Chevrolet 30 Series 1967 Service Manual page 266

BRAKES 5-52
Fig. 81— A ir Brake Chamber Installed
3. Connect air lines.
4. Test relay valve for serviceability as outlined in
"Operating and Leakage Test Section."
AIR BRAKE CHAMBERS (Figs. 80 and 81)
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
chamber 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
sealing 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
chamber when the brakes are cold and properly
adjusted.
Disassembly
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
the plates. It is sometimes necessary to use a screw
driver and gradually pry under the clamp ring to re­
move it. If the clamp ring is to be reused, caution
should be taken against bending it out of shape.
5. Remove pressure plate and diaphragm.
. Remove yoke and lock nut from push rod.
6
7. Release grip on push rod.
. Remove push rod assembly, spring and other details.
8
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.
Assembly
1. Stand push rod assembly upright on a flat surface.
Fig . 8 2 —Governor
CHEVROLET TRUCK SERVICE M ANUAL