MIL-DTL-85405A(AS)
4.5.3 Brake system tests.
4.5.3.1 Parking brake tests. The trailer, loaded with a 4,000 (+100, -0) pound test load
(see 4.5.5.2), shall be placed on a +5, -0 degree inclined ramp, facing uphill, and with parking
brakes applied, the trailer shall not roll. The loaded trailer shall then be tested facing downhill.
This test should be performed after all mobility testing to ensure that the brakes have been
burnished to achieve a successful test.
4.5.3.2 Service brakes. The trailer loaded with 4,000 (+100, -0) pound test load
(see 4.5.5.2), shall be connected to a prime mover and the trailer test brakes shall be tested in the
following manner.
4.5.3.2.1 Brake stopping capability test. Tow the loaded trailer at a speed of 20 mph on
level, dry concrete. Stop by applying brakes of towing vehicle thus actuating the trailer inertia
brake. The trailer shall stop within 30 feet or less from the point where the brakes were first
applied. The trailer shall not exhibit any tendency to jackknife. At the end of five test cycles,
inspect the service brakes and actuating mechanism. Failure to operate or evidence of excessive
heating or distortion shall be cause for rejection.
4.5.3.2.2 Back-up test. After acceptance under 4.5.3.2.1, the trailer shall be subjected to a
back-up force. The service brakes shall hold momentarily but with continued force, shall release
and allow unrestricted rearward travel. The test shall be performed five times.
4.5.4 Towing force test. A scale shall be placed between the prime mover and the towbar of
the trailer, loaded with a 4,000 (+100, -0) pound test load (see 4.5.5.2). The prime mover shall
apply a gradual towing force through the scale to the loaded trailer, with its brakes released and
with the trailer on level, dry concrete. The trailer shall roll before the scale registers 100 pounds.
4.5.4.1 Breakaway test. Manually tow the trailer loaded with a 4,000 (+100, -0) pound test
load. While under tow, exert a pull on the breakaway cable to actuate the brake system. The
wheels should lock, bringing the trailer to a halt. This test shall be repeated, but this time,
actuating the brake system with the manual device affixed to the surge brake, to bring the trailer
to a halt.
4.5.5 Load tests.
4.5.5.1 Overload test. The overload test shall be accomplished by placing an 8,000
(+100, -0) pound test load evenly distributed over the entire trailer deck for a 10 minute period.
At completion of the test, evidence of permanent distortion such as warpage of trailer deck, or
damage such as dents or breakage of component parts, or misalignment of wheels or other defects
detrimental to the intended end use, shall be cause for rejection.
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