SPRING-YM 3832134 - Caterpillar

References
Reference: Specifications, "D6R Series II Track-Type Tractor Hydraulic System"Reference: Schematic, "D6R Series II Track-Type Tractor Hydraulic System"Reference: Testing and Adjusting, "D6R Series II Track-Type Tractor Hydraulic System"Implement Hydraulic System
Illustration 1 g00826258
Components of the hydraulic system (1) Bulldozer lift cylinders (2) Quick-drop valve (3) Bulldozer tilt cylinder (4) End plate (5) Ripper lift control valve (6) Bulldozer tilt control valve (7) Bulldozer lift control valve (8) Inlet manifold (9) Ripper cylinder (10) Ripper control lever (11) Bulldozer control lever (12) Shutoff valve (13) Pressure reducing valve (14) Accumulator (15) Hydraulic tank and filters (16) Implement hydraulic pumpThe hydraulic system controls the bulldozer and the ripper (if equipped). The hydraulic system is a load sensing, pressure compensated system. In a load sensing, pressure compensated system, oil flow does not change according to the load conditions. Cylinder speeds remain constant under all load conditions.
Illustration 2 g00551238
(10) Pilot control lever (ripper) (11) Pilot control lever (bulldozer) (12) Shutoff valveOperator control of the bulldozer is accomplished by using pilot control lever (11). Operator control of the ripper (if equipped) is accomplished by using pilot control lever (10) .When the pilot control lever is moved to an operating position, the hydraulic pilot oil circuit instructs the implement control valve to send pressure oil to the cylinder.
Illustration 3 g00584264
(13) Manifold and reducing valve (14) AccumulatorManifold and reducing valve (13) supplies pilot oil to the control valves for the bulldozer and the attachments. The manifold and reducing valve includes a screen, a relief valve, a check valve, and an attached accumulator (14). The accumulator and the check valve are used to maintain supply pressure during momentary drops in system pressure.A shutoff valve is located between the pressure reducing valve and the pilot control valves. Pilot supply oil from the manifold and reducing valve enters shutoff valve (12). In the UNLOCK position, shutoff valve (12) directs pilot supply oil to the pilot control valve. In the LOCK position, the line from the pressure reducing valve is blocked and the line to the pilot control valves is diverted to the hydraulic tank. This allows the oil from the pilot control valves to drain to the hydraulic tank. Also, when the knob is turned to the LOCK position a switch deactivates a coil on the pilot valve and another switch activates a lamp on the instrument panel. When the coil is activated, the coil is used to hold the bulldozer control lever in the FLOAT position.The valve stack has an inlet manifold (8) and an end cover (4). The valve stack can have as many as three control sections. Refer to Illustration 1.The control valves for the bulldozer and the ripper (if equipped) are controlled by the pilot control system. The bulldozer lift control valve has four positions: RAISE, HOLD, LOWER and FLOAT. FLOAT is a detent position.The bulldozer tilt control valve has three positions: TILT RIGHT, HOLD and TILT LEFT.The ripper lift control valve has three positions: RAISE, HOLD and LOWER.In order to keep the pressure in the system at a