Control Valve Spool Travel Check - Allied Systems W8L Service Manual

3. Improper control valve spool movement.
4. Broken seal rings on clutch shaft.
5. Damaged O-rings on clutch shaft. Troubleshooting
information is given after the subsection.
If the LINE-OUT INCHING pressure differential is not as
specifi ed in Figure 2-22, proceed as follows:
1. Loosen the reverse modulator adjustment locknut
and start engine. Move the control lever towards
LINE-OUT until the brake pressure reads 140 PSI
(9.8 kg/cm²). Use 180 PSI for direct drive PTOs.
2. Turn the adjusting capscrew IN to decrease Reverse
Clutch Pressure, or OUT to increase pressure until
Reverse Clutch Pressure is less than the brake
pressure by the amount shown in Figure 2-22.
3. Tighten locknut and recheck pressure. Repeat steps
1 and 2 if necessary.

Control Valve Spool Travel Check

It may be necessary to check spool travel when control
valve pressures do not meet specifi cations. Figure 2-21
shows the correct travel for the various spool positions.
The control valve spool is self-positioned to BRAKE-
ON. The three other travel positions are determined by
spool assembly internal stops and a detent assembly
in the spool end cap. If spool travel is found to be out
of adjustment, the spool assembly or complete control
valve assembly should be replaced. Ensure that the spool
end cap is installed securely, then perform the check for
smooth return of control lever to neutral from any other
position. Any binding or sticking should be investigated
by removing the spool cap and examining parts for wear.
DETERMINE THIS
POSITION (BRAKE ON)
FIRST AS A REFERENCE
POINT
.750"
(19mm)
BRAKE ON
LINE OUT
BRAKE OFF
Figure 2-21 Control Valve Spool Travel
NOTE: The spool is detented in BRAKE-OFF. If spool
does not lock up in this position, examine the detent
parts inside the spool end cap and repair or replace
as necessary.
Section 2
.500"
(13mm)
.312"
(8mm)
LINE IN
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