Laboratory Wear Tests With Automotive Gear Lubricants

In the past, most of the work with the SAE E.P. Lubricants Testing Machine has been confined to the testing of the load-carrying capacity of gear lubricants under certain fixed operating conditions which simulate high speed and shock load. This paper describes a different use of the machine for the determination of the wear with gear lubricants under conditions simulating high torque and low speed. The modifications to the machine and the procedure used are described in detail.

Data were obtained with a straight mineral oil and 11 representative samples of commercial lubricants commonly used in automotive gears, when operating at 225°F and various constant loads. The loads covered were 90, 135, 180, and 225 pounds (scale reading). These data showed marked differences in the performance of the lubricants in the higher load range. The trends shown by these differences were in reasonable agreement with the known service performance of these lubricants.

Other information given includes an indication of run-in wear, the change in surface roughness of the test cups with wear, and the effect of the original surface roughness on the rate of wear.