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Groundsmaster 4000--D Hydraulic SystemPage 4 -- 17
Raise Cutting Deck
A four section gear pump is coupled to the piston (trac-
tion) pump. The third gear pump section supplies hy-
draulicflowtothe lift/lowercontrolvalveand the steering
control valve. Hydraulic flow from this pump section is
delivered to the two circuits through a proportional flow
divider. The gear pump takes its suction from the hy-
draulic reservoir.
When the cutting decks are in a stationary position, flow
from the gear pump is by--passed through the lift/lower
control valve, counterbalance manifold, oil filter and
traction charge circuit.
To raise a side cutting deck, the appropriate lift lever on
the lift/lower control valve is pulled to allow valv e shift in
the lift/lower control valve. This valve change allows hy-
draulic pressure to the piston end of the lift cylinder and
causes the cylinder shaft to extend, raising the cutting
deck. Oil from the rod end of the cylinder flows to the
tractioncharge circuit.When theliftlever isreleased,the
lift cylinder and cutting deck are held in position.
To raise the front cutting deck, the center lift lever on the
lift/lower control valve is pulled to allow valve shift in the
lift/lower control valve. This valve change allows hy-
draulic pressure to the rod end of the front deck lift cylin-
ders, causing the cylinders to retract. As the cylinders
retract, the front deck raises. Oil from the piston end of
the cylinders returns to the hydraulic reservoir. When
theliftlever isreleased,the liftcylinders andcuttingdeck
are held in position.
An adjustablecounterbalancevalve (CB) in thecounter-
balance manifold maintains back pressure on the deck
lift cylinders to allow some of the cutting deck weight to
be transferred to the traction unit to improve traction. A
relief valve located in the lift/lowercontrol valve limits lift/
lower circuit pressure to 1500 PSI (103 bar). Excess cir-
cuit flow is routed to the oil filter and then to the traction
charge circuit.
Hydraulic
System