MCi Crusader II 1989 Maintenance Manual page 141

Date
1-1-89
Page ___
4-_1_1 - -
MC-9 MAINTENANCE MANUAL
WIDE
PISTON
PISTON RING
RING
.002"
CORRECT GAP CLEARANCE
WITH RINGS IN CYLINDER
. 002"
.010"
J
. 004"
Figure 4-11. Piston Fits and Tolerances.
15. Install the other connecting
rod
and piston in the same
manner.
16. Coat unloader pistons and their bores with special lubri-
cant (dimethyl polysiloxane) prior to installation. If new unloader
kits are being installed. the pistons in the kit are already
lubricated.
17. Install the unloader pistons in their bores with caution
against cutting the 0-rings or distorting the back-up rings.
18. Position unloader plungers in their guides and slip them
in
and
over the tops of the pistons.
19. Install the unloader spring seat in the cylinder block: a
small hole is drilled in the block for this purpose.
20. Position the saddle between unloader piston guides so
its forks are centered on the guides. Install the unloader spring
making sure it seats over the spring seats both in the block and
on the saddle. (See figure 4- 12.)
SEAT
&-GUID~
UNLOADER
ASSEMBLED
LUNGER
)}
UNLOADER
PISTON
BACK-UP
- ~ RING
SADDLE
0-RING
Figure 4-12. Unloader Mechanism.
21. Install inlet valve seats if they have been previously
removed. Position and rnstall inlet valve guides, then drop inlet
valves in their guides. There should be a loose sliding fit
between guides and valves.
22. If previously removed, the discharge valve seats should
be installed. Drop discharge valves into their seats. Install dis-
charge valve springs and cap nuts.
23.
Place the inlet valve springs in the cylinder head. Use a
small quantity of grease to hold them in place, just enough
grease to keep the springs from falling out.
24. Place cylinder head gasket on cylinder block. Carefully
align cylinder head assembly on block and install capscrews
with lockwashers .
INSTALLATION
1. Before installation, clean oil supply line. Before connect-
ing this line to the compressor run the engine briefly to be sure
oil is flowing freely through the supply line.
2. Clean the oil return line passages through the brackets;
these passages must be unrestricted so oil can return to the
engine .
3. Coat compressor cylinder walls and bearings with clean
engine oil before assembling compressor.
4. Always use a new mounting gasket and be sure oil hole In
gasket and compressor is properly aligned with oil return port.
5. Inspect drive coupling and associated parts for ·wear or
damage. They must be tightly fitted on compressor crankshaft.
Replace drive coupling if worn or damaged.
6. Install drive coupling on compressor crankshaft making
sure it properly contacts the shaft and does not ride the key.
Tighten crankshaft nut securely and install cotter pin.
7. Be sure the air cleaner is clean and properly installed.
Compressor intake connections must be tight with no leakage.
8. Clean or replace any damaged, or dirty air or water lines
which may be corroded, before connecting them to the com-
pressor. Use a new discharge flange fitting gasket.
9. Tighten mounting bolts securely and evenly. After install a~
tion, run compressor and check for air, oil, or water leaks at
compressor connections. Also check_ for noisy operation.
GOVERNOR
The governor, operating in conjunction with the compressor
unloading mechanism, automatically controls the air pressure
in the air brake or air supply system between the desired.
predetermined maximum and minimum pressures. The com-
pressor operates continually while the engine runs. but the
actual compression of air is controlled by the governor which
stops or starts compression. The governor has a. piston upon
which air pressure acts to overcome the pressure setting spring
and controls the inlet and exhaust valve to either admit or
exhaust air to or from the compressor unloading mechanism.
OPERATION
Reservoir air pressure enters the D-2 governor at its reser-
voir port and acts on the area of the piston and beneath the inlet
and exhaust valve. As the air pressure builds up, the piston
movesagainstthe resistance of the pressure setting spring. The
piston and inlet and exhaust valve move up when the reservoir
air pressure reaches the cut-out setting of the governor. The
exhaust stem seats on the inlet and exhaust valve and then the
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