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Groundsmaster 4500--D/4700--D Hydraulic SystemPage 4 -- 17
Lower Cutting Decks: Groundsmaster 4500--D
A four section gear pump is coupled to the piston (trac-
tion) pump. The third gear pump section supplies hy-
draulic flow to both the lift control manifold and the
steering control valve. Hydraulic flow from this pump
section is delivered to the circuits through a proportional
flow divider located in the fan control manifold. Maxi-
mum lift/lowercircuit pressure is limitedto 1600PSI (110
bar) by a relief valve (RV) 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
theconsolearmisusedtoraiseandlowerthefive(5)
cutting decks (Fig. 10).
When the cutting decks are in a stationary position (not
raising or lowering), lift circuit flow from the third gear
pump section bypasses the lift cylinders through the lift
control manifold solenoid valve S5 (de--energized) and
proportional relief valve TS. Return flow from the m an-
ifold 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 HI speed
(transport), the cutting decks will no t 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 actsas aninput tothe 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
C2 port restricts oil flow from the lift cylinders to control
deck drop speed. An orifice in the junction manifold fur-
ther controls the lowering speed of the #1 deck. The
junction manifold orifices leading to the #4 and #5 decks
are bypassed during deck lowering.
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.
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 hydraulic tube between
the front wheel and rear axle motors 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 isprovided to the proportional relief valve (TS)
to maintain counterbalance pressure.
Figure 10
1
2
1. Console arm 2. Lift switch
Figure 11
#4 #1 #5
#3#2
GM--4500 CUTTING DECK LOCATIONS
Hydraulic
System