Improvements in Gas and like Engines.
Year: 1893

page_text: 14
Date of Application, 23rd Feb., 1893
Complete Specification Left, 20th Dec., 1893-Accepted, 22nd Mar., 1894
PROVISIONAL SPECIFICATION.
Improvements in Gas and like Engines.
We, JOHN WILLIAM HARTLEY of Kay Park, Kilmarnock Engineer, and
JOHN KERR, of the Firm of Dick, Kerr and Company Limited, of Britannia
Engineering Works, Kilmarnock, Engineer, both in the County of Ayr, do hereby
declare the nature of this invention to be as follows:-
"
Our invention relates to gas and like engines and is specially applicable to
compound engines and part of it is applicable to engines using weak gas such as
Dowson gas. In a compound gas engine using the
"Otto cycle in the
H.P. cylinder, we prefer to arrange two H.P. "Otto" cycle cylinders which
exhaust into one L.P. cylinder placed between them, so that each H.P.
cylinder discharges its contents alternately into the L.P. cylinder. We may
however arrange one H.P. cylinder to act in conjunction with a L.P. cylinder.
In either case we set the L.P. crank at from 50 to 100 degrees behind the
high pressure crank, so that the hot gases from the H.P. cylinder pass from
that cylinder, and begin to act in the L.P. cylinder considerably before the
H.P. piston terminates its stroke. By this means expansion takes place in both
cylinders at the same time, until the end of the H.P. piston's stroke. We
arrange between the two cylinders a suitable valve so constructed that a straight
through passage exists between the cylinders, and by this, and by the angle of the
L.P. crank herein before described, we secure the minimum loss by cooling, and cause
our engine to produce the maximum power from the amount of gas consumed.
We find that when using a rich gas, or with the slow combustion of a poor gas
the combustion of the gases is by no means complete when the said gases leave the
H.P. cylinder, and in order to complete this combustion in the L.P. cylinder we
arrange to displace the exhaust gases contained in the L.P. cylinder after
expansion by pure air, so that when compression occurs in the said L.P. cylinder
in order to bring the contents of clearance space in the cylinder approximately up
to the pressure of the gases passing from the H.P. cylinder, then fresh com-
pressed air is present to combine with the gases remaining unburned in the
H.P. cylinder. In this manner we obtain a much higher average pressure in
the L.P. cylinder than would otherwise be the case. When the L.P. cylinder
is sufficiently large, air may be drawn into it by an automatic snifting valve, when
the piston has completed its expansion. Or air may be forced in by a separate
pump, or when we use only one H.P. cylinder the idle stroke of the L.P. piston
may be utilized to draw in air, suitable valve gear being provided for this
purpose. In our double acting "Otto" cycle gas engines we sometimes supply an
open and single acting L.P. cylinder and expand the gases froin the back end
of the H.P. cylinder only, leaving the front to act as an ordinary "Otto" cycle
gas engine without compounding. In this case, however, we prefer to fire weak
charges in front, and we cut out the ignitions in the front end first, so as to use the
compound part of the engine as much as possible. Sometimes we arrange our
double acting engine " tandem fashion and we have two compound cylinders,
alongside. These compound cylinders may be single or double acting. Instead of
introducing the cold circulation water directly into the jacket and in order to
secure equality of temperature throughout the jacket, we arrange a pipe or passage
outside the jacket connecting the top and bottom thereof, and we force the
circulating feed water into this pipe and thus induce a current of the circulating
water from top to bottom of the cylinder, the outlet or overflow being led away
from each end of the cylinder.
27

page_text: We govern our compound engine of any of the hereinbefore described
modifications by means of a step cam so arranged as to produce weaker impulses;
and so obtain the maximum number of impulses at low loads. Our step cam we
so construct that the gas valve is always given its maximum lift, and it is held
open until the end of each charging stroke; we so shape the cam that the gas
valve is opened later and later in the charging stroke and so the proportion of the
stroke in which the gas is admitted is continuously diminished.
For regulating the speed of gas and like engines we sometimes use a helix or
screw thread which we slide along the cam shaft. The thread being fitted into a
slot in the gas cam causes a section or sections of the gas cam to revolve upon the
shaft, when the helix is being moved to and fro axially along the said shaft by the
governor. Thus the leading edge of the gas cam is made to advance or retire
and to admit gas earlier or later. We divide the cam in two or more sections,
one portion being keyed to the shaft, so that the gas cam is always closed at the
proper time, the other section or sections are revolved by the helix and follow each
other round the shaft, and so form a continuous cam, the cam roller being.broad
enough to cover in width the whole of the sections. To prevent the influence of
the cam being felt by the governor, when the cam engages, we lock the helix on
the shaft by a multiple grooved collar in which a detent engages. This detent is
operated by a separate cam and lever and is pressed home by springs just before
the cam engages. The detent may be relieved about the period when the gas cam
closes, the valve being no longer needed. When the governor arrives at the
position to give the least admission, by the above method, it may arranged to
lisengage a hit and miss lever, and the gas is cut off altogether in the manner
usually employed. We may secure the helix in its position by frictional
resistance operated by the cam acting upon any suitable attached portion. We
move the helix by the spring arrangement already described in Figure 1 of
Patent No. 21496 of 1891.
To
When using Dowson or other weak gas we prefer to charge our cylinder by
first admitting air alone for a portion of the charging stroke then we admit for a
succeeding portion of the stroke, gas alone, cutting off the air supply entirely, and
then air and gas in explosive or combustible proportions so that we obtain an
explosive mixture for igniting the whole charge. By this means we obtain rapid
ignition and a slow burning charge and secure a high terminal pressure.
enable us to perform these changes in the nature of the charge as the stroke
proceeds, we connect the gas valve lever cr the gas valve stem to a flap or butterfly
valve in the air supply pipe and arrange the gas cam so that for a first part of the
charging stroke of the engine, air alone is admitted, the gas valve being closed and
the butterfly valve in the air pipe being full open. The gas valve is then opened
fully by a high cam surface, and when so fully opened the butterfly valve is
moved to entirely close the air supply pipe, and thus gas alone is taken into the
cylinder; after a suitable period, the cam surface chauges to a lower position and
the butterfly valve is now partially opened whilst the gas supply is throttled by
means of an annulus attached on the underside of the gas valve, and which
contracts the opening through the valve so that the proper supply of gas only is
passed through, so that for the termination of the stroke gas and air are admitted
to the cylinder in explosive or combustible proportions. In this manner
produce charge suitable for firing with a weak gas such as Dowson's with a low
initial and a high final pressure, and permitting also of continued combustion in
the L.P. cylinder, and to further this end we ignite the charge after the crank has
passed its centre. We prefer the arrangement herein before described for varying
the admission of the charge, but the same series of operations may be performed
by other gear without departing from one of the essential features of our
invention.
a
we
In order to prevent too intimate mixing in engines such as we have hereinbefore
described using Dowson or other weak gas we sometimes introduce gas at one side
of the cylinder and air at the other, preferably introducing the gas by way of the
A

page_text: exhaust passage so that the combustion, when the mixture is fired after compression,
is more prolonged than is usual with weak gases and so we obtain an expansion
line more suitable for compound engines than that usually given by Dowson gas.
In order to obtain greater power and to equalise the strains which the high and
low pressure pistons exert on the crank, and also to obtain steadier turning, we.
sometimes admit additional gas into the low pressure cylinder which for this
purpose may be increased in size until the terminal pressure is at atmospheric
pressure. This gas may be introduced with the air already mentioned and in the
same manner, the ignition of this being effected by the explosive charge from the
high pressure cylinder. When governing compound gas engines of the kind herein-
before described we hold open the exhaust valve operating to discharge the contents
of the L.P. cylinder in order to prevent the loss of power which would be caused
by the expansion of the compressed contents of the L.P. cylinder into the
H.P. cylinder. The L.P. cylinder is thus alternately filled with exhaust gases
from the exhaust pipe and these exhaust gases are discharged again into the
exhaust pipe by the movement of the L.P. piston, while governing by missing
explosions.
To accomplish this it is necessary that the L.P. exhaust valve should be under
the control of the gas valve, so that immediately the gas valve opens to form an
explosive or combustible charge in the H.P. cylinder, then the exhaust valve of
the L.P. cylinder is put into ordinary operation.
In one form of gear for carrying this into effect the exhaust valve lever has
mounted upon it a roller sliding along a pin, which roller opposes a cam on the two
to one or valve shaft. The cam is divided into two parts by a central flange,
which flange is cut through at one place only so that only at that place can the
roller slide along from one part of the cam to the other. One part of the cam is'
so shaped that while the roller bears upon it the exhaust valve is held open during
the whole time, the other part is shaped to open and close the exhaust valve at the
proper times to secure the correct action of the expanding gases in the low
pressure cylinder. The roller is forced by a spring to that end of its cam at which
the exhaust valve is held continuously open and the lever connects the roller by an
The
appropriate sliding sleeve to the gas valve lever or the gas valve stem.
connection is so arranged that when the gas valve is opened the exhaust valve roller
is passed through the gap in the dividing flange, and it is then operated by the part.
of the cam which properly opens and closes the exhaust valve during the operation
of the L.P. cylinder. The flange retains the roller on this cam after the gas
valve has closed, until the expansion and exhaust is completed and it is returned
again to the other half of the cam by the spring, when the roller comes opposite
to the gap. If the gas valve be opened to give a charge the roller is again passed
through the gap in the central flange, to be operated by the acting cam, but if no
charge is to be given, and the gas valve remains closed, then the roller remains on
that part of the cam which holds the exhaust valve open as herein before
described.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Gas and like Engines.
We, JOHN WILLIAM HARTLEY, of Kay Park, Kilmarnock, Engineer, and
50 JOHN KERR, of the Firm of Dick, Kerr and Company Limited,. of Britannia
Engineering Works, Kilmarnock, Engineer, both in the County of Ayr, do
hereby declare the nature of this invention and in what manner the same is to be
•

page_text: performed, to be particularly described and ascertained in and by the following
statement:--
Our invention relates to gas and like engines and is specially applicable to
compound engines and part of it is applicable to engines using weak gas such as
Dowson gas.
The object of our invention is to improve the action and effectiveness of gas
engines by means of improvement in the details of operation and in the detail
parts.
Our invention comprises :-Improvements in the gear and methods of clearing
out the products of combustion from the cylinder by air; a novel arrangement of
tandem compound gas engine; a method of and device for circulating the water in.
the water jacket of a gas engine a new arrangement of helical cam for controlling
the admission of gas; a method of and device for controlling air and gas supply
when using weak gases such as Dowson or producer gas; a method of increasing
the available pressure in the low pressure cylinder of a compound gas engine
by admitting additional gas to the said low pressure cylinder; and an arrange-
ment of governing gear for controlling the exhaust valve of a low pressure
cylinder.
Referring to the seven accompanying sheets of drawings
:-
Figure 1 is a vertical section and Figure 2 a sectional plan on the line ab of
Fig. 1 showing that part of our invention which deals with clearing out the products
of combustion by air.
Figure 3 is a plan of our new arrangement of tandem compound gas engine.
Figure 4 is a section illustrating our method of causing water circulation in the
water jacket of a gas engine.
Figure 5 is an end elevation of our step cam.
Figure 6 is an elevation part in section showing our helical cam governing gear.
Figure 7 is a transverse section on the line a b Figure 6.
Figure 8 is an end elevation showing the action of the separate parts of the
helical cam.
Figure 9 is a vertical section showing one modification of our gas and air
controlling gear.
Figures 10 to 13 inclusive are sections showing the various positions of the inner
and outer air throttle valves illustrated at Figure 9.
Figure 14 is a section showing the application of a dash pot piston and cylinder
to a gas or other valve.
Figure 15 is an end elevation and Figure 16 is a plan of our valve gear for
controlling the low pressure exhaust valve.
In a compound gas engine using the Otto cycle in the high pressure cylinder, we
prefer to arrange two high pressure Otto cycle cylinders which exhaust into one
low pressure cylinder placed between them so that each high pressure cylinder
discharges its contents alternately into the low pressure cylinder. We may how-
ever, arrange one high pressure cylinder to act in conjunction with a low pressure
cylinder. In either case we set the low pressure crank at from 50 to 100 degrees
behind the high pressure crank so that the hot gases from the high pressure
cylinder pass from that cylinder and begin to act in the low pressure cylinder
considerably before the high pressure piston terminates its stroke. By this means
expansion takes place in both cylinders at the same time until the end of the high
pressure piston's stroke.
We arrange between the two cylinders a suitable valve so constructed that a
straight through passage exists between the cylinders and by this and by the angle
of the low pressure crank herein before described we secure the minimum loss by
cooling and cause our engine to produce the maximum power from the amount of
gas consumed.
We find that when using a rich gas or with the slow combustion of a poor
gas, the combustion of the gases is by no means complete when the said gases
leave the high pressure cylinder and in order to complete this combustion in the

page_text: low pressure cylinder we arrange to displace the exhaust gases contained in the
low pressure cylinder after expansion by pure air, so that when compression occurs
in the said low pressure cylinder in order to bring the contents of clearance space
in the cylinder, approximately up to the pressure of the gases passing from the
high pressure cylinder, then fresh compressed air is present to combine with the
gases remaining unburned in the high pressure cylinder. When the low pressure
cylinder is suffieiently large, air may be drawn into it by an automatic snifting
valve, when the piston has completed its expansion. Or air may be forced in by a
separate pump or when we use only one high pressure cylinder the idle stroke of
the low pressure piston may be utilized to draw in air, suitable valve gear being
provided for this purpose.
When the idle stroke or an idle stroke of the low pressure piston is used for this
purpose of filling the low pressure cylinder with air we use the valve arrangements
shown in Figures 1 and 2.
The exhaust valve A is operated in any usual manner by the spindle A' and the
exhaust gases pass into a circular chamber, under the said valve. The circular
chamber is controlled by two valves B and B and the valve B is operated from the
sleeve B2 through which the exhaust valve spindle A' passes. The lever B³
operates the sleeve B and the valve B, which valve, controls two ports D' D'
opening into the exhaust passage D. The valve B' controls the air ports B and is
operated by contact with the valve B which rotates it to open the air ports after
first moving to close the exhaust ports D' D³. As shown in Figures 1 and 2 the
air ports are closed and the exhaust ports D1 and D2 are open so that when the
exhaust valve A is lifted by its spindle A' then the exhaust gases from
the cylinder Cescape to the exhaust passage D.
When the piston is to make an idle stroke the valve B is rotated in the direction
of the arrow Figure 2 and after closing the ports D' D the advance edge comes in
contact with the valve B' and turns it round sufficiently to open the air ports B‘.
Air is then admitted to the low pressure cylinder C on its forward stroke and so the
clearance spaces are filled with air which assists continued combustion in the low
pressure cylinder.
In our double acting Otto cycle gas engines we sometimes supply an open end
single acting low pressure cylinder and expand the gases from the back end of the
bigh pressure cylinder only, leaving the front to act as an ordinary Otto cycle gas
engine without compounding. In this case, however, we prefer to fire weak charges
in front and we cut out the ignitions in the front end first so as to use the compound
part of the engine as much as possible.
Sometimes we arrange our double acting engine tandem fashion as shown at
Figure 3 and we have two double acting low pressure cylinders alongside. The
two high pressure cylinders in tandem are respectively E and E' and the low
pressure cylinders are F and F¹. Straight passage valves F2 F' connect between
high and low pressure cylinders. These low pressure cylinders may be single or
double acting.
Instead of introducing the cold circulation water directly into the jacket and in
order to equalize the temperature throughout the jacket, we have a pipe or
passage outside the jacket connecting the top and bottom thereof; we force the
circulating feed water into this pipe and thus induce a current of the circulating
water from top to bottom of the cylinder, the outlet or overflow being led away
from each end of the cylinder. Figure 4 shows this arrangement. The cold water
is injected by the jet G and it induces a current from the top of the jacket G by
way of the pipe G; this hot water mixes with the cold jet and passes by G³ to
the bottom of the jacket G. The pipe G proceeds to the water tank and so the
circulation is kept up.
We govern our compound engine of any of the hereinbefore described
modifications by means of a step cam so arranged as to produce weaker impulses
and so obtain the maximum number of impulses even at low loads. Our step cam
we so construct that the gas valve is always given at the least its maximum lift and

page_text: it is held open till the end of each charging stroke; we so shape the cam that the
gas valve is opened later and later in the charging stroke and so the proportion of
the stroke in which the gas is admitted is continuously diminished. Such a step.
cam is illustrated at Figure 5 and the step 1 admits gas for the maximum length of
stroke; the step 2 admits for a less length; 3 for less still and 4 admits the
minimum. In order to secure the required richness of mixture for proper ignition
the height of the steps are gradually increase 1 from 1 to 4 so as to increase the lift.
of the gas valve with diminution of the volume supplied:
For regulating the speed of gas and like engines we sometimes use a helix or
screw thread which we slide along the cam shaft.
The arrangement is shown at Figures 6, 7 and 8. The thread being fitted into a
slot in the gas cam causes a section or sections of the gas cam to revolve upon the
shaft, when the helix is being moved to and fro axially along the said shaft by the
governor. The grooved sleeve I is connected to the sliding piece H having a
helical thread or threads cut on it, and the said sleeve and helix is moved along the
shaft K by the governor through the lever J and spring connection J'. The cam
is built up of four pieces one L keyed to the shaft K and three pieces L' Lº 1,³
loose upon the shaft but held in place by the fixed washer N.
Thus the leading edge of the gas cam is made to advance or retire and to admit
gas earlier or later. We divide the gas cam as described in two or more sections
one portion L being keyed to the shaft so that the gas cam is always closed at the
proper time, the other section or sections are revolved by the helix and follow each
other around the shaft and so form a continuous cam, the cam roller operating the
gas valve lever being broad enough to cover in width the whole of the
sections L L' L' and L.
The leading section L! of the compound gas cam is cut to fit the helical thread
on H and slots are cut in the parts L2 L and L to clear the said helix. The
section L has a pin e operating in a slot in L2 to move it at the proper time
and L has a pin d operating in the same way in a slot in the piece L³. When the
sleeve I is moved in one direction the cam sections L L L expand to produce the
outline shown at Figure 8, the leading cam section moving in the direction
indicated by the arrow in Figure 8 carries I and I³ successively with it. In that
position gas is fully admitted. When the governor moves the sleeve I to reduce
gas supply the section L' is moved back by the helix until it covers L2, then the
part L moves back with it till both cover L³, then I moves back if gas is still
further to be reduced till L L L cover the part L. At that point the gas supply
has been reduced to its minimum.
To prevent the influence of the cam being felt by the governor when the cam
engages with the gas lever roller, we lock the helix H on the shaft K by a multiple
grooved collar I in which a detent M engages. This detent is operated by a
separate cam M and lever and way shaft M M² and is pressed home by springs
just before the compound cam engages. The detent lever M³ may be relieved
about the period when the gas cam closes the valve, being no longer needed.
When the governor arrives at the position to give the least admission by the above
method it may be arranged to disengage a hit and miss lever and the gas is cut off
altogether in the manner usually employed. We may secure the helix in its
position by frictional resistance operated by the cam acting upon any suitable
portion attached to the said helix.
We move the helix by the spring arrangement J already described in Figure 1
of Patent No. 21496 of 1891 granted to us.
When using Dowson or other weak gas we prefer to charge our cylinder by first
admitting a'r alone for a portion of the charging stroke, then we admit for a
succeeding portion of the stroke gas alone cutting off the air supply entirely, and
then air and gas in explosive or combustible proportions so that we obtain an
explosive mixture for igniting the whole charge. By this means we obtain rapid
ignition and a slow burning charge and secure a high terminal pressure. To en ble
us to perform these changes in the nature of the charge as the stroke proceed, we

page_text: connect the
gas valve lever or the gas valve stem to a flap or butterfly valve in the
air supply pipe and arrange the gas cam so that for a first part of the charging
stroke of the engine air alone is admitted, the gas valve being closed and the
butterfly valve in the air pipe being full open. The gas valve is then opened fully
by a high cam surface, and when so fully opened the butterfly valve is moved to
entirely close the air supply pipe and thus gas alone is taken into the cylinder;
after a suitable period the cam surface changes to a lower position and the
butterfly valve is now partially opened while the gas supply is throttled by means
of an annulus attached on the underside of the gas valve, and which contracts the
opening through the valve so that the proper supply of gas only is passed through,
so that for the termination of the stroke gas and air are admitted to the cylinder in
explosive or combustible proportions. In this manner we produce a charge
suitable for firing with a weak gas such as Dowson's with a low initial and a high
final pressure and permitting also of continued combustion in the low pressure
cylinder, and to further this end we ignite the charge after the crank has passed its
centre. We prefer the arrangement hereinbefore described for varying the
admission of the charge, but the same series of operations may be performed by
other gear without departing from one of the essential features of our invention.
The arrangement hereinbefore indicated is shown in section at Figure 9 and the
action is fully illustrated at Figures 10, 11, 12 and 13.
The gas supply valve () is operated through its valve spindle by the lever (³
pivoting from O and lifting the catch piece O³.
A cam on the cam shaft operates the lever O'
The spindle O is connected by a link P to the lever P which lever actuates the
butterfly valve P by means of the link Ps. The valve P is placed in the air
passage within a shell or annular valve Q. This annular valve Q is independently
operated from a separate cam on the cam shaft by the lever Q and suitable
linkage. The action is as follows:-In the position of the valves shown in.
Figure 9 and of P and Q also shown in Figure 10 the air is entering the cylinder
at the beginning of the stroke but no gas has as yet been admitted. When the gas
valve O opens the butterfly valve P' closes the annular valve Q and stops the air
supply gas alone is then entering the cylinder. This position. is shown at Fig. 11.
When this has gone on for a certain period of the stroke the gas valve O still
remains open but the anunlar or outer valve Qmoves by the separate cam and
assumes the position shown in Figure 12, so that air is admitted as well as gas, in
fact mixture is admitted in explosive proportions. As the gas valve O moves
towards closing, the annular or other baffle valve Q returns (operated by its separate
cam) and diminishes the air supply proportionally with the gas supply and finally
the valve closes the air supply simultaneously with the closing of the gas supply.
This last position is shown at Figure 13 where it will be observed that the butterfly
valve P assumes the same position as shown in Figures 9 and 10 at the beginning of
the series. By this device the explosive proportions are maintained at the end of
the charging stroke when required.
:
To silence the gas valve O we arrange a double acting dash pot cylinder R' with.
apertures about the middle and a dash piston R (Figures 9 and 14).
:
In order to prevent too intimate mixing in engines such as we have hereinbefore
described using Dowson or other weak gas, we sometimes introduce gas at one side
of the cylinder and air at the other, preferably introducing the gas by way of the
exhaust passage so that the combustion when the mixture is fired after compression,
is more prolonged than is usual with weak gases and so we produce an expansion
line more suitable for compound engines than that usually given by Dowson gas.
In order to obtain greater power and to equalize the strains which the high and
low pressure pistons exert on the crank and also to obtain steadier turning we
sometimes admit additional gas into the low pressure cylinder which for this
purpose may be increased in size until the terminal pressure is at atmospheric
pressure. This gas may be introduced with the air already mentioned and in the
same manner, the ignition of this being effected by the explosive charge from the

page_text: こ
high pressure cylinder. When governing compound gas engines of the kind
described we hold open the exhaust valve operating to discharge the contents of the
low pressure cylinder in order to prevent the loss of power which would be caused
by the expansion of the compressed contents of the low pressure cylinder into the
high pressure cylinder. The low pressure cylinder is thus alternately filled with
exhaust gases from the exhaust pipe and these exhaust gases are discharged again
into the exhaust pipe by the movement of the low pressure piston, while governing
by missing explosions. To accomplish this it is necessary that the low pressure
exhaust valve should be under the control of the gas valve so that immediately the
gas valve opens to form an explosive or combustible charge in the high pressure
cylinder then the exhaust valve of the low pressure cylinder is put into ordinary
operation.
In one form of gear for carrying this into effect shown at Figures 15 and 16 the
exhaust valve lever S has mounted upon it a roller S2 sliding along a pin S³,
which roller opposes a cam on the two to one or valve shaft.
The cam is divided into two parts T and U by a central flange V, which flange
is cut through at one place ouly as shown at Figure 15 so that only at that place
can the roller S slide along from one part of the cam to the other. One part U
of the cam is so shaped that while the roller bears upon it the exhaust valve S is
held open during the whole time, the other part T is shaped to open and close the
said exhaust valve at the proper times to secure the correct action of the expanding
gases in the low pressure cylinder. The roller S' is forced by a spring S to that
end U of its cam at which the exhaust valve S is held continuously open and the
pin connects the roller S2 by an appropriate sliding sleeve to the gas valve lever
or the gas valve stem. The connection is so arranged that when the gas valve is
opened the exhaust valve roller S2 is passed through the gap in the dividing
flange V and the roller S2 is then operated by the part T of the cam which
properly opens and closes the exhaust valve during the operation of the low
pressure cylinder.
.
The flange V retains the roller S on this cam T after the gas valve has closed
until the expansion and exhaust is completed and it is returned again to the other
half of the cam by the spring when the roller comes opposite to the gap. If the
gas valve be opened to give a charge the roller is again passed through the gap in
the central flange to be operated by the acting cam T, but if no charge is to be
given and the gas valve remains closed then the roller remains on that part of the
cam which holds the exhaust valve open as herein before described.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is
1. In compound gas engines, the method of increasing the efficiency of the low
pressure cylinder consisting in filling the said cylinder with air by means of an idle
forward stroke, a pump, or equivalent arrangement, whereby the said air is
compressed into the clearance spaces on the back stroke and assists in completing
the combustion of the hot gases passed from the high pressure cylinder, sub-
stantially as hereinbefore described.
2. The exhaust valve and air inlet arrangements hereinbefore described with
reference to Figures 1 and 2 of the accompanying drawings, as applied to charging
the low pressure cylinder with air as claimed in the preceding claim.
3. The novel arrangement of a tandem compound engine, comprising two tandem
low pressure cylinders placed beside the high pressure cylinders, the cranks being
arranged at or near right angles to each other; the combination producing an
engine having four power impulses per revolution without dead point, substantially
as and for the purposes herein before described.
4. Circulating the water in a gas engine water jacket by injecting the cold
. entering water by a jet so arranged as to induce a current of hot water from the top
of the cylinder to mix with the cold water passing to the lower part of the cylinder
:

page_text: for the purpose of equalising the temperature of the upper and lower parts of the
water jacket, substantially as herein before described.
5. In a stepped gas governing cam, so arranging the cam steps that the lift of
the gas valve is increased as the steps become shorter in order to keep up the
explosive proportions of gas and air admitted to the engine even at the smaller gas
charges, substantially as hercinbefore described with reference to Figure 5 of the
drawings.
6. In gas engine governing gear operating a controlling cam, made in two or
more parts or segments, one segment being fixed to the valve shaft to maintain a
constant point of gas cut off and one or more segments being capable of movement
round the said shaft, by a sliding helix controlled by the governor, the said helix
being arranged to move one or more segments advancing one in front to alter the
point of admission of gas or other fluid to the cylinder during the charging stroke,
substantially as and for the purposes hereinbefore described.
7. In combination with a compound cam operated by a helix as claimed in the
preceding claim, a detent operated by a cam to hold the sliding helix while the
said compound cam is operating the gas or other valve so as to remove the strain
of keeping the cam in position from the governor, substantially as hereinbefore
described.
8. The arrangement and construction of compound cam, helix, and grooved
sleeve with detent as hereinbefore described with reference to Figures 6, 7 and 8.
of the accompanying drawings.
9. In gas engines using a weak combustible gas, the method of charging the
working cylinder consisting in admitting first air alone, then combustible gas alone
and lastly air and gas in combustible or explosive proportions so as to enable a
weak mixture to be readily ignited and caused to burn out more slowly than is
usual with such gases in order to reduce the maximum pressure while maintaining
the average pressure substantially as and for the purposes hereinbefore described.
10. In gas engines where it is desired to vary the entering charge by altering.
the proportion or order of admitting gas and air, the combination of a gas inlet.
valve and a butterfly or other throttle valve acting on the air supply operated
from the said gas valve, together with an outer throttle valve actuated from a
separate cam which throttle valve controls the air supply by acting in conjunction
with the first named throttle valve substantially as and for the
before described.
purposes herein-.
11. In gas engines, the combination of a gas valve connected to a butterfly valve-
and acting within an outer annular valve in the air pipe, the said outer valve being
operated by a separate cam constructed and operated substantially as hereinbefore
described and as illustrated in Figures 9 to 13 inclusive of the accompanying
drawings.
12. In a compound gas engine, forcing into or admitting gas to the low pressure
cylinder to burn with the hot gases from the high pressure cylinder in order to
increase the average pressure in the said low pressure cylinder substantially as
herein before described.
13. The herein before described governing gear for operating the exhaust valve
of a compound gas engine as illustrated at Figures 15 and 16 of the accompanying.
drawings.
201 1
1000
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for the Applicants.