RING-BACKUP 1076846 - Caterpillar

Illustration 1 g03343398
Main control valve (lower) (1) Pilot section of lower main control valve
Illustration 2 g03343397
Hydraulic schematic of pilot section (1) Pilot section of lower main control valve (2) Pilot pressure relief valve (3) Pilot pressure reducing valve (4) Load sense relief valve (5) Load sense valve (6) Check valve (7) Orifice (8) SpringHigh-pressure oil from the main pumps flows through orifice (7). Pilot pressure reducing valve (3) receives oil from orifice (7) and supplies the pilot oil circuit through check valve (6). Once the pilot oil circuit has reached a pressure that will overcome the strength of spring (8), pilot pressure reducing valve (3) shifts. This action will create a passage for pilot oil to drain to tank. Check valve (6) ensures that the entire circuit does not lose pressure.Once the pressure drops below the force of spring (8), spring (8) will push the spool of pilot pressure reducing valve (3). Pilot pressure reducing valve (3) can now continue to supply oil through check valve (6).