Pulley
in mechanics, one of the six simple machines or mechanical powers. It consists of a small circular plate or wheel which can turn round an axis passing through the centers of its faces, and having its ends supported by a framework which is called the block.
The circular plate has a groove cut in its edge to prevent a string from slipping off when it is put round the pull With a single fixed pulley (that is one in which the block in which the pulley turns is fixed), there is neither gain nor loss of power; for, as the tension in turns is fixed), there is neither gain nor every part of the cord is the same, if a weight be suspended at one extremity, per cent. over the amount contained in an equal weight must be applied at the pure air. A valve mechanism causes alan equal weight must be applied at the pure air. A valve mechanism causes al- per cent. over the amount contained in pulley. the effect of a fixed pulley is simply to change the direction of a force. By means of movable pulleys one can gain mechanical advantage, greater or less, according to the number and mode of mechanical advantage, greater or less, combination of the pulleys.
Fast pulley, a pulley firmly attached to which it communicates motion. Loose pulley, a pulley running free on the still to traverse without being affected by, or affecting the motion of, the shafting. Sliding pulley, a kind of coupling in which the band-pulley is slipped into or out of engagement with an arm freely with. attached to the shaft and rotating therean American inventor; born in Chautauqua co., N. Y., March 3, 1831; learned qua co., N. Y., March 3, 1831; learned cal purity, the mixture which is injected mixture of air and oxygen pass through oxygen in the tank approximates che into the lungs averages only about 30 chemiper cent. oxygen, an increase of about 9 plied at the face mask. The lung motor air to the face mask or exhausts the air consists of a pair of pumps so connected injected by the other pump. Connecthe air enriched. It was felt by some tion may be made to an oxygen tank and people that the backers of the pulmotor claims which they made for their apthe air enriched. It was felt by some paratus and a committee was appointed to make a scientific study of its actual paratus and a committee was appointed Yale University acting under the directo make a scientific study of its actual tion of the United States Bureau of Mines, made a series of experiments on various animals, but the results obtained Mines, made a series of experiments on tion of the United States Bureau of various animals, but the results obtained of which often caused complete collapse PULPIT of the alveoli and small bronchi, and that air was frequently pumped into the stomach in place of the lungs. Like many other instruments they were found to be dangerous in inexperienced or unskilled hands, and it has been suggested that the instruments be used only as an auxiliary to the established manual methods of artificial respiration and only used for periods of a very few minutes.
Many cases of resuscitation by use of the pulmotor reported in the newspapers were, upon investigation, found to be greatly exaggerated.