A power loom is a mechanized loom

Loom

A loom is a device used to weave cloth. The basic purpose of any loom is to hold the warp threads under tension to facilitate the interweaving of the weft threads...

 powered by a line shaft

Line shaft

A line shaft is a power transmission system used extensively during the Industrial Revolution. Prior to the widespread use of electric motors small enough to be connected directly to each piece of machinery, line shafting was used to distribute power from a large central power source to machinery...

. The first power loom was designed in 1784 by Edmund Cartwright

Edmund Cartwright

Edward Cartwright was an English clergyman and inventor of the power loom.- Life and work :...

 and first built in 1785. It was refined over the next 47 years until a design by Kenworthy and Bullough, made the operation completely automatic. This was known as the Lancashire Loom

Lancashire Loom

The Lancashire Loom was a semi-automatic power loom invented by James Bullough and William Kenworthy in 1842. Although it is self-acting, it has to be stopped to recharge empty shuttles. It was the mainstay of the Lancashire cotton industry for a century....

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By 1850 there were 260,000 in operation in England. Fifty years later came the Northrop Loom

Northrop Loom

The Northrop Loom was a fully automatic power loom marketed by George Draper and Sons, Hopedale, Massachusetts beginning in 1895. It was named after James Henry Northrop who invented the shuttle-charging mechanism. -The Loom:...

 that would replenish the shuttle when it was empty and this replaced the Lancashire loom.
The major components of the loom are the warp beam, heddles, harnesses, shuttle, reed and takeup roll.