A method for steering a four-wheeled vehicle includes: determining a front wheel steering angle; determining a responsive low-speed steering angle of the two rear wheels, the responsive low-speed steering angle being (i) negative when the front wheel steering angle is positive, and (ii) positive when the front wheel steering angle is negative; determining a responsive high-speed steering angle of the two rear wheels, the responsive high-speed steering angle being (i) non-negative when the front wheel steering angle is positive, and (ii) non-positive when the front wheel steering angle is negative; determining a responsive rear wheel steering angle being a sum of the responsive low-speed and high-speed steering angles; and controlling a steering actuator to steer the two rear wheels in accordance with the responsive rear wheel steering angle.

A four-wheeled vehicle includes: a frame; two front suspension assemblies and two rear suspension assemblies connected to the frame; two front wheels operatively connected to corresponding ones of the two front suspension assemblies; two rear wheels operatively connected to corresponding ones of the two rear suspension assemblies; a motor connected to the frame; a front differential and a rear differential operatively connecting the motor to the two front wheels and the two rear wheels respectively; and a steering system. The steering system includes a front steering assembly for steering the front wheels and a rear steering assembly for steering the rear wheels. The front steering assembly includes a user-operated steering input device. The rear steering assembly includes an actuator operatively connected to the rear wheels and operable to modify a steering angle thereof. The actuator is mounted to the frame and is disposed completely rearward of the rear differential.

A lift truck (10) has a pair of wheel assemblies (21) each of which is rotatable about a pivot point (24) relative to the chassis (12) of the truck through at least 90 degrees between a forward mode and a sideward mode. The wheel (18,20) of each assembly is laterally offset from the assembly's pivot point (24), causing the wheel to describe an arcuate path over the ground as it transitions between the forward and sideward modes. During the transition, an actuator acts on each wheel assembly (21) to pivot the assembly about the pivot point (24), while drive is applied to the wheel to positively drive the wheel along the arcuate patch at a speed that matches the pivotal rotation caused by the actuator. This positive drive imparted to the wheels (18,20) during the transition prevents the truck from rolling if it is located on a slope during the change in orientation of the wheel assemblies (21).

Electronically controlled hydraulic valves can be directly mounted to rear steering cylinders of a four wheel steering machine to improve steering, reduce space consumption, reduce leak points and allow ease of routing. The valves can receive hydraulic fluid from a pump and release hydraulic fluid to tank, while controlling an amount of hydraulic fluid to the steering cylinder via inlets and outlets in direct contact. The valves can be controlled by a controller that is also in communication with position sensors configured to sense positions of the front and rear steering cylinders, so that the directly mounted valves in the rear can be correspondingly controlled to follow steering in the front.

An all-wheel steer trailer is disclosed which includes an elongated frame, having a forward end and a rearward end, with the forward end of the frame having the rearward end of an elongated tongue secured thereto about a horizontal axis. The rearward end of the tongue is pivotally secured, about a horizontal axis, to a pair of wheels at the forward end of the frame. The invention includes an improved structure wherein the pivoting of the front wheels of the trailer also causes the pivoting of the rear wheels of the trailer so that the rear wheels track the front wheels of the trailer as the trailer is being turned. The trailer includes an improved means for pivoting the rear wheels of the trailer with respect to the front wheels of the trailer as the trailer is being turned.

A high clearance sprayer with a four-wheel steering system includes a steering input, a steering control system, a front steering system, and a rear steering system. The front and rear steering systems are mirrored images of one another, which simplifies and improves the accuracy of the four-wheel steering control methodology. In doing so, the control system may calculate a single value that is used for controlling the front steering system, and an inverse of the single value that is used for controlling the rear steering system. Both of the front steering system and the rear steering system include wheels, steering actuator systems, swingarms, and wheel supports, which all of position of the wheels relative to the sprayer to be rotated. The steering control system may allow for various steering maneuvers to occur, including a turn-steering maneuver and a crab-steering maneuver.

An agricultural tractor including a chassis having a front end and a rear end, the chassis defining a longitudinal axis; a first axle; a second axle; a hood which substantially encloses an engine compartment; and a cab. The first axle and the hood are proximate the front end of the chassis and the second axle and the cab are proximate the rear end of the chassis. The hood and cab are positioned above the chassis, and the cab and chassis are fixed relative to each other and longitudinally spaced apart on the chassis.

Disclosed are a method and apparatus for determining the heading of a 4WS vehicle. The 4WS vehicle's dynamic pivot point is calculated from the steering angles. A distance between the dynamic pivot point and a Global Navigation Satellite System (GNSS) antenna is determined. A time delay is determined in the form of the distance between the GNSS antenna and the pivot point divided by the current vehicle horizontal velocity. The time delay is multiplied by a vehicle yaw rate to obtain a result which is added to a GNSS antenna heading to give a true heading. A control point for the 4WS vehicle is selected to allow that control point to follow a desired trajectory.

A method for operating an industrial truck having three wheels. During longitudinal travel, two steerable wheels run in succession in a first lane, and a third wheel runs in a second lane. The third wheel initially runs on an inside during a turning in while cornering until the industrial truck, during a further turning in, transitions into a revolving motion. The method includes reducing a drive power as of a specific steering angle during the turning in prior to the revolving motion, and disengaging or reversing a direction of a drive rotation of the third wheel after a delay time which begins with the reducing of the drive power, or, continuously reducing the drive power from the specific steering angle during the further turning in, and disengaging or reversing the direction of rotation of the third wheel when transitioning into the revolving motion.

A steerable suspension system for a vehicle, especially useful in a self-propelled vehicle that can include a worker-platform and optionally include pick-up, transport, and delivery apparatus for produce bins. The steerable suspension system includes independent pairs of parallel arms, each pair coupled to a single steerable drive-wheel, serving as both a suspension and as a shock absorber, with the parallel-acting pair of arms maintaining the steering-leg in its substantially vertical position relative to a ground surface. This steerable suspension system aids the steerable movement and suspension of the vehicle, while increasing safety and maneuverability, and helps to reduce the number of workers required to operate the vehicle.