Damage caused by collision
Failure of any major component
Vibration due to misalinement of wheels or frame
Vibration due to the type of construction or mounting
Evidence of abnormal tire wear due to misalinement or unbalance
Failure of any vehicular safety device such as brakes or electrical circuits
Evidence of structural weakness in any part of the vehicles, vehicle components,
accessories or welds
Loose mountings of parts or accessories due to workmanship or vehicular operation.
4.3.3 Turning ability test. A truck-tractor shall be coupled to the semitrailer and driven
through turns up to 900 to the towed vehicle, right and left to determine conformance to 3.3.1.
At the conclusion of five turns in each direction, the tractor and the trailer shall be examined for
evidence of binding, misalinement or other damage.
4.3.4 Brake tests. The semitrailer, carrying the rated payload and coupled to the
truck-tractor, shall be driven on smooth, dry, level pavement and brakes applied from a speed of
20 mph, to determine conformance to the stopping distance required under 3.3.2. Breakaway
situation shall be simulated to verify braking ability upon breakaway.
4.3.5 Parking brake test. To test parking brakes, the semitrailer, with rated payload, shall be
placed on a 10 percent grade, first headed up the grade and then headed down the grade, and
tested to determine conformance to 3.12.1. These tests shall be conducted with the semitrailer
disconnected from the towing vehicle and resting on the landing legs.
4.3.6 Landing leg test. With the trailer disconnected from the towing vehicle and loaded
with the rated payload, the landing legs shall be raised and lowered to vary the height of the
upper fifth wheel from 47 inches to not less than 52 inches from the ground, and tested to
determine conformance to 3.14. The trailer with the rated payload shall be coupled and
uncoupled no less than 5 times and the landing legs shall be examined for binding and or
misalinement. Ground clearance when coupled to the towing vehicle shall be no less than
11 inches below the lowest point of the landing legs.
4.3.7 Ramp operation test. Using the semitrailer mounted controls, the ramp, without
payload, shall be lowered to the ground; elevated so that the loading edge of the ramp is not less
than 54 inches above ground; and lowered and secured in the horizontal travel position. Ramp
operation shall conform to the requirements specified in 3.7.4 when the ramp is being powered
by the ramp hydraulic system specified in 3.8.5. The test shall be conducted five times with
mounted controls and repeated five times with remote controls when furnished.