Self Locking Screw Jacks
Screw jacks has an important advantage that brings extra safety to the application which is called self-locking. During the operation of screw jack, an external actuation is applied on worm shaft to rotate it and consequently to deliver linear travel on lead screw. The external actuation can be provided by an electrical motor, hand wheel or any other power source. It has full control on the translation of lead screw providing that the load on the screw does not exceed the maximum capacity of screw jack. But when the motion is stopped and the torque on the worm shaft is removed, the force on the lead screw remains the same. So there will be a risk of sliding or slipping of lead screw backwards. Fortunately, the design of screw jack system prevents this unintended slippage. When the rotational force on the worm shaft is removed, lead screw remains motionless where it was left and it will not move backwards, regardless of how much load it is carrying.