IN the work reported in this paper the performance of several recognized commercial types of hypoid lubricants has been studied and a comparison made of a number of test methods including: film-strength machine tests; various types of continuous-load tests; laboratory shock tests; and road shock tests. This work has been in progress for more than fifteen months, has involved more than 50 lubricants, and more than 150 individual gear tests, each test requiring the use of a new set of gears.
The results of these tests indicate deficiencies in some of the lubricants under certain of the extreme conditions employed. Of the commercial lubricants studied, those that passed the laboratory shock test lubricate hypoids quite satisfactorily under practically all other test conditions where normal temperatures were used. The performance of the lubricants in the gear tests seems to bear but a slight relation to film-strength data as obtained on laboratory test machines.