Lift Circuit (Machine Serial Number Above 311000000) - Toro Groundsmaster 3280-D Service Manual

Lift Circuit (Machine Serial Number above 311000000)

Raise the Cutting Deck (or Implement)
Groundsmaster ® 3280-D/3320
05138SL Rev B
The charge pump supplies charge fluid for the closed loop traction circuit in
addition to supplying flow for the steering circuit and the lift circuit. The charge
pump takes its suction through a filter from the transaxle reservoir (front axle).
The pump output flows to the steering control valve before reaching the lift
manifold so that the steering circuit has priority. When the lift switch is not set to
raise or lower, fluid flow enters the lift manifold at the P port. Hydraulic pressure
will try and raise the lift arms until the logic cartridge LC shifts open and provides
a fluid path to the tank (front axle). When the logic cartridge opens is controlled
by adjusting the logic cartridge to the desired setting or counterbalance. Refer
to the traction unit Operator's Manual for additional counterbalance adjustment
information.
When the lift switch is set to the Raise position, solenoid valve SV1 is energized,
holding logic cartridge LC closed. Hydraulic flow is directed through solenoid
valve SV2 to the cap end (top) of the lift cylinders. When the cylinders reach the
end of their stroke, or if the lift arms are prevented from raising, the charge pump
relief valve in the hydraulic pump opens and directs the hydraulic flow to the tank
(front axle) until the lift switch is released.
The hydraulic pressure against the cylinder pistons extends the lift cylinders. At
the same time, the pistons push the hydraulic fluid in the lower portion of the
lift cylinders out and to the hydraulic reservoir (front axle). The extending lift
cylinders cause the cutting deck (or implement) to raise.
Page 5–31 Hydraulic System: Hydraulic Flow Diagrams