory and optical devices. Here level testing and cor-
rections are discussed only in general terms, the detailed
investigation being given in the following sections in con-
nection with the instruments concerned.
The second part begins with diopter, mirror, and prism
instruments for setting out right or straight angles, followed
by a discussion of simple instruments for measuring and set-
I ing out horizontal angles of any size, such as scale disk and
compass. After pointing to the surveying or meridian gyro-
scope a detailed description of the theodolite (Fig. 1) and its
use is given with due attention to the particularities of the
different conctructions.
After it short introduction to simple instruments for
leveling (water level, ruler" a. o.) the leveling instruments of
purpose devices, corn planting machines, squirting and spraying
machines (Figs. 2 and 3). Also implements like harrows, rollers,
weeders, diggers, and flat reaper binders, as well as all other
implements which require a low pulling power can be used as
trailers. This makes the RS 09 very economical in all branches
of agriculture, whether in field, fruit and vegetable cultivation,
in courtyards and meadows, or in forestry. The RS 09 can be
used at any time and everywhere in agriculture, independent
of season and weather.
Finally it should be mentioned here that further machines
based on the principle of the tool-carrier have been designed
and put in production; they are variations of the tool-carrier
RS 09. In particular, the corn cultivating tractor HS 26, the
courtyard tractor RS 27, and the dumper TA 23 will go a long
way to close the gaps still existing at the present tine in the
range of application of the tool-carrier principle.
We shall treat these machines in detail in further articles.
?rltn los Ste(f'i.n
mg. I
7'h, ih,odolire
Theo ll11)
of VSH Carl
zei, .
different construction with extras and their application are
described in the third section. Further, the theodolite for
measuring vertical angles, the sextant, and the barometers
are discussed.
The fourth part deals with the instruments for direct
range-finding such as stadia rods and surveyor's tapes and
their testing. The Jdderin instrument for base measuring is
mentioned. The devices and instruments for indirect distance
measuring form the main content. Principle, construction,
use, and attainable precision of both types, i. c. with target
base and with base at the station, are described.
The last part deals with the approved instrument, for
tachymetry. It is subdivided according to instruments with
Reichenbach distance threads, self-reducing or self-computing
taehymeters, surveyor"s boards, and alidades.
The work is well composed as to subject-matter and il-
lustrated by excellent pictures. It will help the expert to
select the most suitable device and to handle it correctly.
To the student it is warmly recommended as text-book.
')' 1?:13 V"erI ag '1'echnik, nerl3n 1937. Ulti 11 >. 379 pp., 361 i11-1r. Full-
i,o!t,erine 26. 1)11.
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WF HARD METAL
CUTTING PLATES
AND
HARD METAL-TIPPED
TOOLS
VEB HARTMETALLWERK IMMELBORN
I M M E LB O R N (T H U R.)
VEB (K)
Glasspritzenfa6rik Grafenroda
Medj
Manufacture of
All-Glass Syringes and
Record Syringe Cylinders
Exhibiters of the Leipzig Fair
H. WERNER GIERMANN
GOTHA/TH U RI NGIA
Scouring and Polishing
Machines
with switch clock -
to be turned by hand or
automatically.
VEB MASCHINENFABRIK GREIZ
Driving belts
Conveyor belts
- endless and by metre -
Conveyor belts
of all special designes.
The great success:
"Wegilif-Kaschierf"
the layer belt on PVC-basis.
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Acid- and alkali-resistant
THE HYGIENIC COVER
FOR RHEUMATIC
PATIENTS
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51.HmIDT&VOLHER
M I I
IF, I
"I HN
d buckles
'''
blades
wil saw circular so ular Saw blades
Swaged Cir blades
. ular SON and Wide
Bevelled Clr des narrow
Bond so blo I Saw b I''
'El - ed materials, bones
for P, astcs press tale, sugar
.
EiTEU10, SO 'S lot Metelo
lot hot EUM119 Ing saw blades
and friction rIpp dia
up to 2000 MM lot Stolle SCIVIS
V11009 idws
for motor cars
RIM, 1 . Rwk"11
VE B TEXTI LMASCH I N E N BAU
AU E - Aue (Saxony)
(formerly Ernst Gessner A.-G., Aue)
for woollen, half-woollen and cotton
goods as well as knitted fabrics.
The cloth speeds are infinitely
variable up to max. 30 m/min.
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WE MANUFACTURE:
Parallel pendulum saws
Double edging, ripping and lath
Two drum sanding machines
Triple drum sanding machines
Triple drum sanding machines
Scraping machines
Scraper grinding machines
Rotary cutting machines
ZWS 9 and 11
DWS 12
DWS 18
ZK 18
ZKS 18
RMM
cutting saws DLKM
Circular veneer peeling machines FRS 8-12
Circular veneer peeling machines FRS 10-26
Hydraulic hot plate presses, 2 openings FSP 2
Hydraulic hot plate presses, 4 openings FSP 4
Hydraulic hot plate presses, 6 openings FSP 6
Hydraulic hot plate presses, 7 openings FSP 7
Hydraulic hot plate presses, 8 openings FSP 8
Hydraulic hot plate presses special construction
Veneer strip assembly machines FVM
Automatic knot hole patching machines AFA
Automatic lath assembling machines LZM
Planing and moulding machines HK 20
Finishing planers PH
Finishing planers SPH 4
Heavy finishing planers SPH 8
Wood wool machines HW
Double end tenoners DZS
Dovetailing machines ZSM
Dovetailing apparatus ZFA
Knot hole drilling machines ABM
HOLZBEARBEITUNGSMASCHINENBAU ? LEIPZIG 0 5, TORGAUER STR. 43 ? PHONE 64321
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0)
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