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SECTION 2. CABLE CONTROL HYDRAULIC VALVE
TROUBLE SHOOTING
2.1 Loss of operation of any service. Also operation of bed chain in 1 direction only may occur. Failure
may be sudden or deteriorate slowly over a few days.
Cause
Series plug (adjacent to item 10 Section 3.2) has failed/come out of position resulting in oil flowing back to tank
which stops the other slices operating.
Solution
Replace blanking plug and valve body if damaged.
2.2 Bed chain no longer operates or operates only very slowly at tractor engine PTO speed.
Failure may be sudden or intermittent.
Possible causes
There are 3 possible causes; the first one is the most likely to be the problem.
a) Dirt or contamination in the Bypass Valve in the flow control slice does not allow it to close resulting in the
oil dumping to tank starving any oil flow to the motor.
b) Dirt or contamination in the Pressure Relief Valve in the flow control slice does not allow it to close resulting
in the oil dumping to tank starving any oil flow to the motor.
C) Failure of the hydraulic motor.
Solution
Remove Bypass Valve or Pressure Relief Valve from the Flow Control Slice, inspect for contamination, clean and
replace.
With reference to Section 3.2, remove the bypass valve by unscrewing the cap adjacent to item 15, remove
bonded seal (15) and the spring below. Using long nose pliers remove the spool and bypass
valve body complete
with '0' rings. Clean and rebuild.
With reference to Section 3.2, remove the pressure relief valve by unscrewing the complete valve from the slice
and inspect the seat for contamination, clean and replace.
2.3 Bed chain speed control stops working on full or part bed chain speed
Possible causes
Flow control spool jammed open by contamination.
Solution
Remove the valve guard from the front of the machine. Slip the rubber shield from around the flow control cam
mechanism up. Undo the 3 grub screws retaining the aluminium adapter body to the top of the valve. Unscrew
the flow control spool from the valve body Remove contamination and
reassemble making sure the adapter body
is fully seated before securing with grub screws.
2.4 Oil leaks from between the interface seals between the slices of the valve.
Possible causes
This is caused by the failure of O rings between the slices of the valve and can be caused by several things.
a) Oil flow in the wrong direction has been passed through the valve block. If a ram is operated in this state
sufficient pressure can be generated within the valve block to separate the valve slices causing the O-rings
to extrude.
b) The valve has been pressurised with the return hose not connected to the tractor.
c) Damage to the return hose quick release fitting does not allow full flow of oil back to tank.
d) The tractor spool valve does not have a free flow return and is generating back pressure within the valve
block.
e) Excessive oil flow has caused the oil seal in the main gallery to be extruded from its recess.
f) Studs holding the valve chest together are not tightened sufficiently.
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