Toro Reelmaster 3550-D Service Manual page 57

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, for raising and lowering the cutting units and for
the traction charge circuit. The gear pump takes its suc-
tion from the hydraulic tank. On Reelmaster 3550−D
machines, the oil flow from gear pump (P2) moves
through the steering circuit first, then through the lift cir-
cuit. To provide separate relief pressures for each circuit
on Reelmaster 3555−D/3575−D machines, the oil flow
from gear pump (P2) moves through the lift circuit first,
then through the steering circuit.
The maximum steering circuit pressure of 1000 PSI (69
bar) is limited by the relief valve located in the power
steering valve. On Reelmaster 3550−D machines, the
maximum lift circuit pressure is also controlled by the re-
lief valve located in the power steering valve. Due to the
increased size and weight of the cutting units on Reel-
master 3555−D/3575−D machines, the maximum lift cir-
cuit pressure of 2000 PSI (138 bar) is controlled by an
additional relief valve located in the lift control manifold.
Lift circuit pressure can be monitored at the test fitting in
lift control manifold port G.
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.
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 not
required for lifting or steering is made available for the
traction charge circuit. Flow in excess of charge circuit
needs then returns to the gear pump inlet.
Reelmaster 3550−D/3555−D/3575−D
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) which sends electrical outputs to
the appropriate lift control manifold solenoid coils in or-
der to raise or lower the cutting units.
When the reel enable/disable switch is in the DISABLE
position, the cutting unit lift and lower operation is under
complete control of the joystick (momentary control) and
the cutting units move up or down only as long as the joy-
stick is held in position.
When the reel enable/disable switch is in the ENABLE
position, the cutting unit raise operation is controlled by
the TEC (sequential control). Momentarily "bumping"
the joystick rearward raises the cutting units to the full up
position on Reelmaster 3550−D machines, or to the par-
tially raised "Turn Around" position on Reelmaster
3555−D/3575−D machines. Hold the joystick rearward
to raise the cutting units to the full up position on Reel-
master 3555−D/3575−D machines.
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 Toro Electronic Controller (TEC). To allow
the front cutting units to be raised before the rear cutting
units, the controller 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 cutting 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.
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.
Page 4 − 25 Hydraulic System