This locomotive is the design of Mr. Henry F. Shaw, of Boston.
This engine has oscillating cylinders placed between the driving-wheels.
Fig. 2 represents a section of one of these cylinders, from which it
will be seen that each has two pistons and piston-rods, which are
connected directly to the crank-pins. His invention is described as
follows in his specification:
"Midway between each set of wheels, e and f, is located the oscillating
steam-cylinder, g, having its journals, g' and g", supported in the
stationary arm, h, which is secured in a suitable manner to the frame,
c. To each cylinder, g, is secured or cast in one piece therewith a
balanced vibratory beam or truss, i, as shown. Within the cylinder, g,
are two movable pistons, k and k', Fig. 2, provided with piston-rods, l
and l', and cross-heads, m and m', as shown.
"n n are slides for the cross-head, m, on the insides of one end of the
truss or beam, i, and n' n', are similar slides in the other end of
said truss or beam, for the cross-head, m'. To the driving-wheel, e,
is attached a crank-pin, passing through the cross-head, m, and to the
driver-wheel, f, is attached a similar crank-pin, F, that passes through
the cross-head, m'. o is the slide-valve within the steam-chest,
G, which slide-valve is operated forward and back by means of the
valve-rod, o¹, the outer end of which is hinged to the upper end of
the slotted lever, o², Fig. 1, that is hung at o³, on the end of the
balanced and vibratory beam of truss, i, as shown. On the crank, F, is
secured an eccentric, that works within the slot of the slotted lever,
o², during the revolution of the crank, F, and in this manner imparts
the requisite motion to the slide valve, o, to admit the steam into the
cylinder, g, alternately between the pistons, k and k', and at the ends
of said cylinder, g, so as to alternately force the pistons, k and k',
from and toward each other, and thus, in combination with the vibratory
motion of the truss, i, impart a rotary motion to the driving-wheels, e
and f.
[Illustration: SHAWS OSCILLATING CYLINDER LOCOMOTIVE.]
"The steam is admitted to and from the cylinder, g, as follows: When
the pistons, k and k', are at the outer ends of their stroke the steam
enters through the channel, p, back of the piston, k, and at the same
time through the channel, p', back of the piston, k', and thus causes
both pistons to move toward each other, the steam between them being
at the same time exhausted through the channels, q and q', the former
communicating with the exhaust, r, by means of the space, s, in the
valve, o, and the latter communicating with the exhaust, r', through the
channel, s', in the said valve, o. The steam that passes to the back of
the piston, k, comes direct from the steam-chest, G, through the open
end of the channel, p, the valve, o, being at this time moved to one
side to leave the port, p, open. The steam is admitted to the back end
of the piston, k', from the steam-chest, G, through the channel, s", in
the valve, o, and from thence to the channel, p'. When the pistons, k
and k', have reached their inner positions the live steam is admitted
through the channels, q and q', direct from the steam-chest, G, to the
former, and through the recess, s³, and channel, s', in the valve, o, to
the latter, the exhaust steam back of the piston, K, passing out through
the channel, p, to the recess, s, in the valve, o, and thence to the
exhaust, r, the exhaust steam back of the piston, k, passing out through
channel, p', and through channel, s", in the valve, o, and thence to the
exhaust, r'.
"The valve-rod, o', is to be connected to a link and reversing lever as
usual, such being, however, omitted in the drawings."
The advantages claimed for it are that "it is composed of very few
parts, and it is very powerful on account of its having a separate steam
actuating piston for each of its driving-wheels. It has great strength
and resistance, owing to the fact that no pressure is exerted on the
journals on which the steam cylinders oscillate, and all the pressure
from the steam pistons is directly transferred to the crank-pins on the
driving-wheels. The engine is perfectly balanced in any position during
the stroke, and it may therefore be run at a much higher speed than the
common engines now in use."
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