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: 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 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.