Lower Cutting Deck - Toro Groundsmaster 4100-D Service Manual

Lower Cutting Deck

A three section gear pump is coupled to the piston (trac-
tion) pump. The gear pump section farthest from the pis-
ton pump supplies hydraulic 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 deck is 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 the cutting deck, 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 deck lift cylinders. The
weight of the cutting deck causes the lift cylinder shafts
to extend, and lowers the deck. Oil from the rod end of
the cylinders is allowed to return to the traction charge
circuit. When the lift lever is released, the lift cylinders,
and cutting deck, are held in position.
Groundsmaster 4100--D
The drop speed of the cutting deck is regulated by an ad-
justable flow control valve that is located in the hydraulic
lines between the lift/lower control valve and the deck lift
cylinders.
To lower a wing deck, the appropriate lift lever (right side
or left side) on the lift/lower control valve is pushed to al-
low valve shift in the lift/lower control valve. This valve
change causes a valve shift in the counterbalance man-
ifold and oil flow to the piston end of the lift cylinder. High-
er hydraulic pressure against the piston end of the
cylinder causes the shaft to extend, and lowers the wing
deck. Oil from the rod end of the cylinder returns to the
traction charge circuit. When the lift lever is released, the
lift cylinder, and wing deck, is held in position.
An adjustable counterbalance valve maintains back
pressure on the deck lift cylinders. A relief valve located
in the lift/lower control valve limits circuit pressure. Ex-
cess circuit flow is routed to the oil filter and then to the
traction charge circuit.
Rev. E
Page 4 - - 11 Hydraulic System