WATER MOTOR. In its broadest sense the term is applicable to all forms of machines or systems of machinery operated by water un der the force of gravity, or in other words, by sshich the energy inherent in a natural water fall is utilized to perform mechanical work. There are three types of such motors, classified as (1) gravity motors; (2) pressure motors, and (3) impulse motors. Of these machines, the water-wheel (qv.). the turbine (q.v.) and the pump (q.v.) have been treated under their respective titles, but in this article the term will be considered as designating those machines which are operated by the element of pressure only, such as hydraulic lifts and water pressure engines.
The Hydraulic Lift, used in elevator serv ice, is the simplest of all water motors. The direct-acting lift consists of a cylinder m which a ram or piston of equal length, with a cage attached to its upper end, works up and down. The level of the water supply must be necessarily above that of the maximum height through which the cage may be lifted, so that when the water is admitted to the cylinder at its lower end, the pressure forces the ram upward and thus lifts the cage. The descent of the ram is accomplished by closing the sup ply valve and opening the discharge valve, the ram descending by its own weight. As the weight of .the ram as greater than necessary to tring down the cage, a part of that weight is balanced by a counterweight attached to the end of a chain that works over a pulley at the top of the lift and is connected to the cage. The most familiar examples are the high speed hydraulic passenger elevators. They are operated by the pressure of water Dumped into tanks situated on the roofs of the buildings in which they are installed, while the operating machinery is located in the basement. (See Etzvieroas). The hydraulic QM'Ss and the hydrau lic ram are devices operated practically under similar principles. In the former, the action depends upon the principle of hydrostatics that a pressure applied to any part of the surface of a liquid is transmitted in all directions and throughout the mass without diminution For example, if a cylinder filled with water has a plunger one inch square working through on' end and another 10 inches square working through the other end, and a pressure of one pound is exerted on the smaller plunger, this pressure will be transmitted to the larger plunger and be delivered by the latter in a multiplied amount equal to the square of its face area expressed in pounds. In this example that pressure would be 100 pounds. Such presses consist essentially of two cylinders connected by piping. The pressure is applied to the plunger of the smaller cylinder and the multiplied pres..
sure is transmitted by that of the larger to the object to be raised or pressed. In construction they vary greatly with the purpose for which they are employed. Those used as hay, cot ton and oil presses consist of four strong iron pillars arranged in the form of a square, which carry a cast-Iron plate solidly attached to their tops. A similar casting is situated at the bottom of the pillars. Through a circular hole in the centre of the lower plate, a plunger carrying a square platen on its head works with an up ward motion and presses the material placed between the platen and the under face of the top plate. In presses used for hydraulic forg ing, the cylinder and plunger are carried by the top plate, while the bottom plate carries the an. il. The plungers work downward in the act of pressing or hammesing. They are made of various sizes and are generally provided with. two pressure plungers and cylinders and they 1 are adapted for purposes varying from the manufacture of revolver cartridge cases to the forging of armor plate, guns and steamship shafts. Armor plate presses capable of exerting a pressure of 14,0130 tons are in use, while 7,000 ion fluid compressors are employed in many ? the larger steel manufacturing plants. A brief description of the construction and work ing of one of the last-named capacity will serve to illustrate the mammoth proportions and enormous power of these machines. It consists of an upper head weighing 120 tons carrying the plunger and a 135-ton base plate containing the hydraulic cylinder. These are supported and held in place by four vertical connecting columns each 50 feet long, and 19 inches in diameter. In operation, the molten metal is poured into a mold built up in sec tions and the mold is raised under a hydraulic pressure of 7,000 tons, while a plunger at tached to the upper head hears down upon the find metal and compresses it.
Hydraulic In the hydraulic ram the force of water flowing by gravity is utilized to raise a portion of its volume to a height above that of the source of supply. Two pipes are employed. The water in flowing through the main or drive pipe acquires sufficient mo mentum to close a valve at the foot of the pope. and the water thus confined automatically opens valve, partially fills an air chamber situated over the foot of the main pipe and compresses the air in it until the pressure within balances the column of water in the main pipe. Then the foot valve of the main pipe opens again and the action described is repeated. In the meantime, the pressure in the air chamber forces the water through a small service pipe leading out of its bottom, to the required height. See