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| Illustration 1 | g01221297 |
Hydraulic Schematic (Secondary Steering) (1) Brake control group (2) Left steering cylinder (3) Right steering cylinder (4) Steering and decking blade valve (5) Priority relief valve for braking system (6) Check valve (7) Check valve for secondary steering (8) Primary steering pressure switch (9) Relief valve for secondary steering pump (10) Secondary steering pump and electric motor (11) Hydraulic tank (12) Hydraulic pump | |
Introduction
The secondary steering is an attachment on the Wheel Skidder. The secondary steering system provides temporary steering control in the event of a failure in the primary steering system. A failure of the primary steering system is the result of low oil pressure in the steering system. The failure can occur for any of the following reasons:
- Hydraulic pump failure
- Engine failure
- Pressure loss in the hydraulic system
System Description
The secondary steering system contains two types of components. These components are electrical and hydraulic.
The secondary steering system contains the following electrical components.
- Primary steering pressure switch
- Secondary steering pressure switch
- Secondary steering test switch
- Primary steering indicator
- Secondary steering indicator
- Secondary steering relay
- Electric motor
- Machine ECM
The secondary steering system contains the following hydraulic components.
- Secondary steering pump
- Relief valve
- Two check valves
System Operation
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The machine's batteries must have a normal charge and the secondary steering electrical system must be okay. A low charge condition, or any defect in the battery, battery cells, or electrical circuit can cause loss of secondary steering and could result in personal injury and/or damage to the machine. |
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| Illustration 2 | g01221714 |
Location of Secondary Steering Relay, Pump and Motor | |
The secondary steering relay is located by the secondary steering pump on the left side of the machine. The secondary steering pressure switch is mounted in the outlet line on top of the secondary steering pump. The secondary steering pressure switch is monitored by the machine ECM.
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| Illustration 3 | g01221669 |
Dash (13) Secondary steering indicator. (14) Primary steering indicator. | |
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| Illustration 4 | g01221729 |
Location of the Secondary Steering Test Switch (15) Secondary steering test switch. | |
While the machine is in normal operation, the secondary steering system is inactive. The operator can test the secondary steering system at any time by pressing secondary steering test switch (15) .
The secondary steering test switch is a momentary switch, which is located on the left side of the dash. The switch will return to the OFF position when the operator releases switch (15). While switch (15) is pressed the secondary steering relay will be energized and secondary steering pump and electric motor (10) will engage. The secondary steering system will become inoperable, when the start switch key is turned to the OFF position.
If hydraulic pump (12) or the engine fails, primary steering pressure switch (8) opens. Primary steering pressure switch (8) opens due to low oil pressure in the steering system. Primary steering pressure switch (8) activates an action alarm and primary steering indicator (14) will be ON. Primary steering pressure switch (8) is mounted on the bottom of hydraulic pump (12).
| NOTICE |
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The alarm system indicates that the primary steering system has failed. Use the secondary steering system to steer the machine to the nearest convenient location. When the machine comes to a complete stop, turn the start switch key to the OFF position. Continuing to operate the machine may result in damage to the system. |
When primary steering pressure becomes low, the secondary steering will be activated. The secondary steering relay will be activated, and secondary steering indicator (13) will be ON. The secondary steering relay sends power to the electric motor. Secondary steering pump and electric motor (10) pumps hydraulic oil from hydraulic tank (11) to the steering system.
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| Illustration 5 | g01230796 |
Location of the Steering and Decking Blade Valve | |
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| Illustration 6 | g01224566 |
Steering and Decking Blade Valve (16) Port for secondary steering. | |
The hydraulic oil flows from the pump through a check valve to port (16) in the front of the priority flow control valve. The oil then flows through a passage to the steering control valve. The oil bypasses the priority flow control valve.