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| MIL-S-46777C
During the road test and while towing rated payload, perform the following and record actual
results:
(a)
Tow the semitrailer on side slopes up to 10 percent, having the curb side downhill
and having the road side downhill.
(b)
Tow the semitrailer over 7-inch-high obstacles such that all combinations of the
wheels have passed over the obstacles. Observe tire-to-surface contact, evidence of
binding or interference, and, after returning the suspension to normal, measure the
diagonals and parallels for evidence of misalinement. Questionable tire-to-surface
contact shall be retested with single sheets of newspaper under the tires. Ability to
remove the newspaper without tearing from under any tire shall be evidence of
insufficient tire-to-surface contact.
(c)
For tandem and multiple axle semitrailers only, weigh the weight imposed on each
semitrailer axle (each axle on a separate scale) simultaneously and record the
weight on each axle. Jack up each axle separately and return it to its scale, again
recording the weight imposed on both the raised axle and those not raised. After
each axle has been raised and all axle weights recorded, compare the suspension
equalization differences between axles.
(d)
Tow the semitrailer over standard, US Bureau of Public Roads V-ditches not less
than 36 inches wide and 18 inches deep. Negotiate the ditches both perpendicular
and at an angle of 45 degrees to the direction of travel for at least 10 times total.
(e)
Measure and record the deviation or off tracking of semitrailer with respect to the
prime mover, when the semitrailer is towed straight ahead on a paved surface.
(f)
Jackknife the semitrailer at angles up to 90 degrees from straight ahead both to the
left and to the right.
(g)
Turn the prime mover, towing the semitrailer, in a suspension, pivoting
sharp-turning circle for two complete turns and repeat in the opposite direction.
(h)
Park the truck-tractor semitrailer combination, that is equipped with semitrailer
supports, on a paved surface. Lower the supports to a height of 4 inches from the
pavement. Uncouple the brake lines, setting the brakes, and unlock the tractor's
fifth wheel jaws. With the tractor in low-low or in second-low gear, quickly engage
the drive train and immediately accelerate the tractor out from under the front of the
semitrailer, rapidly removing all support at the front of the semitrailer and allowing
the supports to strike the paved surface in free fall. Repeat the supports impacts for
a total of at least two free falls. Inspect both the supports and the semitrailer.
Operate the supports from fully retracted to fully raised at least five times after the
test.
(i)
While dumping the payload, measure the semitrailer and all contractor furnished
components in accordance with SAE J1077 to insure sound level compliance with
both DOT Noise Emission Standards and DOL OSHA regulations on construction
job site, based on a normal 8-hour shift per day and 20-miles to go for payload.
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