END BIT 7F7719 - Caterpillar

The steering control valve (10) is pilot operated from the HMU when the truck is in the Manual Mode. The steering control valve (10) is pilot operated from the EH steering valve when the truck is in the Autonomous Mode. The steering control valve is located on the front left side of the front crossmember.
Illustration 10 g03344346
(12) Steering metering pump (HMU)Five pilot lines connect the HMU (12) to the steering control valve when the diverter valve is shifted to the Manual Mode. The pilot lines send pilot oil from the HMU to shift the spools in the steering control valve. The spools control the amount and direction of pressure oil sent to the steering cylinders. Four pilot lines are used for pump supply, tank return, left turn, and right turn. The fifth pilot line is for the load sensing signal.The HMU meters the amount of oil sent to the steering control valve by the speed at which the steering wheel is turned. The faster the HMU is turned, the higher the flow that is sent to the steering cylinders from the steering control valve, and the faster the wheels will change direction.
Illustration 11 g03344363
(14) Steering cylinders
(27) Steering position sensorThe steering cylinders are connected to the frame and the steering linkage and receive oil from the steering control valve to turn the wheels.The steering cylinders are equipped with a position sensor located below a cover on the head end of each cylinder. The position sensors send a signal to the Steering ECM and the Transmission ECM indicating the cylinder piston position within the piston stroke.The Steering ECM and Transmission ECM use the steering cylinder position to calculate the angle of the front tires.The Steering ECM uses the front tire angle information as one of the inputs to control truck steering when the truck is operating in the Autonomous Mode. The Transmission ECM uses front tire angle information to accurately control the turn if the primary system fails.
Illustration 12 g03344368
(9) Relief valve manifold
(11) Diverter valve
(13) EH steering valve
(15) Primary diverter valve manifoldThe relief valve manifold (9), the diverter solenoids (15), the diverter valve (3), and the EH steering valve (4) are located inside the left front frame rail and have been to allow for Autonomous control of the steering system.
Illustration 13 g03346990
(9) Relief valve manifold
(L) Pressure reducing valve
(M) Pressure reducing valve
(N) Primary relief valve
(P) Secondary relief valve
(R) Oil filter
(S) Oil filter bypass valve
(T) Oil filter
(U) Oil filter bypass valveThe relief valve manifold (9) contains the following components:
(L) Pressure reducing valve for primary circuit (P1)
(M) Pressure reducing valve for the secondary circuit (P2)
(N) Primary relief valve
(P) Secondary relief valve
(R) Oil filter for P1
(S) Oil filter bypass valve for P1
(T) Oil filter for P2
(U) Oil filter bypass valve for P2Oil from the solenoid and relief valve flows to the primary pressure reducing valve and the secondary pressure reducing valve. The pressure reducing valves reduce the oil pressure for the primary and secondary