Lift Cylinder Circuit: Lower The Cutting Decks - Toro Groundsmaster 4300-D Service Manual

Lift Cylinder Circuit: Lower the Cutting Decks

Lower the Cutting Decks
Groundsmaster ® 4300-D
16226SL Rev C
g186185
A 4-section gear pump is coupled to the piston (traction) pump. The gear pump
section (P4) supplies hydraulic flow to the lift control manifold and lift cylinders.
The gear pump takes its suction from the hydraulic reservoir.
The lift control manifold includes 3 electrically operated valves. The solenoid
valve (S1) is used to direct fluid flow to extend the lift cylinders (lower the
cutting decks) when energized or retract them (raise the cutting decks) when
de-energized. The solenoid valve (S2) allows hydraulic flow from the rod end
of the lift cylinders when energized, and prevents hydraulic flow from the lift
cylinders when de-energized. Using solenoid valve S2 in this manner also
helps keep the cutting decks elevated once the machine is switched O
proportional relief valve (PRV) is used to control the operation of the logic
cartridge (LC) and acts as a circuit relief valve.
Note: With the engine running, the cutting units can only be lowered if an
operator is in the seat or the parking brake is set, and the mow/speed limiter is
in the M position. The cutting units can also be lowered without the engine
OW
running if the key switch is in the R
When the joystick is moved to the lower position, the controller energizes all of
the lift manifold valves (S1, S2, and PRV). The energized relief valve (PRV)
prevents flow through the valve which allows logic cartridge LC to return to its
unshifted (closed) position. With the valves in this position, the pump flow is
Figure 37
position and the operator is in the seat.
UN
Page 4–27 Hydraulic System: Hydraulic Flow Diagrams
. The
FF