24 research outputs found
STUDIES ON TRIBO-FATIGUE ADDITIVES FOR AUTOMOTIVE GEAR OILS
Tribo-fatigue, an important phenomenon, is influenced by the lubricant base oil and lubricant additives. There are many ~pecifications for
automotive hypoid gear oils which specifies different levels of performance. These specifications do not stipulate any requirements with
respect to fatigue performance of the lubricant. However, tribo-fatigue is recognised as an important parameter for understanding the better
performance of the lubricants. .
In view of this, a programme was undertaken to generate data on tribo-fatigue performance of Indian automotive gear oils and search for
additives which can enhance the fatigue performance of these lubricants. This paper deals with the studies made, on one such boron additive
on a rolling contact four ball fatigue tester and summarises the results obtained and assesses the influence of the additive on tribo-fatigue
performance of formulated gear oils.
Keywords: Tribo-fatigue, gear oils, additives, rolling contact, four ball machine
A Laboratory screening test for evaluation of load bearing capacity (LBC) OF automotive (API GL-4 TYPE) gear oils
In India and in a few other developing countries, about 80% of total auto-gear oils being used are
of API GL-4 level or MIL-L-2105 type. TIlis specification prescribes CRC-L-19, high speed
shock load rear axle and CRC-L-20, high torque low speed rear axle tests. The facility for L-19
test does not exist today where as the test facility for L-20 test is limited due to availability of
few sets of test gears. The current trend for the use of API GL-4 type oils will continu'e in India.
In view of requirement not qnly in India but in some other developing countries, a need is felt to
generate this test facilities at low cost and time. The paper describes the test method for
evaluation of load bearing capacity of GL-4 type oils and cal) be considered as a substitute for
CRC-L-20 test. \
r-
Key Words: Gear oil, evaluation, load bearing capacity, test method
A labroratory screening tests for evaluation of load bearing capacity (LBC) of automotive gear API GL-5 type oils
API GL-5 type automotive gear oils are being used all over the world confirming to the specifications MIL-L-
2105 E that prescribes the performance tests like CRC-L -33, CRC-L-37, CRC-L-42 and CRC-L-60. At
present, in India both API GL-4 and GL-5 type oils are being used. The CRC-L-37 test determines the load
carrying characteristics of gear lubricants in hypoicf'axles under high-speed low torque and low speed high
torque conditions. This test, specified for GL-5 oils is only available in U.S.A., which is expensive and time
consuming.
In view of the difficulty as well as high cost involved, a need is felt to develo
Studies on Rolling Contact Fatigue Lives of EN31 Steel Balls
A study was made on the rolling contact fatigue lives of EN31 steel balls with a mineral oil and containing different
types ':)f chemical compounds as additives using a rolling contact four ball tester. Also two commercial gear oils
and "'0'0 formulated oils were evaluated in a 4-ball tester for their influence on rolling contact fatigue lives of EN31
~eei balls. From the fatigue test data ,the mean test time to failure (MTTF) was determined, This paper
summarises the results obtained and assesses the relative influence of chemical additives on the rolling fatigue lives
Fatigue, lubricants, additives, gear oils, mean time to failure(MTTF), 4-ball machin
EFFECT OF BIOCIDES ON LUBRICITY PERFORMANCE OF METALWORKING FLUIDS (MWF)
It is well known that metalworking fluids (MWF)I coolants are susceptible to
growth of wide range of micro-organism including bacteria, fungi, molds and
yeast. These micro-organisms can have detrimental effects not only on the
performance and life of MWF but also effect the operator's health and the
environment. For controlling these organisms, various types of biocides are
incorporated in the MWF formulations. They may influence the lubrication
characteristics. To examine the. role of biocides in governing the behaviour of
lubricants on the lubricity property, a series of biocides were studied for wearscar
diameter (WSD) on the 4-ball machine at different time interval. It was
observed that the rate at which they act, differ widely to each other with lubricity
and the life of fluids. r.
KEY WORDS: Metalworking Fluids, Lubricity, Wear, Biocides
DEVELOPMENT OF MULTIPURPOSE ENVIRONMENT FRIENDLY LUBRICATING GREASE
The paper reports the work carried on the development of multipurpose grease
using vegetable oil and a by-product (residual oil). This includes formulations and
relevant tribological performance parameters. The studies resulted in two
potential candidates as multipurpose grease formulations
Tribo-Fatigue Studies On Synthetic Auto-Gear Oil Formulations
The influence of polyol esters, with and with out
commercial gear oil additives, on rolling fatigue lives of
EN31 steel balls was studied in a rolling contact fatigue
tester. The fatigue lives obtained thus were compared
with those obtained with Reference gear oil. The study
reveals that commercial gear oil additives are synergistic
with polyol esters in improving fatigue lives of EN31 steel
balls
Tribo-Fatigue studies of Gear oils on a rolling contact 4-BALL machine
This work has evaluated the rolling contact fatigue lives of EN-31 steel balls with
several gear oil formulations using a 4-ball tester under accelerated test conditions.
From the fatigue data generated Weibull plots are made and rolling fatigue lives L1o,
Lso, characteristic life r] are determined for all the gear oils. Theoretical estimation of
lubricant film thickness at the contact of surfaces for each gear oils is made. An
attempt was made to assess the influence of film thickness on fatigue lives of steel
balls.
KEYWORDS
Rolling fatigue lives, gear oils, 4-ball machine, weibull plot, film thicknes
Friction and Wear Characteristics of Organic Thiophosphoro Derivatives- A Critical Appraisal
The friction- and wear-reducing characteristics of a number of
oil soluble sulphurised and phosphosulphurised derivatives for
automotive and industrial applications have been reviewed. A
critical appraisal of the suggested causes and mechanism of
friction reduction and anti wear characteristics has been made.
A review of the investigations carried out so far indicates that
the creation of in situ films of simple inorganic salts, such as
molybdenum disulphide, iron sulphide or phosphates of low
shear strength and lamellar structures, does not appear to be
the primary cause of low friction and wear.
The authors have, therefore, undertaken a programme to
synthesise and study the chemistry and tribochemical reactions
in relation to friction and wear characteristics of hydrocarbonsoluble
thiophosphoro derivatives of alkyl phenol, alcohols and
fatty esters, in order to establish relationships between the reactivity,
chemical nature and crystal structure of films formed
on rubbing surfaces, and antifriction and antiwear characteristics.
Molybdenum salts of various phosphorothio derivatives of
pentadecylphenol and lauryl oleate of specific structures have
been synthesised, and the friction and wear properties of their
blends in mineral oil base stock have been studied. It can be
clearly inferred from the results that type of bonding between
sulphur, phosphorus and molybdenum, and reactivity of these
derivatives with rubbing surfaces, determine their frictionreducing
and anti wear characteristics. Their reactivity with
iron and the nature of films formed are under investigation.
friction, wear,
molybdenum
sulphurised, thiophosphoro derivatives