ADAPTER 6K1964 - Caterpillar

Right Turn (Coordinated Steering)
Illustration 2 g01193448
When the operator turns the steering wheel to the right, the spool of the steering control valve shifts. Pump supply oil enters the steering control unit, flows across the spool of the steering control valve, and flows into the metering section.When the steering wheel is turned, the metering pump also turns. The metering pump directs flow through the spool of the steering control valve and into the head end of the right steering cylinder and the rod end of the left steering cylinder. Oil which flows into the steering cylinders causes the machine to turn right. As the operator turns the steering wheel faster, the metering pump increases the flow to the steering cylinders. Therefore, the machine turns faster. Oil in the rod end of the right steering cylinder and oil in the head end of the left steering cylinder returns to the tank through the control spool.The metering pump continues to direct flow to the steering cylinders until the operator stops turning the steering wheel. When the steering wheel stops turning, the centering springs in the control spool return the spool to the center position. Oil is blocked at the steering cylinder. In this case, the machine continues to turn at the same radius until the operator moves the steering wheel again.Note: If a shock load causes the pressure in the lines to the steering cylinders to increase to 21045 kPa (3050 psi), the steering relief valves open. The makeup valves allow displaced oil from the high pressure side of the steering cylinders to flow into the low pressure side of the cylinders. This action fills any void which was created by movement of the cylinders.The machine ECM monitors the position of the front wheels and uses the input to control the position of the rear wheels. With the steering mode switch in the COORDINATED position, as the front wheels steer to the right, the machine ECM sends a signal to the left rear steering solenoid.When the left steering solenoid is energized, oil is metered across the spool. This oil delivered to the inlet check valve, shuttle valve, and the counterbalance valve in the line to the head end of the rear steering cylinder. The inlet check valve opens, and oil flows into the rod end of the steering cylinder. As pressure builds in the rod end of the steering cylinder, the cylinder retracts and the counterbalance valve opens. The counterbalance valve allows oil from the head end of the rear steering cylinder to flow into the return line.At the shuttle valve, pressure in the line to the rod end of the steering cylinder shifts the shuttle valve. This pressure then acts against the differential pressure valve, in conjunction with the spring. The differential pressure valve allows enough oil to flow across the steering proportional valve to create a 1035 kPa (150 psi) pressure drop across the valve. Larger proportional valve openings require more flow to create the same pressure drop, resulting in