IMPROVEMENTS IN GAS ENGINES
Year: 1875

page_text: LETTERS PATENT to William Woods Smyth, of Maidstone, in the
County of Kent, and George Greenway Hunt, of No. 1, Rectory
Villas, Brockley Road, New Cross, in the County of Kent, for the
Invention of "IMPROVEMENTS IN GAS ENGINES.”
Sealed the 21st August 1875, and dated the 26th June 1875.
PROVISIONAL SPECIFICATION left by the said William Woods Smyth
and George Greenway Hunt at the Office of the Commissioners of
Patents, with their Petition, on the 26th June 1875.
..
We, WILLIAM WOODS SMYTH, of Maidstone, in the County of Kent,
and GEORGE GREENWAY HUNT, of No. 1, Rectory Villas, Brockley Road,
New Oross, in the County of Kent, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN GAS ENGINES," to be as follows:-
This Invention has for its object improvements in gas engines.
We construct gas engines with two single-acting cylinders placed, by
preference, opposite to each other, and alike in all respects. In each

page_text: cylinder is a piston, and the two pistons are fixed at the end of a common
piston rod or rods, which by a connecting rod gives motion to a crank,
or in other convenient way the piston rod is connected with the
mechanism it is desired to drive. Each cylinder also contains a loose
piston which together with the main piston operates in the following
manner: When both pistons are near the inner end of the cylinder a
small quantity of gas and air is admitted between them by means of a
semi-rotary valve mounted upon the main piston, or by other appropriate
valve gear. This charge of gas and air is then fired, and the explosion
blows the loose piston to the further or outer end of the cylinder. The
cylinder is fitted at its outer end with a cover which operates as a valve
yielding to allow the escape of air from the cylinder, so that the loose
piston when projected by the explosion sweeps the air in front of it out
of the cylinder. When the air has been expelled the cover closes and
prevents the return of air past it. A partial vacuum is left after tho
explosion between the two pistons, and the atmospheric pressure on the
main piston drives it to the other. end of the cylinder, producing the
effective stroke. At the end of this stroke the two pistons come in
contact at the outer end of the cylinder, and in the return stroke the
main piston draws the loose piston back with it, a valve in the cylinder
cover being opened to admit air at this time behind the loose piston. As
the pistons approach the inner end of the stroke gas and air is again
admitted between them ready for the next stroke, and this operation
occurs alternately in the two cylinders, giving effective double action.
Sometimes we employ one double-acting cylinder in place of two:
single-acting cylinders. In this case there are two loose pistons, one on
either side of the main piston. The action is similar to that of the
engine already described. The explosion of a charge of gas and air
throws one of the loose pistons to the end of the cylinder. The pressure
of the air on the main piston next causes this piston to follow, drawing {
the other loose piston with it; then as the stroke is being completed
another charge of gas and air is admitted behind the main piston, and
between it and the second loose piston. This charge is in turn fired and
causes the return stroke of the engine.