This horizontal steam engine, recently constructed by Mr. E.D. Farcot
for actuating a Cance dynamo-electric machine, consists of a cast iron
bed frame, A, upon which are mounted all the parts. The two jacketed,
cylinders, B and C, of different diameters, each contains a
simple-acting piston. The two pistons are connected by one rod in
common, which is fixed at its extremity to a cross-head, D, running in
slides, E and F, and is connected with the connecting rod, G. The head
of the latter is provided with a bearing of large diameter which
embraces the journal of the driving shaft, H.
The steam enters the valve-box through the orifice, J, which is
provided with a throttle-valve, L, that is connected with a governor
placed upon the large cylinder. The steam, as shown in Fig. 2 (which
represents the piston at one end of its travel), is first admitted
against the right surface of the small piston, which it causes to
effect an entire stroke corresponding to a half-revolution of the
fly-wheel. The stroke completed, the slide-valve, actuated by an
eccentric keyed to the driving shaft, returns backward and puts the
cylinders, B and C, in communication. The steam then expands and
drives the large piston to the right, so as to effect the second half
of the fly-wheel's revolution. The exhaust occurs through the valve
chamber, which, at each stroke, puts the large cylinder in connection
with the eduction port, M.
The volume of air included between the two pistons is displaced at
every stroke, so that, according to the position occupied by the
pistons, it is held either by the large or small cylinder. The
necessary result of this is that a compression of the air, and
consequently a resistance, is brought about. In order to obviate this
inconvenience, the constructor has connected the space between the two
pistons at the part, A', of the frame by a bent pipe. The air, being
alternately driven into and sucked out of this chamber, A', of
relatively large dimensions, no longer produces but an insignificant
resistance.
[Illustration: FARCOT'S SIX H.P. STEAM ENGINE.
Fig. 1.--Longitudinal Section (Scale 0.10 to 1).
Fig. 2.--Horizontal Section (Scale 0.10 to 1).
Fig. 3.--Section across the Small Cylinder (Scale 0.10 to 1).
Fig. 4.--Section through the Cross Head (Scale 0.10 to 1).
Fig. 5.--Application for a Variable Expanion (Scale 0.10 to 1).]
As shown in Fig. 5, there may be applied to this engine a variable
expansion of the Farcot type. The motor being a single acting one, a
single valve-plate suffices. This latter is, during its travel,
arrested at one end by a stop and at the other by a cam actuated by
the governor. Upon the axis of this cam there is keyed a gear wheel,
with an endless screw, which permits of regulating it by hand.
This engine, which runs at a pressure of from 5 to 6 kilogrammes,
makes 150 revolutions per minute and weighs 2,000 kilogrammes.
--_Annales Industrielles_.
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