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 .
Generally to say,manual screw jack is used when sluice gate is small and electricity is not available,while electric screw jack is used when the gate is heavy.
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.