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against the cylinder deck (middle bowed away from
cylinder deck). Use new gaskets when reinstalling valve
plates and cylinder heads.
1.
2.
3.
Figure 4-12. Suction Valve & Positioning Springs
b. Compression Rings
1. Depending on date of manufacture, the
compressor may be equipped with double or single ring
pistons. This variation may also exist with replacement
piston assemblies. If double ring pistons and ring sets are
to be installed, both compression rings must be installed.
Also, double ring and single ring pistons may be installed
in the compressor.
2. The compression ring is chamfered on the inside
circumference. This ring is installed with the chamfer
towards the top. If using a double ring piston, stagger the
ring end gaps so they are not aligned.
The gap between the ends of the piston rings can
be checked with a feeler gauge by inserting the ring into
the piston bore about one inch below the top of the bore.
Square the ring in the bore by pushing it slightly with a
piston. The maximum and minimum allowable ring gaps
are 0.33 and 0.127 mm (0.013 and 0.005 inch)
c.
Installing the Components
1. Install the crankshaft through the pump end of
the compressor. Do not damage main bearings. Push
pistons from the inside of the crankcase through the
cylinders being careful not to break the rings. Place
chamfered side of connecting rod against radius of
crankpins. Install matching connecting rod caps through
bottom cover plate.
2. The oil screen (located in the bottom of the
crankcase), is connected to the inlet of the oil pump.
Whenever the compressor crankcase is opened, inspect
the screen for holes or an accumulation of dirt. The
screen can be cleaned with a suitable solvent.
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Suction Valve
Suction Valve Positioning Spring
Valve Plate Dowel Pin
Compression ring
Figure 4-13. Piston Rings
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There are two types of oil pumps; vane and gear. See
Figure 4-3 to identify which oil pump is used, then follow
the correct procedure below.
Vane Oil Pump (See Figure 4-6):
a. Install the bearing head assembly with a new gasket
on the compressor crankshaft. Carefully push oil pump
on by hand ensuring that the bearing head mounts flush
to the crankcase body. The top of the bearing head is
marked on the mounting flange.
b. Align the gasket and install the eight capscrews in the
mounting flange.
c.
Install the drive segment with the two capscrews and
lock washer.
d. Insert the oil feed guide with the large diameter in.
Insert the guide retaining spring so that it fits over the
smaller diameter of the feed guide. The pump cover can
now be installed.
e. Place the pump cover, with a new gasket, over the
guide retaining spring and compress the spring to enable
installation of the cover capscrews.
Gear Oil Pump (See Figure 4-7):
a. Install the pump end thrust washer on the two dowel
pins located on the bearing head.
Ensure that the thrust washer does not fall off
the dowel pins while installing the oil pump.
b. Install the bearing head assembly with a new gasket
on the compressor crankshaft. Carefully push the oil
pump on by hand ensuring that the thrust washer remains
on the dowel pins, the tang on the end of the drive
segment engages the slot in the crankshaft, and the oil
inlet port on the pump is aligned with the oil pickup tube
in the crankcase. The pump should mount flush with the
crankcase.
c.
Align the gasket and install the eight capscrews in the
mounting flange.
3. Install rotor with key. Screw on equalizer tube
and lock screw assembly with lock washer and bend over
tabs of lock washer. Assemble suction strainer to motor
and cover and bolt cover to crankcase. Assemble valve
plates and gaskets. Assemble cylinder heads and gaskets.
Feel if the shaft will turn by hand.
4. Install oil suction screen and bottom plate.
4.8 CHECKING THE COMPRESSOR
OIL LEVEL
a. To Check the Oil Level in the Compressor:
1. Operate the unit in six cylinder cooling for at
least 20 minutes.
2. Check the front oil sight glass on the compressor
to ensure that no foaming of the oil is present after 20
minutes of operation. If the oil is foaming excessively
after 20 minutes of operation, check the refrigerant
system for flood-back of liquid refrigerant. Correct this
situation before performing step a.3.
4-7
CAUTION
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