[ales]

I'm assuming you mean the lifts that are used in workshops to lift cars? Most use a screw principle - the two posts have screw-like shafts running inside them, and those are rotated by the motor(s). The horisontal elements (the ones that the car rests on) have the holes with threads that the shafts go through, and as the shafts rotate, the screw principle makes the car go up or down, depending o the direction of rotation. Usually the lidts have one electric motor on top of one post, and the two shafts are linked somehow to each other (chain running through the floor) to ensure that they both rotate at the same speed and the car is raised evenly.