Abstract: An anti-tip system is provided for improving the stability of a powered vehicle, such as a powered wheelchair. The vehicle includes a drive-train assembly pivotally mounted to a main structural frame. A suspension system biases the drive-train assembly and its connected anti-tip wheel to a predetermined resting position. The drive-train assembly bi-directionally rotates about a pivot in response to torque applied to or acceleration forces on the vehicle. A linkage arrangement is provided and is characterized by a suspension arm pivotally mounting to the main structural frame about a pivot at one end thereof and an anti-tip wheel at the other end. The linkage may further include at least one link operable to transfer the bi-directional displacement of the drive-train assembly to the suspension arm. The link may include a bell crank member and/or may be resiliently compressible.

Abstract: An anti-tip system is provided for improving the stability of a powered vehicle, such as a powered wheelchair. The vehicle includes a drive-train assembly pivotally mounted to a main structural frame. A suspension system biases the drive-train assembly and its connected anti-tip wheel to a predetermined resting position. The drive-train assembly bi-directionally rotates about a pivot in response to torque applied to or acceleration forces on the vehicle. A linkage arrangement is provided and is characterized by a suspension arm pivotally mounting to the main structural frame about a pivot at one end thereof and an anti-tip wheel at the other end. The linkage may further include at least one link operable to transfer the bi-directional displacement of the drive-train assembly to the suspension arm. The link may include a bell crank member and/or may be resiliently compressible.

Abstract: An anti-tip system is provided for improving the stability of a powered vehicle, such as a powered wheelchair. The vehicle includes a drive-train assembly which is pivotally mounted to a main structural frame. A suspension system biases the drive-train assembly and its connected anti-tip wheel to a predetermined resting position. The drive-train assembly bi-directionally rotates about a pivot in response to torque applied to or acceleration forces on the vehicle. A linkage arrangement is provided and is characterized by a suspension arm pivotally mounting to the main structural frame about a pivot at one end thereof and an anti-tip wheel at the other end. The linkage may further include at least one link operable to transfer the bi-directional displacement of the drive-train assembly to the suspension arm. The link may include a bell crank member and/or may be resiliently compressible.

Abstract: A linkage arrangement for an active anti-tip system is provided for improving the stability of a powered vehicle, such as a powered wheelchair. The vehicle includes a drive-train assembly which is pivotally mounted to a main structural frame. A suspension system biases the drive-train assembly and its connected anti-tip wheel to a predetermined resting position. The drive-train assembly bi-directionally rotates about a pivot in response to torque applied to or acceleration forces on the vehicle. The linkage arrangement is characterized by a suspension arm pivotally mounting to the main structural frame about a pivot at one end thereof and an anti-tip wheel at the other end. The linkage further includes at least one link operable to transfer the bi-directional displacement of the drive-train assembly to the suspension arm and may also include a bell crank link member.

Abstract: A power wheelchair is provided having one or more anti-tip wheels for stabilizing the movement of the frame about the drive wheels. An anti-tip wheel is attached to the end of a suspension arm which is pivotally attached to the frame of the wheelchair. A spring resiliently supports the anti-tip wheel in a neutral position relative to the ground upon which the drive wheels of the wheelchair normal ride. A retaining system selectively fixes position of the anti-tip wheels relative to the frame. The retaining system employs a plurality of teeth, with one portion disposed in combination with said suspension arm, and at least one other tooth disposed for engaging said one portion to provide unidirectional retention of the position of said suspension arm relative to the frame. The engagement of the teeth to lock the position of the suspension arm may be responsive to the torque generated by the motor.

Abstract: An anti-tip system is adapted for use in a powered wheelchair for purposes of curb-climbing and ride stability. The anti-tip system includes at least one anti-tip wheel, a suspension arm for mounting the anti-tip wheel and a pair of links coupling the suspension arm to the main structural frame of the wheelchair. Each of the links is pivotally mounted to the main structural frame of the wheelchair about a first pivot point and is pivotally mounted to the suspension arm about a second pivot point. In a first embodiment of the anti-tip system, the links include an upper and lower link, wherein the upper link is extensible to facilitate angular displacement of the suspension arm to permit rearward displacement of the anti-tip wheel in response to an externally applied load.

Abstract: A wheelchair is provided with front anti-tip wheels adapted to assist the wheelchair in mounting an obstacle that the wheelchair approaches obliquely. The anti-tip wheels may function as casters, capable of rotating about a vertical axis, or may be fixed for rotation about a horizontal axis only. The anti-tip wheels may include lateral convex surfaces which tend to allow the anti-tip wheel to slide or roll over the obstacle. The lateral convex surfaces may be provided by a laterally oriented rolling element, a convex-shaped hub, a convex-shaped housing that partially surrounds the wheel, or a ball-shaped wheel. Alternatively, rotation of the anti-tip wheel may be controlled such that the wheel rolling surface faces and engages the obstacle.

Abstract: A bi-directional anti-tip system for a wheelchair includes a pair of anti-tip system subassemblies actively lifting a leading anti-tip wheel when traveling in either forward or reverse directions. The anti-tip system subassemblies operate to couple a leading anti-tip wheel to the drive assembly such that pivot motion thereof effects vertical displacement of the leading anti-tip wheel and to decouple a trailing anti-tip wheel from the drive assembly to null pivot motion inputs therefrom. In one embodiment, rheonetic links actively couple and decouple the anti-tip system subassemblies. The system may also include compliant bearings or extensible links for inward displacement of the anti-tip wheel upon impact with a curb.

Abstract: A curb-climbing rear wheel drive power wheelchair is disclosed having a pair of drive wheels, at least one ground-engaging idler wheel connected to the frame forward of the drive wheels and at least one anti-tip wheel mounted above ground aft of the drive wheels. Each drive wheel and an associated drive assembly are mounted to a motor support bracket that is pivoted to the frame of the wheelchair. The drive assembly is mounted such that its motor is angled upward and rearward from the bracket. The anti-tip wheel is attached to one motor support bracket such that pivoting of the motor support bracket causes vertical displacement of the anti-tip wheel.

Abstract: An anti-tip system is provided for stabilizing a vehicle, such as a power wheelchair, about a pitch axis and relative to a ground plane. The anti-tip system includes at least one anti-tip wheel. The mounting assembly for the anti-tip wheel is configured such that it traverses linearly in a direction toward or away from the ground plane and is responsive to an acceleration or deceleration of the wheelchair. As the wheelchair accelerates or decelerates, rotational motion of the drive train assembly is transmitted to a guide subassembly within the mounting to effect translation of the anti-tip wheel. Upward translation of the anti-tip wheel enables the wheelchair to negotiate obstacles, e.g., curbs or steps, while downward translation or force enhances stability when stopping the wheelchair or while moving down sloping terrain or surfaces. The anti-tip wheels may be castors and normally contacting the ground during operation.

Abstract: A curb-climbing rear wheel drive power wheelchair is disclosed having a pair of drive wheels, at least one ground-engaging idler wheel connected to the frame forward of the drive wheels and at least one ground-contacting anti-tip caster wheel mounted to the wheelchair aft of the drive wheels. The drive wheels and anti-tip caster wheels are mounted on common suspension arms, pivoted to the frame of the wheelchair behind the drive wheels and resiliently suspended, so that the anti-tip caster wheels move up and down in response to movements of the drive wheel suspension.

Abstract: A curb-climbing rear wheel drive power wheelchair is disclosed having a pair of drive wheels, at least one ground-engaging idler wheel connected to the frame forward of the drive wheels and at least one anti-tip wheel mounted above ground aft of the drive wheels. The drive wheels and anti-tip wheels are mounted on common suspension arms, pivoted to the frame of the wheelchair behind the drive wheels and resiliently suspended, so that the anti-tip wheels move up and down in response to movements of the drive wheel suspension.

Abstract: A power wheelchair with front anti-tip wheels for substantially eliminating partial tips of the wheelchair is described. The anti-tip wheels are attached to the end of an extension arm which is attached to the frame of the wheelchair. A spring connects the anti-tip wheels with the frame at a second point. The spring tends to hold the anti-tip wheels in a neutral position at a predetermined height above the ground. A lowering mechanism is provided which positions the anti-tip wheels in a position engaged with or just above the ground. A retaining system holds the anti-tip wheels on or near the ground until the user or a release trigger device releases the retaining system, at which time the anti-tip wheels return to the neutral position. While the retaining system is disengaged, the wheels are free to rise in response to an upward force in order to climb over an obstacle in the wheelchair's path of travel.

Abstract: A wheelchair is provided with front anti-tip wheels adapted to assist the wheelchair in mounting an obstacle that the wheelchair approaches obliquely. The anti-tip wheels may function as casters, capable of rotating about a vertical axis, or may be fixed for rotation about a horizontal axis only. The anti-tip wheels may include lateral convex surfaces which tend to allow the anti-tip wheel to slide or roll over the obstacle. The lateral convex surfaces may be provided by a laterally oriented rolling element, a convex-shaped hub, a convex-shaped housing that partially surrounds the wheel, or a ball-shaped wheel. Alternatively, rotation of the anti-tip wheel may be controlled such that the wheel rolling surface faces and engages the obstacle.

Abstract: A suspension system for mounting a pair of wheels to a wheelchair is disclosed. The system includes a crossbar pivotally mounted to the wheelchair so as to pivot about a longitudinal axis. At least one spring assembly is located between the crossbar and the wheelchair frame for controlling the pivoting of the crossbar. A hinge assembly is mounted on each lateral end of the crossbar. The hinge assembly includes a first hinge component attached to the crossbar so as to be rotatable about a vertical axis, and a second hinge component resiliently connected to the first hinge component. The resilient connection biases the second hinge connection against rotation with respect to the first hinge component. A wheel and yoke assembly are mounted to the second hinge component.

Abstract: A stabilizing system for a reclinable wheelchair connects anti-tip members to the wheelchair seat such that pivoting of the seat causes pivoting of the anti-tip members. In one embodiment, the stabilizing system includes cables connected at opposite ends to the seat and to the anti-tip members. The cables may be connected to the seat bottom or, alternately, to the seat back. The anti-tip members may incorporate a pivoting suspension member that includes a drive motor for the wheelchair. Pivot control mechanisms connected to the cables can be used to permit a predetermined amount of seat pivot without corresponding pivot of the anti-tip members. The stabilizing system alternatively includes axially compressible link members connecting the seat back to the anti-tip members to provide controlled pivoting of the anti-tip members based on pivoting of the seat.

Abstract: A stabilizing system for a reclinable wheelchair connects anti-tip members to the wheelchair seat such that pivoting of the seat causes pivoting of the anti-tip members. In one embodiment, the stabilizing system includes cables connected at opposite ends to the seat and to the anti-tip members. The cables may be connected to the seat bottom or, alternately, to the seat back. The anti-tip members may incorporate a pivoting suspension member that includes a drive motor for the wheelchair. Pivot control mechanisms connected to the cables can be used to permit a predetermined amount of seat pivot without corresponding pivot of the anti-tip members. The stabilizing system alternatively includes axially compressible link members connecting the seat back to the anti-tip members to provide controlled pivoting of the anti-tip members based on pivoting of the seat.

Abstract: A curb-climbing rear wheel drive power wheelchair is disclosed having a pair of drive wheels, at least one ground-engaging idler wheel connected to the frame forward of the drive wheels and at least one ground-contacting anti-tip caster wheel mounted to the wheelchair aft of the drive wheels. The drive wheels and anti-tip caster wheels are mounted on common suspension arms, pivoted to the frame of the wheelchair behind the drive wheels and resiliently suspended, so that the anti-tip caster wheels move up and down in response to movements of the drive wheel suspension.

Abstract: A suspension system for mounting a pair of wheels to a wheelchair is disclosed. The system includes a crossbar pivotally mounted to the wheelchair so as to pivot about a longitudinal axis. At least one spring assembly is located between the crossbar and the wheelchair frame for controlling the pivoting of the crossbar. A hinge assembly is mounted on each lateral end of the crossbar. The hinge assembly includes a first hinge component attached to the crossbar so as to be rotatable about a vertical axis, and a second hinge component resiliently connected to the first hinge component. The resilient connection biases the second hinge connection against rotation with respect to the first hinge component. A wheel and yoke assembly are mounted to the second hinge component.

Abstract: A power wheelchair with front anti-tip wheels for substantially eliminating partial tips of the wheelchair is described. The anti-tip wheels are attached to the end of an extension arm which is attached to the frame of the wheelchair. A spring connects the anti-tip wheels with the frame at a second point. The spring tends to hold the anti-tip wheels in a neutral position at a predetermined height above the ground. A lowering mechanism is provided which positions the anti-tip wheels in a position engaged with or just above the ground. A retaining system holds the anti-tip wheels on or near the ground until the user or a release trigger device releases the retaining system, at which time the anti-tip wheels return to the neutral position. While the retaining system is disengaged, the wheels are free to rise in response to an upward force in order to climb over an obstacle in the wheelchair's path of travel.