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THE FRANKLIN INSTITUTE,
State of Pennsylvania,
PROMOTION OF THE MECHANIC ARTS.
MECHANICAL AND PHYSICAL SCIENCE, CIVIL ENGINEERING, THE
JOHN F. FRAZER,
Assisted by the Committee on Publications of the Franklin Institute.
PUBLISHED BY THE FRANKLIN INSTITUTE, AT THEIR HALL.
On the Expansive Working of Steam in Locomotives. By DANIEL KINNEAR CLARK, C. E.-(With a Plate.)*
[Abstract of a Paper read at the Institution of Mechanical Engineers.]
In locomotives, the adoption of a low standard of boiler pressure is the first obstacle in the way of carrying out the expansive working of steam, as the more expansively the steam is worked, the less is the work done by the engine. The second obstacle is, in many locomotives, the exposure of the cylinders, by which the steam within is partially condensed. Moreover, the proportion of steam so condensed increases with the degree of expansion, in a very formidable ratio, which will be afterwards submitted to examination.
The object of this paper is to show at what rate in practice the efficiency of steam is increased by expansive working in locomotives with the best existing arrangements of cylinders, valves, and valve-gear, and to point out the conditions on which expansive action may be most successfully carried out.
I.-Of the Action and Capabilities of the Link-Motion.-The action of the valves in the "distribution" of the steam (a term borrowed from the French) is regulated by three elements, the lap, the lead, and the travel. * From the London Civil Engineer and Architect's Journal, September, 1852. VOL. XXV.-THIRD SERIES.-No. 1.-JANUARY, 1853,