Toro GreensPro 1240 Service Manual page 65

Right Direction
Left Direction
GreensPro ™ 1240/1260
14211SL Rev A
The hydraulic traction circuit consists of a bidirectional variable displacement
piston pump connected in a closed loop to a hydraulic motor. The hydraulic
pump is driven by the engine through a rubber drive coupling.
Pressing down the right motion control pedal, angles the hydraulic pump swash
plate to create a flow of fluid. This fluid flow is directed to the hydraulic motor
through the "A" port to rotate the drive roller in the right direction. The traction
pressure is limited to 16,000 kPa (2,320 psi) by the right traction relief valve
located in the hydraulic pump.
The angle of the swash plate determines pump flow and ultimately traction
speed. When the motion control pedal is pressed a small amount, a small
swash plate angle results in low pump output and lower traction speed. When
the motion control pedal is pressed fully, the pump swash plate angles fully to
provide maximum pump output and traction speed.
The fluid flowing through the hydraulic motor returns to the variable displacement
pump and is continuously pumped through the traction circuit as long as the
motion control pedal is pressed.
The hydraulic pump is equipped with a case drain to allow internal leakage to be
removed from the pump. The case drain is connected to the hydraulic tank.
A gerotor charge pump in the pump provides a constant supply of charge fluid to
the closed loop traction circuit for lubrication and to make up for fluid that is lost
due to internal leakage in the hydraulic pump. The charge pump takes its suction
from the hydraulic tank through a filter. Charge pressure is limited to 552 kPa
(80 psi) by a check valve in the charge circuit. The charge pump flow is directed
to the low pressure side of the closed loop circuit.
The traction circuit operates essentially the same to move the machine to the
left direction as it does to move the machine in the right direction. However,
the flow through the circuit is reversed. Pushing down the left motion control
pedal angles the variable displacement pump swash plate in the hydraulic pump
in the opposite direction to create a flow of fluid. This fluid is directed out the
pump "B" port to the motor which turns the drive roller in the left direction. The
traction pressure is limited to 16,000 kPa (2,320 psi) by the right traction relief
valve located in the hydraulic pump.
The fluid flowing through the hydraulic motor returns to the variable displacement
pump and is continuously pumped through the closed traction circuit as long as
the motion control pedal is pushed.
The charge circuit functions the same in left direction as it does in the right
direction.
Page 5–19 Hydraulic System: Hydraulic Flow Diagrams