Forest's Gas Motor

| September/October 1997

Forest gas motor

Richard E. Lee

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, G'.

'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, N.

'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.