. American engineer and railroad journal . the link block is asource of error in all motions, whether the radial link is fixedor shifting, but it is much more promment in the latter case,arising from the much longer arc in »vhich this form of linktravels in comparison with the arc described where the linkoscillates upon a fixed center. This is the principal disadvantage of the Walschaert gear,and there is theoretically another in the fact of its constant lead,which may become apparent when the motion is applied to alocomotive intended to be operated at any considerable range ofspeed. In additi
. American engineer and railroad journal . the link block is asource of error in all motions, whether the radial link is fixedor shifting, but it is much more promment in the latter case,arising from the much longer arc in »vhich this form of linktravels in comparison with the arc described where the linkoscillates upon a fixed center. This is the principal disadvantage of the Walschaert gear,and there is theoretically another in the fact of its constant lead,which may become apparent when the motion is applied to alocomotive intended to be operated at any considerable range ofspeed. In addition to the presence of the former defect in theJoy motion it has further disadvantages, arising from the numberof its parts and joints liable to wear loose; more connecting,or main rod failures, and the interference which the verticalplay of the main axle on a rough track exerts with the regularsteam distribution. It was to overcome these objectionable features that the Baker-Pilliod valve gear was originally designed. One of these inti-. IMPROVED B.\KER-PILLIOD DESIGN OF V.«iLVE GEAR .\S APPLIED TO A CONSOLIDATION LOCOMOTIVE The old design of the Baker-Pilliod gear has been fully de-scribed and illustrated in this journal,t and its underlying prin-ciples, which of course, still apply, are no doubt fully understood,but before proceeding with a comparison between it and thepresent design it may be well to mention the subject of radialvalve gears in general, in order to better make apparent howordinarily existing defects have been overcome in this arrange-ment. The name radial valve gear has been applied to a numberof reversing gears differing widely in general appearance anddetail, but alike in basic principle, inasmuch that they all derivethe mid-gear motion of the valve from some source that is equiv-alent to an eccentric with 90 deg. angular advance, and that theycombine with this motion another equivalent to that of an eccen-tric with no angular advance. Well-known examples
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
