Screw mechanism

A mechanism in which a threaded screw engages a mating component to convert rotation into linear motion or amplify force.

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Lead screw: A threaded shaft that converts rotation into controlled linear movement of a nut or carriage. Its rotating shaft and translating nut provide the mechanism’s clearest motion-conversion example.
Inclined plane: A flat surface set at an angle that trades a longer path for a smaller required force. An unwrapped screw thread forms an inclined plane around a cylinder.
Screw jack: A lifting device that raises a load by turning a threaded screw. It uses screw-based mechanical advantage to lift heavy loads through small increments.
Rack and pinion: A gear system in which a rotating pinion moves a straight toothed rack. It also converts rotation to linear motion, but uses meshing teeth rather than a screw thread.
Screw thread: A helical ridge or groove that engages a matching thread to transmit motion or force. Its helix sets the relationship between each turn and the resulting axial travel.
Mechanical advantage: The ratio of a machine’s output force to its input force. A screw’s pitch and operating radius determine how much force it can multiply.
Screw press: A press that applies force through the axial movement of a threaded screw. It uses rotation to generate high compressive force for pressing or forming.
Worm drive: A gear transmission in which a screw-like worm drives a toothed wheel on a different axis. It shares helical contact and possible self-locking, but primarily transmits rotation between shafts.
Lead (engineering): The axial distance a threaded component advances in one revolution. It determines linear travel per turn and contributes to mechanical advantage.
Work (physics): Energy transferred when a force moves an object through a distance. A screw exchanges greater input distance for greater output force, without creating energy.