TM 9-2330-390-14&P
1-18. BRAKE SYSTEM.
a.
The brake system is a full air with wedge-type brake assemblies at each wheel. Brakeshoes are made of
a non-asbestos organic compound.
b.
Air to operate the brakes is supplied by the towing vehicle and is routed to the dolly set through the
intervehicular and intradolly air hoses. Service supply lines are routed along the right side of the dolly set; emergency
supply lines are routed along the left side.
c.
The service brakes apply and release the brakes when the brake pedal in the towing vehicle is pressed
during normal driving. Air to apply the brakes is directed from the air reservoirs through the relay emergency valve
(front dolly) and full function valve (rear dolly) to the airbrake chambers mounted at each wheel of front and rear
dollies.
d.
The parking brake system operates on the rear doily only. It applies and releases the parking brakes
when the parking brake lever is operated. Spring fail-safe airbrake chambers, mounted piggyback to the service
airbrake chambers on the rear dolly, allow functioning of the parking brake system.
(1)
Parking brakes are applied by a large spring in the spring fail-safe airbrake chambers. The spring is
normally retracted by air pressure.
(2)
When the parking brake lever is raised, air pressure is removed from behind the spring and the
parking brakes apply.
(3)
Parking brakes are released by restoring air pressure to the spring fail-safe airbrake chambers to
retract the spring.
e.
The emergency breakaway system stops the dolly set by applying the brakes in the event that the
emergency supply line from the towing vehicle is severed during a breakaway.
f.
With both the parking and emergency breakaway systems, loss of air pressure causes brakes to apply.
Restoration of air pressure allows brakes to release. Brakes that have been applied due to air pressure loss can be
manually released (caged) to allow movement of the dolly set.
g.
Major components of the brake system include the following:
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