Forest’s Gas Motor

By Staff
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Fig 1.Elevation. Fig 2.Back View. Fig 3.Transverse Section. Fig 4.Horizontal Section. Fig 5.Moment of Inflammation. Fig 6.Moment of Ignition.

Richard E. Lee, 1128 Rathbone Avenue, Aurora, Illinois
60506-5807 sent us this brief piece, stating, ‘I found this
engine in an old Scientific American Supplement, March 4, 1884-1
was unable to find it in my books. May be others would be
interested in this odd engine.’

The text reads as follows:

‘The new Forest gas motor, which is at present running in
the machine hall of the Conservatories des Arts et Metiers,
constitutes one of the simplest types of this sort of engine that
has thus far been devised.

‘As shown in the accompanying figures, it consists of a cast
iron base, A, to which are bolted two standards, B, which support a
cylinder, C. This latter is cast in a piece with a helix, the
object of which is, by offering a greater surface to the
surrounding air, to facilitate the cooling of the cylinder when
heated by successive explosions of the gaseous mixture. In the
cylinder, C, there is adjusted a piston, P, which is connected by a
rod, D, with a rocking lever, E. This latter, which is jointed at
its lower extremity with the base, A, oscillates under the action
of the connecting rod, D, and communicates motion to the driving
shaft, G, by means of the connecting rod, F, and the crank,

‘The driving shaft rests on two pillow blocks, H and H’,
cast in a piece with the front plate of the cylinder, and is
provided with a cam, J, that acts upon the distributing slide
valve, L, which carries a roller, M, at its extremity. This valve,
which is thrust forward by the cam, J, at every revolution of the
flywheel, is pulled back to its initial position by a spring,

‘The gas for actuating the motor enters, through the pipe,
O, the ports of the valve seat, P, which is also provided with
ports for the entrance of the air. The gas and air mix in the
hollow part of the valve, L, and are afterward distributed in the
cylinder, C, where they are inflamed by means of the burner, Q,
which is fixed to the slide valve and becomes lighted by the
burner, R, at every stroke of the piston. To permit of regulating
the entrance of the air, according to the speed that it is desired
the motor shall have, the valve seat, P, is provided with a small
movable plate containing vertical apertures, and capable of being
moved at will in a horizontal direction so as to partially cut off
the air ports.

‘The escape takes place through the pipe, s, which
communicates with the interior of the distributing slide valve.
This motor is made in five different sizes, of 4, 10, 15, 25, and
75 kilogram-meter powers.

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