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Service
If work is being performed on only one
or two vanes they may be held with an
appropriate wrench, on the heavy part
of the vane, as they are aligned and the
clamping screws are properly torqued.
A clamping fixture (step 4) may be con-
structed if the entire vane assembly re-
quires alignment and tightening.
1. Lubricate the vane and housing vane hole with
Molycote and oil.
2. Carefully place vane in PRV housing.
Each vane and matching housing
vane hole are stamped with a num-
ber. Make sure all numbers match.
The vanes are originally ground to
provide for a minimal clearance
paddle to paddle and to the housing.
Replacement vanes will require some
"fitting" to achieve proper clearance.
Shimming may also be required to ad-
just the ball studs to drive ring. When
properly adjusted 5 - 25 pounds of
force will be required to rotate the
completed assembly.
3. Ensure both sides of washer (204), vane arm (228),
and lower surface of washer (229) are clean, dry, and
free of Molycote and oil. Place washer (204), vane
arm (228), and washer (229) over the vane stem. Cen-
ter all holes and insert cap screw (205) through the
assembly. Only tighten cap screw until snug.
4. Refer to Fig. 28 for use of vane clamping fixture.
3/4" plywood can be used as clamping fixture ma-
FIG. 28 – VANE CLAMPING FIXTURE
54
terial. Align vanes, place clamping fixture disks in
position, and tighten clamping bolt. Properly torque
vane clamping screws and remove fixture. Make
final individual vane adjustments as above.
REMOVING CONTROL SHAFT AND CONTROL
SHAFT COVER
The current design control shaft is a one piece shaft
with the shaft lever welded to the inboard end. The
older design, still in service on many machines, is of
two piece construction and the lever arm is bolted on.
Although some spares are still available for service, it
is recommended that the new style shaft and cover be
installed whenever the compressor is being overhauled.
Some old style PRV covers control shaft covers were
of solid construction, but all machines now use a shaft
cover that has seal return oil circulating through inter-
nal passages. The circulating oil helps lubricate the con-
trol shaft O-rings and also warms the shaft cover to
minimize frost buildup when running at temperatures
below freezing. If a refrigerant or oil leak is detected
around the control shaft cover, proceed as follows:
1. Pump down the system and remove the charge.
Remove the seal oil lines from the control shaft
cover.
2. Loosen the cap screws, lockwashers, and nuts hold-
ing the external lever. Remove the external lever
assembly.
3. Remove the two cap screws and carefully pull the
shaft cover off the control shaft. Remove gasket.
4. Inspect the control shaft O.D. and the shaft cover
ID for corrosion or damage. Check the O-rings for
excessive swelling or splits. Check the gasket for
signs of damage. The earlier two piece shafts had a
tongue and groove joint between the shaft sections
that allowed the front part to be removed without
opening the PRV housing. The outer portion of the
control shaft had a rubber bushing vulcanized to it
that formed a gas proof seal when clamped between
the internal gasket and the PRV shaft cover. Check
this bushing for splits or separation.
If the control shaft must be removed, the PRV housing
must be removed. Refer to Removing the Pre-rotation
Vane Assembly and proceed as follows:
1. Remove fulcrum screw (232) from rod end bear-
ing (233), freeing the control shaft (206) internal
lever.
2. Remove retaining ring (234) and pull control shaft
and lever from the PRV housing. Remove control
shaft thrust collar.
LD07344
FORM 220.11-NM2 (602)
YORK INTERNATIONAL
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