■«hm- 



T 



S\*--0 



Figure 28. — Rear elevation of Pioneer and detail of valve shifter; valve face and valve. (Drawing by J. H. White.) 



the rear cylinder head and supported in the rear 

 by a yoke. The yoke is one of the more finished and 

 better made pieces on the entire engine (fig. 27). 

 The main rod is of the old pattern, round in cross 

 section, and only 1,'j inches in diameter at the largest 

 point. 



VALVE GEAR 



The valve gear is of the Stephenson shifting-link 

 pattern (see fig. 27), a simple and dependable motion 

 used extensively in this country between about 1850 

 and 1900. The author believes that this is the original 

 valve gear of the Pioneer, since the first mention (1854) 

 in the Annual Report of the Cumberland Valley Rail- 

 road of the style of valve gear used by each engine, 

 '-iii''; that tin- /'inn,,r was equipped with a shifting- 

 link motion. Assuming this to be the original valve 

 gear of the Pioneer, it must be regarded as an early 

 application, because the Stephenson motion was just 

 being introduced into American locomotive practice 



in the early 1850's. Four eccentrics drive the motion; 

 two are for forward motion and two for reverse. The 

 link is split and made of two curved pieces. The 

 rocker is fabricated of several forged pieces keyed and 

 bolted together. On better made engines the rocker 

 would be a one-piece forging. The lower arm of each 

 rocker is curiously shaped, made with a slot so that 

 the link block may be adjusted. Generally, the only 

 adjustment possible was effected by varying the length 

 of the valve stem by the adjusting nuts provided. A 

 simple weight and lever attached to the reversing 

 shaft serve as a counterbalance for the links and thus 

 assist the engineer in shifting the valve motion. There 

 are eight positions on the quadrant of the reversing 

 lever. 



MISCELLANEOUS NOTES 



The cab is solid walnut with a natural finish. It is 

 very possible that the second cab was added to the lo- 

 comotive after the 1862 fire. A brass gong used by the 



266 



l.l I I ETIN 240: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



