Chevrolet 10 Series 1968, Service Manual

Page: 305 / 713

BRAKES 5-62
i
SPRING NON PRESSURE
PLATE
MOUNTING BOLTS
PUSH ROD YOKE
II
i
LOCK NUT
INLET
PORT
DIAPHRAGM
PRESSURE
PLATE
INLET _
PORT ~ *■
CLAMP RING
NUTS AND
BOLTS
CLAMP
RING
F ig . 9 3 -A ir Brake Chamber (Clamp Ring Type)
AIR BRAKE CHAMBERS (Figs. 93 and 94)
Brake chambers in the air brake system convert com­
pressed air pressure energy into mechanical force and
movement which applies the vehicle brakes.
Leakage Test
With a full pressure application, check the brake cham­
ber for leakage. No leakage is permissible.
If leakage is detected around the flange, or clamping
ring, the bolts should be tightened evenly but only enough
to stop the leakage otherwise the diaphragm, flange seal­
ing surface or clamping ring could be distorted.
Removal
1. Disconnect air line and push rod yoke.
2. Remove brake chamber.
Installation
1. Mount brake chamber to mounting bracket.
2. If possible, push rod should point down to obtain
maximum drainage.
3. Install yoke and its nut on push rod and connect to
slack adjuster.
4. Check the angle formed by the push rod and slack
adjuster. The angle should never be less than 90°
when full air pressure is applied to the brake cham­
ber when the brakes are cold and properly adjusted.
Disassem bly
1. After cleaning the exterior of the brake chamber,
mark it in such a way that it can be assembled the
same way. If the brake chamber is to be dismantled
on the vehicle, for example to change the diaphragm
or spring, first back off the slack adjuster to relieve
the return spring pressure against the pressure
plate, then follow disassembly procedure below.
2. Pull out push rod and clamp it at the non-pressure
plate with vise or vise grip pliers. If necessary, use
air pressure to move the push rod out. Grips of
vise or vise grip pliers should be covered or taped
to prevent damage to push rod.
3. Remove clamp ring nuts and bolts.
4. Spread clamp ring slightly, just enough to slip it off
F ig . 9 4 -A ir Brake Chamber Installed
the plates. It is sometimes necessary to use a
screw driver and gradually pry under the clamp ring
to remove it. If the clamp ring is to be reused, cau­
tion should be taken against bending it out of shape.
5. Remove pressure plate and diaphragm.
6. Remove yoke and lock nut from push rod.
7. Release grip on push rod.
8. Remove push rod assembly, spring and other details.
Cleaning and Inspection
Clean all metal parts and inspect them for damage.
Damaged parts should be replaced. If it is necessary to
replace the return spring, be sure the correct replace­
ment spring is used. Inspect diaphragm and any other
rubber parts for wear or deterioration and replace if
necessary.
Assem bly
1. Stand push rod assembly upright on a flat surface.
2. Position return spring and non-pressure plate on
push rod.
3. Press the non-pressure plate down against the ten­
sion of the spring until the plate bottoms on the flat
surface.
4. Now clamp the push rod at the non-pressure plate in
a vise or with vise grip pliers whose grips have been
taped or covered.
5. With the push rod held in this manner, place the
clamp ring over the clamping surface of the non­
pressure plate.
6. Position diaphragm in pressure plate and joint the
two with the non-pressure plate by working the clamp
ring over the clamping surface of the pressure plate
with the use of vise grip pliers or like tool drawing
the clamp lugs together.
7. Assemble bolt and nut in clamp. It is sometimes
CHEVROLET TRUCK SERVICE MANUAL