TORQUE, LOW TEMPERATURE OF GREASE LUBRICATED WHEEL BEARINGS: D4693
EXPLANATION
This test method determines the extent to which a test grease retards the rotation of a specially manufactured, spring loaded, automotive type wheel bearing assembly when subjected to low temperatures. Torque values, calculated from restraining force determinations are a measure of the viscous resistance of the grease. This test is used for specification purposes and correlates with its precursor which has been used to predict the performance of greases in automotive wheel bearings in low temperature service.
TEST SUMMARY
A freshly stirred and worked sample of grease is packed into the bearings of a specially manufactured, automotive type spindle bearings hub assembly. The assembly is heated and then cold soaked at -40° C. The spindle is rotated at 1 r/min and the torque required to prevent rotation of the hub is measured at 60 s.
TEST PRECISION
Repeatability: 0.22 M
Reproducibility: 0.55 M
Where M is the average of two results.
This test method has no bias.
