Active anti-tip system for power wheelchairs

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.