Steering Pump and Motor Assembly
1600 SRM 974
19. Install the end cap and align the scribe (mark)
you made earlier on the wear plate, gerotor, end
cap, and housing.
20. Install capscrews and tighten in a crisscross pat-
tern to 16 - 18 N•m (140 - 160 lbf in) as shown in
Figure 6.
21. Remove the SCU from the vise.
22. Install the check/relief valve or check ball and
plug. Use a new O-ring and tighten the plug to
17 N•m (150 lbf in).
Figure 6. Tightening Sequence
INSTALL
WARNING
If the hoses are incorrectly connected, the
steering disk can move rapidly with high force
when the truck is started.
Do not place the
hands near the disk when starting the lift
truck after connecting the pump.
1.
Align the SCU with the mounting bracket and
install the capscrews and lockwashers.
2.
Remove the caps from the hydraulic lines and the
plugs from the SCU. Install the hydraulic lines
on the SCU.
3.
Replace the steering control handle. Replace the
shoulder screw, lockwasher, and nut that hold
the steering control handle to the SCU.
4.
Install the drive unit cover and the battery com-
partment cover. Remove the blocks from the tires
and wheels. Connect the battery and test the
SCU. Check for leaks. Close the drive unit com-
partment cover.
Steering Pump and Motor Assembly
DESCRIPTION
This pump and motor also supply oil for the aux-
iliary hydraulic functions. The steering pump and
motor assembly are fastened to the lift truck frame.
The steering pump and motor operate when the key
switch is ON and the operator has both the brake
pedal and the operator sensing switch depressed.
The steering pump is a small gear pump fastened to
a permanent magnet DC motor. The steering pump
has a built-in priority valve to ensure priority flow to
the power steering. When both the power steering
and auxiliary functions are used at the same time,
the priority valve will ensure that full flow is pro-
vided to the power steering. The inlet (suction port)
of the pump is connected to the hydraulic tank with
a hydraulic hose.
The pump outlet (pressure) ports are connected to
both the SCU and the main control valve with hy-
draulic hoses. The hose to the main control valve is
the excess flow line. The hydraulic oil in this line will
either be directed to the auxiliary functions or to re-
turn the oil to the hydraulic tank when the steering
disk is not being rotated or the auxiliary functions
are not being used. There are two hoses to the SCU.
One hose is the priority flow line to the SCU. The
other hose to the SCU is the load-sensing hose. The
load-sensing hose is used to determine the amount of
oil required to operate the SCU for the priority valve.
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