Use of Bench Tests to Evaluate Water-Glycol Hydraulic Fluid Lubrication

The anti-wear lubrication performance of a series of hydraulic fluids was determined using various bench wear tests including: Four-Ball, Pin-on-V-Block Falex Wear Test, Timken Block-on-Ring, a recently developed cyclic contact stress (3-vane-on-ring) test and the ASTM D-2882 Vickers V-104C vane pump test. These bench tests were selected since they are used in the fluid power industry for fluid selection, qualification and performance troubleshooting. The results of this work showed that none of the bench tests evaluated provided any correlation with the wear rates obtained with the ASTM D-2882 pump test. Bench wear test correlations are possible only if the conditions of the wear test, such as wear contact geometry, loading, speeds, and materials reasonably model the specific wear contact of interest in the hydraulic pump. Even then, the general reliability of the bench testing conditions should first be validated by hydraulic pump testing.