Toro Field Pro 6040 Service Manual page 81

Forward Direction
Reverse Direction
Traction Circuit Charge
Field Pro® 6040
22267SL Rev A
charge pump and a cooling fan. The left side piston pump drives an external
fixed displacement gear pump for attachment hydraulic needs. The traction
pumps are driven by the engine via a single V-belt. V-belt tension is controlled by
a spring loaded idler.
With the engine running and the traction control levers in the N
the traction pumps supply no flow to the wheel motors. When a traction control
lever is moved in the F
swash plate in the traction pump so oil flows out the A port on the top of the
pump. Oil flow from the pump is directed to the wheel motor to turn it in the
forward direction. Maximum forward traction pressure is limited by a 20,000 kPa
(2900 psi) relief valve located in the side of the pump assembly.
The angle of the swash plate determines the stroke of the pump pistons and
therefore the volume of hydraulic fluid flow and ultimately wheel motor speed.
When the traction control lever is moved a small amount, the swash plate angle
is slight resulting in low pump output and lower traction speed. When the traction
control lever is moved fully, the pump swash plate angle is dramatic providing
significant pump output and maximum traction speed.
Hydraulic fluid flowing from the wheel motor returns to the piston (traction) pump
B port on the top of the pump. Hydraulic fluid is continuously pumped through
the closed loop traction circuit as long as the traction control lever is in the
F range of movement.
ORWARD
Note: The A port and the forward relief valve are located on the side of the pump
opposite the traction control linkage. The B port is located on the same side of
the pump as the traction control linkage.
The traction circuit operates essentially the same in reverse as it does in the
forward direction. However, the flow through the circuit is reversed. When a
traction control lever is moved in the R
lever positions the swash plate in the traction pump so oil flows out the B port on
the top of the pump. Oil flow from the pump is directed to the wheel motor to
turn it in the reverse direction. Maximum reverse traction pressure is limited by a
20,000 kPa (2900 psi) relief valve located in the side of the pump assembly.
Hydraulic fluid flowing from the wheel motor returns to the piston (traction) pump
A port on the top of the pump. Hydraulic fluid is continuously pumped through
the closed loop traction circuit as long as the traction control lever is in the
R range of movement.
EVERSE
Note: The B port and the reverse relief valve are located on the same side of
the pump as the traction control linkage. The A port is located on the side of the
pump opposite the traction control linkage.
The piston (traction) pumps are equipped with case drains to allow normal
internal fluid leakage to be removed from the pumps. The case drains are
connected to the hydraulic reservoir.
A fixed displacement pump (located in the right side piston pump) provides a
constant supply of charge fluid to the closed loop traction circuits. The charge
fluid provides lubrication for traction circuit components and also replenishes
the traction circuit oil that is lost due to internal leakage. Charge pump flow
is directed to the piston pumps and the low pressure side of the closed loop
traction circuits. Charge pressure is limited to 620 kPa (90 psi) by a relief valve
direction, the linkage from the lever positions the
ORWARD
EVERSE
Page 5–15
EUTRAL
direction, the linkage from the
Hydraulic System: Hydraulic Flow Diagrams
position,