Patent ID: 8056672

Claim:
An electro-hydraulic steering control system for directing fluid to a steering actuator arrangement for use on a work machine, comprising: a pilot pressure actuated main steering control valve connected in fluid communication with a steering actuator arrangement and configured for controlling fluid flow to and from the steering actuator arrangement; right and left manually-operated pilot pressure control valves connected in fluid communication with said main steering control valve so as to control the main steering control valve to effect only a low aggressive steering mode in the steering actuator arrangement; a manually-operated steering control device coupled for effecting operation of said manually-operated pilot pressure control valves; right and left proportional electro-hydraulic (EH) pilot pressure control valves connected in fluid communication with said main steering control valve through a path exclusive of said manually-operated pilot pressure control valves; an electronic control unit (ECU) including a processor and memory and being electrically coupled to said EH pilot pressure control valves, with said ECU being coupled for receiving input signals indicative of the pressure called for by said manually-operated steering device during actuation of one or another of said right and left manually-operated pilot pressure control valves, and of an existing ground speed of the work machine; said ECU acting to activate said EH pilot pressure control valves to connect pilot fluid pressure control pressure to the main steering control valve in addition to the fluid pressure connected to the main steering control valve so as to effect a more aggressive steering mode in the steering actuator arrangement only when the vehicle speed is low indicating off-road operation.