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Greensmaster 3320/3420Hydraulic System Page 5 -- 26
Lift/Lower Circuit Problems
Problem Possible Cause
Gear pump is noisy (cavitation). Reservoir oil level is low.
Gear pump suction line is restricted.
Gear pump suction line has an air leak.
Cutting units will not lift or lift slowly. Engine speed is too low.
Reservoir o il level is low (other hydraulic systems affected as well).
Cutting unit suspension components are binding or damaged.
Lift cylinder attachment pins are binding.
Electrical problem exists that prevents lift control manifold solenoid
valve operation (see Chapter 5 -- Electrical System).
Relief valve in power steering valve is leaking or damaged ( see
Steering/Lift Relief Valve Pressure Test in the Testing section of this
chapter).
Solenoid valve (S1) in lift control manifold is leaking or damaged
(valve not shifting to its energized position).
Lift cylinder(s) leak internally.
Spool in power steering valve is sticking (see Power Steering Valve
Test in the Testing section of this chapter).
Gear pump is worn or damaged (steering and charge circuits af-
fected as well) (see Steering/Lift Circuit Gear Pump Flow Test in
the Testing section of this chapter).
Front cutting units (#2 and #3) raise,
but will not stay up.
(NOTE: Lift cylinders and control
manifold check valves cannot pro-
vide an absolutely perfect seal. The
cutting u nits will eventually lower if
left in the raised position)
Solenoid valve (S3) in lift control manifold is leaking or damaged.
Front lift cylinders leak internally.
Center cutting unit (#1) raises, but
will not stay up.
(NOTE: Lift cylinders and control
manifold check valves cannot pro-
vide an absolutely perfect seal. The
cutting u nits will eventually lower if
left in the raised position)
Solenoid valve (S4) in lift control manifold is leaking or damaged.
Center lift cylinder leaks internally.