Toro Groundsmaster 5900 Series Service Manual page 126

Front Cutting Deck Lower
Right Cutting Deck Lower
Hydraulic System: Hydraulic Flow Diagrams
A three (3) section gear pump is coupled to the piston (traction) pump. The
gear pump section furthest from the piston pump supplies hydraulic flow to the
steering, cutting deck lift and traction charge circuits. Hydraulic flow from the final
pump section is directed to the appropriate circuits by a pressure compensator
valve located in the steering/deck lift control manifold.
An adjustable counterbalance valve (RV3) in the steering/ deck lift control
manifold maintains back pressure on the deck lift cylinders to allow some of the
cutting deck weight to be transferred to the traction unit to improve traction. A
relief valve (RV2) located in the steering/deck lift control manifold limits lift/lower
circuit pressure to 103 bar (1500 PSI).
Each of the cutting decks (front, right and left) can be lowered independently with
the use of three (3) deck lift/lower switches on the armrest console
Pressing the front of a switch provides an input for the slave Toro Electronic
Controller (TEC) to lower a cutting deck. The controller provides electrical
outputs to solenoids in the steering/deck lift control manifold to allow appropriate
valve shift to cause a cutting deck to lower.
When the cutting decks are in a stationary position, all solenoids in the
steering/deck lift control manifold are de−energized. In this position, the flow
from the final gear pump section is by−passed through solenoid valve (S1),
the counterbalance valve (RV3), the charge oil filter and then is routed to the
traction charge circuit.
Note: To lower a cutting deck, the traction speed needs to be in low range (mow)
and the operator seat must be occupied.
To lower the front cutting deck, the front of the center console switch is
depressed. The switch acts as an input to the slave TEC which provides an
electrical output to solenoid valve S6 in the steering/deck lift control manifold.
Energized solenoid valve S6 shifts to allow a passage for oil flow from the barrel
end of the front deck lift cylinders. The weight of the cutting deck causes the front
deck lift cylinders to retract and lower the front cutting deck.
When the deck switch is released, the control manifold solenoid is de−energized
and the lift cylinders and front cutting deck are held in position.
To lower the right wing deck, the front of the right console switch is depressed
to act as an input to the slave TEC. The controller provides an electrical output
to solenoid valves S1, S8 and S9 in the steering/deck lift control manifold. The
energized solenoid valves shift to allow a passage for circuit oil flow to the rod
end of the right wing deck lift cylinder. Shifted S1 prevents oil flow from returning
directly to the traction charge circuit. Shifted S8 allows an oil path to the shaft
end of the lift cylinder to retract the lift cylinder and lower the right wing deck. Oil
from the retracting cylinder flows through orifice OR7 to control the drop speed of
the cutting deck. Flow is then directed through the shifted S9, counterbalance
valve (RV3) and then is routed to the traction charge circuit.
When the deck switch is released, the control manifold solenoids are
de−energized and the lift cylinder and right wing deck are held in position.
Page 5–26
(Figure 40).
Groundsmaster ® 5900 & 5910
16227SL Rev B