36
308986
Service – Hydraulic System
Displacement Pump
Disconnecting the Displacement Pumps
NOTE:
For displacement pump repair instructions,
refer to the separate displacement pump manual
307430, supplied.
WARNING
To reduce the risk of serious injury whenever you
are instructed to relieve pressure, always follow the
Pressure Relief Procedure
on page 23.
1.
Flush the pump if possible. Stop the pump at the
bottom of its stroke. Relieve the pressure.
2.
Relieve pressure in the accumulator, if used.
Disconnect the hydraulic supply, return, and drain
lines from the motor. Disconnect all hoses from the
pump.
3.
Plug all hydraulic connections to avoid contamina-
tion.
4.
Take note of the orientation of the pump fluid
outlets to the hydraulic fluid inlet of the motor.
5.
Unscrew the tie rod locknuts (23) and the exten-
sion rod locknuts (14). Slide the displacement
pumps down off the tie rods (5). See Fig. 26.
6.
Remove the screws (12) and lockwashers (13)
from the tie plate (6). Pull the tie plate off the
displacement pumps (7).
7.
Remove the cotter pins (11). Unscrew the rod
extensions (10) from the displacement rods (R).
Inspect the o-rings (24).
8.
If you are servicing the hydraulic motor (1), remove
the tie rods (5), yoke (4), gasket (3), and
coupler (2).
NOTE:
For hydraulic motor repair instructions, refer to
the separate motor manual 307158, supplied.
Reconnecting the Displacement Pumps
1.
Apply thread sealant to the threads of the coupler
(2) and screw it onto the hydraulic motor. Place the
gasket (3) on the yoke (4). Apply sealant to the
threads of the yoke and screw it into the coupler.
See Fig. 26.
2.
Apply thread sealant to the top threads of the tie
rods (5). (The top is the end with short threads,
and without flats.) Screw the rods into the base of
the hydraulic motor (1).
3.
Lubricate the o-rings (24) and install them on the
displacement rods (R). Lubricate the threads of the
rods.
4.
Screw the extension rods (10) onto the displace-
ment rods (R). Align the holes in the rods and
insert the cotter pins (11).
5.
Attach the tie plate (6) to the displacement
pumps (7), using the six screws (12) and lock-
washers (13). Orient the fluid outlets of the dis-
placement pumps as was noted in step 4 under
Disconnecting the Displacement Pumps.
6.
Slide the tie plate (6) onto the tie rods (5) until the
threads of the extension rods (10) protrude from
the yoke (4). Screw the locknuts (14) onto the
extension rods. Torque to 40–50 ft-lb (53–68 N
S
m).
7.
Screw the tie rod locknuts (23) onto the tie
rods (5). Torque to 40–50 ft-lb (53–68 N
S
m).
8.
Remount the pump and connect all hoses.
9.
Reconnect the ground wire if it was disconnected
during repair.
10. Turn on the hydraulic power to the motor and run
the pump slowly, to make sure it is operating
properly.
11. Fill the packing nut/wet-cup 1/3 full of ISO pump
lube.
Summary of Contents for HYDRA-CAT FIXED RATIO
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