. Spons' dictionary of engineering, civil, mechanical, military, and naval; with technical terms in French, German, Italian, and Spanish . truction of the Heart-shaped Cam.—This cam, whose form is sufElciently indicated by itaname, is used to con- 3161. .8,0 -t -i-^-« vert the continuousrotatory motion of afehaft into a recipro-cating rectilinear mo-tion of a rod, andbO on. The only da-tum necessary to theconstruction is thelength of the strokerequired. To construct theheart-shaped eccen-tric, take a lengthA B, Fig. 3161, equalto the stroke; pro-duce it first to C, B Cbeing equal to thelea
. Spons' dictionary of engineering, civil, mechanical, military, and naval; with technical terms in French, German, Italian, and Spanish . truction of the Heart-shaped Cam.—This cam, whose form is sufElciently indicated by itaname, is used to con- 3161. .8,0 -t -i-^-« vert the continuousrotatory motion of afehaft into a recipro-cating rectilinear mo-tion of a rod, andbO on. The only da-tum necessary to theconstruction is thelength of the strokerequired. To construct theheart-shaped eccen-tric, take a lengthA B, Fig. 3161, equalto the stroke; pro-duce it first to C, B Cbeing equal to theleast thickness ofmetal to be retainedabout the shaft ; thento Ö, C a being equalto the radius of theshaft. Describe thecircles a C, a B, a A ;divide each half ofthe circle A a intoeight equal parts, forexample ; the greaterthe number, the moreexact will be the con-struction. Draw theradii al, a2, a3 ... ;divide in like mannerA B into eight equalparts, and from thecentre a describethe circles passing through the points of division ; the point in which each of these circles meets the radius of thesame number is a point in the GEAEING. 1641 If the cam is to work against a roller, which is generally the case, the angle B must berounded a little to give it the form of the roller ; and a length equal to the radius of this rolleradded to the radius A a, which length is placed between the stroke A B and the thickness B C. The heart-shaped cam possesses several valuable properties. 1. It intercepts upon aU the lines passing through the centre a equal length ; this enables it toturn in a frame. 2. The spaces traversed in a straight line by the frame or rod are exactly proportional to theangular velocity of the cam ; whence it follows that if the rotatory motion of the shaft is uniform,the rectilinear motion produced is uniform also. Trace of a Cam con- 3j^g2. verting a Continuous -, Botatory Motion into a ■V Unifoi^mly Periodical ^. I- ,^ Motion.—Suppose the ^-•-_--- 1 -
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Keywords: ., bookcentury1800, bookdecade1870, bookidsp, booksubjectengineering
