Steering System 174Service Manual – SW8000Hydraulic DiagramsSteering Control Unit DescriptionThe Steering Control Unit uses the input fromthe steering wheel to turn the drive wheel inthe appropriate direction to steer the machine.When the Operator turns the steering wheel,the steering wheel shaft rotates the RotaryValve and Rotary Meter, which are connected bya mechanical link inside of the Steering ControlUnit.• The direction in which the Rotary Valvemoves determines which side of theSteering Cylinder receives the hydraulic oilto turn the drive wheel left or right. Notethat when the Operator stops turning thesteering wheel, the springs in the SteeringControl Unit return the Rotary Valve to theneutral (closed) position to hold the SteeringCylinder rod in its current position.• The number of degrees that the RotaryMeter rotates determines the volume of oilthat the Steering Cylinder receives from theRotary Valve. This allows the drive wheelto turn in proportion to the steering wheelrotation.Steering Cylinder StationaryRotaryValve1100PSIA TL RRotaryMeterOil to Cooler, Filterand ReservoirOil from "A" Port onHydraulic ManifoldAssemblyRotaryValveRotaryMeterSteeringControlUnit
