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Reelmaster 3550−D Hydraulic SystemPage 4 − 23
Lift Circuit: Raise
The tandem gear pump is directly coupled to the vari-
able displacement piston pump/hydrostat which is belt
driven by the engine. The rear section of the tandem
gear pump (P2) supplies hydraulic flow for the steering
circuit (priority flow), for raising and lowering the cutting
units and for the traction charge circuit. The gear pump
takes its suction from the hydraulic tank. Maximum
steering and lift circuit pressure of 1000 PSI (69 bar) is
limited by the relief valve located in the power steering
valve.
The lift control manifold includes four (4) electrically op-
erated solenoid valves. Solenoid valve S1 causes circuit
flow to by−pass the lift cylinders when de−energized
and directs flow to the cylinders when energized. Direc-
tional solenoid valve S2 is used to direct oil flow to raise
the cutting units when energized and lower them when
de−energized. When energized, solenoid valve S3 al-
lows hydraulic flow to and from the front cutting unit lift
cylinders (#1, #4 and #5) and prevents oil passage to
and from these lift cylinders when de−energized. When
energized, solenoid valve S4 allows hydraulic flow to
and from the rear cutting unit lift cylinders (#2 and #3)
and prevents oil passage to and from these lift cylinder
when de−energized.
The console joystick is used to raise and lower the cut-
ting units. The joystick acts as an input to the Toro Elec-
tronic Controller (TEC) to send electrical outputs to
appropriate lift control manifold solenoid coils in order to
raise or lower the cutting units.
Lift circuit pressure can be monitored at the test fitting in
lift control manifold port G1.
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, S3 and S4) are de−energized. Flow from
gear pump (P2) is directed through the steering control
valve, de−energized solenoid valve S1 in the lift control
manifold and then to the traction charge circuit. Flow in
excess of charge circuit needs then returns to the gear
pump inlet.
1. Reel motor location 2. Weight location
Figure 23
FRONT
#3
#4 #5
1
2
#1
#2
2
1
1
2 11
CUTTING UNIT LOCATIONS
Raise Cutting Units
NOTE: The operator must be in the operator seat in or-
der to raise the cutting units.
When the joystick is moved to the raise position by the
operator, solenoid valve S1, S2, S3 and S4 are ener-
gized by the TEC controller. To allow the front cutting
units to be raised before the rear cutting units, the con-
troller slightly delays energizing solenoid S4 after the
joystick is moved. The energized solenoid valves direct
gear pump oil flow to the rod end of the lift cylinders.
Flow control orifices in the lift control manifold (OR1,
OR3, OR5 and OR7) are bypassed when raising the cut-
ting units.
Hydraulic pressure causes the lift cylinder shafts to re-
tract, and raise the cutting units. Flow control orifices in
the lift control manifold (OR2, OR4, OR6 and OR8) con-
trol the cutting unit raising speed by providing a restric-
tion for the return flow from the lift cylinders. The internal
relief valve in the steering control valve allows lift circuit
pressure to be limited to 1000 PSI (69 bar) while raising
the cutting units.
When the joystick is released, solenoid valves S1, S2,
S3 and S4 are de−energized so the lift cylinders and cut-
ting units are held in position.
Hydraulic
System