US Patent 9579242 Electric mid-wheel drive wheelchair

A wheelchair of the mid-wheel drive type has a chassis frame, a pair of from and rear link arms that are pivotally connected to the chassis frame. Front caster wheels and drive wheels are fixed to the front link arms. Rear caster wheels are fixed to the rear link arms. A coupling operatively connects each front link arm to an adjacent rear link arm to transmit pivotal movement of one of the front and rear link arm to an opposite pivotal movement of the other of the front and rear link arm.