has been found to be related to the frictional
qualities of transmission fluids. This relationship has been studied in two types of alipar&us : one a full-scale transmission set-up
and the other a bench apparatus.
In full-scale transmissions, fluids were evaluated with respect to shift performance, severity of stick-slip,
and oxidation
resistance.
Shift performance and severity of stick-slip
were dctcrmincd
by analysis of recorded
variables such as output shaft torque and
engine speed as functions of time. Hy measuring fluid acidity periodically during each
investigation
an interrelationship
between
fluid oxidation r-esistance an(l stick-slip
\\A‘found.
In the bench apparatus, m(asurcments
OI
friction as a function of sliding slxxd wcr(
made with load and fluid temperature as
parameters. These measurements were made
not only with new fluids but also with fluids
conditioned by transmission use. .\ corrcl;ttion was found between fluid pcrformancc in
a transmission and the friction characteristics
determined in the bench apparatus. On the
basis of the fluid friction characteristics lx~i-tinent comments arc made regarding the
friction mechanism.
3.1. Lubricatiou
author obtains the generalized differential
equation of a variable ?I upon which pressure
distribution, as well as other characteristics,
depends. This equationisintegrated
in the case
of two-dimensional motion ; as an application,
the problem of plane surfaces and constant
viscosity is discussed and it is shown that
parameter K = 6 VP, I//? h22(hi/hzPr) has an
important influence.
For circular cylindrical surfaces, the density
depends on an integral expression the solution
of which is obtained by means of conventional
graphical and numerical computations.
Finally on the basis of the assumption that
the viscosity also varies with pressure, a
general method is given for solving the twodimensional problem.
Problems
of Lubrication
M. M. Freundlich
cation
Eng.,
in Space.
and C. H. Hannan. Lubvi1961) 72-77; 7 figs.,
17 (2) (Feb.
z tables, I ref.
With the aim of operating eventually small
motors in space for a period of over a year,
the authors have collected a large number of
standard or experimental oils and greases and
have tested them in three phases. In the first
phase, they eliminated the lubricants with
the highest evaporation rates in tests in a
vacuum of IO.-~ mm Hg. The fifteen best of
these were finally tested as lubricants in R-r
size bearings in motors operating at 4000 rev/
min in a vacuum of 10-s mm Hg. After IOOO
hours of operation, an inspection of the disassembled bearings showed that several oils
and oil and grease combinations had deteriorated during these tests to such a slight extent
that it can be assumed that they would have
operated for a considerably longer time had
the tests been continued.
Gear Lubrication.
Part I. (in German)
Getriebeschmierung
A. A. Bartel. VDI Zeitschvift,
103 (6) (1961)
251-264;
12 figs., 5 tables, 91 refs.
Survey on recent progress on the above field
with special reference to gas lubrication and
heavy duty liquid lubrication. A classification
is given of different types of damage to gearing.
Detailed discussions
on the influence of
pressure as related to structure of lubricating
liquids. The practical consequences of present
knowledge are reviewed.
Effects of Fluid Film
dynamic Lubrication.
N. Tipei. ASLE Trans.,
4 figs., 4 refs.
Pressure
on Hydro-
3 (2) (1960)
277-280:
The effect of pressure upon hydrodynamic
lubrication is reflected by the variation of the
density and viscosity of the lubricant.
Proceeding from the function that relates
density to pressure in the case of liquids, the
Flow
Properties
of Lithium
Stearate-Oil
Model Greases as Functions of Soap Concentration and Temperature.
Walther H. Rauer, .4lfred I’. Finkelstein and
Stephen E. Wiberley. ASLE
Trans.,
3 (r)
(1960) 2r5mm~24; II figs., 3 tables, 13 refs.
Lithium stcaratc-oil
greases having 4. 8, and
I LT/, soap were prepared and flow properties
of the greases were investigated, at 0.25 and
37.8 ‘C. Flow data were obtained with a cone
and plate viscometer equipped with automatic
programming and recording of shear stress
UL’YSUS
rate of shear, and of shear stress z)wsus
time at selected shear rates. Flow curves,
shear stress Z~~YSUS
shear rate, were obtained
for an initial and a repeat 3oo-set cycle of
shear with maxima of 1520 set-i and of
r5,zoo SK 1. Flow curves were measured fothighly worked samples, previously sheared at
19,000 set-* for IOOOsec. The rate of change
of shearing stress required to maintain a
constant rate of shear was measured at nine
shear rates in the interval from 190 set-i to
19,000 see-*. Similar flow measurements
were made on greases containing stearic acid
additives. Initial flow resistance, ascribed to
soap structural elements, showed temperature
and concentration dependence differing from
that of the sheared soap, and was destroyed