Vehicle System Testing and Adjusting 35
The probable Hydraulic cause:
1. Sleeve in a solenoid valve for unload function is
stuck to a housing.
Problem: Mast will not lower completely or will
not lower at all.
WARNING
First of all, the button for an emergency manual
override valve in solenoid block as seen below
should be pushed and twisted 180 degree
counterclockwise. Then, the override will be
locked in position until released. This makes it
possible to lower the mast or carriage when lift
spool is shifted for lowering. After lowering the
mast or carriage to the ground and a start key
off, the suspected causes can be inspected. If
mast or carriage con not be lowered by this, its
cause would be mechanical problem or a
hydraulic problem rather than an electrical
problem. After the related problems are
completely fixed, in order to release the manual
override for the normal operation, the push
button should be pushed and twisted 180 degree
clockwise.
Probable Electric Cause:
1. Not to supply the electric power to solenoid valve
in solenoid block.
Probable Hydraulic cause:
1. A broken lift lock solenoid valve in solenoid block.
Probable Mechanical Cause:
1. Lift cylinder damaged or bent.
2. Load roller defective (bearing) or not adjusted
correctly.
3. Not enough lubricant on the parts of mast which
that moves.
Problem: Safety lift lock doesn’t work.
Probable Electric Cause:
1. The electric switch (on-off) below a seat was
damaged.
2. The electric parts (relay and controller) related to
a lift lock solenoid for in solenoid block is trouble.
Probable Hydraulic cause:
1. Lift lock solenoid valve is damaged or
contaminated.
2. Emergency manual override valve is released.
Unload solenoid in
solenoid block
button of an emergency manual
override valve in solenoid block
Safety lift lock function : Once the operator leaves
a seat more than 3 seconds or a start key switch
is off, the lift cylinder doesn’t lower, even thou
h
lift spool is pulled for lowering. Once the operator
sits on seat and the key switch is on, the lowerin
will normally work immediately.
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