Function

Function

Fully electro-hydraulic steering mode (steer-by-wire) In this operating mode, the Orbitrol steering unit is hydraulically shortcircuited by the corresponding steering definition valve solenoid coils (Y1897) and has no limitation (the steering wheel can be turned endlessly). The steering commands come from the redundant steering wheel sensors (B1501 and B150-2). The electro-hydraulic steering module (A55) executes the steering commands according to the selected steering program. The vehicle is steered via the automatic steering solenoid coils (Y190). In this process, the steering movements made are detected by the redundant steering angle sensors (B151 and B152). Fully electronic steering operation (steer-by-wire) is automatically active under the following conditions: –The floating axle (1) or the rigid axle (2) is the front axle in direction of travel. –The fieldwork steering mode is selected (ground speed < 20 km/h) –A special steering program is active. The steering hydraulics pump (218) supplies the proportional automatic rigid axle steering valves (Y190-1a, Y190-1b) and the proportional automatic floating axle steering valves (Y190-2a, Y190-2b) with volume flow.The steering logics shut-off valves (Y188-1, Y188-2, Y188-3 and Y188-4) as well as the steering logics definition valves (Y189-5, Y189-7 and Y189-9) are energised. Example (see circuit diagram): The cab position actuates the steering sense valve (V).When turning the steering wheel, volume flow from port L of the Orbitrol steering valve (IV) flows through the actuated steering sense valve (V) and the definition valve (Y189-7) back into the Orbitrol steering valve (IV). The Orbitrol steering valve (IV) is hydraulically shortcircuited.The steering logics shut-off valves (Y188-1, Y188-2, Y188-3 and Y188-4) are open. The steering logics shut-off valves (Y188-1 and Y188-2) open so that volume flow flows to the rigid axle steering hydraulic cylinder (232-2).The steering logics shut-off valves (Y188-3 and Y188-4) open so that volume flow flows to the floating axle steering hydraulic cylinder (232-1).The energised proportional automatic rigid axle steering valves (Y190-1a, Y1901b, Y190-2a, Y190-2b) determine the size and direction of the volume flow during steering.Control of the proportional valves is by the electro-hydraulic steering module (A55).