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MIL-T-83808
3.3.2.3 D r i v e l i n e c o m p o n e n t s . Driveline components shall be adequate to transmit the maximum de-
livered torque (not including parasitical losses) of the engine as developed through the maximum gear
train reduction
Axles. The load rating of each axle shall be not less than the imposed load on the axle, meas-
3.3.2.4
ured at the ground, with the vehicle at gross weight The front axle shall be equipped for steering When a
four wheel drive vehicle is required (see 6.2), the front axle shall be equipped for steering and shall incor-
porate a torque proportioning differential with a bias ratio of not less than five to one or a limited slip differ-
ential. The axles shall be planetary final drive type.
3.3.2.4.1 Rear axle differential ratio. A conventional limited slip or a torque proportioning differential
with a bias ratio of not less than five to one shall be provided for the rear axle such that vehicle will meet
the performance requirements specified herein. When required (see 6.2), a no spin differential shall utilize
a heavier front axle and more weight to the front of the vehicle to hold it down during staffing and turns
ste m. The vehicle shall be equipped with a power assisted steering system, with
3.3.3
manual steering available in the event of power assist failure. The steering system shall not require more
than four turns lock to lock The static vehicle, at idle, shall be capable of steering from extreme left to
extreme right in a maximum of five seconds in accordance with Figure 8 of MIL-STD-1472. The steering
system shall be capable of returning to the neutral position when traveling 10 MPH in a right or left turn
and releasing the steering wheel. The vehicle's steering system shall have easily accessible adjustments
for caster, camber and toe-in. The power steering system shall be independent of other vehicle hydraulic
systems The steering system shall also meet the emergency steer criteria in SAE J53
ee I The steering wheel shall have a diameter of 18 inches minimum. Not less
3.3.3.1
than four inches clearance shall be provided around the steering wheel in all directions.
3.3.4
Brakes
3.3.4.1
Brake system. The brake lines shall be securely anchored to the chassis and protected from
damage. Brake lines shall not be copper or aluminum tubing Brake lines shall not contain a 90" fitting of
less than five inches in radius of curvature. Brake lines shall be readily detachable at their axle ends
Through frame connectors shall be provided at each point where lines pass through metal members
Operation of the service brakes shall not result in evidence of excessive fading as governed by SAE
J992b. The brake system shall be functionally compatible with the tow vehicle brake system- The towing
vehicle should not add to yaw, sway, skid, tip, tilt or jackknife under maximum braking conditions and
minimum stopping distances.
Ser vice and parking brakes The service brakes shaft stop the tractor at curb weight within 20
3.3.4.2
feet from 20 MPH on a 0.7 coefficient of friction surface. The parking brake shall be a manually engaged
mechanical brake system independent of the service brakes.
Service brakes Automatic adjusting heavy duty disc brakes shall be furnished on the front
3.3.4.3
wheels, and self-adjusting heavy duty drum brakes shall be furnished on the rear wheels. Power assisted,
by hydraulic, brakes shall be provided. Also, the service brakes shall have:
a. A maximum of 100 pounds foot pressure and shall be required to lock brakes in accor-
dance with SAE ARP 1247B.
b. Braking capability and fool pressure shall remain constant during any/all engine speed and
vehicle maneuvers
c
Physical arrangement of the tractor brakes shall allow brake (accelerator clearance for
heavy snow boots (reference MIL-STD-1472).
d. The brakes shhaall be hydrau lic in accordance with SAE ARP 1247B.
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