PULLEY

In Mechanics, one of the six simple machines, or mechanical powers. It consists of a wheel, moveable about an axis, and having a groove cut in its circumference, over which a cord pa es. The, axle is supported by a box or sheave, called the block, which may eithet be moveable, or lived to a firm support. A single pulley serves merely to change the direction of motion; but several of them may be ccnoincd In various ways, by which a mechanical advantage or purchase is gained, greater or le , according to their number and the mode [s. 1015]