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| Illustration 1 | g06311707 |
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(1) Implement hydraulic pump
(2) Implement/Steering hydraulic pump | |
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| Illustration 2 | g06311713 |
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Hydraulic Pump (4) Pump shaft (5) Swashplate (6) Control piston (7) Bias piston (8) Nine pistons (9) Bias spring (10) Pump rotating group | |
Implement pump (1) and implement/steering hydraulic pump (2) are mounted on the rear of the engine. Implement pump (1) and implement/steering hydraulic pump (2) are tandem, axial piston type pumps that have variable flow, and pressure output depending on control oil from the pump control valves. The implement pump (1) is mounted directly to the engine drive. The implement/steering hydraulic pump (2) is mounted to the implement pump.
Flow from the implement/steering hydraulic pump (1) goes to the pilot manifold. The oil flows to the steering valve and the Implement shutoff valve to the implement control valves. When an implement control valve is activated, a signal oil passage is opened to the pump control valve. The pump control valve upstrokes the implement hydraulic pump (1) in order to meet the system demands.
When the engine is running, pump shaft (4) rotates pump rotating group (10) with nine pistons (8). Swashplate (5) does not rotate. When the swashplate pivots, the swashplate angle changes. This results in a change of pump displacement.
When pump shaft (4) turns pump rotating group (10), the angle of the swashplate (5) moves pistons (8) in and out of the cylinder barrel as the piston follows the angle of the swashplate. As a piston (8) is moved out of pump rotating group (10), the piston pulls oil from the hydraulic tank, through the hydraulic pump inlet and into the piston cylinder. As the pump rotating group (10) continues to rotate, the piston is moved into the pump rotating group (10). Piston (8) pushes the oil from the cylinder barrel through the pump outlet.
The hydraulic pumps have two pistons that are used for stroking: bias piston (7) and control piston (6). Bias piston (7) is used to upstroke the hydraulic pump. The force of the bias spring and the pump pressure act on bias piston (7). Control piston (6) is used to destroke the hydraulic pump. The control piston (6) has a larger area than the bias piston. The pressure and flow compensator valve changes the hydraulic pump displacement by regulating the pressure to control piston (6) which is supplied by pump discharge pressure. When the pressure and flow compensator valve applies pump pressure to control piston (6), bias piston (7) and bias spring (9) are forced to destroke the hydraulic pump.