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| Illustration 1 | g01074635 |
Hydraulic Schematic for the Steering Pilot System (1) Left steering cylinder. (2) Right steering cylinder. (3) Steering control valve. (4) Steering control valve spool. (5) Steering quad check valve. (6) Steering pressure reducing valve. (7) Steering pilot relief valve. (8) Steering neutralizer valve for right turn. (9) Steering neutralizer valve for left turn. (10) Check valve. (11) Pilot valve (STIC Steering). (12) Steering pilot check valve. (13) Oil cooler. (14) Check valve (cooler bypass). (15) Fluid sampling port. (16) Piston pump (steering). (17) Breaker relief valve. (18) Steering pilot and brake oil filter. (19) Gear pump (steering pilot). (20) Hydraulic tank for the steering and brake systems. (A) Pressure port for the right steering cylinder. (B) Pressure port for the left steering cylinder. (C) Pressure port for the pilot circuit. (D) Pressure port for the steering pump. | |
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| Illustration 2 | g00118214 |
Component Locations (15) Fluid sampling port. (16) Piston pump (steering). (19) Gear pump (steering pilot). | |
The pilot circuit controls the movement of steering control valve spool (4) in steering control valve (3). While the engine is running, oil is drawn from hydraulic tank (20) by steering pilot gear pump (19). Pressure oil then flows from steering pilot gear pump (19), and through steering pilot and brake oil filter (18) .
After flowing through oil filter (18), the pilot oil circuit divides into two branches. In one branch, the oil flows through the steering pilot relief valve (7), through the oil cooler (13), and then back to the hydraulic tank (20) .
However, if the oil is cold, the oil may flow through cooler bypass check valve (14) instead of flowing to oil cooler (13). Steering pilot relief valve (7) limits the amount of pressure in the pilot circuit.
In the other branch, the pilot oil flows through pilot check valve (12), and then to steering pilot valve (11). Check valve (10) prevents pilot oil from flowing to steering pressure reducing valve (6) .
Pilot oil pressure then flows from steering pilot valve (11), to the steering neutralizer valve for right turns (8), and the steering neutralizer valve for left turns (9). The oil then flows to steering quad check valve (5), and then to spool (4) in steering control valve (3) .