Screw (simple machine)

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A screw is one of the six simple machines. A simple screw is a helical inclined plane. A screw can convert a rotational force (torque) to a linear force and vice versa. The ratio of threading determines the mechanical advantage of the machine. More threading increases the mechanical advantage. A rough comparison of mechanical advantage can be done by taking the circumference of the shaft of the screw and divide by the distance between the threads.

[edit] Examples

• Automated garage door, where a motor drives a long finely threaded shaft at relatively high speed and lifts the heavy door at a slower rate
• Rack and pinion, where the pinion is turned by the steering wheel and pulls the rack to turn a heavy vehicle
• Archimedes' screws and worm gears are examples of this machine.

[edit] See also

• Screw (disambiguation)
• Screw - the threaded fastener
• Archimedes' screw