ASTM D4290: Leakage of Wheel Bearing Greases

ASTM D4290 – Leakage Tendencies of Automotive Wheel Bearing Grease Under Accelerated Conditions

Automobile wheel bearings are exposed to high loads, high speeds and high temperatures. For the bearings to operate efficiently for long periods of time they require a grease that resists mechanical and thermal changes, one that will not separate, slump, soften or leak. The grease also needs to resist the formation of sludge, varnish, gum and lacquer. This test quantitatively determines bearing leakage and qualitatively reports observations of the grease appearance at the end of the test.

This method uses a specifically designed hub-spindle-bearing assembly. A standard quantity of test grease is packed into the inboard and outboard tapered roller bearing cones. An additional standard quantity of grease is packed into the hub and the unit is assembled as per the method. A thrust load is applied, the spindle speed and the temperature are set and the bearings are allowed to spin for the predetermined time. The amount of grease and oil that falls from the assembly is measured. Reported are the grams of grease that leak from the bearings and any observations of the grease condition, such as the formation of gums, varnish or lacquer-like material.