Toro 30411, Service Manual

Page: 55 / 262

Rev. E Groundsmaster 4100--D Hydraulic System Page 4 -- 13
Raise 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 the lift/lower control
valve and 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 suc-
tion 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 raise the cutting deck, the center lift lever on the lift/
lower control valve is pulled to allow valve shift in the lift/
lower control. This valve change allows hydraulic
pressure to the rod end of the deck lift cylinders, causing
the cylinders to retract. As the cylinders retract, the cut-
ting deck raises. Oil from the piston end of the cylinders
returns to the hydraulic reservoir. When the lift lever is
released, the lift cylinders, and cutting deck, are held in
position.
To raise a wing deck, the appropriate lift lever (right side
or left side) on the lift/lower control valve is pulled to al-
low valve shift in the lift/lower control. This valve change
allows hydraulic pressure to the piston end of the lift cyl-
inder and causes the shaft to retract, raising the wing
deck. Oil from the rod end of the cylinder flows 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 lift cylinders. A relief valve located in the
lift/lower control valve limits circuit pressure. Excess cir-
cuit flow is routed to the oil filter and then to the traction
charge circuit.
Hydraulic System