220.127.116.11 Rear air suspension system. When specified for model 4x2, class 24 to 28, and
model 6x4, class 39 and up (see 6.2), the rear axle(s), except on dump trucks, shall have an air
suspension system. The suspension system shall have not less than 58 percent of the sprung
weight on the air bags. The system shall have leveling valves with time delay to minimize
constant air consumption. There shall be a hydraulic shock absorber near each air bag. The
system shall have full provisions for lifting, towing and jacking the vehicle. Truck tractors shall
have an air dump valve with in cab control within reach of the seated driver.
3.3.13 Axles. Except as specified in 18.104.22.168 and 22.214.171.124, axle ratings shall be at least
equal to the load imposed on each axle, measured at the ground, with the vehicle loaded to
specified GVW. In addition, for model 8x4 and 8x6, axle ratings shall be at least equal to the
load imposed on each axle, measured at the ground, with the pusher axle up and the vehicle
loaded to specified GVW.
126.96.36.199 Oil lubricated axles. When specified (see 6.2), the front and rear wheel bearings
and axle spindles on 4x2, 6x4 and 8x4 models and the rear wheel bearings and axle spindles on
4x4, 6x6 and 8x6 models shall have oil lubrication. The hubcaps, except for driving axles, shall
have a window or plug for visually determining the oil level. There shall be provisions for
venting or withstanding internal pressure buildup and for replenishing the oil supply.
188.8.131.52 Rear bogie. Model 6x4, 6x6, 8x4 and 8x6 vehicles shall have a rear bogie. The
rear bogie shall be of the four-wheel type, complete with axles, springs, torque rods and all other
necessary parts. Axle gear ratios shall provide the performance specified in 3.2.1 through 3.2.4.
The rear bogie rating on model 8x4 and 8x6 shall be at least equal to the total load imposed,
measured at the ground, with the vehicle loaded to specified GVW and the pusher axle elevated
off the ground.
184.108.40.206 Rear bogie differential action. The bogie shall permit differential action
between the two axles. The bogie shall have a manual or automatic controlled lockout assuring
equal power to each rear drive axle. The manual lockout control shall be in the cab accessible to
the seated driver.
220.127.116.11 Front drive axle. The front axle on 4x4, 6x6 and 8x8 mode be shall be driven
from a driveline in the powertrain. See 3.5.23.
18.104.22.168 Pusher axle, on line. Pusher axles on 8x4 and 8x6 vehicles shall conform
22.214.171.124 Two-speed axle. 4x2 truck tractors and 4x2 dump trucks, both up to class 23
with manual transmissions, or when specified (see 6.2), other 4x2 and 6x4 models shall have a
two speed axle. The two speed axle shall have electric, vacuum, or air shift. The axle shall have