Toro Groundsmaster 4700-D Service Manual page 53

Lower Cutting Decks: Groundsmaster 4700- -D
A four section gear pump is coupled to the piston (trac-
tion) pump. Gear pump section P3 supplies hydraulic
flow to both the lift control manifold and the steering con-
trol valve. Hydraulic flow from this pump section is deliv-
ered to the circuits through a proportional flow divider
located in the fan control manifold. Maximum lift/lower
circuit pressure is limited to 1600 PSI (110 bar) by a relief
valve (R1) in the lift control manifold. Lift circuit pressure
can be monitored at lift control manifold test fitting G1.
The Groundsmaster 4700--D has three (3) lift switches
to control the cutting decks (Fig. 12). The center switch
is for the five (5) center decks, the left switch controls the
left, rear deck (#6) and the right switch controls the right,
rear deck (#7) (Fig. 13).
When the cutting decks are in a stationary position (not
raising or lowering), lift circuit flow from pump section P3
bypasses the lift cylinders through the lift control man-
ifold solenoid valve S1 and proportional relief valve TS
which are de--energized. Return flow from the manifold
is routed to the oil filter and traction charge circuit.
NOTE: The operator must be in the operator seat in or-
der to lower the cutting decks. Also, when in high speed
(2WD), the cutting decks will not lower.
Cutting Deck Lower
To lower the center five (5) cutting decks on a Ground-
smaster 4700--D, the front of the center lift switch is de-
pressed. The switch acts as an input to the TEC--5002
controller which then provides an electrical output to so-
lenoid valve S6 in the lift control manifold. This ener-
gized solenoid valve shifts to allow oil flow from the rod
ends of the center five (5) deck lift cylinders. The weight
of the cutting decks cause the lift cylinders to extend and
the center decks to lower. An orifice in the lift control
manifold restricts oil flow from the lift cylinders to control
deck drop speed. Additionally, an orifice in the junction
manifold further controls the lowering speed of the #1
deck.
To lower a side cutting deck on the Groundsmaster
4700--D (deck #6 or #7), the front of the appropriate lift
switch is depressed. The switch acts as an input to the
TEC--5001 controller which then provides electrical out-
put to the appropriate solenoid valves in the lift control
manifold: S1, S3 and S4 for deck #6 or S1, S8 and S9
for deck #7. The energized solenoid valves shift to allow
pump flow to the barrel end of the deck lift cylinder and
a passage for oil from the rod end of the cylinder. The
cylinder extends to lower the side cutting deck. An orifice
in the lift manifold restricts oil flow from the lift cylinder
to control side deck drop speed.
Groundsmaster 4500--D/4700--D
When a deck switch is released, the solenoid valves
controlled by the switch are de--energized and the lift
cylinders and cutting decks are held in position.
Cutting Deck Float
Cutting deck float allows the fully lowered cutting decks
to follow ground surface contours. On a Groundsmaster
4700--D, S6 (center decks), S4 (left deck #6) and S9
(right deck #7) are energized for deck float. These ener-
gized solenoids provide an oil passage to and from the
lift cylinders to allow cylinder and cutting deck move-
ment while mowing.
Counterbalance
Once the cutting decks are fully lowered, the lift control
manifold proportional relief valve (TS) maintains back
pressure (counterbalance) on the deck lift cylinders.
This counterbalance pressure transfers cutting deck
weight to the machine to improve traction.
A pressure sensor located in the 4WD/2WD control
manifold is used by the TEC--5002 controller as an input
to determine traction circuit pressure. Based on this
sensor input, a PWM (Pulse Width Modulation) signal
from the TEC--5002 controller is provided to the propor-
tional relief valve (TS) to maintain counterbalance pres-
sure.
1. Lift switch (#1 to #5)
2. Lift switch (#7)
GM- -4700
CUTTING DECK
LOCATIONS
Page 4 - - 19
3
2
1
Figure 12
3. Lift switch (#6)
#4 #1 #5
#2
#6 #3
Figure 13
Hydraulic System
#7