Wheel Bearings Grease Requirements
(1) Heat resistance
Under normal speed and road conditions, wheel bearings’ load and temperature are not high. However, when the car is going downing a slope or braking at fast speed, the friction heat of the brake drum will be transferred to the bearing. As a result, bearing temperature can reach 130~150℃. Therefore, grease need to have excellent high temperature performance.
(2) Shear stability for wheel bearings grease
Automobile wheel bearing grease is subjected to strong mechanical shear during high-speed operation of the wheel. As a result, grease need to have long life time without being softened or lost.
(3) Water resistance and rust resistance
Outdoor driving is affected by weather and road conditions. Grease inevitably comes into contact with rain and dust, which will destroy the colloidal structure of the grease and causing bearing corrosion. Therefore, grease need to have good water resistance, colloidal stability and excellent rust prevention.
(4) Low temperature
When a car is driving in a severe cold zone, the grease is required to have an ideal low-temperature torque to meet the needs of low-temperature lubrication.
(5) Extreme pressure and wear resistance
When a car is driving, especially during transportation, bearings are affected by the speed, road conditions and load factor. Therefore, it is prone to friction and wear, and the grease need to have a certain degree of anti-wear.
(6) Anti-oxidation, long life
The frictional heat generated when the car is running or braking keeps the grease at a higher temperature for a long time. It will accelerate oxidation, rancidity, and deterioration of grease, and affects service life of grease and bearing. Therefore, lubricate grease has to be oxidation resistant and long life.
(7) Adhesion for wheel bearing grease
In order to meet the needs of high-speed vehicle operation, wheel bearing grease has increased the base oil viscosity of grease and a tackifier to improve the adhesion of the grease.
Factors to Consider When Choosing Grease
(1) Determine the low temperature performance of the grease (such as: low temperature torque, similar viscosity, etc.) according to the lowest operating temperature.
(2) Determine the high temperature performance of the grease (such as dropping point, evaporation loss, etc.) according to the maximum operating temperature.
(3) Determine the base oil viscosity, consistency and mechanical stability of the grease according to the normal speed of the bearing.
(4) Determine the water resistance, mechanical stability and rust resistance of the grease according to the environmental conditions of the equipment.
(5) Determine whether the grease has extreme pressure according to the load conditions of the equipment
At present, the recommended grease for automobile wheel bearings are as below:
complex lithium grease,
composite aluminum grease,
polyurea grease, etc.