Vehicle steering system having a rear steering control mechanism

A vehicle steering control mechanism for use with a vehicle having a steering input device, a front steering subsystem operably coupled to the device and coupled to front motive members to steer the front motive members, a rear steering subsystem coupled to rear motive members to steer the rear motive members, the control mechanism comprising:

• a movable input member configured to be coupled to the steering input device so as to move in response to input from the device;
• a movable output member configured to be coupled to the rear steering subsystem, wherein the rear steering subsystem adjusts steering of the rear motive members in response to movement of the output member, wherein the control mechanism operates in a rear steering state in which force is transmitted from the input member to the output member to move the output member and a dwell state in which the output member does not move in response to movement of the input member;
• at least one stationary surface;
• a nut threadably coupled to the output member;
• and
• at least one spring coupled between the at least one stationary surface and the nut, wherein the at least one spring biases the nut and the output member to a centering position, wherein the rear steering subsystem steers the rear motive members to a straight position in response to the output member being moved to the centering position.

A method for controlling a front steering subsystem to steer front motive members and a rear steering subsystem to steer rear motive members on a vehicle, the method comprising:

• applying a first force to a steering input device to move a portion of the device;
• transmitting a second force based on the first force to an input shaft of the front steering subsystem, whereby the front steering subsystem adjusts steering of the front motive members based on movement of the input shaft;
• and
• transmitting a third force based on the first force to an input member so as to move the input member through a first distance during which the input member moves relative to an output member coupled to an input shaft of the rear steering subsystem and through a second distance during which the third force is transmitted from the input member to the output member to move the output member and the input shaft of the rear steering subsystem, whereby the rear steering subsystem adjusts steering of the rear motive members based upon movement of the output member, wherein at least one of the second force and the third force is greater than the first force.

A vehicle steering system comprising:

• front vehicle motive members;
• rear vehicle motive members;
• a steering input device;
• a front steering subsystem operably coupled to the steering input device and coupled to the front motive members to steer the front motive members;
• a rear steering subsystem coupled to the rear motive members to steer the rear motive members;
• and
• a rear steering control mechanism including:
• a movable input member coupled to the steering input device so as to move in response to input from the device;
• a movable output member coupled to the rear steering subsystem, wherein the rear steering subsystem adjusts steering of the rear motive members in response to movement of the output member, wherein the control mechanism operates in a rear steering state in which force is transmitted from the input member to the output member to move the output member and a dwell state in which the output member does not move in response to movement of the input member, wherein the front steering subsystem includes an output shaft that moves in response to input from the device and wherein the output shaft is coupled to the input member so as to transmit force to the input member, wherein the front steering subsystem includes a first front powered steering gear having an input shaft coupled to the input device, and a second front powered steering near coupled between the output shaft and to the first front powered steering gear, wherein the first front powered steering gear is coupled to the front motive members, wherein the first front powered steering gear is coupled to the output shaft and wherein the second front powered steering gear drives the output shaft.

A vehicle steering system comprising:

• front vehicle motive members;
• rear vehicle motive members;
• a steering input device;
• a front steering subsystem operably coupled to the steering input device and coupled to the front motive members to steer the front motive members;
• a rear steering subsystem coupled to the rear motive members to steer the rear motive members;
• and
• a rear steering control mechanism including:
• a movable input member coupled to the steering input device so as to move in response to input from the device;
• and
• a movable output member coupled to the rear steering subsystem, wherein the rear steering subsystem adjusts steering of the rear motive members in response to movement of the output member, wherein the control mechanism operates in a rear steering state in which force is transmitted from the input member to the output member to move the output member and a dwell state in which the output member does not move in response to movement of the input member, wherein the output member is biased towards a centering position and wherein the rear steering subsystem steers the rear motive members to a straight position in response to the output member being in the centering position and, wherein the control mechanism includes a spring coupled to the output member to bias the output member to the centering position.

A vehicle steering system comprising:

• front vehicle motive members;
• rear vehicle motive members;
• a steering input device;
• a front steering subsystem operably coupled to the steering input device and coupled to the front motive members to steer the front motive members;
• a rear steering subsystem coupled to the rear motive members to steer the rear motive members;
• and
• a rear steering control mechanism including:
• a movable input member coupled to the steering input device so as to move in response to input from the device;
• a movable output member coupled to the rear steering subsystem, wherein the rear steering subsystem adjusts steering of the rear motive members in response to movement of the output member, wherein the control mechanism operates in a rear steering state in which force is transmitted from the input member to the output member to move the output member and a dwell state in which the output member does not move in response to movement of the input member;
• a nut threadably coupled to the output shaft and guided to move along an axis of the output shaft in conjunction with rotation of the output shaft;
• a carriage having a first drive face facing a first side of the nut and a second drive face fixed to the first drive face while facing a second side of the nut, wherein the carriage moves along the axis;
• a first stationary surface facing the first drive face;
• a second stationary surface axially spaced from the first stationary surface and facing the second drive face;
• a drive structure between the nut and the first drive face, wherein the structure is movable along the axis between the first drive face and the first stationary surface;
• and
• a spring captured between the first drive face and the drive structure, wherein the spring biases the drive member against the nut and the first stationary surface and wherein the spring biases the second drive face against the nut and the second stationary surface to bias the nut and the output member to a center position and to resiliently bias the output member against rotation, wherein the positioning of the output in the centering position results in the rear motive members being positioned in a straight position.

A vehicle steering control mechanism for use with a vehicle having a steering input device, a front steering subsystem operably coupled to the device and coupled to front motive members to steer the front motive members, a rear steering subsystem coupled to rear motive members to steer the rear motive members, the control mechanism comprising:

• a movable input member configured to be coupled to the steering input device so as to move in response to input from the device;
• a movable output member configured to be coupled to the rear steering subsystem, wherein the rear steering subsystem adjusts steering of the rear motive members in response to movement of the output member, wherein the control mechanism operates in a rear steering state in which force is transmitted from the input member to the output member to move the output member and a dwell state in which the output member does not move in response to movement of the input member;
• a nut threadably coupled to the output member and guided to move along an axis of the output member in conjunction with rotation of the output member;
• a carriage having a first drive face facing a first side of the nut and a second drive face fixed to the first drive face while facing a second side of the nut, wherein the carriage moves along the axis;
• a first stationary surface facing the first drive face;
• a second stationary surface axially spaced from the first stationary surface and facing the second drive face;
• a drive structure between the nut and the first drive face, wherein the structure is movable along the axis between the first drive face and the first stationary surface;
• and
• a spring captured between the first drive face and the drive structure, wherein the spring biases the drive structure against the nut and the first stationary surface and wherein the spring biases the second drive face against the nut and the second stationary surface to bias the nut and the output member to a centering position and to resiliently bias the output member against rotation, wherein the positioning of the output member in the centering position results in the rear motive members being positioned in a straight position.