6-10
1A
LIFT
Lift lock
valve
22B7HS11
Lowering
When the seated operator shifts the lever forwards, the spool retracts into the valve, and the oil is
directed from the cylinder, past the lift lock check valve, past the spool metering notches, and to
the common tank cavity.
Θ
1A
LIFT
Lift lock
valve
22B7HS12
Pressure is limited by the main relief valve.
LIFT SECTION
Operation
The lift section has a single work port to direct flow to the lift cylinder. Only one work port is used,
because the lift cylinder is single-acting(gravity returns the mast to the lowered position).
The lift section also contains part of the components which comprise the safety features. There is
a lift lock check valve. At the neutral position, pressures in the lock valve are equalized across the
lift lock poppet. In this manner, the spring bias keeps the lift lock valve closed and prevents
lowering of the mast.
Lifting
When the operator shifts the lever backwards, the spool is extended out of the valve, and this
opens the internal fluid passages that lift the mast. Oil flows through the high pressure parallel
cavity, past the load check valve, through the spool metering notches, past the lift lock check
valve, and to the head side of the lift cylinder.
4)
(1)
Η