992G Wheel Loader and 854G Wheel Dozer Steering System Steering Neutralizer Valve Caterpillar


Steering Neutralizer Valve
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Illustration 1g01057442
Top view of machine is shown with the location of neutralizer valves on engine end frame.


Illustration 2g00118089
Neutralizer Valve in the CLOSED Position
(1) Stem
(2) Inlet port
(3) Outlet port
(4) Tank port
(5) Spring

When the steering neutralizer valves are engaged, the flow of pilot oil to the steering control valve is blocked. Pilot oil will then drain from the steering control valve. This causes the machine to stop articulating at the end of a complete turn. This occurs just before the front of the machine contacts the frame.

A left turn stop is used for the left neutralizer valve, and a right turn stop is used for the right neutralizer valve. Both the left turn stop and the right turn stop are mounted on the front of the frame. Both of the neutralizer valves are mounted on the rear frame. Both the right neutralizer valve and the left neutralizer valve are identical. Additionally, both the right turn stop and the left turn stop are identical.

Pilot oil flows from the STIC steering and transmission control to either the right neutralizer valve or to the left neutralizer valve. This happens before the oil flows to the steering control valve. Oil flows from the STIC steering and transmission control into the neutralizer valve through inlet port (2).

Spring (5) holds stem (1) to the left. Oil flows past stem (1) and through outlet port (3). The oil then flows to the steering control valve.

When the machine is turned to the far right, the right turn stop contacts stem (1) of the right neutralizer valve. This should only occur when the STIC steering and transmission control is moved to the full RIGHT TURN position and spring (5) compresses.

As the stem moves right, the stem blocks the flow of oil through port (2). Because pilot oil cannot flow from port (2) to port (3), no pilot oil can flow to the control valve.

As the stem moves right, pilot pressure is drained through port (3) and the flow of oil passes stem (1) to the tank port (4).

When the flow of pilot oil stops acting on the spool in the steering control valve, the control valve spool returns to the NEUTRAL position. This causes the steering action to stop.

When the STIC steering and transmission control is moved back to the left, the return oil from the end of the steering control valve spool flows through the line. The return oil then flows into port (3) of the right neutralizer valve. The oil then flows past the stem, through port (4), and back to the hydraulic oil tank for the steering and brake systems. This allows the steering control valve spool to move back to the CENTERED position, and the machine begins to turn to the left.

As the machine moves to the left, the right turn stop will move away from stem (1). The force of spring (5) acts against stem (1). This causes the stem to move left. As the stem moves left by a small amount, the stem opens port (2). This allows pilot oil to flow past the stem and through port (3).

The left neutralizer valve operates in the same manner as the right neutralizer valve.

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