308986
35
Service – Pneumatic System
Displacement Pump
Disassembly
1.
Remove the locknuts (113) from the top of the
yoke (114) of the two outer displacement rods. See
Fig. 25. Unscrew the outer locknuts (122) from the
top of the tie plate (121) on the two displacement
pumps. Use a screwdriver and hammer to loosen.
NOTE:
The tie rods (111) shown in Fig. 25 are
removed from the tie plate (121) for clarity only and
do not require removal.
2.
Remove the two outer pumps from the tie plate.
Remove the washers (115) from the rods of each
pump.
3.
Three Displacement Pump Models Only.
Using a wrench on the flats of the center pump’s
displacement rod, screw the rod out of the
yoke (114). See Detail B in Fig. 25. Remove the
pump from the yoke (114) then the washer (115)
from the rod on the pump.
4.
Refer to the appropriate instruction manual for
servicing the displacement pump.
Reassembly
1.
Three Displacement Pump Models Only
Slide the center displacement pump rod through
the tie plate (121), center locknut (123), and wash-
er (115). Thread the displacement rod into the
yoke (114) by turning the complete cylinder. Use a
wrench on the flats of the displacement rod for final
tightening. Torque to 53–67 ft-lb (72–91 N
S
m)
.
Push the cylinder up into place in the tie plate and
install the center locknut (123).
2.
All pumps
Slide the outer two displacement pump rods
through the tie plate (121), outer locknuts (122),
and washers (115). Install the locknuts (113)
loosely on the displacement rods. Push the cylin-
ders up into place in the tie plate and install the
outer locknuts (122).
122
115
111
123
121
Fig. 25
C
DETAIL B
113
114
122
1
Torque to
53–67 ft-lb
(72–91 N
S
m)
1
1
3.
Move the air motor to the bottom of its stroke.
Check for movement of the air motor yoke at each
displacement rod. With the rods centered, tighten
the locknuts (113) securely and torque to 53–67 ft-
lbs (72–91 N
S
m)
.
4.
Tighten the throat packing nut just enough to
prevent leakage, no tighter.
5.
Reconnect the swivel unions to the pumps. Hold
the intake valve (C) steady with a wrench to pre-
vent it from turning.
Summary of Contents for HYDRA-CAT FIXED RATIO
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