1600 SRM 974
Steering Control Unit
When the steering disk stops moving, the metering
action in the metering section also stops. The neu-
tral position springs return the sleeve to the neutral
position. When this action occurs, the pressure stays
in the steering motor to keep the steer tire in posi-
tion. Oil from the pump flows through the SCU to
the tank or other parts of the system. To return the
steer tire to the straight position, the steering disk
must be rotated in the opposite direction. The SCU
will operate as described, but all parts will rotate in
the opposite direction.
REMOVE
Clean around the ports of the SCU prior to removing
the hydraulic hoses.
1.
Identify and tag all hydraulic hoses attached to
SCU for later installation.
2.
Remove all hydraulic hoses attached to SCU, be-
ing careful not to spill any hydraulic oil.
3.
Install a cap onto each hydraulic hose and install
a plug into each port of the SCU. This is done to
prevent oil from spilling and dirt from entering
the system.
4.
Remove the capscrews and lockwashers that hold
the SCU to the bracket and remove the SCU.
5.
Place SCU on a clean work bench. The work
bench should have a vise with soft jaws.
6.
Wipe up any spilled oil.
REPAIR
NOTE:
Cleanliness is very important when repair-
ing the SCU. Always repair the SCU in a clean work
area. During repairs, always protect machined sur-
faces.
NOTE:
Before disassembly, drain the oil, plug the
ports and thoroughly clean the exterior of the SCU.
Put the control unit in a vise with soft jaws. See
Figure 2.
NOTE:
When removing O-rings carefully clean and
inspect the groove for the O-ring. (Any dirt, burrs, or
foreign material in the groove may cause the O-ring
to leak hydraulic oil.)
Always replace any O-rings that are removed during
repair of the SCU with new O-rings.
1.
STEERING CONTROL UNIT
2.
VISE
3.
ALIGNMENT SCRIBE (MARK)
Figure 2. Steering Control Unit in Vise
Disassemble (Before May 2002)
1.
Scribe (mark) a line across the housing, gerotor,
and mounting cap. This is done so the unit can be
reassembled by aligning the marks. It is critical
to reassemble the SCU correctly because there
are holes drilled into the different parts to allow
oil to circulate through the SCU.
NOTE:
Refer to Figure 3 for the following instruc-
tions.
2.
Remove the capscrews that hold the mounting
cap and remove the mounting cap.
3.
Remove dust seal, pressure seal, and O-ring (8)
from the mounting cap. Carefully clean and in-
spect all surfaces of the mounting cap.
4.
Remove thrust race and thrust bearing from the
shaft of the spool.
5.
Remove the drive pin by gently pulling on the
shaft enough to free the drive pin from the gero-
tor. Remove the drive pin from the shaft.
6.
Remove the gerotor. Carefully clean and inspect
all surfaces of the gerotor.
7.
Remove the O-ring (8) from the housing. Care-
fully clean and inspect all surfaces of the hous-
ing.
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