Toro Groundsmaster 4700-D Service Manual page 51

Lower Cutting Decks: Groundsmaster 4500- -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.
On the Groundsmaster 4500--D, a single lift switch on
the console arm is used to raise and lower the five (5)
cutting decks (Fig. 10).
When the cutting decks are in a stationary position (not
raising or lowering), lift circuit flow from gear pump sec-
tion P3 bypasses the lift cylinders through the lift control
manifold solenoid valve S5 (de--energized) and propor-
tional relief valve TS. 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 five (5) cutting decks on a Groundsmaster
4500--D, the front of the lift switch is depressed. The
switch acts as an input to the TEC--5002 controller which
then provides an electrical output to solenoid valve S6
in the lift control manifold. This energized solenoid valve
shifts to allow a passage for oil flow from the rod ends
of the five (5) deck lift cylinders. The weight of the cutting
decks causes the lift cylinders to extend and lowers all
of the cutting decks. 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 man-
ifold further controls the lowering speed of the #1 deck.
When the deck switch is released, the solenoid valve S6
is 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
4500--D, lift control manifold solenoid valve S6 is ener-
gized for deck float when the decks are fully lowered.
This energized solenoid provides an oil passage to and
from the lift cylinders to allow cylinder and cutting deck
movement while mowing.
Groundsmaster 4500--D/4700--D
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)
#4
GM- -4500 CUTTING DECK LOCATIONS
Page 4 - - 17
1
Figure 10
#1 #5
#2 #3
Figure 11
Hydraulic System