. American engineer and railroad journal . s give almostno assistance, since they do not mark the forward motion in theneighborhood of the dead points, or the internal frictional resist-ance of the machine. These mistakes are frequently made throughan imperfect understanding of the case, since good admission linescan always be obtained by increasing the lead. As illustratingthis statement it may be said that the first standard freight loco-motive with an Allen valve and a large lead gave faultless admis-sion , while the older and better-working locomotives withthe common valves gave card
. American engineer and railroad journal . s give almostno assistance, since they do not mark the forward motion in theneighborhood of the dead points, or the internal frictional resist-ance of the machine. These mistakes are frequently made throughan imperfect understanding of the case, since good admission linescan always be obtained by increasing the lead. As illustratingthis statement it may be said that the first standard freight loco-motive with an Allen valve and a large lead gave faultless admis-sion , while the older and better-working locomotives withthe common valves gave cards with the admission line falling offvery decidedly. The inadequateness of the indicator lines to furnish sufficientdata for the determination of a satisfactory valve motion must betaken as the answer to the second portion of the question. It, is,therefore, necessary to guard against accepting an indicator cardas an evidence of the good action of the steam and the satisfactoryoperation of the valve motion. In this matter we must rely upon. Lead for Locomotive Valves. for plain valves, while an inside lap of from inch to inchhas generally given very satisfactory results, and these proportionshave been made a fixed rule in all of the shops, end every valvethat is brought in for repairs is changed so as to coincide withthem. A variation in the action of the valve necessarily follows,on account of the irregularity due to the use of thelink motion, wherein the forward lead is about inch greaterthan it is at the back. It was only upon the adoption of these standard dimensions thatthe same efficiency was obtained in all locomotives of the same con-struction. Hence it was essential that there should be an entrymade in the workshop books, in which every improvement made inthe locomotives brought in for repairs should be recorded in accord-ance with the following form: LOCOMOTIVE NO. Left. Right. 1. (full gear).... cut-off (ba
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
