PISTON 4Z6389 - Caterpillar

Illustration 1 g03307917
Left Side of Machine (1) Steering manifoldSteering manifold (1) is located on the left side of the machine in the engine compartment. A door on the left side of the machine provides access to this component.Steering manifold (1) contains components used to control steering and offset.
Illustration 2 g03307936
Steering Control Manifold (2) Compensator spool (3) Front counterclockwise solenoid (4) Front clockwise solenoid (5) Main relief valve (6) Counterbalance valves (7) Margin spool (8) Steering shunt solenoid (9) Rear counterclockwise solenoid (10) Rear clockwise solenoid (11) Counterbalance valves (12) Warm up valveThe steering control valves for the front drum and the rear drum are located in the steering manifold. Each steering control valve is controlled by two solenoids. One solenoid controls clockwise drum rotation and one solenoid controls counterclockwise drum rotation. The steering control valves direct oil to one end of the steering cylinder while opening the other end to the hydraulic tank.The steering shunt valve is controlled by steering shunt solenoid (8). The machine ECM energizes the solenoid in order to enable the steering system. In this condition, the shunt valve is closed and oil from the steering pump is routed to the steering control valve. When the shunt solenoid is de energized, the shunt valve opens and sends oil from the pump directly to the hydraulic tank. In this condition, the steering system is disabled. The machine ECM disables the steering system when the machine electronic control system registers a level "three" fault. The machine ECM also disables the steering system when the parking brake is applied.Main relief valve (5) limits steering system pressure to 20000 1000 kPa (2900 145 psi). When the main relief valve is open, steering oil flows into the hydraulic tank.Margin spool (7) regulates the flow of supply oil to the steering system. When the flow of supply oil into the system is greater than the demand of the system, the margin spool directs unused oil into the hydraulic tank.The shuttle valves (not shown) inside the steering manifold, compare pressure requirements and send the highest pressure requirement to the margin spool. One shuttle valve compares the pressure at the rod end of the cylinder and the pressure at the head end of the cylinder. A second shuttle valve compares the highest pressure in the steering cylinder and the external load sensing pressure signal coming from the side cutter attachment (if equipped) .Counterbalance valves (6) and (11) ensure that the steering cylinder will not move unless pressurized oil is in one end. When steering oil is made available to one end of the steering cylinder, this pressure shifts the counterbalance valve on the other end of the steering cylinder. This shift opens the other end of the steering cylinder to the hydraulic tank.A check valve (not shown) is installed in parallel with each counterbalance valve (6) and (11). These check valves prevent hydraulic oil from flowing out of a steering cylinder unless the corresponding counterbalance valve is open.When the hydraulic oil temperature is