초록 ▼

A steering system for an articulated vehicle has pivotal wheel steering such as front axle wagon-wheel steering, a hydraulic actuator for pivoting the axle with respect to the vehicle, and a pair of hydraulic actuators for causing articulation of the vehicle. The system includes sensors for providin

A steering system for an articulated vehicle has pivotal wheel steering such as front axle wagon-wheel steering, a hydraulic actuator for pivoting the axle with respect to the vehicle, and a pair of hydraulic actuators for causing articulation of the vehicle. The system includes sensors for providing signals dependent on the degree of front wheel pivot relative to the vehicle and the degree of articulation of the vehicle. These signals are detected by a microprocessor controller which in turn controls the sequence of actuation of the axle and articulation hydraulic actuators. The actuators are operated sequentially so that small directional changes of the vehicles are achieved solely through pivoting of the axle. Operation of the axle and articulation actuators is controlled by a manual steering unit having a conventional hydraulic steering valve, with sequencing being provided through manipulation of a hydraulic fluid diverter valve. The timing and duration of the diverter valve actuation is controlled by the controller as a function of various dynamic turning parameters of the vehicle and the response time of the valve. A make-up valve system is also preferably included for automatically returning the articulation cylinders to their home position under certain conditions as the vehicle operates in a pivotable wheel steering mode.

대표청구항 ▼

An improved steering system for an articulated vehicle of the type having first and second frame portions each provided with at least one pair of ground-engaging wheels, with the wheels associated with the first frame portion being mounted for pivotable wheel steering through pivoting movement of su

An improved steering system for an articulated vehicle of the type having first and second frame portions each provided with at least one pair of ground-engaging wheels, with the wheels associated with the first frame portion being mounted for pivotable wheel steering through pivoting movement of such wheels with respect to the first frame portion, first hydraulic actuator means for pivoting the wheels of the first frame portion with respect to the first frame portion, and second hydraulic actuator means for articulated steering by articulating the first and second frame portions relative to one another, the improvement comprising: first means for determining the degree of pivot of at least one wheel of the first frame portion relative to the first frame portion; second means for determining the degree of articulation of the first and second frame portions; steering control means for selecting the direction of vehicle travel, including a manual steering member, at least first and second hydraulic fluid conduits, and hydraulic valve means for directing pressurized hydraulic fluid to the first conduit when movement of the manual steering member by a vehicle operator indicate the vehicle is to turn toward a first direction and to the second conduit when movement of the manual steering member by the vehicle operator indicates the vehicle is to turn in a second opposite direction; and system control means for controlling the first and second hydraulic actuators in response to said degree of pivot, said degree of articulation and the pressurized hydraulic fluid in the first and second conduits, including electrically operated hydraulic control valve means, in hydraulic fluid communication with the first and second conduits and the first and second hydraulic actuator means, for diverting the flow of pressurized hydraulic fluid in the first and second conduits sequentially between the first and second hydraulic actuators to effect steering of the vehicle by pivotable wheel steering and articulation steering.