Steering systems for lift trucks

A steering system for a lift truck, the lift truck having a chassis with a longitudinal axis, the steering system comprising:

• a first wheel assembly and a second wheel assembly, each mounted on the chassis at a respective pivot point, the first and second wheel assemblies being spaced apart from one another in a transverse direction on opposite sides of said longitudinal axis;
• each wheel assembly having a respective ground-engaging wheel rotatable on a respective axle, the ground-engaging wheel being laterally offset from the pivot point on which the wheel assembly is mounted to the chassis;
• each wheel assembly having a respective brake which can be selectively applied to the respective ground-engaging wheel in response to a control input;
• wherein each wheel assembly is rotatable about its pivot point in a plane parallel to a ground surface when the lift truck is supported on the ground surface, with freedom to rotate through at least 90 degrees between a forward mode wherein the wheel axle is directed transversely towards the longitudinal axis and a sideward mode wherein the wheel axle is parallel to the longitudinal axis, wherein the lateral offset of the wheel from the pivot point causes the wheel to describe an arcuate path over the ground as it transitions between the forward and sideward modes;
• an actuator acting on each wheel assembly operable to control the angular orientation of the wheel assembly about the pivot point;
• drive means operating on each of said wheels to drive the wheels over the ground;
• and
• a controller which is operable to cause a transition between forward and sideward modes for each of the wheel assemblies by (i) simultaneously actuating the actuator of the first wheel assembly to cause the first wheel assembly to pivotally rotate about its pivot point with the wheel of the first wheel assembly unbraked, and braking the wheel of the second wheel assembly during the pivotal rotation of the first wheel assembly, followed by (ii) simultaneously actuating the actuator of the second wheel assembly to cause the second wheel assembly to pivotally rotate about its pivot point with the wheel of the second wheel assembly unbraked, and braking the wheel of the first wheel assembly during the pivotal rotation of the second wheel assembly.