Lifting table is an common appliance of Hand Crank Screw Jack. Hand crank table base lift mechanism includes two 2.5 ton screw mechanisms for crank table base, four 2.5 ton screw mechanisms for crank table base, and two 5 ton screw mechanisms for crank table base. All our screw mechanisms have self-locking function, don't require any lock mechanism, they will hold and stop any position without turning hand crank.