ASTM D1478 – Standard Test Method for Low-Temperature Torque of Ball Bearing Grease
Description:
Significance and Use
5.1 This test method was developed using greases having very low torque characteristics at −54 °C (−65 °F). Specifications for greases of this type commonly require testing at this temperature. Specifications for greases of other types can require testing at temperatures from −73 °C to −18 °C (−100 °F to 0 °F).
5.2 This test method has proved helpful in the selection of greases for low-powered mechanisms, such as instrument bearings used in aerospace applications. The suitability of this test method for other applications requiring different greases, speeds, and temperatures should be determined on an individual basis.
5.3 Test Method D4693 may be better suited for applications using larger bearings or greater loads. However, greases having such characteristics that permit torque evaluations by either this test method or Test Method D4693 will not give the same values in the two test methods (even when converted to the same torque units) because the apparatus and test bearings are different.
Scope
1.1 This test method covers the determination of the extent to which a grease retards the rotation of a slow-speed ball bearing by measuring starting and running torques at low temperatures (below −18 °C (0 °F)).
1.1.1 Torque measurements are limited by the capacity of the torque-measuring equipment.
1.1.2 This test method is not suitable for greases exhibiting torque values greater than 50 000 g·cm at the selected test temperature.
NOTE 1: When initially developed, the original dynamometer scale limited the torque capacity to approximately 30 000 g·cm; the original dynamometer scale is obsolete, however. The suggested replacement scale has not been evaluated; it could extend the limit to approximately 50 000 g·cm.
1.2 The values stated in SI units are to be regarded as standard.
1.2.1 Exceptions—The values given in parentheses are for information only. The exception is torque values that are given in cgs-metric units, which are widely used in grease specifications.
ASTM D1475