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| Illustration 1 | g00495532 |
Hydraulic Schematic for Secondary Steering Systems that use Metering Pumps (1) Secondary steering valve. (2) Metering pump (steering). (3) Neutralizer valve for a left turn. (4) Left turn stop. (5) Neutralizer valve for a right turn. (6) Right turn stop. (7) Steering control valve. (8) Selector spool. (9) Directional spool. (10) Crossover relief valve for the steering cylinders. (11) Left steering cylinder. (12) Right steering cylinder. (13) Primary steering pressure switch. (14) Check valve. (15) Secondary steering pressure switch. (16) Check valve. (17) Secondary steering pump and electric motor. (18) Signal line. (19) Relief valve for the secondary steering pump. (20) Steering pump. (21) Flow control orifice. (22) Breaker relief valve. (23) Relief valve for the case drain for the steering pump. (24) Hydraulic oil tank. (AA) Pressure tap for checking steering pump pressure. (BB) Pressure tap for checking signal pressure. | |
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| Illustration 2 | g00296719 |
Component Locations for the Secondary Steering System Left Side View (1) Secondary steering valve. (12) Right steering cylinder. (17) Secondary steering pump and electric motor. | |
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| Illustration 3 | g00296724 |
Component Locations for the Secondary Steering System Right Side View (2) Metering pump (steering). (7) Steering control valve. (11) Left steering cylinder. (24) Hydraulic oil tank. | |
Note: The secondary steering system is an attachment for these machines. The secondary steering system should only be used if there is a failure of the primary steering system. Additionally, only use the secondary steering system to steer the machine off the road.
The secondary steering circuit consists of the following components. Secondary steering valve (1), metering pump (2), steering control valve (7), left steering cylinder (11), right steering cylinder (12), secondary steering pump and electric motor (17) and hydraulic oil tank (24) .
Secondary steering valve (1) is located on the lower left frame. Secondary steering valve (1) is also located near secondary steering pump and electric motor (17). Metering pump (2) is attached to the bottom of the steering column, and located under the floor of the operator's compartment.
Steering control valve (7) is located on the right side of the machine under the operator's platform. Steering control valve (7) is also located above hydraulic oil tank (24).
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| Illustration 4 | g00296925 |
(25) Primary steering indicator. (26) Secondary steering indicator. (27) Master action light. | |
During normal machine operation, check valve (14) is off the seat, while check valve (16) is seated. Check valve (16) prevents pressure oil from flowing back to secondary steering pump (17) .
If steering pump (20) or the engine fails, primary steering pressure switch (13) changes state. Primary steering pressure switch (13) changes state due to low oil pressure in the steering system. Primary steering pressure switch (13) sends a signal to the monitoring system. The monitoring system then causes a Warning Category 3 alarm to occur.
| NOTICE |
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The alarm system indicates that the primary steering system has failed. Continuing to operate the machine could result in additional damage to the steering system components. Use the secondary steering system to steer the machine to a safe stop immediately. When the machine comes to a complete stop, turn the start switch key to the OFF position and remove the key. Investigate the cause of the problem before resuming operation. Do NOT use the secondary steering system as a limp-home mode procedure. Do NOT use the secondary steering system for steering the machine when the machine is being towed. |
A Warning Category 3 alerts the operator that engine shutdown should occur as soon as possible. This helps prevent injury to the operator and potential damage to the machine.
A Warning Category 3 causes both master action light (27) and primary steering indicator (25) to turn on. A Warning Category 3 also causes the action alarm to sound. Do not operate the machine until the cause has been corrected.
After a one second delay, the relay for secondary steering pump and electric motor (17) actuates. At the same time, secondary steering indicator (26) turns on.
Secondary steering pump and electric motor (17) draws oil from hydraulic oil tank (24). The oil then flows to secondary steering valve (1). This causes check valve (16) to unseat. The oil pressure then causes check valve (14) to seat. This prevents pressure oil from flowing back to steering pump (20). The pressure oil then flows to steering control valve (7) .
The steering oil that is pumped from secondary steering pump and electric motor (17) causes secondary steering pressure switch (15) to change state. Secondary steering pressure switch (15) activates secondary steering indicator (26) .
The condition of the secondary steering is tested during engine start-up. During the three second test, secondary steering indicator (26) turns on, and the action alarm sounds. This verifies that the steering system is pressurized.
Note: The machine can be articulated during the three second test.
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| Illustration 5 | g00296927 |
(28) Test switch for the secondary steering. | |
The secondary steering system can be manually tested. Test switch (28) for the secondary steering system is located on the upper left console. Test switch (28) is a momentary on, normally open switch.
Push test switch (28) in order to determine if secondary steering pump and electric motor (17), and secondary steering indicator (26) are operational. When test switch (28) is pushed, secondary steering pump and electric motor (17) runs. This causes secondary steering indicator (26) to turn on. This also causes the action alarm to sound.
Relief valve (19) is for the secondary steering pump. Relief valve (19) limits the amount of oil pressure in the secondary steering circuit.