TABLE III. Semitrailer specifications (continued).
Min. 8-in. travel range from compression to rebound each axle.
Cushioning bumper stops, anti-sway components linking
road-side and curbside, and heavy duty shock absorbers
Provide positive cushioning stops other than shock absorbers to
halt rebound and withstand min. 2-g unsprung weight
deceleration, typical of lowering the semitrailer with a crane.
Air spring suspension of trailing member type, having piston or
multiple bellows per SAE J551, internal bumpers.
Provide air pressure protection valve, air controls, and air-tight
Plumbing of flexible hose and reusable swivel fittings, same as
for air braking system.
Ride frequency max. 130-CPM at center of dump body. Height
control valves, closed center time delay type protected from road
splash, debris, and obstacle damage.
Time delay limits min. 3-sec. to max. 8-sec.
Guarded driver over-ride air control on roadside front for
selection of (1) high, maximum suspension height, (2) average,
normal automatic height, and (3) low, depleted-air height.
Tires comply with TRA Year Book and DOT FMVSS for
highway speeds and 50 mph for ML tires.
Tires at least 100 level quality intended for use on powered units.
Provide all tires with traction-road-lug type tread. Unless
otherwise specified, provide 2-ea. widebase single tubeless tires
on each axle, min. size 18-22.5 ML, min. LR-H (16 PR).
When specified (see 6.2), furnish 4-ea. conventional radial dual
tubeless tires on each axle, min. size 12R22.5 min. LR-G
When specified (see 6.2), furnish 4-ea. conventional bias dual
tube-type tires on each axle, min. size 11.00-22 min. LR-G
(14PR); provide heat resistant radial type inner tubes, tire flaps,
and multi-piece rims with the wheels.
When specified (see 6.2), furnish 1-ea. inflated spare tire and
wheel assembly with each semitrailer.