Greensmaster 3300/3400 Hydraulic SystemPage 5 -- 17
Raise Cutting Units
The tandem gear pump is directly c oupled to the piston
(traction) pump. The rear gear pump section supplies
hydraulic flow for the steering circuit (priority flow), for
raisingandloweringthecuttingunitsandforthetraction
chargecircuit. Thegearpumptakesits suctionfromthe
hydraulic reservoir. Maximum circuit pressure of 1160
PSI (80 bar) is limited by the relief valve located in the
power steering valve.
The liftcontrol manifoldincludes four (4)electricallyop-
eratedsolenoidvalves.Solenoidv alveS1causescircuit
flow to by--pass the lift cylinders when de--energized
anddirects flowto thecylinderswhen energized.Direc-
tionalsolenoid valve S2is usedto directoil flow toraise
the cutting units when de--energized and lower them
whenenergized.Whenenergized,solenoidvalveS3al-
lows hydraulic flow to and from the front cutting unit lift
cylinders (#2 and #3) and prevents oil passage to and
from the lift cylinders when de--energized. When ener-
gized, solenoid valve S4 allows hydraulic flow to and
fromthecentercuttingunitliftcylinder(#1)andprevents
oil passage to and from the lift cylinder when de--ener-
gized.
The console arm joystick is used to raise and lower the
cutting units. The joystick acts as an input to the TEC
controller to send electrical outputs to appropriate lift
control manifold solenoid coils inorderto raise or lower
the cutting units.
While operating the machine during conditions of not
raising or lowering the cutting units (joystick in the neu-
tral (center) position), all of the lift manifold solenoid
valves(S1,S2,S3andS4)arede--energized.Flowfrom
therear gearpumpsectionisdirected throughthe pow-
ersteeringvalve,de--energizedsolenoidvalveS1inthe
lift control manifold, oil filter and to the traction charge
circuit. Flow in excess of charge circuit needs then re-
turns to the gear pump input.
Raise Cutting Units
Whenthejoystickismovedtotheraiseposition,theToro
Electronic Controller (TEC) energizes lift control man-
ifold solenoid valves S1, S3 and S4 for approximately
three(3) seconds.This timeframeensures thatthecut-
ting units will be fully raised. The controller provides a
shortdelayinenergizingsolenoidvalveS4whichdelays
the raising of the center cutting unit (#1).
Energized lift manifold solenoids S1, S3 (front lift cylin-
ders) and S4 (center lift cylinder) direct circuit flow to-
wardthe liftcylinders inthecorrect directiontoraisethe
cutting units. The front lift cylinders retract to raise the
cuttingunitswhilethecenterliftcylinderextendstoraise
the cuttingunit. Hydraulicpressureagainst thelift cylin-
der pistons moves their shafts causing the cutting units
to raise. At the same time, the lift cylinder pistons push
the hydraulic fluid out of the cylinders to de--energized
solenoid valve S2. Return flow continues to the oil filter
and then to the traction charge circuit.
A0.037orifice(OR1)controlsraising speedfor thecen-
tercuttingunit(#1).Flowtothefrontliftcylinders(cutting
units#2and#3)bypassestheliftmanifoldorifices(OR2
and OR3) when the front cutting units are being raised.
When the lift control manifold solenoid valves are de--
energized by the TEC controller, spring action returns
the valves to their original position stopping lift cylinder
movement. The lift cylinder position is locked in place
sincethereis nocomplete circuitof flow toand fromthe
lift cylinders. Hydraulic flow by--passes the lift cylinders
and is routed to the oil filter and charge circuit.
Hydraulic
System
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