DEVELOPMENT* 



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J7IFTEEN years ago a leading American railroad 

 built a locomotive which was believed most suit- 

 able for the passenger traffic at that time. But actual 

 use pointed out many constructional features that 

 could be improved upon; and t too, the introduction of 

 heavier cars and longer trains necessitated the con- 

 tinual increase of the locomotive *s pulling power and 

 steaming capabilities. Diligently and untiringly the 

 company labored on until there was finally evolved a 

 most successful locomotive combining speed with 

 power, and what is of utmost importance a high 

 degree of reliability. 



HOW a great railroad developed a 

 most remarkable steam locomotive 

 is an absorbing story to those interested 

 in mechanical achievements, especially in 

 view of the fact that the development has 

 called for infinite pains in every detail 

 and much hard and patient toil. This 

 story is woven around the evolution of 

 the Pennsylvania Railroad's class E-6-S 

 locomotive handling most of the import- 

 ant passenger trains and which is the re- 

 sult of some five years' experimenting, 

 although its origin dates back even fur- 

 ther. 



Fifteen years ago the Pennsylvania 

 Railroad built the engine shown in the 

 first view. This was the first locomotive 

 of the Atlantic type to be used on that 

 road, and included much that was com- 

 mon on other roads at the time, together 

 with certain features that were identi- 

 fied chiefly with that railroad. The 



tender, however, was of the English type, 

 mounted on six wheels after the fashion 

 of that country. From a mechanical 

 point of view this engine, No. 820, was a 

 success. By reason of its "Mother Hub- 

 bard" form of construction, however, 

 which had the effect of separating the 

 engineer and fireman, it was not alto- 

 gether satisfactory. 



As a result the engine shown in the 

 second illustration was built, with the 

 cab in the normal location. The English 

 tender was retained in this case, but was 

 ultimately abandoned. With gradual 

 modifications, this type remained stand- 

 ard on the Pennsylvania for a decade. 

 When the motive power officials had 

 reached the conclusion that this type had 

 arrived at the limit of its possibilities, 

 something new was decided upon. 



The new idea is displayed in the seventh 

 picture. Briefly described, this engine, 



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