ASTM D1478 test method for low-temperature torque of ball bearing grease
6. Apparatus
6.1 Fig. 1 shows a suitable torque test apparatus assembly. It consists of the components described in 6.1.1-6.1.5.
6.1.1 Low-Temperature Box - Any well-insulated box of at least 0.03 m3 (1 ft3) interior volume, in which the air temperature can be controlled and maintained within 0.5°C (1°F) of the test temperature.
NOTE 2 - Caution: Direct impact on the test bearing by an air stream colder than the test temperature must be avoided to preclude erroneous results. Baffles should be used where necessary to prevent such direct impact. The drive mechanism can be mounted externally as shown in Fig. 2, or the entire drive mechanism can be inserted directly into the box. When the drive is mounted externally, the temperature measured at a point on the surface of the test shaft between the test bearing and wall of the box shall be not more than 0.5°C (1°F) above the test temperature.
6.1.2 Drive Assembly, as shown in Fig. 2, including drive motor, gear reductor, and test shaft. The test shaft shall receive the test bearing against a shoulder having a diameter smaller than the inner race shoulder of the bearing. Use a spacer washer of the same diameter and at least 1.6 mm (1/16 in.) thick, along with a test bearing lock nut, to clamp the inner ring of the test bearing to the 1 r/min shaft.
6.1.3 Housing (Cage) - Bearing housing, load disk, load ring, clamp rod, and associated parts made in accordance with Fig. 3. Adjust the housing mass to 454 +/- 3 g.
6.1.4 Torque-Measuring Equipment - A calibrated dynamometer scale having a range of approximately 0 to 10 kg, 0 to 100 N, or 0 to 25 lb, with a large face diameter (approximately 200 mm (8 in.), or larger) and a suitable connecting cord.
NOTE 3 - Substitution of other suitable torque-measuring equipment, such as a strain-gage load cell, is permitted.
6.1.5 Spindle and Grease Cup, as shown in Fig. 4 and Fig. 5, respectively.
7. Materials
7.1 Test Bearing - No. 6204 size open ball bearing (Standard 20-1987, AFBMA Code 20BCO2JO) containing eight 7.9 mm (5/16 in.) balls, separated by a two-piece, pressed steel cage, and manufactured to ABEC-3 (Annular Bearing Engineering Committee) tolerances with the standard radial clearance of 0.021 to 0.028 mm (0.0008 to 0.0011 in.).
7.2 Stoddard Solvent, conforming to Specification D235, Type I.
NOTE 4 - Warning: Combustible. Health Hazard.
7.3 n-Heptane, commercial grade or ASTM Knock Test Reference Fuel, n-heptane.
NOTE 5 - Warning: Flammable. Health Hazard.
