Screw Jack

Screw Jack Points : Screw Jack, Definition Definition A screw jack is a simple machine which is commonly used to lift heavy loads such as motor car. It consists of a long screw rod R passing through a threaded block "B" and handle "H" which is called Tommy-bar to turn the threaded block B. As a result it rises up and lifts the heavy load. The distance between two successive screw threads is called pitch. When the effort is applied to the handle H, the effort moves in a circle of radius "r" where r is the length of.Tommy bar. In this rotation block B moves up.
When the handle is turned through one complete revolution in a circle of radius "r", the effort moves through a distance 2nr and the load is raised through a height "h" in this case.
As the pitch of the screw is very small as compared jack to length of the Tommy-bar so the mechanIcal advantage of screw jack is very large.