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MAINTENANCE
Crusader
MC-8
[ ,.o,_4_-_18 _ _ _ _ DATE----=:J-=..:_ulyLL,_19_73 _ _ ]
MANUAL
REMOVAL AND INSTALLATION
Block or hold vehicle by means other than air
brakes. Open drain cocks and exhaust air pressure
from the air brake system. Disconnect air lines at
brake valve. Disconnect pedal linkage. Remove
mounting bolts and remove brake valve.
Clean air lines to brake valve. Mount brake valve
and tighten mounting bolts. Connect pedal linkage.
Connect air lines to valve. Test brake valve for ser-
vice as outlined in "Service Checks" section.
Remove
three
mounting
bolts.
Remove
and
disassemble lever actuajing mechanism. Lift off
mounting plate. Remove piston and spring assembly
from body. Remove rubber grommets from piston.
Do not disassemble the pressure regulating spring
and piston assembly unless the exhaust seat has been
damaged and has to be replaced. Remove piston-
return spring from body. Remove inlet cap nut from
body. Remove inlet valve guide, inlet and exhaust
valve assembly.
Wash all metal parts in cleaning solvent and dry.
Wipe all rubber parts clean.
Carefully inspect the exhaust seat.
If
seat is worn
slightly, lap on a piece of crocus cloth on a flat sur-
face.
If
seat is worn excessively, or damaged in any
way, the piston and pressure regulating spring assem-
bly must be replaced. Inspect outside surfaces of
piston which contacts bore in body of valve for scrat-
ches, nicks or out-of-round condition. Replace piston
if necessary. If pressure regulating spring is damaged
in any way, it must be replaced. Replace rubber
grommets with new ones.
Check mounting plate for cracks or breakage.
Replace if necessary. Replace boot if cracked or
deteriorated. Inspect the body for scores and ex-
cessive wear where the piston contacts the body.
If
excessive wear or grooves are found, the body should
be replaced. Inspect small bleed hole leading to
piston cavity in body to be sure it is open and not ob-
structed. Replace inlet and exhaust valve assembly if
valve or seats are worn or damaged.
REASSEMBLY
Install new grommets on piston. Lubricate the
piston grommets, piston and piston bore with barium
grease. Install piston return spring, piston and spring
assembly in body. Install mounting plate and secure
in place with the three cap screws and lockwashers.
Install inlet and exhaust valve assembly after
positioning guide on the inlet valve seat. Place new
grommet under inlet_ valve seat and install inlet cap
nut.
ADJUSTMENT
If
the brake valve does not release, it indicates that
the exhaust valve is not opening sufficiently. This can
be caused by:
I.
Improper adjustment of the linkage or lever ad-
justing screw which would prevent the lever on
the valve from returning to the fully released
position. (refer to following illustration).
2.
Lack of lubrication in the body causing the piston
Figure 4-11: E-1 Brake Valve lnstal led
and spring assembly to bind.
3. Dirt or other foreign matter between the heel of
the pedal and bracket.
If
the brake valve does not apply promptly, or does
not apply fully, it indicates that the inlet valve is not
opening sufficiently.
QUICK RELEASE VALVES
DESCRIPTION
The quick-release valves speed up the release of air
pressure from the brake chambers. When a brake
valve application is released, the e:-hausts of the
quick-release valves open and the air pressure ac-
cumulated in the brake chambers 1s exhausted
through the two quick-release valves, rather than
exhausting back through the brake valve.
A line from a delivery port of the brake valve is
connected to the top port ot each quick-release valve.
The two side ports are for brake chamber con-
nections and the bottom ports are the exhaust.
OPERATION
When a brake valve application is made, air
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