TOPIC 3. DRIVE WHEEL BRAKES

TM 10-3930-644-14&P

A. DESCRIPTION

NOTE

Refer to REPAIR MANUAL for

The master cylinder mad hydraulic fluid reservoir are

MASTER CYLINDER, INSPECTION,

combined in one casting and are joined by intake and

DISASSEMBLY,

REPAIR

and

by-pass

ports

located

the

cylinder

wall.

REASSEMBLY.

(See Figure 3.) Internal parts are removed or installed at

the push rod end of the cylinder. The stop plate holding

C. INSTALLATION

the internal parts is retained by a lockwire clipped into

the cylinder bore.

The cylinder piston is operated

1. Ensure that master cylinder is completely

through a push rod connected to the brake pedal. The

reassembled prior to installing.

push rod and cylinder opening is enclosed with a rubber

2. Replace master cylinder assembly in its relative

boot.

mounting

location

and

install

securing

It is impractical to thoroughly clean the cylinder and fluid

capscrews.

reservoir an the truck. For this reason the following

3. Attach brake pedal pushrod to cylinder and

instructions should be observed:

secure with clevis pin previously removed.

4. Connect brake hydraulic line to cylinder.

B. REMOVAL

5. Refer to LUBRICATION CHART and fill cylinder

with proper high grade hydraulic brake fluid.

1. Remove floor and toe plate.

SAE specification R-71 is recommended.

2. Disconnect brake hydraulic line attached to

6. Bleed brake system as outlined under

master cylinder.

appropriate heading, REPAIR MANUAL.

3. Remove clevis pin holding the pushrod to the

7. Replace floor and toe plate.

brake pedal assembly.

4. Remove capscrews that mount the master

cylinder to the inside of the truck frame and

remove.

TOPIC 3. DRIVE WHEEL BRAKES

A. DESCRIPTION

In order for the self-adjusting brakes to operate property,

the self-adjuster assembly must be properly torqued. If it

The brake shoes are self-adjusting through the use of a

becomes necessary to re- move and disassemble the

friction operated self-adjuster in each drive wheel. The

self-adjuster in the field, use the following recommended

friction between the two slide assemblies of the self-

procedure to assemble the self-adjuster.

adjuster is great enough to prevent the brake shoe

springs from fully retracting the self-adjuster, but not

B. ADJUSTMENT

great enough to prevent the hydraulic pressure from :

expanding it. The self-adjuster assembly is mounted to

1. Assemble components as Illustrated in Figure 4.

the brake shoes with roll pins. The roll pin holes in the

brake shoes are 1/32" oversize to provide proper

working clearance between the brake shoe lining and

drum.

CAUTION

Exercise care when self-adjuster is

handled or installed. Do cont bend

the tags of the slide assemblies in

any way because the holes for the

roll pins must be parallel with each

other. If the holes are ac parallel, the

roll pins will lie at a slight angle

through the mounting holes in the

brake shoes. Improper alignment of

the roll pins could lead to improper

brake shoe retraction due to lack of

Figure 4. Brake Self-Adjuster Assembly

proper roll pin clearance in the brake

shoe holes. This in turn could create

brake shoe drag on the drum.

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