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| Illustration 1 | g00814857 |
Hydraulic Schematic for Steering Systems that use Metering Pumps (1) Steering metering pump (2) Neutralizer valve for a left turn (3) Left turn stop. (4) Neutralizer valve for a right turn (5) Right turn stop. (6) Steering control valve (7) Selector spool (8) Directional spool (9) Crossover relief valve for the steering cylinders (10) Left steering cylinder (11) Right steering cylinder (12) Signal line (13) Steering pump (14) Flow control orifice (15) Breaker relief valve (16) Relief valve for the case drain for the steering pump (17) Hydraulic oil tank (AA) Pressure tap for checking steering pump pressure (BB) Pressure tap for checking signal pressure | |
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| Illustration 2 | g00296439 |
Right Side View Steering Components (1) Metering pump. (2) Neutralizer valve for a left turn. (3) Left turn stop. (4) Neutralizer valve for a right turn. (5) Right turn stop. (6) Steering control valve. (11) Right steering cylinder. (13) Steering pump. (17) Hydraulic oil tank. (AA) Pressure tap for checking steering pump pressure. (BB) Pressure tap for checking signal pressure. | |
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| Illustration 3 | g00296440 |
Left Side View Steering Components (10) Left steering cylinder. | |
The primary steering system is made up of two basic circuits. The two basic circuits are the pilot circuit and the high pressure circuit. When a machine is equipped with the secondary steering attachment, the steering system includes one additional circuit.
Metering pump (1) is attached to the bottom of the steering column, and located under the floor of the operator's compartment. Neutralizer valves (2) and (4) are located on the front center section of the upper frame. The neutralizer valves are also located under the operator's compartment and near the upper hitch.
Steering control valve (6) is located on the right side of the machine under the operator's platform. Steering control valve (6) is also located above hydraulic oil tank (17). Hydraulic oil tank (17) is located on the right side of the machine.
Steering pump (13) is located under the operator's cab on the right side of the machine. A pressure and flow compensator valve is attached to steering pump (13) .
Pilot Circuit
The pilot circuit consists of the following components. Metering pump (1), neutralizer valve for a left turn (2), neutralizer valve for a right turn (4), selector spool (7), directional spool (8), steering pump (13), flow control orifice (14) and hydraulic oil tank (17) .
The pilot system controls the movement of selector spool (7) and directional spool (8) in steering control valve (6) .
Steering pump (13) draws oil from hydraulic oil tank (17). Pressure oil from steering pump (13) flows to steering control valve (6). The oil then flows through flow control orifice (14). Flow control orifice (14) reduces the amount of oil flow to metering pump (1) .
Metering pump (1) is a small hydraulic pump that is used as a metering valve and as a directional control valve. When the operator turns the steering wheel, a spool and a sleeve rotates inside the metering pump. This allows the oil to flow to either neutralizer valve (2) or neutralizer valve (4). Turning the steering wheel faster causes more oil to flow to the neutralizer valve.
The oil then flows to steering control valve (6). The pressure of the oil causes selector spool (7) to move either right or left. This causes directional spool (8) to move in the same direction as selector spool (7). Directional spool (8) allows the high pressure oil to flow to the steering cylinders.
High Pressure Circuit
The high pressure circuit consists of the following components. Steering control valve (6), crossover relief valve for the steering cylinders (9), left steering cylinder (10), right steering cylinder (11), steering pump (13), backup relief valve (14) and hydraulic oil tank (17) .
The high pressure circuit provides the high pressure oil for the steering cylinders. Oil is drawn from hydraulic oil tank (17) by steering pump (13). Steering pump (13) is a variable piston pump. A pressure and flow compensator valve is attached to steering pump (13). The pressure and flow compensator valve helps control the output of the pump.
A backup relief valve in steering control valve (6) prevents excessive pressure in the high pressure circuit if there is a malfunction with the pressure and flow compensator valve.
When the pilot oil moves directional spool (8), the pressure oil is directed to the steering cylinders. When a right turn is made, the pressure oil flows to the head end of steering cylinder (10). The pressure oil also flows to the rod end of steering cylinder (11). This causes the machine to turn right.
When a left turn is made, the pressure oil flows to the head end of steering cylinder (11). The high pressure oil also flows to the rod end of steering cylinder (10). This causes the machine to turn left.
Crossover relief valve (9) prevents excessive pressure spikes in the steering cylinders. The pressure spikes could develop if one of the front tires hits an object.