118 



PATTERN MAKING 



one right and one left, will be necessary. One half of this box is 

 illustrated at S, Fig. 215, as also a sectional view at T. The dotted 

 lines show the manner in which the passage is widened to retain 

 the full size of the opening throughout. 



Only one core box will be needed for the two steam ports. 

 Three views of the box are given in Fig. 210. At G one side is 

 removed, giving a side view of the construction of the box. H 

 shows a cross section through G with the end u removed, and F is 

 a view from above. The core is swept off on the upper side for the 

 length of c r, and the bar e e as well as the end u must be movable 

 so that the core can betaken from the box. Both ends of the core 



change from circular 

 into straight parts just 

 at the entering of the 

 cylinder, and at the 

 entering of the steam 

 chest. 



The entire set of 

 patterns *re simple 

 and easy of construc- 

 tion, if carefully made 

 drawings are furnish- 

 ed to work from; the 

 time and labor re- 

 quired, depending entirely upon the size of the cylinder. 



In some slide-valve cylinders, the steam chest is cast separate 

 and bolted to the cylinder, thus affording free access to the valve 

 seat /-, and a better opportunity for finishing and fitting. In this 

 case the main cylinder core and the two steam inlet cores are made 

 together in the same box, as illustrated in Fig. 217, in which one 

 side of the core box is cut away to a depth of one half of the length 

 of the steam port openings, or to the line <\ <, which must be just 

 one half of the inside width of the box as shown at // and at F, 

 Fig. 216. 



The part which has been cut away is replaced by the three 

 blocks u, ii and l>, which are shaped to give the required si/.e and 

 form to the steam-i>or1 cores. 



Fig. 217. 



