ASTM D3527 Test Method for Life Performance of Automotive Wheel Bearing Grease
10. Procedure
10.1 Prior to each test, check the freedom of movement of the thrust loading shaft (Fig. 3) in the spindle. If binding is noted, remove and clean both shaft and spindle bore.
10.2 Install the new cups in the cleaned hub in the location shown in Figs. 1 and 2.
10.3 Weigh an inboard and outboard bearing cone to the nearest 0.1 g. Fill the cones with test grease using an extra set of cups and the grease packer shown in Figs. 4 and 5. Use care to avoid moving the rollers or bearing components while removing the cones from the cups and in all subsequent wiping and handling steps. Strike off excess grease flush with the front face of the cone (near small end of rollers) using a small spatula. Wipe all grease from cone bore, cone back face, exterior cage surfaces, and exposed roller surfaces with a clean, lint-free cloth or towel and reweigh. Adjust the grease weight in the inboard cone to 3.0 +/- 0.1 g and in the outboard cone to 2.0 +/- 0.1 g by wiping or adding grease to the groove between the cage and the cone back face. Apply a thin film of grease on the cups.
10.4 Install the leakage collector, inboard cone, hub, and outboard cone on the spindle (Fig. 2). Lock the components in place with the end cap and screw. Install the spindle connector.
10.5 Referring to Fig. 3, adjust the thrust load as follows: tighten the compression nut G until the spring F is seated against the back plate E, but not compressed. Bring the lock nut H up to the compression nut G. Without moving H, compress F by tightening G until the compression gage J will fit between H and G. Hold J in position and back off G until J is held firmly between H and G.
NOTE 3 - Compression gage J has been machined such that insertion and adjustment of G causes spring F to compress and apply a 111-N (25-lbf) axial load on the wheel bearings.
10.6 Insert the thermocouple in the spindle thrust rod and position the junction at the center of the outboard bearing position. Close the cabinet and position the motor to operating location. (Warning - Do not engage the drive at this point. Start the motor and adjust the speed to 1000 +/- 50 rpm. At this point observe and record the unloaded motor current N.)
10.7 Turn off the motor, engage the drive coupling and lock in position. Set the timer to begin a 20-h cycle. Restart the motor and again adjust the speed to 1000 +/- 50 rpm. Turn on the heaters and adjust the oven temperature to maintain the spindle temperature at 160 +/- 1.5°C (320 +/- 2.7°F). When the spindle temperature has stabilized at the test temperature, make no further adjustment of the oven temperature for the duration of the test.
10.8 A steady-state running torque will develop in the first 2 h of operation as indicated by a stabilized value on the meter. Record this value as steady-state current T. Determine the motor cutoff value as follows:
C = 8(T - N) + N
where:
C = motor cut-off value, amps,
T = steady-state current, amps, and
N = unloaded motor current, amps.
Set the automatic torque cutoff of motor to value of C.
10.9 Permit the apparatus to operate under the prescribed conditions of load, speed, and temperature until the preset torque limit is exceeded at which point the test will be terminated automatically. Record the time the unit shuts down.
NOTE 4 - The motor is protected by a 30 s time delay.
10.10 Allow the tester to cool to a safe handling temperature and disassemble. If the tester is disassembled hot, use insulated gloves.
11. Parts Cleanup
11.1 With a suitable spatula, remove as much grease as possible from the grease collector, end cap, and spindle connector.
11.2 Place the parts in a suitable clean container (preferably stainless steel) and cover with Penetone ECS (Warning - See 8.3). Install a loosely fitting cover and heat gently (70 +/- 10°C) until the parts are clean (several hours). Avoid prolonged (overnight) heating as parts corrosion can occur.
11.3 Remove the parts from the solvent and wash with hot running water. Rinse immediately with isopropyl alcohol (Warning - See 8.2). Air dry. If the parts will not be used immediately, apply a film of SAE 10W engine oil.
11.4 Use a suitable spatula to scrape grease off of the spindle. Remove the remaining deposits from the spindle using 00 grade steel wool and Stoddard solvent (Warning - See 8.4). If strongly adherent deposits resist this treatment, remove the spindle and clean in hot Penetone ECS.
