Steam engines produce a reciprocating motion in which large masses oscillate back and forth in harmonomic motion. From an engineering viewpoint, this makes little sense, as the reciprocating parts must continually be accelerated. Most applications require that the reciprocating motion must be converted to rotational motion using the cross-head mechanism invented by James Watt ca. 1750.
The first electric motors were made in two styles: those
in which elements rotate
, and those in which they translate (and reciprocate). The latter design
was a dead end, but there are interesting early examples illustrated below
and in the section on Daniel
Davis, Jr. Note that reciprocating steam engines are no more,
and have been replaced with turbines.
| These two pictures, showing the front
and back of a double-beam axial engine, show two different pieces of apparatus.
At the top is an engine from the collection of the National Museum of American History of the Smithsonian Institution; the picture was taken about 1975,
The lower picture, taken in 2001, shows an engine in the Greenslade Collection.
Comparison with an original Daniel Davis double beam axial engine shows that the design of the walking beams in these examples is more ponderous, suggesting that they were made by a successor to Davis, such as Palmer and Hall.
| The version of Page's
Reciprocating Armature Engine at the right is at the University of
Texas. Its age is bounded by the fact that the University of Texas was
started in 1890.
It was clearly made by the maker of the double-beam axial engine above.
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