PLATE & FILM GP 4415842 - Caterpillar

Illustration 1 g06068148
Left Side of Machine
(1) Steering manifold
(2) Pressure reducing valve
(3) Motor shift solenoid
(4) Flow compensator
(5) Right steer solenoid
(6) Counterbalance valve
(7) Left steer solenoidSteering manifold (1) is on the left side of the machine, mounted to the machine frame over the left wheel. The left side compartment door provides extra access to the manifold.Steering manifold (1) controls oil flow from the feeder pump to the following locations:
Main implement manifold
Steering cylinder
Shift spools of the propel motors
Front-wheel assist clutch valveReference: For additional information about hydraulic control of the clutch and shift solenoids, refer to the Systems Operation/Test and Adjust, "AP300F Asphalt Paver Propel System" publication.The steering priority valve (not shown) ensures that the steering system receives oil before the other auxiliary systems. This valve compares the steering load pressure signal to the output pressure of the auxiliary pump. When the pump pressure exceeds the steering demand, the pressure acts against the steering priority spring. This force causes the valve spool to shift. When the spool shifts, the valve spool directs excess supply oil to the main implement manifold.Supply oil from the priority valve is directed to flow compensator (4) and to pressure reducing valve (2). The flow compensator controls the flow of supply oil to the steering circuit. The pressure reducing valve provides supply oil at a reduced pressure to the clutch valve and the motor shift valve.Steering manifold (1) contains steer solenoids and counterbalance valves. Steer right solenoid (5) is energized when the operator steers right with the steering wheel. This solenoid controls oil flow to the rod end of the cylinder. Steer left solenoid (7) is energized when the operator steers left. This solenoid controls oil flow to the head end of the cylinder.Steering manifold (1) is equipped with two adjustable counterbalance valves (6). The counterbalance valves prevent the steering cylinder from being moved in either direction unless the appropriate steer solenoid is energized. The counterbalance valves limit the pressure in the steering system to 20000 kPa (2900 psi).The machine ECM provides input to the steering solenoids on the manifold. The input signal strength is based on the steering position sensor and the desired steering angle.Steering manifold (1) contains a series of resolver valves. These resolver valves compare the load pressure signals from the steering system, tow point system, and screed lift system. This signal network sends the highest pressure in the hydraulic circuit out port"LS" of the steering manifold. This signal is sent to the compensator valve on the feeder pump.