Four-wheel steering system

In an automotive vehicle, a four-wheel steering system comprising:

• a front steering gear for steering a pair of front wheels of said vehicle in response to rotation of a steering wheel of said vehicle and including a rear steer control shaft rotatable about a first axis of said vehicle in a direction corresponding to the direction of rotation of said steering wheel and at a predetermined ratio relative to said steering wheel rotation,
• a rear steering gear for steering a pair of rear wheels of said vehicle in response to rotation of a rear pinion shaft of said rear steering gear about a second axis of said vehicle parallel to and spaced from said first axis,
• means defining a housing on said vehicle into which each of said control shaft and said rear pinion shaft extends,
• a gear on said rear pinion shaft within said housing rotatable as unit with said rear pinion shaft,
• a gear sector meshing with said gear on said rear pinion shaft and supported on said housing for rotation about a third axis parallel to each of said first and said second axes,
• said second and said third axes being disposed in a common plane containing said first axis and on opposite sides of said first axis,
• means on said gear sector defining a track extending radially relative to said third axis,
• a crank assembly on said control shaft within said housing rotatable as a unit therewith about said first axis having a wrist pin assembly thereon movable radially relative to said first axis through a plurality of eccentric positions relative to said first axis from a null position on said first axis,
• a connecting means on said wrist pin assembly received in said track on said gear sector and slidable therealong so that said gear sector rotates in a negative steer phase direction when said wrist pin assembly is displaced in a negative phase direction relative to said first axis from said null position and rotates in a positive steer phase direction when said wrist pin assembly is displaced in a positive phase direction relative to said first axis from said null position, and
• control means operative to selectively locate said wrist pin assembly in one of said null position and said plurality of eccentric positions displaced from said null position.