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| Illustration 1 | g01469884 |
(1) Hydraulic tank (3) Charge pump (4) Piston pump ( hydrostatic) (5) Piston motor ( hydrostatic) (6) Rear axle (7) Transfer gear group (8) Drive shaft (9) Hydraulic oil filter (10) Front Axle | |
The hydrostatic system contains the following items: Hydraulic tank (1), charge pump (3), piston pump (4), piston motor (5), rear axle (6), Transfer gear group (7), drive shaft (8), hydraulic oil filter (9) and front axle (10).
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| Illustration 2 | g01144652 |
(4) Piston pump ( hydrostatic) (3) Charge pump | |
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| Illustration 3 | g01469913 |
(1) Hydraulic tank (2) Gear Pump (3) Charge Pump (4) Piston pump (5) Piston motor (9) Hydraulic oil filter (11) Forward/Neutral/Reverse valve (12) Speed sensing Valve (13) Crossover relief and makeup valves (14) Creeper control valve (15) Speed selector valve (16) Servo valve (17) Shuttle valve (18) Pressure override valve (19) Charge relief valve (A) PC port (B) PS (C) FA (D) MH (E) M1 | |
The piston pump (4) supplies oil to the piston motor (5). The piston motor (5) is mounted to the transfer gear group (7). The transfer gear group (7) is connected with the rear axle (6). The transfer gear group (7) is connected with a drive shaft (8) to the front axle (10) .
The hydraulic oil flows from the hydraulic tank (1) to the charge pump (3). The charge oil flows through the hydraulic oil filter (9) to the speed sensing valve (12) .
Most of the charge oil to the speed sensing valve (12) enters the charge circuit. The oil then goes to the crossover relief valves (13) .
The makeup valves in each crossover relief valve (13) open. The charge oil flows through the drive loop to the following components: piston pump ( hydrostatic) and piston motor ( hydrostatic). When the system is full of charge oil, the relief valve (19) for the charge pump opens. Most of the charge oil goes to the pump case. The oil then goes back to the tank (1) .
The oil also flows through the speed sensing valve (12). The oil provides signal pressure to the Forward/Neutral/Reverse valve (11). When the direction control is in the NEUTRAL position, the oil is blocked to the pump actuator at the Forward/Neutral/Reverse valve (11) .
When the operator moves the direction control switch to the FORWARD position, the Forward/Neutral/Reverse valve (11) shifts to the FORWARD position and signal oil from the speed sensing valve (12) flows to the pump actuator. The signal pressure acts against the centering springs of the pump. Because the signal pressure is too low, the pump will not upstroke and the machine will not move.
As the operator depresses the accelerator pedal, the engine speed increases causing the signal pressure to increase. The increase of pressure causes the pump to upstroke. As the pump upstrokes, the speed of the machine increases.
As the engine speed continues to increase, the signal pressure from the speed sensing valve (12) also increases. The increase in signal pressure will move the displacement control valve of the motor. This allows the high pressure oil to flow to the actuator of the motor to destroke the motor. Destroking the motor causes the motor to rotate faster. When the motor is fully destroked, the pump is fully upstroked and the engine is at maximum rpm. The machine speed is maximum.
Any resistance to the rotation of the motor increases the drive pressure. The increase of pressure causes the engine to slow down. The slowing down of the engine causes the signal pressure to decrease. As the signal pressure decreases, the pump destrokes. As the pump destrokes the speed of the machine is reduced.
The displacement control valve of the motor continually balances the signal pressure and the drive pressures. The pressure must be continually balanced in order to prevent the engine lugging.
When the operator moves the direction control switch to the REVERSE position, the Forward/Neutral/Reverse valve (11) shifts to the REVERSE position and signal oil from the speed sensing valve (12) flows to the pump actuator. The signal pressure acts against the centering spring of the pump actuator. Because the signal pressure is too low, the pump will not upstroke and the machine will not move.
As the operator depresses the accelerator pedal, the engine speed increases causing the signal pressure to increase flow. The increase of flow causes the motor to turn faster. As the motor turns faster, the speed of the machine increases.
As the engine speed continues to increase, the signal pressure from the speed sensing valve (12) also increases. The increase in signal pressure will move the displacement control valve of the motor. This allows the high pressure oil to flow to the actuator of the motor to destroke the motor. Destroking the motor causes the motor to rotate faster. When the motor is fully destroked, the pump is fully upstroked and the engine is at maximum rpm. The machine speed is maximum.
Any resistance to the rotation of the motor increases the drive pressure. The increase in pressure causes the engine to slow down. The slowing down of the engine causes the signal pressure to decrease. As the signal pressure decreases, the pump destrokes. As the pump destrokes the speed of the machine is reduced.
The displacement control valve of the motor continually balances the signal pressure and the drive pressures. The pressures must be continually balanced in order to prevent the engine lugging.