E-text prepared by Chris Curnow, Harry Lamé,
and the Online Distributed Proofreading Team
()
from page images generously made available by
Internet Archive
(http://www.archive.org)
| Note: | Images of the original pages are available through Internet Archive. See http://www.archive.org/details/steamengines00newyrich |
MACHINERY’S REFERENCE SERIES
EACH NUMBER IS A UNIT IN A SERIES ON ELECTRICAL AND
STEAM ENGINEERING DRAWING AND MACHINE
DESIGN AND SHOP PRACTICE
NUMBER 70
STEAM ENGINES
CONTENTS
| Action of Steam Engines | 3 |
| Rating and General Proportions of Steam Engines | 11 |
| Steam Engine Details | 15 |
| Steam Engine Economy | 30 |
| Types of Steam Engines | 36 |
| Steam Engine Testing | 41 |
Copyright, 1911, The Industrial Press, Publishers of Machinery,
49-55 Lafayette Street, New York City.
CHAPTER I
ACTION OF STEAM ENGINES
A steam engine is a device by means of which heat is transformedinto work. Work may be defined as the result produced by a forceacting through space, and is commonly measured in foot-pounds; a foot-poundrepresents the work done in raising 1 pound 1 foot in height.The rate of doing work is called power. It has been found by experimentthat there is a definite relation between heat and work, inthe ratio of 1 thermal unit to 778 foot-pounds of work. The number778 is commonly called the heat equivalent of work or the mechanicalequivalent of heat.
Heat may be transformed into mechanical work through the mediumof steam, by confining a given amount in a closed chamber, and thenallowing it to expand by means of a movable wall (piston) fitted intoone side of the chamber. Heat is given up in the process of expansion,as shown by the lowered pressure and temperature of the steam, andwork has been done in moving the wall (piston) of the closed chamberagainst a resisting force or pressure. When the expansion of steamtakes place without the loss of heat by radiation or conduction, therelation between the pressure and volume is practically constant; thatis, if a given quantity of steam expands to twice its volume in a closedchamber of the kind above described, its final pressure will be one-halfthat of the