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TRUCK SERVICE MANUAL
TM 5-4210-230-14&P-1
BRAKES-PARKING
DESCRIPTION
The Model DCM parking brake features a balanced
design which provides improved mechanical efficiency and
equally divides the input force between both shoes. This
extends lining life and reduces transmission rear bearing
stress.
The DCM brake operates both as a parking and an
emergency brake. Equal torque output is exerted in either
direction of vehicle travel with minimum input force and
stroke. Stops are controlled with maximum protection against
damage to vehicle chassis components. Cam design applies
brake with either direction of lever movement.
DISASSEMBLY
There are only nine (9) parts in the DCM parking
brake. The following instructions are given as an aid in
disassembling and reassembling this unit.
Refer to Fig. 1 for parts identification during
"Disassembly" and "Reassembly".
Disconnect end yoke pin connecting control rod or
cable, whichever is applicable, to brake operating lever (7).
Remove brake drum mounting bolts and pull drum
(1) free of brake or drop prop-shaft, whichever is necessary.
Pull one shoe off the anchor pin sufficiently to allow the strut
(2) to be pulled free of the retaining lance on the shoe table.
Lift the strut (2) away from the cam shaft (3) and pull it free
from the retaining lance on the other shoe.
Remove both shoe return springs (6). Brake shoes
(4) can now be removed by lifting them off the anchor pins.
The backing plate (5) may be removed after the four
mounting bolts are removed. These bolts are shoulder bolts
having a thin head to provide clearance for the strut (2).
To remove operating lever (7) from camshaft (3)
unscrew lock-nut (9) from cam-shaft and pull lever free.
Cam-shaft assembly may then be pulled out of back plate (5).
CLEANING, INSPECTION AND REPAIR
If linings are oil soaked or greasy, replace with new
lining preparatory to replacement. If linings are not greasy,
brush dirt from them with a wire brush; then wipe off with a
cloth. Wash all parts other than brake lining in a clean
cleaning solvent and dry with compressed air.
Inspect brake shoe linings for wear, cracks or
breakage. If linings are worn to near rivets they must be
replaced. Inspect brake drum for deep scores or damage,
and if damaged, replace.
If linings are worn too near rivet heads, or are
otherwise damaged, punch out old rivets and remove linings
from brake shoes. Install new linings tightly against brake
shoes using new rivets. Umbrella type rivets may be used for
increased lining life. Compress rivets tightly using riveting
equipment. If any other parts of the brake assembly show
signs of wear or damage, replace as required.
REASSEMBLY
Reassembly of the parking brake unit is essentially
the reverse of disassembly, however, a few suggestions
mentioned below may prove helpful.
When installing the operating lever (7) on the cam-
shaft (3), the cam must be in the neutral position. Position
the operating lever on the cam-shaft so that it will connect
with the linkage.
The cam-shaft lock-nut (9) should be tightened
sufficiently to prevent the assembly from rocking, but still
allow it to turn freely.
It is important that the brake shoe return springs (6)
be installed on the lever side of the brake shoes (4) as they
act as both a hold down and return spring.
LUBRICATION
The only lubrication required on the parking brake
unit is to apply a thin coating of grease to all bearing surfaces.
DO NOT overlubricate brake parts.
CTS-2210P Page 3
PRINTED IN UNITED STATES OF AMERICA
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