cables are for example speedometer type cables intended to supply rotational motion to remote locations in the present invention the drive transmitting cables are connected at their other end to separate worm gear drives 46 one of these gear drives is preferably fixedly mounted on each interior side of frame 16 at a location forward of guide track 36 a drive nut bracket 48 is provided which is for example fixed to each link 28 drive nut 50 is removably mounted in bracket 48 drive nut 50 includes a threaded interior bore 52 and is fixed in bracket 48 with respect to forward or rearward movement a correspondingly threaded drive rod 54 is rotatably mounted in each gear drive 46 and extends through the threaded bore in each drive nut in operation the rotational output of drive motor 40 is transmitted through cables 44 to the worm gear drives each worm gear drive thereby causes drive rod 54 to rotate drive rods 54 do not travel longitudinally with respect to gear drives 46 as a result of this rotation however due to their threaded connection each drive nut 50 is displaced by the rotation of its respective drive rod 54 depending upon the direction of rotation drive nut 50 moves forward or rearward with respect to frame 16 since drive nut 50 is fixed in bracket 52 with respect to forward and rearward motion link 28 support bracket 20 and seat portion 12 are likewise urged forward or rearward the movement of seat portion 12 is restricted by the path permitted by guide track 36 roller elements 38.