- Saw switch
- Left joystick control
- Right joystick control
When the saw switch is moved to the ON position, an input signal is sent to the IQAN control system. The IQAN control system sends an output signal to the solenoid of the saw motor valve. The saw motor valve shifts. Oil from the saw pump flows to the saw motor.
The left joystick control and the right joystick control regulate the movements of the hydraulic components of the felling head system.
The joystick controls send input signals to the IQAN control system. The IQAN control system sends output signals to functions of the felling head system.
The felling head system is equipped with the following hydraulic components:
- Saw pump
- Saw motor
- Saw motor valve
- Saw activation valve
- Accumulator arm cylinders
- Grapple arm cylinders
- Tilt cylinder (lateral movement)
- Tilt cylinder (up and down)
These hydraulic components control the two functions: cutoff system and holding system.
Cutoff System
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| Illustration 1 | g00927821 |
Partial schematic of the cutoff system (1) Saw motor valve (2) Bypass valve (saw pump) (3) Saw activation valve (4) Bypass valve (saw motor) (5) Saw motor (6) Pressure sensor (saw pump) (7) Load sensing valve (8) High pressure cutoff valve (9) Saw pump (10) Makeup valve (11) Displacement control valve (A) Return to tank (B) Inlet from tank (C) Case drain (G) Pressure tap (saw pump) (M) Pressure tap (upstroke pressure) (AA) Pressure tap (discharge pressure) | |
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| Illustration 2 | g00925563 |
Location of the components at the rear of the machine (1) Saw motor valve (3) Saw activation valve (7) Load sensing valve (8) High pressure cutoff (9) Saw pump (12) Implement control valve | |
The cutoff system is controlled by saw pump (9), saw motor valve (1), and saw motor (5). The saw pump is mounted on the pump drive that is attached to the engine.
Saw pump (9) supplies hydraulic oil to saw motor valve (1) and saw motor (5). Saw pump (9) is a variable displacement axial piston pump. Saw motor (5) is a variable displacement bent axis motor.
ReferenceFor more information on the saw pump, refer to Systems Operation/Testing and Adjusting, "Piston Pump (Saw)" for the machine that is being serviced.
ReferenceFor more information on the saw motor, refer to Specifications, Systems Operation, Testing and Adjusting, "General Information" for the felling head that is being serviced.
ReferenceFor more information on the cutoff system, refer to Specifications, Systems Operation, Testing and Adjusting, RENR4370, "Cutoff System".
Saw pump and Saw Motor in Standby Condition
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| Illustration 3 | g00927736 |
Saw pump and saw motor (1) Saw motor valve (2) Bypass valve (saw pump) (3) Saw activation valve (4) Bypass valve (saw motor) (5) Saw motor (7) Load sensing valve (8) High pressure cutoff valve (9) Saw pump (10) Makeup valve (11) Displacement control valve | |
The Illustration 3 shows the major components of the saw pump and the saw motor in STANDBY condition. The saw pump is moved to the maximum displacement position by spring force. When the engine is running, bypass valve (2) is open to the hydraulic tank in order to keep the pump at maximum output.
When the switch for the saw is not activated, saw activation valve (3) is in the OFF position. The spring chamber on bypass valve (2) drains through saw activation valve (3). Saw activation valve (3) blocks the flow of oil from the spring chamber of bypass valve (4). Spring force and pressure from saw pump (9) closes bypass valve (4). Bypass valve (2) opens in order to direct the flow of oil from saw pump (9) to the oil cooler and the return filter. Then, the oil flows to the hydraulic tank. No pump flow goes to saw motor (5) .
Saw Pump and Saw Motor (Start-up and Running Position)
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| Illustration 4 | g00927742 |
Saw pump and saw motor (1) Saw motor valve (2) Bypass valve (saw pump) (3) Saw activation valve (4) Bypass valve (saw motor) (5) Saw motor (7) Load sensing valve (8) High pressure cutoff valve (9) Saw pump (10) Makeup valve (11) Displacement control valve | |
When the switch for the saw is pressed, an electrical signal energizes saw activation valve (3). Saw activation valve (3) blocks the oil flow from the spring chamber on bypass valve (2). The spring chamber on bypass valve (4) drains to the hydraulic tank. Bypass valve (2) closes and bypass valve (4) opens. This causes oil to flow from saw pump (9) through saw motor valve (1) to saw motor (5) .
A signal pressure that is equal to the load pressure of the saw is directed to the spring chamber of load sensing valve (7). The load sensing valve moves to the left. The oil on the right side of the large minimum angle servo piston flows back to the hydraulic tank. The swashplate of the saw pump moves to the maximum displacement.
If the system pressure of the saw pump exceeds the pressure setting of high pressure cutoff valve (8), the pressure pushes high pressure cutoff valve (8) to the right against spring force. System pressure of the saw pump is directed to the large actuator piston in order to destroke saw pump (9). As system pressure decreases the spring force pushes high pressure cutoff valve (8) to the left.
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| Illustration 5 | g00927743 |
Saw pump and saw motor (1) Saw motor valve (2) Bypass valve (saw pump) (3) Saw activation valve (4) Bypass valve (saw motor) (5) Saw motor (7) Load sensing valve (8) High pressure cutoff valve (9) Saw pump (10) Makeup valve (11) Displacement control valve | |
As the speed of the saw increases the pressure decreases in the system, the force of the spring moves displacement control valve (11) to the left. The maximum angle piston is open in order to drain through displacement control valve (11). System pressure on the small minimum angle piston moves the barrel of saw motor (5) toward the minimum angle for high speed and lower torque.
Holding System
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| Illustration 6 | g00922548 |
(5) Saw motor (13) Grapple arms (14) Grapple arm cylinders (15) Accumulator arms (16) Accumulator arm cylinders (17) Mounting bracket (18) Lateral tilt cylinder | |
The main components of the holding system are grapple arms (13), grapple arm cylinders (14), accumulator arms (15), accumulator arm cylinders (16), mounting bracket (17), and lateral tilt cylinder (18) .
Grapple arms (13) and accumulator arms (15) are controlled independently of each other. The grapple arms and the accumulator arms are used to hold a tree after the tree is cut.
When the button that activates the accumulator 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 accumulator arm cylinders (16). This causes accumulator arms (15) to close.
When the button that activates grapple arms (13) 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 grapple arm cylinders (14). This causes grapple arms (13) to close.
Lateral tilt cylinder (18) is used to tilt the felling head sideways.
When the button that activates the lateral tilt 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 lateral tilt cylinder (18). This causes lateral tilt cylinder (18) to extend. The felling head tilts to the LEFT.
Note: Some felling heads are equipped with a full tilt position. For more information about the full tilt position, refer to Specifications, Systems Operation, Testing and Adjusting, RENR4370, "Tilt System".
Mounting bracket (17) is attached to the stick of the machine and the tilt cylinder. The tilt cylinder tilts the felling head downward after the tree is cut. This will allow the tree to be lowered to the ground.
When the button that activates the tilt cylinder 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 the tilt cylinder. This causes tilt cylinder to extend. The felling head tilts DOWNWARD.