A Jack is a mechanical device used to lift / elevate heavy loads or to employ great forces. Jacks are usually rated for a maximum lifting capacity (example, 1.5 tons or 3 tons). Industrial jacks can be rated for many tons of load. A bottle jack also called whiskey jack is a hydraulic jack which resembles shape of a bottle, consisting of a cylindrical body and a neck, from which the hydraulic ram emerges. In a floor jack or a trolley jack, a horizontal piston pushes on the short end of a bellcrank, with the long arm providing the vertical motion to a lifting pad, kept horizontal with a horizontal linkage.