Toro Groundsmaster 5900 Series Service Manual page 123

Front Deck Raise
Groundsmaster ® 5900 & 5910
16227SL Rev B
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 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 manifold limits lift/lower circuit
pressure to 103 bar (1500 PSI).
g287732
1. Left deck raise/lower switch
2. Front deck raise/lower switch
Each of the cutting decks (front, right and left) can be raised independently with
the use of three (3) deck raise/lower switches on the armrest console
40). Pressing the rear of a switch provides an input for the slave Toro Electronic
Controller (TEC) to raise a cutting deck. The controller provides electrical outputs
to solenoids in the steering/deck lift manifold to allow appropriate valve shift to
cause a cutting deck to raise.
When the cutting decks are in a stationary position, all solenoids in the
steering/deck lift 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 raise a cutting deck, the engine must be running. Also, the operator
seat has to be occupied or the parking brake must be applied with the traction
pedal in neutral.
To raise the front deck, the rear of the center console switch is depressed. The
switch acts as an input to the slave TEC which provides an electrical output to
solenoid valves S1 and S5 in the steering/deck lift manifold. The energized
solenoid valves shift to allow a passage for circuit oil flow to the barrel end of
the front deck lift cylinders. Shifted S1 prevents oil flow from returning directly
to the traction charge circuit. Shifted S5 allows an oil path through orifice OR4
(to control raising speed), the check valve at OR5 and to the barrel end of the
lift cylinders to extend the lift cylinders and raise the front deck. Oil from the
extending cylinders returns to the hydraulic reservoir.
When the deck switch is released, the manifold solenoids are de−energized and
the front deck lift cylinders and front deck are held in position.
1
Figure 40
3. Right deck raise/lower switch
Page 5–23 Hydraulic System: Hydraulic Flow Diagrams
2
3
(Figure