Lower Cutting Unit - Toro Groundsmaster
4000?D Service Manual

PRELIMINARY – For Toro Distributor and Toro Company use only.

Lower Cutting Unit

A four section gear pump is coupled to the piston (trac-
tion) pump. The third gear pump section supplies hy-
draulic flow to both the lift/lower control valve and the
steering control valve. Hydraulic flow from this pump
section is delivered to the circuits through a proportional
flow divider. This pump section takes its suction from the
hydraulic reservoir.
When the cutting units 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 lower a side cutting unit, the appropriate lift lever on
the lift/lower control valve is pushed to allow valve shift
in the lift/lower control. This valve change causes a
valve shift in the counterbalance manifold and oil flow to
the rod end of the lift cylinder. Higher hydraulic pressure
against the rod end of the cylinder causes the shaft to
retract, and lower the cutting unit. Oil from the piston end
of the cylinder returns to the traction charge circuit.
When the lift lever is released, the lift cylinder is held in
position.
Hydraulic System
To lower the front cutting unit, the center lift lever on the
lift/lower control valve is pushed to allow valve shift in the
lift/lower control. This valve change allows a passage for
oil flow from the rod end of the front deck lift cylinder. The
weight of the cutting deck causes the lift cylinder to ex-
tend, and lower the cutting unit. Oil from the rod end of
the cylinder is allowed to return to the traction charge cir-
cuit. When the lift lever is released, the lift cylinder is held
in position.
The drop speed of the front cutting units is regulated by
an adjustable flow control valve that is located in the hy-
draulic lines between the lift/lower control valve and the
front deck lift cylinders.
An adjustable counterbalance valve maintains back
pressure on the side deck lift cylinders. A relief valve lo-
cated in the lift/lower control valve limits circuit pressure.
Excess circuit flow is routed to the oil filter and then to
the traction charge circuit.
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