Jack (device)

using a jack to lift a staff car, January 1945 A jack is a mechanical lifting device. Most often, the term "jack" denotes equipment used to apply great forces or lift heavy loads. There are also smaller, more delicate jacks used as part of the action of keyboard instruments. Of the jacks of the first category (heavy lifting), a mechanical jack employs a screw thread. A hydraulic jack uses hydraulic power. The most common function of a jack is as a car jack, floor jack or garage jack, which lift vehicles so that maintenance can be performed. Jacks are usually rated for a maximum lifting capacity (for example, 1.5 tons or 3 tons). Industrial jacks can be rated for many tons of load.

using a jack to lift a staff car, January 1945]] ]] A jack is a mechanical lifting device. Most often, the term "jack" denotes equipment used to apply great forces or lift heavy loads. There are also smaller, more delicate jacks used as part of the action of keyboard instruments. Of the jacks of the first category (heavy lifting), a mechanical jack employs a screw thread. A hydraulic jack uses hydraulic power. The most common function of a jack is as a car jack, floor jack or garage jack, which lift vehicles so that maintenance can be performed. Jacks are usually rated for a maximum lifting capacity (for example, 1.5 tons or 3 tons). Industrial jacks can be rated for many tons of load. ==In musical instruments== |right|thumb]] "Jack" in the context of musical instruments may refer to part of a piano action, which lifts other action parts in the course of sending the hammer toward the string. In a harpsichord, jacks are small strips of wood that lift the plectrum so that it can pluck the string. Small bottle jacks are used to lift pianos short distances, for instance in attaching wheels or installing protective pads for flooring.

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