ASTM D4998 Standard Test Method for Evaluating Wear Characteristics of Tractor Hydraulic Fluids
9. Procedure
9.1 FZG Test Machine Assembly - Assemble the test machine according to the instructions given in Section 3, except employ a modified, low speed drive motor as described in Annex A1.
NOTE 1 - In addition to other precautions, machinery guards are supplied with the FZG test machine to protect personnel from hazards associated with rotating machinery. These should be properly installed before operating the equipment.
NOTE 2 - In addition to other precautions, the electrical connections for the drive motor and heater should be installed in accordance with the current edition of the National Electrical Code.
9.2 Machine Cleaning - Flush the test gear case and associated parts with mineral spirits solvent (see 7.1). (Warning - Combustible. Vapor harmful. Keep away from heat, sparks, and open flame. Keep container closed. Use with adequate ventilation. Avoid prolonged breathing of vapor or spray mist. Avoid prolonged or repeated skin contact.) Fill the gear case with mineral spirits solvent to a level that is above the shaft center line. Manually rotate the shafts so that the bearings are rinsed. Drain mineral spirits solvent from the gear case. Refill gear case with fresh mineral spirits solvent, manually rotate shafts, and drain. Dry gear case with compressed air.
9.3 Gear Condition - Examine the gear tooth faces with a magnifying lens of 3 to 6 power. Do not use gears with imperfections on the tooth faces.
9.4 Gear Cleaning - Wash the test gears in mineral spirits solvent, then acetone (see 7.2), and finally in pentane (see 7.3). After cleaning, handle the gears only with clean tongs or with clean gloves. Allow the gears to dry. To prevent water condensation following gear cleaning, carefully warm the gears to room temperature with a clean, steam hot plate or bearing heater with surface temperature below 75 °C.
9.5 Gear Weighing - Weigh the individual gears using an analytical balance. The gears shall be clean, dry, and at ambient temperature. Record the mass of each gear, rounding to the nearest milligram. Add the mass of each gear and record the sum as initial total gear mass (TMi).
9.6 Gear Installation - Install the test gears.
9.7 Test Procedure - Fill the gear case with test fluid until level with the shaft centerline. Install all machine guards in their proper operating positions. Set the temperature controller to 121 °C. With the heater on and no torque applied, start motor to run at 100 r/min test speed. When temperature stabilizes at (121 +/- 3)°C for (20 to 25) min, stop the motor and apply a tenth stage load. The tenth stage load consists of applying a torque of 373 N·m by means of the torque arm, weights, and the bolted load clutch. Turn on the motor and operate at (100 +/- 3) r/min for 20 h +/- 10 min. Deviations from these limits are to be listed in the report's comments section.
9.8 Gear Removal, Cleaning, and Weighing - Remove the test gears, using extreme care to avoid gear damage. Clean and weigh the gears as described in 9.4 and 9.5. Record the total mass of both gears after testing as total final mass, (TMf).
9.9 Gear Tooth Inspection - Record the number of teeth on each gear that show only the original grinding pattern, scratches, scoring, or scuffing. In this test, scratches are the least severe type of defacement, scoring is intermediate, and scuffing is the most severe. If a tooth exhibits more than one type of defacement, record only the more severe one.
10. Calculation
10.1 Gear Mass Change - Determine the total mass change (TMC) of the precision test gears as follows:
TMC = (TMi) - (TMf)
where:
TMi = total initial mass, and
TMf = total final mass.
