. Model engine construction, with practical instructions to artificers and amateurs. e engines have. This isomitted, as small boilers do not steam well with one,for it contracts the orifice of the funnel, and the fireburns badly. The outer fire-box and boiler barrel ismade of No. 24 sheet copper, the internal fire-box,fire-tube, and tube-plate of No. 21 sheet copper. Semi-portable or underneath engine (see Fig. 53and Sheet No. 10). This engine is made by placinga locomotive boiler on the top of a flat-bed en-gine ; a support or saddle-plate is fixed above thecylinder for the smoke-box to rest
. Model engine construction, with practical instructions to artificers and amateurs. e engines have. This isomitted, as small boilers do not steam well with one,for it contracts the orifice of the funnel, and the fireburns badly. The outer fire-box and boiler barrel ismade of No. 24 sheet copper, the internal fire-box,fire-tube, and tube-plate of No. 21 sheet copper. Semi-portable or underneath engine (see Fig. 53and Sheet No. 10). This engine is made by placinga locomotive boiler on the top of a flat-bed en-gine ; a support or saddle-plate is fixed above thecylinder for the smoke-box to rest upon. The bed-plate is a brass casting, or is made out of No. 20sheet brass, and riveted together. In real engines,the cylinder, steam-chest, stop-valve chamber, andsaddle-plate are combined in one casting. As this SEMI-POBTABLE ENGINE. 195 would involve special patterns, and be troublesomein a model, we take the steam by means of anoutside pipe leading to and screwed direct into thevalve-casing, the exit from the boiler being con-trolled by a cock or a stop-valve. The steam-pipe. Perspective view of Semi portable EngineFig. 53. inside the boiler (see Sheet No. 10) is bent at rightangles, its mouth being plugged, and a number ofholes drilled in the upper surface for steam to enter,and in this way dry steam is got, instead of using adome. The saddle-plate is a brass casting, eithercast on the cylinder or, if separate, firmly soldered 196 MODEL ENGINE CONSTRUCTION. all round to it and to the valve-casing. The undersurface is flat, the upper surface is cast with thesame curvature as the bottom of the smoke-box,and supports it, this last being attached to it at thesides by small bolts and nuts. Before fixing theplate, a hole should be drilled vertically through it,one end communicating with the cylinder exhaust-port, and the other tapped to take the blast-pipewhich passes up to about the middle of the fire-tube in the smoke-box (see drawings). Make thebed-plate—if it is to be a b
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectmachinery, bookyear18
