Levers 1, located in front and in back of ratchet-type rack 2, are hinged to pairs of pawls, 3 and 4 . Each pair of pawls is connected by a strip perpendicular to the plane of the drawing. When levers 1 are oscillated, the levers, with the load suspended from the hook, climb upward by means of pawls 3 and 4 whose strips engage the teeth of rack 2. Springs 5 hold the pairs of pawls, 3 and 4, against rack 2.
$489$SL,MH$