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| Illustration 1 | g00685714 |
Schematic of the All Wheel Drive System (1) IQAN monitoring and control system. (2) Speed selector switch. (3) Operation mode switch. (4) All wheel drive solenoid valve. (5) Neutralizer valve solenoid. (6) Pressure tap. (7) Pressure reducing valve. (8) Front travel motor. (9) All wheel drive valve. (10) Front differential lock valve. (C) Port for charge pump oil. (D) Port for the power train pump. (E) Port for the power train pump. | |
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| Illustration 2 | g00570399 |
Switch Locations (1) IQAN monitoring and control system. (2) Speed selector switch. (3) Operation mode switch. | |
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| Illustration 3 | g00570410 |
Location of the Control Valves (4) Solenoid valve (all wheel drive). (5) Solenoid valve (neutralizer). (6) Pressure tap. (11) Hydraulic oil tank. | |
The six wheel harvesters have the capability of blocking pump oil to the front travel motors and neutralizing the front travel motors. These capabilities are achieved by the following components:
- All wheel drive valve (9)
- All wheel drive solenoid valve (4)
- Neutralizer valve solenoid (5)
All wheel drive is activated when the machine is in first speed and in work mode.
When the machine is in the first speed and in the work mode, no electrical signal is sent from IQAN (1) to all wheel drive solenoid valve (4) or neutralizer valve solenoid (5). Both solenoid valves are in the neutral position. This activates all wheel drive valve (4) .
Now, the spring in all wheel drive solenoid valve (4) shifts the spool position downward. Charge pump oil flows to all wheel drive valve (9) and all wheel drive valve (9) shifts downward.
The spool in all wheel drive valve (9) will only shift downward when the charge pump oil reaches 690 kPa (100 psi).
When all wheel drive valve (9) shifts downward, front power train pump oil flows through all wheel drive valve (9) to differential lock valve (10). Then, the oil flows to front travel motors (8) .
Freewheeling
Freewheeling is available in roading mode only. Roading mode allows you to engage the following speeds: first speed, second speed and third speed. Working mode allows you to engage first speed only.
When the machine is in second speed or third speed, an electrical signal is sent from IQAN (1) to all wheel drive solenoid valve (4) and neutralizer valve solenoid (5). This causes both solenoid valves to shift upward.
When neutralizer valve solenoid (5) shifts upward, the oil from the case drain ports of front travel motors (8) will flow to the hydraulic oil tank.
When all wheel drive solenoid valve (4) shifts upward, charge pump oil flows to all wheel drive valve (9). This causes all wheel drive valve (9) to block oil from the front power train pump to front travel motors (8). By supplying case pressure into the front travel motors, front travel motors (8) are allowed to freewheel. Freewheeling is accomplished by permitting the housing to rotate with internal circulation of hydraulic fluid only.
Reference: For more information about freewheeling, refer to System Operation, "Hydrostatic Drive System".