. Railway mechanical engineer . ameter,the first oversize is 2 1/16 in., the next 2l/% in. and so onproviding the valve rods are sufficiently large to admit of theextra size without reducing their strength below the dangerpoint. The smaller of the two taper ends should, as in the caseof the knuckle pin, be made in sizes to equal the body andthe larger end such size as may be necessary in order tocontinue the taper from the small to the large end. The holes for the cotter keys and the key to prevent thepin from turning may be drilled, the end threaded and after-wards casehardened, or where used
. Railway mechanical engineer . ameter,the first oversize is 2 1/16 in., the next 2l/% in. and so onproviding the valve rods are sufficiently large to admit of theextra size without reducing their strength below the dangerpoint. The smaller of the two taper ends should, as in the caseof the knuckle pin, be made in sizes to equal the body andthe larger end such size as may be necessary in order tocontinue the taper from the small to the large end. The holes for the cotter keys and the key to prevent thepin from turning may be drilled, the end threaded and after-wards casehardened, or where used in a soft state, the bodymay be ground to standard gage or micrometer size. Thetaper ends are in some cases ground to step sizes at the timeof manufacture so that they may be fitted by simply reamingthe lever to the required size. In other cases these surfacesare only rough machined at the time of manufacture andwhen fitting, the taper ends are ground to fit the of these practices have certain advantages. Where the. ii <i Fig. 6—Step Sizes for Eccentric Rod Pins Class A BCDEFGH M in. 2 in. 1 in. 3^2 in. 1 in. ljiin. 1 A in. IK in. Standard M 2tV in. 1 in. 3A in. 1 in. l%in. 1 A in. l^in. 1st Step M in. 2A in. 1 in. 3A in. 1 in. 1% in. IA in. 1J4 in. 2nd Step Note—Blank out body B in. large. Center and grind in. all over except thread^. Grind body B to sizes given, usinglimits of plus or minus in. Place in stock. tapers are ground they may be fitted in any shop by simplyreaming the levers. To offset this, it becomes necessary tomaintain a greater variety of pins of differing step sizes,also maintaining a uniform taper of reamers in all is at times a difficult problem and another objection isthat of enlarging the holes owing to the more frequent ream-ing which will hasten the time that the levers must bescrapped. Simply reaming the levers enough to true the surfaces ofthe holes and fitting the
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
