- Work tool pump
- Saw motor
- Combination valve
- Collector arm cylinders
- Grapple arm cylinders
These hydraulic components control the two functions: cutoff system and holding system.
Cutoff System
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| Illustration 1 | g01094406 |
Partial Schematic of the Cutoff System (1) Charge pump (2) Charge filter (3) Saw motor (4) Proportional solenoid (5) Control piston (6) Work tool pump (A) High pressure discharge (B) High pressure return (C) Case drain (G) Pressure tap (work tool pump) (M) Pressure tap (upstroke pressure) | |
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| Illustration 2 | g01094433 |
(4) Proportional solenoid. (6) Work tool pump. | |
The cutoff system is controlled by work tool pump (6), proportional solenoid (4), and saw motor (3). The work tool pump is mounted on the pump drive that is attached to the engine.
Work tool pump (6) supplies hydraulic oil to saw motor (3). Work tool pump (6) is a variable displacement axial piston pump. Saw motor (3) is a variable displacement bent axis motor.
Reference: For more information on the work tool pump, refer to Systems Operation, "Piston Pump (Work Tool)" for the machine that is being serviced.
Reference: For more information on the saw motor, refer to Specifications, Systems Operation, Testing and Adjusting, "General Information" for the felling head that is being serviced.
When the switch for the saw is not activated, proportional solenoid (4) is in the NEUTRAL position. No pump flow goes to the saw motor.
When the switch for the saw is pressed, an electrical signal energizes proportional solenoid (4). Proportional solenoid (4) acts on the control piston (5). The solenoid causes the control piston to shift to one side. This causes oil to flow from work tool pump (6) to saw motor (3) .
Reference: For more information on the cutoff system, refer to Specifications, Systems Operation, Testing and Adjusting, "Cutoff System" for your felling head.
Holding System
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| Illustration 3 | g01094521 |
(7) Grapple arms. (8) Grapple arm cylinders. (9) Collector arms. (10) Collector arm cylinders. | |
The main components of the holding system are grapple arms (7), grapple arm cylinders (8), collector arms (9) and collector arm cylinders (10) .
Grapple arms (7) and collector arms (9) are controlled independently of each other. The grapple arms and the collector arms are used to hold a tree after the tree is cut.
When the button that activates the collector arms is pressed, a solenoid valve on the implement control valve is energized. This sends pilot oil pressure to the control valve. The pilot pressure shifts the spool on the control valve. The movement of the spool creates a load signal. The load signal upstrokes the implement pump. Now, oil pressure from the implement pump flows through the spool to collector arm cylinders (10). This causes collector arms (9) to close.
When the pedal that activates the grapple is pressed, pilot oil pressure is sent to the implement control valve. The pilot pressure shifts the spool on the control valve. The movement of the spool creates a load signal. The load signal upstrokes the implement pump. Now, oil pressure from the implement pump flows through the spool to grapple arm cylinders (8). This causes grapple arms (7) to close.