ASTM D6121 Test Method for Evaluation of the Load Carrying Capacity of Lubricants
ASTM D6121 Standard Test Method for Evaluation of the Load Carrying Capacity of Lubricants Under Conditions of Low Speed and High Torque Used for Final Hypoid Drive Axles
10. Test Procedure
10.1 Gear Conditioning Phase:
10.1.1 Set the temperature control to maintain a lubricant temperature of 297 +/- 3°F (147.2 +/- 1.7°C). See Table A6.1 for alternate versions.

10.1.2 With the engine warmed up and with no load on the dynamometers, shift smoothly to a gear appropriate for the test conditions.

10.1.3 After reaching the appropriate gear, accelerate smoothly to 440 +/- 5 wheel r/min and apply dynamometer load to achieve a torque load of 395 +/- 15 lbf-ft (533 +/- 20 Nm) on each wheel (see Note 1).

NOTE 1 - The time required to accelerate to the test conditions of 440 wheel r/min and 395 lbf-ft is about 2 min.

10.1.4 The test starts when required speed and torque conditions are reached. Record the time as start of the test.

10.1.5 After reaching speed and load conditions, run the test for 100 6 1 min.

10.1.6 To ensure accuracy of the test, record speed, load, and temperature at a minimum of once every 10 min.

10.1.7 At the end of 100 min, close the throttle smoothly, shift transmission to neutral, and record ending time and temperature of the lubricant.

10.1.8 At this time, an optional inspection of the gear set condition is permitted. If chosen, remove the inspection plug located at the top of the axle cover and note the condition of the ring gear in accordance with CRC Rating Manual 17.

10.2 Gear Test Phase:
10.2.1 Set the temperature control to maintain a lubricant temperature of 275 +- 3°F (135.0 +/- 1.7°C). See Table A6.1 for alternate versions.

10.2.2 With the engine warmed up and with no load on the dynamometers, shift smoothly to a gear appropriate for the test conditions.

10.2.3 After reaching the appropriate gear, accelerate smoothly to 80 +/- 1 wheel r/min and a dynamometer load to achieve a wheel torque load of 1740 +/- 35 lbf-ft (2349 +/- 47 Nm).

10.2.4 The test phase starts when required speed, torque, and temperature conditions are reached. Record the time as start of the test phase.

10.2.5 After reaching speed, load, and temperature conditions, run the test for 24 +/- 0.2 h.

10.2.6 To ensure test accuracy, record speed, load, and temperature at a minimum of once every hour.

10.2.7 At the end of 24 h, close the throttle smoothly, shift the transmission to neutral, and record time and temperature of the lubricant.

10.2.8 Disconnect the drive shaft and axle shafts from the dynamometers, and remove the test unit from the test stand while the test unit is hot.

11. Axle Post Test Measurements
11.1 Break and Turn Torques:
11.1.1 While the unit is hot, determine and record the torque required to break and to turn the pinion shaft of the completely assembled test unit.

11.1.2 Allow the unit to cool and record the torques required to break and to turn the pinion shaft of the completely assembled test unit.

11.2 Drain the axle of test lubricant. This may occur anytime after 10.2.7 has been completed.

11.3 Backlash Measurements - Remove the cover plate. Record backlash at four equally spaced locations on the ring gear and calculate the average of the four readings.

11.4 Completely disassemble the differential and the pinion shaft assemblies for inspection.

12. Determination of Test Results
12.1 Pinion Bearing Rating:
12.1.1 Examine the bearings for wear, surface fatigue corrosion, and deposits in accordance with CRC Rating Manual 17.

12.2 Gear Rating:
12.2.1 Examine the tooth surfaces on the drive side of the pinion and ring gear for the following distresses in accordance with CRC Rating Manual 17 and Annex A9: burnishing, wear, pitting, spalling, ridging, rippling, scoring, discoloration, corrosion, and deposits. Rate each distress by identifying its level of distress in accordance with Table 1. Refer to Annex A9 for levels of distress for pitting/spalling.

12.2.2 Four distress types (ridging, rippling, scoring, and wear) are assigned a numerical value between 0 and 10 corresponding to the rated level of distress, as shown in Table 1. The pitting/spalling distress type is assigned numerical values, as shown in Table A9.1.

12.2.3 When using the nonlubrited hardware, gear set C1L426/P4L415A, determine a numerical pitting/spalling value, excluding any pitting/spalling value between 9.3 and 9.9, inclusively, in the wear step area of the drive side pinion tooth, as per Annex A10.
12.2.3.1 When using the nonlubrited hardware, gear set V1L303/P4L514A, determine a numerical pitting/spalling value, excluding any pitting/spalling value between 3.0 and 9.9, inclusive, in the wear step area of the drive side pinion tooth, as per Annex A10.

12.2.3.2 Report this rating value on Figs. A7.2 (Form 1) and A7.4 (Form 2) for reference oil tests and Figs. A7.3 (Form 1A) and A7.4 (Form 2) for non-reference oil tests of the test report package.

12.2.3.3 A second pitting/spalling value obtained in either case may be determined by including any pitting/spalling in the wear step area of the drive side pinion tooth, as per Annex A10. If this rating method is used, report this rating value in the comment section on Fig. A7.6 (Form 4) of the test report package for information only.

12.3 For a test rating to be valid, the gears shall be rated by an individual who has participated in a CRC sponsored, high-volume, gear-rater calibration workshop within the previous twelve months.

12.4 Test Validity - The test is determined to be operationally valid if the percent deviation of the critical operating parameters and number of shutdowns are within the limits specified and defined in Annex A8.