Railway and Locomotive Engineering . tlength, as 18 in., and divide it into 36equal parts, each part representing 10° of aturn, and at each point of division erectperpendiculars thereon and mark themfrom 0° to 360° consecutively. Then,starting at 10°, lay oflf the advance of .28in., on the 20° line lay oflf .56 in., at 30°lay off .84 in., and so on to the 360°mark. When these points are connectedthe lower diagram line of Fig. 1 will bedrawn and this will be the development ofthe inclined plane corresponding to an in-crease of pitch from 10 in. to 1034 in. The plane for the second turn can bede
Railway and Locomotive Engineering . tlength, as 18 in., and divide it into 36equal parts, each part representing 10° of aturn, and at each point of division erectperpendiculars thereon and mark themfrom 0° to 360° consecutively. Then,starting at 10°, lay oflf the advance of .28in., on the 20° line lay oflf .56 in., at 30°lay off .84 in., and so on to the 360°mark. When these points are connectedthe lower diagram line of Fig. 1 will bedrawn and this will be the development ofthe inclined plane corresponding to an in-crease of pitch from 10 in. to 1034 in. The plane for the second turn can bedeveloped in the same way by drawing asecond line and laying off the proper dis-tances as before; starting with .30 in. atthe 10° line. For the sake of convenient reference, thelength of each ordinate is marked at itsfoot for each turn. Also on Fig. 2 of thesecond turn the grand total of the ordinatesis given. This is the sum of the twocorresponding ordinates of the first and January, 1921 RAILWAY AND LOCOMOTIVE ENGINEERING 25. second turn, and represents the distance ofthe diagram or slope of the second turnfrom the base line of the first turn. When this has been done it still re-mains to develop the second or upper lineof the diagram for the guidance of thepatternmaker, if the worm is to be cast. If the worm is to be made of cast ironan allowance of % in. must be made forshrinkage. Hence each ordinate must beincreased by a proportional amount, whichcan be very readily done by the use ofthe proportional dividers. Such instru-ments do not open conveniently to morethan 3 in., for which distance the shrink-age allowance will be 1/32. Then on thediagram for the first turn draw the linesHI from 110° to 210°. These lines to be1/32 in. apart and the lower one 3 in. fromthe base line FG of the diagram. Drawthe lines KL from 220° to 310° ; these linesto be 1/16 in. apart and the lower one 6in. from the base. Finally, draw the linesMN from 320° to 360° ; these to be 3/32in.
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyork, bookyear19
