Middletown, Pennsylvania
One that dates back to 1840 can be seen at the preserved
charcoal furnace at Cornwall, Pa. While it is conventional in
design it shows the trend of engineering at that period of time.
Matthias Baldwin, the founder of the Baldwin Locomotive Works and
one of the pioneers in locomotive building, built a 5 hp. vertical
piston rod which in turn connected two straight bars sliding on the
opposite sides. On outside of cylinder to the upper ends there were
pivoted the two forked ends of the connecting rods whose single end
turned the crank pin. This engine can be seen in Franklin Institute
in Philadelphia, Pa. The Huber Company in 1905 built an engine with
an additional though smaller cylinder protruding downward just in
front of the right hand drive wheel. It used the regular Hechworth
(sometimes called Wolf) valve gear commonly used by Huber. While
the feed steam pipe extended from the dome through the boiler to
the vertical cylinder steam chest.
A concrete mixer with a revolving drum in a steel frame was
driven with a two cylinder double acting engine. In variance from
the many such engines this had the cylinder set at a 90 degree
angle and both connecting rods working on the same crank pin. This
like in the Huber engine, was not practical from an engineering
standpoint because of the condensation of steam being in proportion
to the exposure of all parts conveying or containing steam. It can
be reasonably assumed that cylinders set at 90 degrees would double
or at least render the condensing factor excessive.
Another engine with a forked connecting rod was one used on the
Boston steam shovel. Here the blank end of the cylinder was
anchored to the floor of the shovel body by means of four legs, two
of which carried the crank shaft bearing while the piston rod moved
through the packing gland in the upper end of the cylinder. It too,
carried a yoke filled with a small cross head on each end. Guides
cast to the upper cylinder head supported these. The forked ends of
the connecting rod were hinged to the wrist pins protruding from
the yoke. The eccentric was direct from the crank shaft to the stem
of the slide valve. In its day the Boston shovel was a large one
and a conventional type of engine would have been too tall if it
had been vertical while space was not available for a horizontal
engine.
