Some time back I took a large tredmill apart. The incline adjust mechanism was a motor coupled to a right angle worm drive with double output shafts. Those 2 shafts were linked to a pair of boxes that created linear motion of some large acme thread rod. Inside the box was another worm and wheel with acme threaded hole in the middle of the worm wheel.
Perhaps a mechanism similar to the actuator on an adjustable bed would work for you... longer of cousre.
Steve |