 | |
| Illustration 1 | g00513085 |
Sectional View of Pilot Manifold Valve (1) Pilot manifold (2) Passage to the automatic track tensioning circuit (3) Passage (pilot system high pressure circuit) (4) Pilot relief valve (high pressure circuit) (5) Passage (pilot system low pressure circuit) (6) Passage to the hydraulic tank (7) Passage to the hydraulic activation control selector valve and the pilot accumulator (8) Check valve | |
 | |
| Illustration 2 | g00513094 |
Sectional View of Pilot Manifold Valve (1) Pilot manifold (6) Passage to the hydraulic tank (7) Passage to the hydraulic activation control selector valve and the pilot accumulator (9) Line to the pilot accumulator (10) Line to the hydraulic activation control selector valve (11) Pilot relief valve (low pressure circuit) | |
There are two relief valves in the pilot hydraulic system. Pilot relief valve (4) and pilot relief valve (11) in series protect the pilot system high pressure circuit. Pilot relief valve (11) protects the pilot system low pressure circuit.
Pilot oil enters pilot relief valve (4) and the track tension circuit (2). Pilot relief valve (11) and pilot relief valve (4) work together in order to limit the pressure in the track tension circuit. Pilot relief valve (11) and pilot relief valve (4) in series act as a differential pressure regulator. Pilot relief valve (4) has a differential pressure setting of 3000 kPa (435 psi) and dumps into passage (5). Pressure in passage (5) is maintained by relief valve (11) to 4000 kPa (580 psi). Therefore, the pilot oil in track tension circuit and passage (3) is maintained at 7000 kPa (1000 psi). This pressure is the sum of the pressure settings of pilot relief valve (11) and pilot relief valve (4) .
Check valve (8) limits the flow of oil between passage (5) and passage (7) to one direction. Pilot oil flows through passage (7) into the pilot accumulator and the hydraulic activation control selector valve.
Passage (7) provides oil to hydraulic activation control selector valve line (10). Passage (7) provides oil to pilot accumulator line (9) .
Passage (6) returns the oil flow from pilot relief valve (11) to the hydraulic tank.
Any change to the low pilot system pressure also changes the high pilot system pressure. Always set the low pilot system pressure before you set the high pilot system pressure.