MCi Crusader II 1989 Maintenance Manual page 155

Date 1-1-89
Page 4-25
MC-9 MAINTENANCE MANUAL
If the brake chamber is to be dismantled on the vehicle (for
example to change the diaphraam or spring). first back off the
slack adjuster to relieve the return spring pressure against the
pressure plate, then follow disassembly procedure below.
1. 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
CAUTION: Jaws of vise or vise grip pilers
should be covered or taped to prevent
damage to the push rod.
2. Remove clamp ring nuts and bolts. 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 remove it lf the clamp ring is to be reused, caution
should be taken against bending it out of shape.
3. Remove pressure plate and diaphragm.
4. Remove yoke and lock nut from push rod.
5. Release grip on push rod and remove push rod assembly,
spring and other parts.
6. Clean all metal parts and inspect for damage. Damaged
parts should be replaced. If it is necessary to replace the return
spring, be sure the correct replacement spring is used.
DRIVE AXLE BRAKE CHAMBERS
The driving axle brake chambers combine the functions of a
conventional service brake chamber with a secondary dia-
phragm and locking mechanism to give service and parking
brake operation.
Operation of the brake chambers under various conditions
has been described earlier in this section.
MAINTENANCE
NOTE: The following procedure is applica-
ble to all brake chambers on the coach.
Depending on experience and type of operation, the drain
slot in the actuator non-pressure plate should be checked and
cleaned of any restricting road grime, mud, ice, snow, etc.
Brakes should be adjusted as is customary with any brake
chambers. Push rod travel should be as short as possible
without dragging brakes. Excessive travel not only shortens the
normal service life of diaphragms but gives slow braking
response, wastes air, and could possibly result in decreasing
brake torque.
Push rod to slack adjuster alignment should be checked in
both the applied and released positions. The rod should move
out and return property wjthout binding. Check the angle
formed by the slack adjuster arm and push rod. It should be 90°
or greater when the actuator is in the applied or the released
position.
Every year or after 50,000 miles (80,000 km) depending on
type of operation, disassemble the actuator, clean all parts and
lubricate the locking mechanism. Install. new diaphragms and
other rubber parts if they are worn or deteriorated. A grease
nipple is providec;j in the brake chamber for lubricating the
interior
with
a high quality chassis lubricant
When diaphragms or return spring or both are replaced, like
parts in the corresponding actuator on the same axle should
also be replaced.
REMOVAL
1. Block and hold the vehicle by means other than air brakes.
With the actuators in the released position. disconnect or com-
pletely remove the air lines from parking and service ports of the
chamber.
WARNING: Air wlll be exhausted from the
line that la connected to the par1'1ng port
when the control valve la operated. If this
llne la not removed, It should be secured
In
such a way that
It
will not whip and cause
injury or damage aa the air exhausts.
2. After disconnecting only the parking and service port
lines. operate the parking control valve. The action will exhaust
the isolated air supply and air from the locking port
3. As a safety precaution, the service system should also be
vented. if it is separate. Disconnect the air line at the actuator
lock port ·
4. Remove the yoke pin cotter pin and knock out the yoke
pin.
5. Remove the mounting nut~. then the actuator.
DISASSEMBLY
1. Clean the chamber exterior of all road grime then mark it
in such a way so it can be assembled in the same manner. Refer
to figures 4-31 and 4-32.
2. Remove yoke and yoke lock nuts. Remove boot splash
guard and felt breather.
3. Remove auxiliary and service clamping ring nuts and
bolts. Spread clamping rings slightly, just enough to slip them
off the plates.
NOTE: It may be neceuary to uae a soft
mallet driver to break the clamping rings
loose. If the ring• are being reused, care
should be taken against bending them out
of shape.
Figure 4-31. Drive Axle Brake Chamber.