TIP ASSEM. (R.H.) 4V3453 - Caterpillar

Illustration 1 g01826514
Drum Offset Manifold in HOLD (1) Priority spool (2) Offset cylinder (3) Pilot opened check valves (4) Drum offset valve (5) Relief valve (6) To hydraulic tank (7) To fan motor in port (8) From port "ef" of steering pumpThe steering pump provides the oil to the drum offset manifold. The manifold contains a priority valve, a relief valve, a solenoid operated drum offset valve and two pilot opened check valves. Before the engine is started, the spring in the priority valve forces the valve down, and the top envelope of the valve is active. As the engine is started, the steering pump begins to produce flow. Pump supply oil flows to the priority valve. At this time, the priority valve directs all available pump flow to the drum offset valve. When the drum offset valve is in the HOLD position, the control spool blocks the supply oil, and pressure quickly builds in the system. Oil inside the manifold, downstream of the priority valve, flows through an orifice and acts against the bottom of the priority valve, against the spring which acts on the top of the valve. As the pressure against the bottom of the priority valve increases, the priority valve shifts up, and excess oil from the steering pump then flows to the fan motor. Since there is flow in the system, the priority valve reaches an equilibrium position where the drum offset valve has oil pressure available for operation, but the majority of the oil flow is directed to the fan motor.The pilot opened check valves block the outlet passages from the offset cylinder, locking the cylinder in the current position.
Illustration 2 g01826515
Drum Offset Manifold in OFFSET LEFT (1) Priority spool (2) Offset cylinder (3) Pilot opened check valves (4) Drum offset valve (5) Relief valve (6) To hydraulic tank (7) To fan motor in port (8) From port "ef" of steering pumpWhen the drum offset switch is in the OFFSET LEFT position, the offset left solenoid is energized. The drum offset valve directs oil to the pilot opened check valves. Oil flows through the pilot opened check valve which is located in the line to the head end of the offset cylinder and opens the pilot opened check valve which is located in the line to the rod end of the cylinder. The cylinder extends, and the displaced oil from the rod end of the cylinder returns to the hydraulic tank.Just after the offset left solenoid is energized, the pressure which acts on the bottom of the priority spool decreases and the pressure acting on the top of the spool increases. This action causes the priority spool to shift, directing additional oil to the drum offset valve. Eventually, the priority valve reaches an equilibrium position where the drum offset valve receives sufficient oil for operation of the offset cylinder, and the remainder of the oil flow is directed to the fan motor.