Apparatuses and methods for steering a vehicle

A drivable lift assembly for lifting a load with respect to a support surface, comprising:

• a chassis having a steer axis extending approximately vertically through a central region of the chassis;
• a load carrying structure adapted to carry a load;
• a support assembly coupling the load carrying structure and the chassis, the support assembly being adapted to move the load carrying structure relative to the chassis between a stowed position and a deployed position, such that the load carrying structure has a raised center of gravity in the deployed position;
• first and second pairs of wheels adapted to roll on an underlying support surface, each wheel interfacing with the underlying support surface through a respective contact patch;
• a first pair of spindles coupling the first pair of wheels to the chassis via at least one axle, and a second pair of spindles coupling the second pair of wheels to the chassis via at least another axle, each spindle adapted to support one of the wheels for rotation about a spindle axis;
• first and second pairs of kingpins, each kingpin pivotally coupling a respective spindle relative to the chassis about a king pin axis extending through the spindle to intersect the associated spindle axis, wherein each kingpin is offset from the contact patch of the wheel on an inboard side of the drivable lift assembly;
• a steering system having a plurality of actuators coupled to the first and second pairs of wheels and being adapted to position the wheels between a driving arrangement and a rotating arrangement relative to the chassis, such that in the rotating arrangement each spindle axis of each wheel in the first and second pairs of wheels intersect the steer axis such that the chassis rotates and spot steers about the steer axis;
• and
• a propulsion system coupled to the first and second pairs of wheels and adapted to drive the wheels;
• wherein each actuator is connected to an associated spindle via a pivotal connection spaced apart and offset from the spindle axis, wherein the pivotal connection lies in a plane defined by a respective spindle axis sweeping from the driving arrangement to the rotating arrangement;
• wherein the propulsion system is configured to rotate a first and a second wheel of the first and second pairs of wheels in a forward direction relative to the chassis and rotates a third and a fourth wheel of the first and second pairs of wheels in a reverse direction that is opposite the forward direction when the steering system is in the rotating arrangement to rotate and spot steer the chassis about the steer axis.

A vehicle for lifting a load with respect to a support surface, comprising:

• a chassis having a footprint and a vertical axis;
• a load carrying structure adapted to carry a load;
• a support assembly coupling the load carrying structure and the chassis, the support assembly being adapted to move the load carrying structure relative to the chassis between a stowed position and a deployed position, such that the load carrying structure has a raised center of gravity in the deployed position;
• a first pair of wheels adapted to roll on an underlying support surface and coupled to the chassis using a first axle and a first pair of spindles, each spindle of the first pair of spindles adapted to support a respective wheel of the first pair of wheels for rotation about a spindle axis;
• a second pair of wheels adapted to roll on an underlying support surface and coupled to the chassis using a second axle and a second pair of spindles, each spindle of the second pair of spindles adapted to support a respective wheel of the second pair of wheels for rotation about a spindle axis;
• and
• a steering system having a first extensible tie rod associated with the first pair of spindles and a second extensible tie rod associated with the second pair of spindles, each tie rod having a first terminal end connected to one spindle, and a second terminal end connected to the other spindle, each extensible tie rod having a first rod section and a second rod section connected to one another using an actuator in an intermediate region of the tie rod;
• wherein the steering system is configured to position the first and second pairs of wheels between a driving arrangement and a rotating arrangement relative to the chassis;
• wherein the steering system is configured to extend the first and second extensible tie rods in the rotating arrangement until the vehicle is configured to rotate about a steer axis extending approximately vertically through a central portion of the chassis, each spindle axis of the first and second pairs of spindles intersecting the steer axis in the rotating arrangement;
• and
• wherein the steering system is configured to retract the first and second extensible tie rods in the driving arrangement such that each spindle axis of the first pair of spindles are along a first common axis and each spindle axis of the second pair of spindles are along a second common axis.