Vehicle System System Operation 19
The hydraulic system has a hydraulic tank (14) and
a gear pump (11) which is installed at the engine.
The gear pump (11) sends the pressurized fluid
through hydraulic line (15) to control valve (7).
The first block of control valve contains a steering
spool to supply the control flow (12 LPM) through
hydraulic line (8) to steering unit with the higher
priority. In case of no movement of spools the
remainder of fluid from the first block of control valve
returns through a hydraulic line (16) back to a
hydraulic tank.
The movement of spool makes a fluid for a lift
cylinder (1,3) and/or tilt cylinder (6) and/or side shift
cylinder (5). The hydraulic fluid from each cylinder
flows through control valve, hydraulic line (16) and a
filter-return (13), and back to a hydraulic tank (14).
The relief valve-main (10) releases the excessive
pressure to the hydraulic tank when the pressure in
the lift circuit or tilt circuit goes higher than setting
pressure shown at CONTROL VALVE SECTION of
SPECIFICATION. The relief valve-auxiliary (9)
releases the excessive pressure to the hydraulic
tank when the pressure in auxiliary circuit goes
higher than setting pressure shown at CONTROL
VALVE SECTION of SPECIFICATION.
The speed when lift cylinders are lowered is
controlled by the flow regulator valve (22).
Flow protector (2)&(4) integrated to lift cylinder acts
as a fuse valve if the line between control valve (flow
regulator) and flow protector is broken when the lift
cylinder is raised or lowered. This prevents the
sudden fall of mast or carriage if a hydraulic line is
broken.
There is a counter-balance valve ( or, tilt lock valve)
in tilt spool to prevent the cavitation (development of
air pocket) in tilt cylinder.
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