. Elements of technology :. s. They are connected with a toothed wheel in sucha manner, that one pallet enters between the teeth of the wheelwhenever the other is thrown out of their reach. As the wheelrevolves, its teeth successively impinge against one or the otherof these pallets, and by causing them successively to escape,communicate to their axis a vibrating, or alternate crutch scapement. Fig. 37, is an arch situated in the sameplane with the scape wheel, and parallel to the plane in whichthe pendulum vibrates. Its pallets successively enter and escapefrom the teeth of the whe
. Elements of technology :. s. They are connected with a toothed wheel in sucha manner, that one pallet enters between the teeth of the wheelwhenever the other is thrown out of their reach. As the wheelrevolves, its teeth successively impinge against one or the otherof these pallets, and by causing them successively to escape,communicate to their axis a vibrating, or alternate crutch scapement. Fig. 37, is an arch situated in the sameplane with the scape wheel, and parallel to the plane in whichthe pendulum vibrates. Its pallets successively enter and escapefrom the teeth of the wheels, and receive from it a vibratingmotion. In the old or common watch scapement. Fig. 38, acontrate, or crown wheel is used as the scape wheel and thepallets a and b are placed upon the axis of the balance wheel, ELEMENTS OF MACHINERY. 245 SO as to meet the teeth successively on opposite sides of thecircumference of the scape wheel. A variety of other morecomplicated forms of the scapement are also in 37. Fig. CONTINUED RECTILINEAR MOTION. A long continued rectilinear motion is not to be produced inthe parts of a machine, except so far as it partakes of the na-ture of a rotary or a reciprocating motion. Thus a bandpassing round pullies is a modification of rotary motion, anda rack, which is obliged to return at intervals, has a reciprocatingmotion. But to a certain extent, the motions of both may beregarded as continuously rectilinear. Band.—If it is required to produce motion in a right line,which shall be always in one direction, as for example in thefeeding parts of machines, a band passing round pullies ordrums, is the method most commonly practised, as in Fig. a precise velocity is required, the band may be perforatedwith holes, and received upon short pins at the circumferenceof the wheels ; or the rag wheel and chain represented in , may be substituted. 246 ELEMENTS OF MACHINERY.
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Keywords: ., bookauthordukeuniversitylibraryjantzcoll, booksubjecttechnology
