Wheel hub assembly and method of testing
A wheel hub assembly includes a mounting base and a wheel hub supported for rotation on the mounting base by a plurality of bearings disposed within an annular space between the hub and base. A sealing system is provided that seals all points of intrusion into the space such that liquid contaminants are inhibited or precluded from entering the space and reaching the bearings when the assembly is subjected to an immersion/thermal shock test in which the assembly is heated to an elevated temperature and then immersed on a cold bath of the liquid contaminant. A method of testing the sealing integrity of wheel hub assemblies is also provided.
1. A method of evaluating water intrusion into a newly manufactured wheel hub assembly comprising a mounting base, a wheel hub, an annular gap between the mounting base and the wheel hub, lubricated bearings disposed in the annular gap for supporting the wheel hub for rotation relative to the mounting base, and a sealing arrangement for limiting the intrusion of water into the annular gap, comprising the steps of:
placing the wheel hub assembly into a heating chamber for a period of time until at least a portion of the wheel hub assembly reaches a target elevated temperature of about 200° F.;
removing the wheel hub assembly from the heating chamber after the portion of the wheel hub assembly is heated to at least the target elevated temperature;
providing a cooling environment comprising a liquid that is maintained at a target reduced temperature in the range of 35-40° F.;
immersing the wheel hub assembly, after removing it from the heating environment, into the cooling environment such that the wheel hub assembly experiences a temperature differential of 160-165° F. from the target elevated temperature to the liquid of the cooling environment; and
removing the wheel hub assembly from the cooling environment after a pre-determined time period.
2. The method of evaluating water intrusion into a wheel hub assembly of claim 1 , further comprising the steps of:
taking a first measurement of the mass of the wheel hub assembly prior to the step of placing the wheel hub assembly into the heating environment; and
taking a second measurement of the mass of the wheel hub assembly after removing the wheel hub assembly from the cooling environment.
3. The method of evaluating water intrusion into a wheel hub assembly of claim 2 , further comprising the step of:
drying the external surface of the wheel hub assembly after removing the wheel hub from the cooling environment and prior to taking the second measurement of the mass of the wheel hub assembly.
4. The method of evaluating water intrusion into a wheel hub assembly of claim 3 , wherein the second measurement of the mass of the wheel hub is no more than 3.0 grams greater than the first measurement of the mass of the wheel hub.
5. The method of evaluating water intrusion into a wheel hub assembly of claim 3 , wherein the second measurement of the mass of the wheel hub is no more than 1.0 gram greater than the first measurement of the mass of the wheel hub.
6. The method of evaluating water intrusion into a wheel hub assembly of claim 3 , wherein the second measurement of the mass of the wheel hub is no more than 0.1 gram greater than the first measurement of the mass of the wheel hub.
7. The method of evaluating water intrusion into a wheel hub assembly of claim 3 , wherein the second measurement of the mass of the wheel hub is equal to the first measurement of the mass of the wheel hub.
8. The method of evaluating water intrusion into a wheel hub assembly of claim 1 , further including the step of subjecting the wheel hub assembly to a slurry of mud and salt in water while subjected to a load.
9. The method of evaluating water intrusion into a wheel hub assembly of claim 8 , wherein the load includes a radial force of approximately 7.35 kN and an axial force of approximately 2.2 kN.
10. The method of evaluating water intrusion into a wheel hub assembly of claim 9 , wherein the wheel hub assembly is subjected to the slurry of mud and salt in water for approximately 2 hours.