MIL-DTL-11891G(AT)
3.3.4.7.2 Procedure. The metal base of the specimen shall be mounted to one head of the
testing machine using care in centering and adjustment so that the tension shall be uniformly
distributed across the strip width. The machine shall then be started and, when the applied force
causes the elastomer to begin separating from the metal, the recorder shall be started. Force shall
continue to be applied and recorded continuously throughout the test. The point of separation of
the elastomer from the metal shall be observed carefully throughout the test. In the event that
tearing up into the elastomer occurs, the specimen should be cut back to the metal without
stopping the machine.
3.3.4.7.3 Acceptance. The roadwheel path adhesion shall be not less than 60 pounds per
inch of width and the pad adhesion shall not be less than 120 pounds per inch of width.
Successful adhesions will be those that result in a separation in the rubber (rubber tear) without
evidence of separation in the rubber-to-metal interface. The bond between metal and all bonding
agents/cements shall be higher than the component compound so that separation during adhesion
tests occurs only in the rubber. The elastomer pulled off the metal plate/shoe body and that
remaining shall be examined for any defects including cracks, blisters, or porosity. Discontinuity
(non-knit) of the elastomer resulting in any indication of separation of the elastomer shall be cause
for rejection. All data generated during this test will be provided to the Government.
3.3.4.8 Ozone resistance. Prepare specimens in accordance with procedure B of
ASTM D518. The specimens shall be smoothly finished in accordance with ASTM D3182 and
ASTM D3183 and obtained from either of the following (see 4.7.2.11):
a. Three samples each shall be taken from each compound used on the track
roadwheel path and ground pad (integral and/or replaceable) and shall not include
any outer surface.
b. Samples may be taken from each uncured compound production molding blanks,
prepared in the form of ASTM tensile slabs, and certified as being of an equivalent
state of cure as the production molded component (roadwheel path stock and
ground pad).
3.3.4.8.1 Procedure. Specimens shall be tested in accordance with ASTM D1149 and
mounted in accordance with procedure B of ASTM D518, except the length of the clamping
strips shall be such as to facilitate placement within the ozone chamber. Specimens shall then be
placed in the chamber and exposed for 7 days at a temperature of 104 + 3.6°F having a partial
pressure of ozone of 50 millipascals. The specimens shall show no evidence of cracks when
inspected at seven power magnification. Test results will be reported to the Government.
3.3.4.9 Optional ozone test procedure. As an option, the following procedures may be
used in place of the above to accommodate the ozone test requirement (see 4.7.2.11).
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