. American engineer and railroad journal . ues of M. These values of M when combined with thepermissible stress will givi value of modulus of re- sistance. Thus an underframe type may be chosen for all classes ofservice and cars of different lengths built upon it by changing thesection modulus to suit the moments. An increase or decreasein the thickness of cover plates used or the weight of section forbeams will usually be all that is demanded. The work of mathematically designing the varying cars of un-equal lengths and similar lading found in a complete equipmentis measurably simplified by t
. American engineer and railroad journal . ues of M. These values of M when combined with thepermissible stress will givi value of modulus of re- sistance. Thus an underframe type may be chosen for all classes ofservice and cars of different lengths built upon it by changing thesection modulus to suit the moments. An increase or decreasein the thickness of cover plates used or the weight of section forbeams will usually be all that is demanded. The work of mathematically designing the varying cars of un-equal lengths and similar lading found in a complete equipmentis measurably simplified by the adoption of this all the calculations for the stresses occasioned bythe bending moments of both vertical and horizontal loads itshould be carefully borne in minrPthat the direct axial stresses,tensile and compressive, have an effect in reducing the per-missible straining of the girders by these moment loads. Thisis so frequently overlooked and not considered that it is deemedadvisable to make it of particular < HAERT VALVE GEAR VPPLIED I NATION L0( HAN PACIFIC RAILWAY. WALSCHAERT VALVE GEAR. Canadian Pacific Railway. One of the prime essentials of any good valve gear is that themotion of the valve, when once set, shall be exact and invari-able. This necessarily requires a substantial and rigid construc-tion throughout, parts which are light but stiff, so they will notspring and bind; hardened bushings and pins to prevent wearand lost motion; ample bearing surface to allow etticient lubri-cation, and secure fastening of all carrying memoers to a prac-tically rigid support. Experience has shown tnat these con-ditions are more easily fulfilled with a gear of the Walschaerttype than with the Stephenson motion, and that locomotives soequipped remain square much longer. It will be noticed, how-ever, that all of the recent designs of Walschaerl gear are con-siderably heavier and more substantial in every wa) than werethe earliest attempts, and it is n
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
