VAI 



that the valve has no inside lap, and thai the ouuide lap 

 !.ree-eighths of an inch. The inside Up is generally small 

 compared nl. t)..- "ide lap. 



n the piston U at the beginning of iu stroke the steam 

 port is generally open by a small amount called the /Wof the 

 uta 



The reciprocating motion of the alide valve U nearly always 

 derived from an eccentric fixed on the crank -shaft of the 

 engine. Slide valves are generally made of brass, brotue, or 

 oast iron. 



fig. 00, is shown a 



Motional elevation of a simple slide valve for a steam-engine, the 

 section being taken through the centre line of the valve spindle, 

 \\inl. <u - M shown a cross section and elevation, and at (/) a plan 

 of the same. Draw all these views mil size, and also a sectional 

 elevation at A B. The valve is made of brass, and the vahre spindle 

 nn< I nuts of wrought . 



/* Volte Cttsiny, <r>., for Stfam***y 



Draw, half size, the views shown at (a), (6), and (r), fig. 60 ; aUo a 



sectional plan st L M . (6) is an elevation of the valve casing with the 



cover and the valve removed, (a) U a sectional elevation, the section 



rough the axes of the steam cylinder and valve spindle. 



(r) is a sectional plan, the section being a horizontal one through 



of the exhau- lie steam 



are clearly shown in the sectional plan . in t:.. sectional elevation 



their positions are shown by dotud circles. 



stroke of the piston is in this case 1*2 inches, so thai from 

 ilimensions given at (a) it must cotue within s quarter of an 

 UK h of each end of the : this is called the cyhmlrr a 



i>,. . . 



The piston has three Ramsbottom rings, a quarter of an inch 

 and a quarter of an inch apart. 



Dytindi i and rahn tat . m M i- resatira 



ck consists of a sligi al plug 



i corresponding casing oast on a pipe. Through the 



A In. h may be made by turning the plug to form 



continuation of the hole in the pipe, and thus allow the fluid 



maybe tum<xl n.un.1 si that the solid part of 



he -. across the hoi.- in and thus prevent the 



