MIL-DTL-11891G(AT)
APPENDIX D
D.3.4 T157I design characteristics. The T157I pad is part of a single pin track. See
figure 24 for a T157I track illustration.
D.3.5 Test course. The Preparing Activity will select the test course for conducting all
on-vehicle qualification tests. The preferred course is located at the U.S. Army Yuma Proving
Ground (YPG), Yuma, Arizona. Yuma has been traditionally selected for on-vehicle track testing
because of climate, course, and test result consistency. The following standard track laying
vehicle (tank and other tracked vehicles) test courses at YPG are designated for testing track for
this specification.
a. Paved course. The dynamometer course is a 2 mile, smooth, near level
(0.8 percent grade), 30 foot wide roadway with 500 foot radius turnarounds at
each end, surfaced with a high strength asphalt. The course is located at an
elevation of approximately 470 feet above sea level and is staked at 0.1 mile
intervals throughout its length with accurately surveyed distance markers.
b. Gravel course. The tank gravel course is a 3.6 mile compacted and graded gravel
course and is for testing track laying vehicles under conditions simulating a
secondary gravel road. The course consists of short straight sections and curves of
varying radii with many moderate and sharp turns.
c. Hilly cross-country course. The tank hilly cross-country B course is 2.7 miles long
and has short steep grades (35 percent) with a greater proportion of slopes less
than 20 percent. This course has surfaces varying from sand and gravel to exposed
bedrock. The loose gravel, sharp stones, and rocks present a severe cutting and
abrasion problem for tracks and roadwheels.
d. Level cross-country course. The tank level cross-country course traverses areas of
level, sandy terrain with many bumps that provide a severe test of track laying
vehicles. The dust conditions are typical of cross-country operation on dry soil.
One lap is 6.7 miles.
D.3.6 Operational mode summary. The operational mode summary for the test shall
consist of 21% paved (concrete, asphalt, or macadam), 45% on gravel composed mostly of small
stones, and 34% on cross-country (equal amount of hilly and level). During the test, the vehicle
shall not traverse more than 50 continuous miles over any type of terrain. Vehicle direction
around the test courses shall be changed periodically to assure approximately equal clockwise and
counterclockwise test operation.
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