Section III. PRINCIPLES OF OPERATION - TM-9-2330-202-14-P0039

TM 9-2330-202-14&P

Section III.

PRINCIPLES OF OPERATION

NOTE

Change 2 adds the M101A1. Specific M101A1 information is contained in this

chapter and designated in the chapter and section indexes.

HYDRAULIC BRAKE SYSTEM (M101A2, M101A3, M116A2,

M116A2E1, AND M116A3).

Brakes are applied automatically by the hydraulic brake system when the towing vehicle slows or stops, or

when the trailer breaks away from the towing vehicle.

The major components of the hydraulic brake system and their functions are as follows:

Hydraulic Brake Actuator Assembly. This assembly transmits the braking forces of the towing vehicle

to the trailer by inertia. It consists of a drawbar coupler, master cylinder, breakaway chain and lever,

and leaf spring.

Drawbar Coupler. The drawbar coupler attaches to the towing vehicle and controls the master cylin-

der. When the towing vehicle goes forward, the drawbar coupler is pulled and the brakes are

released. When the towing vehicle slows down, the trailer pushes the drawbar ring into the towing

vehicle and applies the brakes.

Master Cylinder. The master cylinder changes the mechanical motion of the drawbar coupler and

breakaway lever into hydraulic pressure. It has a built-in shock absorber to prevent jerky drawbar

coupler movement. The shock absorber prevents hydraulic pressure from building up when the tow-

ing vehicle backs up.

Breakaway Chain. The breakaway chain is attached to the towing vehicle. If the trailer breaks away

from the towing vehicle, the breakaway chain will pull up on the breakaway lever and apply the

brakes.

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