Table of Contents
Advertisement
FIGURE 2
When piston (9) has been rapidly retracted, fluid
flows from the reservoir (15) through by-pass port
(12) into the cylinder. P re s sure from the brake shoe
retracting spring forces the wheel cylinders inward
forcing fluid toward the master cylinder. The pressure
exerted on the check valve (14) forces it off its seat
permitting fluid to return to the master cylinder and
through port (10) to the reservoir. A residual line
pressure of 10 to 12 pounds is maintained in the tubes
and wheel cylinders at all times by the check valve.
This assures immediate braking upon application of
pressure on the brake pedal.
A clearance of 1/4" must be maintained be-
tween the end of the push rod (3), Figure 2 and the
piston (9). If this clearance is not maintained, the
piston cannot return sufficiently to uncover port
(10) resulting in high line pressure and dragging
brakes.
A diaphragm is incorporated in the stop light
switch assembly mounted on the end of the mas-
ter cylinder. Fluid pressure from the master cylin-
der against the diaphragm closes electrical
contacts to operate the stop lights when the brake
pedal is depressed. If the correct push rod clear-
ance is not maintained and high line pressure
results, the brake stop lights will continue to burn
after the brake pedal has been released.
MASTER CYLINDER
REMOVAL
1. Disconnect the stop light wires at the stop light
switch, and the brake tubes at the master cylinder
connector.
2. Remove the brake pedal to push rod clevis pin
(28) Figure 1, and disconnect the brake pedal
retracting spring (22).
3. Remove the two bolts attaching the master cyl-
inder to the frame and remove the master cylin-
der.
REPAIR
1. Thoroughly clean the exterior of the cylinder
before disassembly.
2. Remove the filler plug (1), Figure 2 and drain
the brake fluid:
3. Release the rubber boot (4) from the master
cylinder groove, and remove the boot and push
rod (3).
4. Re move the retainer snap ring (5). This permits
removal of the p i s ton stop plate (6), piston
(9), piston cup (11), sp ring (13), and check
valve (14) for inspection and replacement if
necessary.
NOTE: Do not use gasoline, kerosene or carbon
tetra-choloride for cleaning solution. Use clean
alcohol only. Keep parts free from mineral oil
of any kind.
INSPECTION
Inspect the Master cylinder for light pitting or
scratches. Hone the cylinder bore to restore the
smooth bore necessary for efficient operation. Af-
ter honing, the by-pass port (12) must be cham-
fered slightly to remove the burr.
Check the by-pass port to be certain it is unob-
structed. Run a wire through the port to clear it of
any foreign substances.
ASSEMBLY
1. Wash all master cylinder parts in clean alcohol.
2. After washing, dip all parts in" Hudson Hydrau-
lic Brake Fluid" for lubrication.
3. Install the check valve (14) and piston return
spring (13). See Figure 2.
4. Assemble the primary cup (11) and the piston
assembly (9) and the piston stop plate (6).
NOTE: Always install new rubber cups.
5. Install the retainer ring (5) in the master cylinder
groove.
BRAKES 138
Advertisement
Table of Contents
