n. The act of uniting or joining.n. The act of marrying.n. The act of embracing sexually; copulation.n. That which couples or connects, as rafters in a building.n. Specifically— In music: A couplet. A couple.n. The general name for a great variety of mechanical appliances for uniting parts of constructions or parts of machines, for the purpose of adding strength, of transmitting motion from one part to another, or of making a continuous passage, as for a liquid, a gas, or an electric current. A buckle. binding-screw, or fish-plate may illustrate the first: a clevis, a bell-coupling, shaft-coupling, or car-coupling, the second; a pipe-coupling or binding-post, the last. In a narrower sense a coupling is: A device for uniting the ends of shafting or a coupling-box. (See cut under coupling-box.) Such couplings are divided into two simple classes, those that are fixed permanently on the shafting and those that are adjustable, connected or not at will, or working automatically under variations of the power. Those operated by hand, whatever the particular application of the power, are called shifting couplings. The automatic couplings depend chiefly on friction, the adjustment being such that under a certain load the power is communicated, while a sudden addition to the load may exceed the friction and throw the coupling out of operation. A device for uniting two railroad-cars in a train. The form at one time used almost exclusively in the United States, and still retained for freight-cars, is a single link or shackle fitting into jaws at the ends of the draw-bar and held in position by pins. This has been superseded on passenger-cars by self-acting couplings, consisting usually of hooked jaws, which slide past each other and are self-locking by means of springs or their own weight. Levers are also used to operate the couplings from the car-platform. Also called coupler.n. The part which unites the front and rear axles, or the axle-bolster, of a carriage; the perch or reach. In some carriages the bottom of the carriage forms the only coupling.n. The space between the tops of the shoulder-blades and the tops of the hip-joints of a dog.n. a kind of permanent coupling which consists of two disks keyed on the connected ends of the two shafts. In one of the disks there are two recesses, into which two corresponding projections on the other disk are received, and thus the two disks become locked together. This kind of coupling wants rigidity, and must be supported by a journal on each side, but it possesses the double advantage of being easily adjusted and disconnected.n. a kind of permanent coupling in which the boss-ends of the connected shafts are made semi-cylindrical, so that they overlap each other. The coupling-box is a plain cylinder bored to fit, and is kept in its place by a parallel key or feather, as shown in the annexed figure.n. a form of coupling belonging to the class of friction-couplings. It is represented in its best form in the annexed figure. On the shaft B is fixed a pulley, which is embraced by a friction-band a as tightly as may be required. This band is provided with projecting ears, with which the prongs b b of a fixed cross d on the driving-shaft A can be shifted into contact. This cross is free to slide endwise on its shaft, but is connected to it by a sunk feather, so that being thrown forward into gear with the ears of the friction-band, the shaft being in motion, the band slips round on its pulley until the friction becomes equal to the resistance, and the pulley gradually attains the same motion as the clutch. The arms and sockets c c, which are keyed fast on the shaft A, are intended to steady and support the prongs, and to remove the strain from the shifting part.n. in mill-work, a kind of permanent coupling of which the coupling-box is made in halves and square, corresponding to the form of the two connected ends of the shafts. The two halves of the box are bolted together on the opposite sides, as represented in the annexed figure.n. a kind of permanent coupling in which the coupling-box consists of a plain ring of metal, supposed to resemble a tailor's thimble, bored to fit the two connected ends of the shafts. The connection is secured either by pins passed through the ends of the shafts and the thimble, or by a parallel key or feather bedded in the boss-ends of the shafts, and let into a corresponding groove cut in the thimble. This last is now the more common mode of fitting. This kind of coupling is also known under the names of ring coupling and jump-coupling.n. Same as pipe-coupling.
