Standard Test Method for Low-Temperature Torque of Ball Bearing Grease
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 −75 to −20°C (−100 to 0°F).
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.
Test Method D 4693 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 D 4693 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.
FIG. 1 Torque Test Apparatus Assembly
FIG. 2 Drive (Top View)
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 -20°C (0°F)).
1.1.1 Torque measurements are limited by the capacity of the torque-measuring equipment. Note 1 - When initially developed, the original dynamometer scale limited the torque capacity to approximately 30 000 gcm; the original dynamometer scale is obsolete, however. The suggested replacement scale has not been evaluated; it could extend the limit to approximately 75 000 gcm.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. The exception is torque values that are given in cgs-metric units, which are universally used in grease specification.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard and warning statements, see 6.1.1, 7.2, 7.4, 8.7, and 8.11.
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