ASTM D4693 for low-temperature torque of grease-lubricated wheel bearings
ASTM D4693 standard test method for low-temperature torque of grease-lubricated wheel bearings
11. Calculation
11.1 Calculate torque using one of the following equations:
T = 0.00981 x F x L
(SI units)
where:
T = torque, N•m,
F = force, kgf, as determined from pen displacement and calibration determined in 7.4, and
L = distance between spindle and load-cell centerlines, mm
or
T = 0.113 x F x L
(mixed units)
where:
T = torque, N•m,
F = force, lb, as determined from pen displacement and calibration determined in 7.4, and
L = distance between spindle and load-cell centerlines, in.
12. Report
12.1 Report the following for each torque test:
12.1.1 Date of test and grease identity,
12.1.2 Corrected spindle temperature, °C, at start of run,
12.1.3 Torque, N•m, at 60 s test time, and
12.1.4 Maximum torque (see section 10.14).
NOTE 13 - To provide information, Table 1 shows the torque results obtained in NLGI Reference System A (Batch 3).
13. Precision and Bias
13.1 Precision - The precision of the method as determined by statistical examination of interlaboratory results is as follows:
13.1.1 Repeatability - The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values in only one case in twenty.
Repeatability = 0.22 M
where M is the average of the two results.
13.1.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories with identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values in only one case in twenty.
Reproducibility = 0.55 M
where M is the average of the two results.
13.2 Bias - The procedure in this test method has no bias because the value of low temperature torque can be defined only in terms of a test method.
14. Keywords
14.1 low temperature torque; lubricating grease; wheel bearing grease
