Greensmaster 3300/3400 Hydraulic SystemPage 5 -- 15
Lower 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.
Lower Cutting Units
When the joystick is moved to the lower position, the
Toro Electronic Controller (TEC) energizes all of the lift
controlmanifoldsolenoidvalvesforapproximatelythree
(3) seconds. This time frame ensures that the cutting
unitswillbefullyloweredtoallowthemtofloatduringop-
eration.Thecontrolleralsoprovidesashortdelayinen-
ergizing solenoidvalve S4 which delaysthe lowering of
the center cutting unit (#1).
EnergizedliftmanifoldsolenoidsS1andS2directcircuit
flow toward the lift cylinders in the correct direction to
lower the cutting units. The front lift cylinders extend to
lower the cutting units while the center lift cylinder re-
tracts to lower the cutting unit. Hydraulic pressure
againstthe lift cylinderpistons movestheirshafts caus-
ingthecuttingunitstolower.Atthesametime,theliftcyl-
inderpistonspushthehydraulicfluidoutofthecylinders
toenergized solenoidvalves S3(front liftcylinders) and
S4 (center lift cylinder). Return flow continues through
energized solenoid valve S2, to the oil filter and then to
the traction charge circuit.
Lowering speed for each of the front cutting units (#2
and #3) is controlled by a 0.028 orifice (OR2 and OR3)
intheliftcontrolmanifold.A0.037orifice(OR1)controls
lowering speed for the center cutting unit (#1).
If the lift cylinders should reach the end of their stroke
whiletheliftmanifoldsolenoidsarestillenergized,liftcir-
cuit pressure will increase. The lift circuit lower relief
valve (RV) in the lift control manifold allows lift circuit
pressureto belimited to400 PSI(27.6bar) whilelower-
ing the cutting units.
NOTE: Adjustment of the lift control manifold lift circuit
lower relief valve (RV) is not recommended.
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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