MIL-DTL-11891G(AT)
a fatigue test machine (see 4.7.2.14) having a static load and a dynamic (oscillating) load as
specified in 3.3.4.12a below as applicable. Cyclic loading will be at 1800 cycles per minute with
automatic load sensing and compensation capability. Fifteen (15) track block samples of each
compound being submitted for qualification will be required with 12 being tested. The highest
and lowest cycles to failure will not be counted and the results will be the average of the
remaining ten (10) track block samples. All test results will be provided to the submitting
contractor indicating acceptance or rejection of the samples (see 4.7.2.14).
a. T107 ground side chevron pads are to be subjected to a dynamic load of
1600 pounds and a static load of 1600 pounds for a total load of 3200 pounds.
The minimum average fatigue life (blowout) shall not be less than 50 000 cycles
with no individual block of the original twelve (12) samples below 45 000 cycles.
3.3.4.13 Product marking. Unless otherwise specified (see 6.2), each track shoe assembly
(roadwheel path elastomer) and track shoe pad (replaceable or integral) shall have the following
information permanently and plainly marked on it. Every attempt possible should be made to
locate this information in an area that may not get damaged/worn during field use.
a. Manufacturer's name or rubber manufacturer's code number.
b. National stock number of the track shoe assembly and/or track shoe pad kit as
applicable.
c. Week of month and year of manufacture.
d. Compound number and mold number.
3.4 Phase III endurance tests.
3.4.1 Bushing endurance. The bushing qualification/endurance testing will be conducted
in accordance with the test requirements of Appendix A and results provided to the Government.
Compounds that have passed all qualification test requirements and have documented data
supporting compliance to all requirements will be listed on the QPL by number and source for all
track bushings with the exception of T158 and T158LL track systems.
3.4.1.1 Endurance test requirements. The bushing endurance test for qualification will be
conducted in accordance with the requirements of Appendix A. The minimum acceptance criteria
for fatigue life-to-failure for all 9 specimens tested is 110 000 compression load cycles
simultaneous with 440 000 torsional cycles without exceeding 0.144 inches of radial deflection at
the bushing center line. The minimum average of 8 specimens, dropping the highest bushing test
cycles, shall not be less than 130 000 cycles.
3.4.1.2 Process Fingerprint Plan. Following qualification and prior to any production, the
contractor's Process Fingerprint Plan (see 3.3) with the predicted and actual target values and
ranges shall be reviewed by the contractor with the Government QAR to determine whether any
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