Jackscrew

n. machine that raises heavy objects

A jackscrew is a type of  jack which is operated by turning a leadscrew. It is also known as a screw jack, and are commonly used as car-jacksA jackscrew's compressive force is obtained through the tension force applied by its leadscrew. An Acme thread is most often used, as this thread is very strong and can resist the large loads imposed on most jackscrews while not being dramatically weakened by wear over many rotations. These types are self-locking, which makes them more intrinsically safe than other jack technologies like hydraulic actuators which require continual pressure to remain in a locked position. Most jackscrews are lubricated with grease.
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Noun
1. screw-operated jack
(synonym) screw jack
(hypernym) jack

(n.)
A jack in which a screw is used for lifting, or exerting pressure. See Illust. of 2d Jack, n., 5.
  

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