Chevrolet 30 Series 1967 Service Manual page 220

BRAKES 5-4
DUO-SERVO
TWINPLEX
Fig. 6 —Duo-Servo and Twinplex W h ee l Cylinders
1. Push Rod
2. Boot
3. Piston
4. Piston Cup
shoes are always primary shoes, self-energizing in
either direction of drum rotation. Brake anchor supports,
bolted to the axle housing flange in conjunction with the
flange plate, have removable slotted anchor pins at the
shoe heels and adjusting screws at the shoe toes which
act as anchors in the reverse direction of rotation. Each
adjusting screw is threaded into or out of its support by
means of an adjusting wheel. Brakes are accessible for
adjustment through adjusting slots in the flange plate.
WHEEL CYLINDERS
Four types of wheel cylinders are used on Chevrolet
Trucks. Wheel cylinders are identified with type of brake
with which they are used (figs.
SW ITCH
G10-20
5. Spring
6. Housing
7. Spring
and 7). On Duo-Servo
6
SW ITC H
CA-KA-PA10, CA30
Fig . 8— -Brake Pipe Distribution and Sw itch Assembly
TYPE "F*
TYPE "FR-3"
Fig. 7—W h eel C ylinders Used w ith Types *'F " and
" FR-3"
1. Boot
2. Brake Shoe G u id e
3. Piston
4. Piston Cup
5. Cup F ille r
brakes, wheel cylinder housing construction varies on
different models, however, internal construction is the
same as illustrated in Figure
On Duo-Servo brakes one wheel cylinder is used at
each brake, mounted on the flange plate between upper
ends of brake shoes as shown in Figure 2. On Twinplex
and Wagner, " F " and " FR -3" type brakes, two cylinders
are used at each brake, mounted on the flange plate be­
tween shoe ends as shown in Figures 3, and 4, and 5.
A bleeder valve for purging air from the hydraulic
Brakes
6. Piston Spring
7. C ylin d er
8. Brake Shoe Anchor
Slot
9. Push Rod
.
6
SW ITCH
PA20-30
CHEVROLET TRUCK SERVICE M ANUAL