MCi Crusader II 1989 Maintenance Manual page 143

Date
1-1-89
Page
4-13
MC-9 MAINTENANCE MANUAL
LEAKAGE TEST
Leakage checks on the governor are made at its exhaust
port in both cut-in and cut-out positions.
1. In the cut-in position, check exhaust port for inlet valve
leakage by applying a soap solution at the port. Leakage could
also be past the bottom piston O-ring.
2. In the cut-out position check the exhaust port to deter-
mine leakage at the exhaust valve seat or stem O-ring. In this
position leakage could also be past the upper piston grommet.
REMOVAL AND INSTALLATION
1. Applying parking brake.
2. Drain air brake system and disconnect reservoir air line.
3. Remove governor mounting bolts, then governor.
4.
Clean mounting pad on both compressor and governor
block. Clean connecting line, or lines. Also be sure compressor
unloading port is clear and clean.
5. Install governor using a new governor mounting gasket.
Connect air lines to governor. Test governor as outlined in
Service Checks.
DISASSEMBLY
1. Clean governor exterior. of road dirt and grease using a
good cleaning solvent and brush.
2. Unscrew the top cover. With a pair of retaining ring pliers,
remove the spring assembly retaining ring. ·
3. Remove the adjusting screw and spring assembly. Remove
the locknut, then the hex-shaped upper spring seat from the
adjusting screw.
4. Remove the pressure setting spring, lower spring seat,
spring guide and the other lower spring seat from the adjusting
screw.
5. Remove the exhaust stem and its spring from the top of the
piston.
6. With the body in the inverted position, tap it lightly and the
piston should fall out.
7. Remove the inlet and exhaust valve springs and the valve
from the piston.
8. Remove the two piston O-rings and with a hooked
wire
remove the exhaust stem O-ring.
9. Clean or remove the unloader and reservoir port filters.
CLEANING AND INSPECTION
1. Clean all metal parts with cleaning solvent Wipe rubber
parts dry.
2. Inspect body for cracks or other damage. Be particularly
careful that all passages in the body, filters, exhaust stem, and
the piston are not obstructed.
3. Check springs for cracks. distortion or corrosion. Replace
all parts not considered serviceable during these inspections.
REASSEMBLY
Prior to reassembly lubricate the tower body bore. the top of
the piston, the piston grooves, piston grommets, piston setting
spring guide and the adjustable screw with ,~commended lub-
ricant, MCI Part No. 4A-15-113.
1. Install the exhaust stem O-ring in its groove in the stem
bore of the piston. Drop the inlet and exhaust valves into place
at the bottom of the piston.
2. Install the inlet valve spring with its narrow end against the
valve. Press the spring down until the large coiled end snaps
into the groove inside the piston.
3. Position the exhaust stem spring over the exhaust stem,
then carefully press the stem into the stem bore of the piston.
4. Install the piston in the body.
5.
Install one lower spring seat, spring guide, the other lower
spring seat, pressure setting spring, and the hex-shaped upper
spring seat on the adjusting screw, in that order. Screw the
upper spring seat down until the dimension from the top of the
seat to the bottom of the stem head is approximately 1.142"
(29.006 mm).
6. Install the locknut. Before placing the adjusting
screw
and
stem assembly in the governor body, check to be sure the
exhaust stem and its spring are in place in the piston.
7. Install the adjusting screw and spring assembly retaining
ring. At this point, make the adjustment as outlies under Service
Checks.
8. After the adjustment is made. the top cover should be
screwed on tightly until it seals the body against the entrance of
any foreign matter.
9. If necessary, install new filters in the reservoir and
unloader ports. These cup-shaped filters can be installed with
the head of a pencil.
DUAL BRAKE APPLICATION VALVE
DESCRIPTION
The brake valve is the control unit of the air brake system.
See figure 4-14. It provides the driver with an easily operated
and graduated means of applying or releasing the vehicle
brakes. The brake valve is operated through a lever with a
linkage connection to the brake pedal.
The dual brake valve has two separate supply and delivery
circuits for service and emergency braking. The service brake
portion is that section of the valve between the spring seat
which contacts the plunger and the relay piston: the f;lmergency
brake portion is that part between the relay piston and the
exhaust cavity.
The service brake portion of the valve is similar in operation
to a standard single-circuit air brake valve, and under all oper-
ating conditions the emergency brake portion of the dual brake
valve uses a common exhaust protected by an exhaust
diaphragf!J.
MAINTENANCE
Every 300 operating hours. 20.000 miles (32,000 km) or every
three months. clean any accumulated dirt. gravel or foreign
material away from the heel of the treadle, plunger boot and
mounting plate. Check the plunger boot for cracks. holes or
deterioration and replace if necessary.
With the lever type brake valve. check to be sure that. with
brakes fully applied, the pedal contacts the pedal stop. With
brakes released. check to be sure that the lever arm contacts
the stop button on the brake valve. Adjust pedal linkage to
provide for this. After any adjustment, check the bral,<e valve
delivery pressure.
Lubricate the plunger using a silicone base lubricant
TMC/MCI Part No. 21-7512-11.
Every 3.600 operating hours or 100,000 miles (161,000 km)