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Groundsmaster 4500--D/4700--D Hydraulic SystemPage 4 -- 19
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
flowto boththe liftcontrol manifoldand thesteeringcon-
trol valve.Hydraulic flow fromthis pumpsection is deliv-
ered to the circuits through a proportional flow divider
located in the fan control manifold. Maximum lift/lower
circuitpressureislimitedto1600PSI(110bar)bya relief
valve (R1)in thelift controlmanifold. Liftcircuit 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
isfor thefive (5)center decks,the left switchcontrols the
left,rear deck (#6) and theright switchcontrols theright,
rear deck (#7) (Fig. 13).
When the cutting decks are in a stationary position (not
raisingor lowering),liftcircuit flowfrom pumpsectionP3
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) c utting 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 whichthen provides anelectrical output toso-
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
ofthe cuttingdecks causethelift cylindersto extendand
the center decks to lower. An orifice in the lift control
manifold restricts oilflow from the liftcylinders 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 controllerwhich thenprovides 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 energizedsolenoid valvesshift toallow
pump flow to the barrel end of the deck lift cylinder and
a passage for oil from the rod end of the cylinder. The
cylinderextendstolowerthesidecuttingdeck.Anorifice
in the lift manifold restricts oil flow from the lift cylinder
to control side deck drop speed.
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 followground surfacecontours. Ona Groundsmaster
4700--D, S6 (center decks), S4 (left deck #6) and S9
(right deck#7) are energizedfor 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 isused bythe TEC--5002 controlleras aninput
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) tomaintain counterbalance pres-
sure.
1. Lift switch (#1 to #5)
2. Lift switch (#7)
3. Lift switch (#6)
Figure 12
1
3
2
Figure 13
#4 #1 #5
#7#6 #3
#2
CUTTING DECK
GM--4700
LOCATIONS
Hydraulic
System