GMC 4000 Series Service Manual page 261

Sec. 5C
Page 254
EXTERNAL CONTRACTING BAND TYPE BRAKE
External contracting band type parking brake
is mounted at rear of transm ission (fig.
Brake drum is attached to the transmission
output shaft flange in conjunction with the propeller
shaft universal joint flange. The band and lining
assembly is supported around the drum by a bracket
on the adjustment side and an anchor bar on the
stationary side. Both supports are attached to the
transm ission case. The band contracts around the
drum when brake is applied.
Linkage connecting parking brake lever to
brake operating cams varies on different models,
however, adjustment is made at brake assembly
in same manner.
BAND TYPE ADJUSTMENT (Fig. 1)
1. Place hand lever in fully released position.
Disconnect brake rod or cable from operating cams
by removing cotter pin and clevis pin.
2. Remove lock wire from anchor adjusting
screw and turn anchor screw as necessary to ob­
tain 0.010" to 0.015" between lining and drum.
Install lock wire in anchor screw.
3. Loosen lock nut on locating bolt and tighten
adjusting nut on locating bolt until there is a clear­
ance of . " between lower end of lining and
0 0 2 0
drum. Measure clearance about 1-1/2 inch from
end of lining. When correct clearance is obtained,
tighten lock nut on locating bolt.
4. Loosen lock nut on adjusting bolt and tighten
adjusting nut on adjusting bolt to obtain clearance
of . " between upper end of lining and drum.
0 0 2 0
Measure clearance about 1-1/2 inch from end of
lining. Tighten lock nut on adjusting bolt.
5. Adjust end on brake rod so that clevis pin
may be freely inserted through operating cam s and
rod end. Install clevis pin and cotter pin, then
tighten lock nut on rod end.
BRAKE BAND REMOVAL (Fig. 1)
1. Disconnect brake rod or cable from oper­
ating cam s. Remove clevis pin and operating cams
from upper end of adjusting bolt.
2. Remove nuts, washers, and tension spring
from lower end of adjusting bolt. Lift adjusting
bolt straight up out of brake band brackets and
support, stripping release springs and cam shoe
from bolt as bolt is removed.
3. Remove nuts from locating bolt, then re­
move bolt.
4. Remove lock wire from anchor screw, then
back screw out until clear of anchor bar.
5. Slide band and lining assembly straight to
G M C S E R V I C E M A N U A L
SECTION 5C
PanJiinxj, Rtovkel
rear off brake drum and anchor bar (fig.
moving band and lining assembly off over propeller
).
1
shaft.
INSPECTION
ness or scoring. If drum is worn or damaged, it
must be replaced.
rivet heads, new lining must be installed.
place if weak or broken.
BRAKE BAND INSTALLATION (Fig. 1)
peller shaft. Place anchor screw spring in depres­
sion of anchor bar, and com press spring as band
10 Washer
Figure 1 — Contracting B a n d (External) Parkin g Brake (TypicalI
1. Examine braking surface of drumfor rough­
2. Inspect brake lining. If worn down close to
3. Examine tension and release springs; re­
1. Place band and lining assembly over pro­
1 Brake Band
2 Cams
3 Links
4 C levis Pins
5 Cam Shoe
Lock Nut
6
7 Adjusting Nut
Locating Bolt
8
9 Tension Spring
), re­
1
11 Adjusting Nut
12 Lock Nut
13 Lock Washer
14 Brake Lining
15 R elease Springs
16 Brake Drum
17 Adjusting Bolt
18 Anchor Bar
19 Anchor Screw
20 Lock Wire
T P M - 9 8 7 3