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Service
A-4 Seal parts may be supplied as components or
assemblies. If field assembly is required refer to
compressor print for instructions. Fit seal into the
seal ring housing and install seal ring cover with
gasket.
2. Coat balance piston O.D. and balance piston seal
ring ID with Molycote and oil. Slide the spring
washer over the insert pin and position the seal ring
in the recess. Note orientation of the seal ring step
face, be sure it's correct (See Figs. 25). Bolt up the
balance piston seal cover. Use a feeler gauge to set
clearance 75% open at the top, 25% on bottom, and
equal on the sides. This allows for rotor sag when
the sump is removed and the rotor is resting on the
labyrinth seals.
3. Check that the sump piston ring is not stuck or bro-
ken. Lubricate the O.D. of the sump housing and
piston ring. Some heavy grease my help keep the
piston ring centered. Coat the ID of the piston ring
housing with Molycote and oil. Pad the rotor hex
to prevent seal damage. Coat the seal ID and the
rotor shaft O.D. with Molycote and oil. If the sump
gasket requires replacement be sure new gasket is
the same thickness. Remove all jack bolts from the
sump flange. Use the protective sleeve if compres-
sor is equipped with probes. Failure to use the
sleeve will result in damage to probes.
4. Position sump over guide pins and ease into the
compressor until the sump piston ring enters the
housing. Use studs and nuts to pull the sump evenly
into compressor until the cap screws can be started.
Keep the sump as square as possible. Do not force,
or damage to the piston ring may result.
5. Relax the lifting rigging. After the sump has been
seated and all bolts torqued, install the discharge
end bearing. If the suction end bearing is in place,
the rotor should turn easily. Install the thrust
bearing and oil pump assembly. Replace all oil
lines and fittings (See Replacing Oil Pump As-
sembly, Thrust Bearing and Discharge End Jour-
nal Bearing).
REMOVING PRE-ROTATION VANE ASSEMBLY
If it becomes necessary to remove the Pre-rotation Vane
housing (154), refer to Figs. 26 and Foldout Fig. 4B.
52
Proceed as follows:
1. Follow instructions outlined in Preparation for Ser-
vice. Lockout/tagout main motor drive. Transfer
refrigerant from unit to pumpout receiver. (Refer
to Form 160.71-NM3 if a pumpout receiver is
available.)
2. De-energize oil heaters.
3. Drain oil from the seal return cavity in the oil
reservoir.
4. Remove the PRV actuator and mounting bracket.
5. Remove oil tubing from the bearing housing.
6. Remove the coupling guard, driven coupling disk,
drive coupling disk, shaft seal compressor drive
shaft, bearing, bearing housing, PRV sleeve, and
seal ring(s).
7. Remove the internal vent tube (67) between the
casing and the PRV assembly (Refer to Foldout
Fig. 4B). The vent line adapter must be removed
to expose the equalizer tube.
8. Remove the hex head cap screws (26) securing
the pre-rotation vane housing to the compressor
casing. Use screws as jack bolts to loosen the PRV
assembly. Try to keep from breaking the gasket.
FIG. 25 – EXPLODED VIEW, BALANCE PISTON
SEAL ASSEMBLY
FORM 220.11-NM2 (602)
LD07341
YORK INTERNATIONAL
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