. The street railway review . are the larger built-up wheels, which as now gener-ally made have the joints in the rims at the ends of the arms. Manyexcellent papers have been written upon the subject of fly-wheel de-sign, in which it is shown that the joint when placed midway be-tween adjacent arms is in the worst possible position; as ProfessorBenjamin, in his recent paper before the A. S. M. E. stated it, toput a joint midway between adjacent arms is like putting a joint inthe middle of a girder. The radial centrifugal force acting uniformly round the rim like afluid pressure tends to separa
. The street railway review . are the larger built-up wheels, which as now gener-ally made have the joints in the rims at the ends of the arms. Manyexcellent papers have been written upon the subject of fly-wheel de-sign, in which it is shown that the joint when placed midway be-tween adjacent arms is in the worst possible position; as ProfessorBenjamin, in his recent paper before the A. S. M. E. stated it, toput a joint midway between adjacent arms is like putting a joint inthe middle of a girder. The radial centrifugal force acting uniformly round the rim like afluid pressure tends to separate the rim, and the joints, no matterwhere placed, must resist this stress. The centrifugal force of theportion between the arms acts to load that portion as a beam andthus additional stresses are introduced. The point in this portionat which the joint is placed greatly affects the stress placed on thejoint. Considering the solid segment in Fig. i, we have a beam fixedat both ends and uniformly loaded. The maximum bending mo-. liSUAL DE3IGN Some time since the writer, having occasion to design a fly-wheelto meet rather unusual conditions, investigated the question of fly-wheel design and considered some changes that might easily be ment under such conditions is WL -7- 12, where W is the total uni-formly distributed load and L the distance between supports. Thismaximum bending moment occurs at the two supports; midway be-tween the supports the moment is WL -j- 24. There are two points,about one-fifth way from each support, where the moment is zero,these being the points of contrary flexure. If we place midway between the arms a joint of the type shown(with inward projecting lugs to receive bolts) in the cut, we practi-cally have two beams fixed at one end. The maximum bending mo-ment in each of these beams, fixed at one end and uniformly loaded,would be WL -=- 8, where W is the total load on both beams and Lis the total length of both beams. This, it is seen, is 50 per centgreat
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
