The working principle of the hand operated worm gear screw jack is that the worm (also called the input shaft) is manually rotated by the hand wheel. the worm wheel(also called the worm gear) is rotated by the worm, and the trapezoidal lifting screw is moved by the rotating worm wheel.
Rotating Nut Design ( Traveling Nut )
These jacks have a fixed length lifting screw that rotates . Loads are attached to a flanged “traveling” nut that translates up and down the length of the rotating screw . This type of jack is ideal for applications that cannot accommodate a screw protection tube or that require a flush mount .
A safety nut on a screw jack is an auxiliary nut, which follows the “lifting nut” on a rotating screw jack or the worm gear on a translating screw jack.