Improvements in Gas Motor Engines.
Year: 1893

page_text: Date of Application, 7th Nov., 1893
Complete Specification Left, 7th Aug., 1894-Accepted, 6th Oct.,
1894
PROVISIONAL SITUAL
Improvements in Gas Motor Engines.
I, JOHN HENRY HAMILTON of Sandiacre in the County of Derby, Engineer.
do hereby declare the nature of this invention to be as follows:-
This invention relates to that class of engine described in my Complete
Specification 60150 and consists in an improved arrangement of tandem engine
which I now proceed to describe.
The engine described in the above Specification has a larger air cylinder placed
in front of the motor cylinder and to the enlarged end of the piston which works in
this larger cylinder I secure two parallel rods these rods being preferably in the
horizontal axial plane of the cylinders and passing backwards through the annular
space around the motor piston and out through the end of this annular space
alongside the motor cylinder.
Behind this motor cylinder and in line with it is placed another motor cylinder.
The piston of the latter may have a cross bridge and projecting lugs at its front
end to which lugs the back ends of the side rods are secured.
These lugs may work in slots in the forward portion of the back cylinders or the
top front portion of this cylinder may be cut away to allow of the easy removal of
the piston.
The admission valves may be placed on top of the cylinders and the exhaust
valves below.
The air passage leading from the annular air pump space being then continued
back to the back motor cylinder will form a top tie for holding the cylinders
together.
The valve gearing is so arranged that explosions occur alternately in the motor
cylinders thus instead of the air being compressed and re-expanded on each alternate
stroke it is discharged on each back stroke; through the combustion chamber of
the front motor cylinder on one back stroke, and through that of the back motor
cylinder on the next back stroke. All the valves may be operated from one side
shaft.
Dated this 6th day of November 1893.
J. H. HAMILTON.
COMPLETE SPECIFICATION.
Improvements in Gas Motor Engines.
I, JOHN HENRY HAMILTON of Sandiacre in the County of Derby, Engineer
do hereby declare the nature of this invention and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement:―
This invention relates to that class of engine described in my Complete
Specification No. 6015" and consists in an improved arrangement of tandem engine
which I now proceed to describe with reference to the accompanying drawing in
which Fig. 1. represents a longitudinal sectional elevation and Fig. 2 a sectional
plan.
Two motor cylinders K & L are placed in line with each other and with another
larger cylinder M in which works the enlarged end of the front piston A. The
latter carries the gudgeon or pin C. to which is jointed the connecting rod.

page_text: It has also secured to it the side rods B B the latter being preferably in the
horizontal axial plane as shewn. These side rods pass backwards alongside
the motor cylinder L and are connected at their rear ends to the crosshead D
which may be cast in one with the back motor piston P or secured to the latter.
The ends of this crosshead may work in slots in the sides of the cylinder K when
the latter is long enough to bolt to the back end of the cylinder L, but I prefer to
cut away the upper front portion of this cylinder, or to make the cylinder short as
hewn and provide guides as at E for guiding the front end of the piston P
The air inlet valve may be of the same kind as described in my Complete
Specification No. 6015 and is shewn at F a passage X X conducting the air to
the cylinders K L & M.
The part T of the air passage between the cylinders K and L may be removable
so as to allow of the easy withdrawal of the piston P and when in place it forms a
top tie for holding the cylinders together.
The admission valves for gas and air are shewn at G and G₁ and the exhaust
valves at H. H. The former may be arranged as described in my Complete
Specification No. 41899 and both admission and exhaust valves may be operated
from one side shaft through cams and levers in the usual way, the cams being
arranged so that when one piston is making its explosion stroke the other is making
its suction stroke. The action of the engine is as follows:
Supposing the pistons to be commencing their forward stroke as shewn and that
this is the explosion stroke of the back piston P and the suction stroke of the front
piston A..
Air is then drawn in through the valve F part of it passing through the valve G
to the front motor cylinder and part to the annular space Y behind the enlarged
end of the piston A.
On the return stroke the exhaust valve H¹ of the cylinder K being opened the
admission valve G' being also opened after the pistons have made a portion of the
return stroke the air in the space Y is first slightly compressed say to 2 lbs. per
square inch above atmospheric pressure and then passed through the valve Ginto
the cylinder K mixing with and expelling the products of combustion therefrom.
The exhaust valve H is not closed till after the crank has passed the dead centre
thus allowing time for the pressure in the cylinder K and space Y to fall nearly to
atmospheric pressure.
The gas valve of the cylinder K is now opened and the same series of operations
are repeated only that the front cylinder now makes its explosion stroke and back
cylinder its suction stroke. There is thus an explosion at each forward stroke
when working at full power.
As the scavenging air is discharged through the combustion chamber of one or
other of the motor cylinders at each return stroke such a large- clearance space as
is described in my Specification 601500 above referred to, is unnecessary but I
prefer to make the clearance space such that the admission valve. of the motor
cylinder need not be opened till nearly half stroke.
As the pressure in the space Y is always low stuffing boxes for the rods B B are
unnecessary the said rods may work through long bushes V V instead and these
bushes may have light spring rings inserted.
It is obvious that the two motor pistons might be connected directly by one
central rod passing through a stuffing box in the back end of the front notor
cylinder but I consider the arrangement above described to be the best.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is:
1. In gas motor engines of the four stroke type the use of an annular space such
as Y in communication by a passage such as X with the admission valves of two
motor cylinders all arranged so that the air in Y shall be slightly compressed
during the beginning of each back stroke and afterwards discharged through the

page_text: combustion chamber of that cylinder which is making its exhaust stroke substantially
as described.
2. In gas motor engines of the 4 stroke type the arrangement consisting of two
side rods connected to the enlarged end of the front motor piston and also to a
crosshead or lugs attached to or formed in one piece with the back motor piston
substantially as described.
3. The general construction and arrangement of parts substantially as described
and illustrated by the accompanying drawings.
Dated this 6th day of August 1894.
J. H. HAMILTON.