Screw jack: A type of jack that consists of a threaded cylinder that is moved up or down when the handle of the jack is turned.Mechanical advantage of screw jack:When an effort is applied to the handle, the effort moves in a circle of radius "d" while "d" is the length of the rod and the block "B" moves up equal to the pitch of the screw jack. If the handle is turned through one complete revolution in a circle of radius "d" the effort moves through a distance 2πd and consequently the load is raised through a height h. Hence, the mechanical advantage is given by:M.A. = 2