Jack screw lift come in two types: screw lifting and nut lifting. These two types have different installation space requirements. With screw lifting, the screw passes through the base, and the head of the screw connects to the material for lifting; there must be sufficient travel space above and below the mounting surface. With nut lifting, the bottom end of the screw connects to the worm gear key in the base, and a nut is attached to the screw for lifting and connecting to the material; there only needs to be sufficient travel space above the mounting surface. When the screw base cannot be changed, the nut lifting type can be chosen. It is important to note whether the screw's rotation in place is self-impeded in the nut lifting type.