DECIMAL CLASSIFICATION 
621 
Mechanical engineering 
May be subdivided like 620.0 and by form numbers 
Steam engineering 
Subdivide like 620-and 620.0, but use 621.101 as below. Other generalities of 
steam engineering are in 621.71 and 621.18 
Applied thermodynamics 
Theory and use of steam in steam. engin General energy considerations 
Steam economy 
General } 
Expansion, entropy; extension of expansion approaching vacuum (con. 
densers) superheating, cylinder condensation, jacketing, etc. For 
condensers, superheaters, etc. see 621.197 
II Mechanism of steam engin Design of engin parts 
ITI General 
112 Types of engins: structural 
Reciprocating engins in general. Types specified below are all recipro- 
cating, except 1 Primitiv and g Other 
Primitiv 
Single acting 
Double acting 
According to transmission of motion 
Direct connected 
Indirect: beam connected 
According to position 
Horizontal 
Vertical 
Oscillating 
Inclined 
According to terminal pressure 
Condensing 
In early period called ‘low pressure’ 
Noncondensing 
In early period called ‘high pressure 
According to expansion 
Single expansion 
Compound 
Double expansion: cross compound 
’ % tandem ¢ 
«“ angle “ 
Triple expansion 
Quadruple expansion 
Other types } 
Steam turbins 
Better clast 621.165 
Rotary engins 
Better clast 621.166 
Marine engins 
For propulsion see 623.8 Naval architecture 
General 
See also 621.11 and 621.18 
Types of marine engins 
Primitiv 
Inventions of Papin, Perier, Fulton, Stevens, etc. 
Beam and side lever engins 
Horizontal, inclined, vertical engins 
Oscillating 
Launch engins 
Other special engins 
Marine steam turbins 
Qee also 621.163