IMPROVEMENTS IN MOTIVE-
Year: 1882

page_text: LETTERS PATENT to Dugald Clerk; of Glasgow in the County of Lanark,
North Britain, Engineer.. for an Invention of "IMPROVEMENTS IN MOTIVE-
:
PROVISIONAL SPECIFICATION left by the said Dugald Clerk at the Office
of the Commissioners of Patents on the 18th October 1882.
DUGALD CLERK, of Glasgow, in the County of Lanark, North Britain, Engineer,
." IMPROVEMENTS IN MOTIVE-POWER ENGINES WORKED BY COMBUSTIBLE GAS OR
VAPOR
"
This Invention has for. its object to improve the construction and action of
motive-power engines worked by combustible gas or vapor. In some existing gas
engines power is developed only at each alternate outstroke of the main piston, and
in others only at each outstroke, but in engines made according to the present
Invention power is developed during each instroke as well as during each outstroke,
which improved action involves various obvious practical advantages.
In one modification of the improved engines an ignition cylinder has working in
it a plunger piston connected in the ordinary way to the crank of a first-motion
shaft carrying a fly wheel. At the back of the ignition cylinder, but separated
from it by an intermediate casing, there is a cylinder of larger sectional area having
in it a piston connected to the ignition piston by a rod passing through a suitably
packed passage formed through the intermediate casing, or by external rods or other
suitable connections. The larger cylinder, hereinafter termed the expansion cylinder,
acts as a compressing pump at the end furthest from the ignition cylinder, and
forces an explosive mixture of combustible gas or vapor and air into a reservoir.
In the intermediate casing there are passages and valves, and also spaces for water
to circulate through to prevent overheating, the main valves being by preference
piston valves and moving at right angles to the axis of the cylinders, being worked
by eccentrics on the crank shaft acting through bellcranks.
During the first part of the outstroke of the ignition piston the explosive gaseous
mixture enters from the reservoir into the ignition cylinder, and being cut off at a

page_text: variable point of the stroke is ignited by preference when the piston reaches about
half stroke or earlier. The increased pressure due to the ignition acts during the
remainder of the outstroke and at the end of the outstroke a valve in a separate
passage opens a communication with the near end of the expansion cylinder in which
the heated gases act expansively during the instroke of the ignition piston. By the
instroke the gases are expelled as completely as possible from the ignition cylinder,
and as any remaining traces are expanded down to a low pressure and have their.
temperature much reduced, there is little or no liability to prematurely ignite the
fresh clinrge of explosivo gas entering the cylinder.
For the purpose of regulating the speed of the engine there is an additional valvo
in the passage by which the explosive mixture of gases finds its way to the ignition
cylinder, this additional valve being opened by connections deriving motion from a
part working with the main piston valve, through an intermediate piece controlled
by a speed governor. If the speed.increases to a moderato extent the intermediate
piece is moved so as to cause the earlier closing of the additional valve and the
consequent carlier cut-off of the gases in the ignition cylinder; but if the increase
of speed, is considerable then the intermediate piece moves so that the additional
valve remains shut until the speed is reduced, and an ignition is missed, or it may
be more than one. A snifting valve is fitted in communication with the passage
between the two cylinders to admit air when the internal pressure is less than that
of the atmosphere and to thereby avoid a loss of power which would otherwise occur
when tlic supply of explosive mixture has been temporarily shut off.
The ignitions are effected by means of the piston slide valve working in the inlet
passage of the ignition cylinder, the parts and arrangements for effecting the
ignitions being substantially the same as those described in the Specification of
Letters Patent granted to the present applicant and dated 14 March 1881 N° 1089.
The exhaust from the inner end of the expansion cylinder is controlled by the same
piston valve which controls the passage between the two cylinders.
For engines of moderate and large powers and when it is desired to economise
gns as much as possible, the parts are proportioned so that the explosive mixture
of gases is forced into the reservoir under considerable pressure; but for small
powers the engine may be modified. so as to work with little or no compression;
but in all cases the combustible gas or vapor and air are drawn in so as to form,
'n mixture which is practically uniform. In engines constructed for large powers
or so as to compress the explosive gaseous mixture to a high pressure there
may be two cylinders besides the ignition cylinder arranged so that there may bo
a third stage of expansion.
In another modification of the improved engines the compound or two-expansion-
stages feature of the engines herein before described is adapted to an engine which
in other respects is constructed and operates like the engine described in the
earlier specification hereinbefore referred to. In that engine as so described there
is a displacement cylinder which is single acting, and there is a power or ignition
cylinder from which the gases exhaust through ports uncovered by the piston as
it approaches the end of its outstroke. By the present Invention the exhaust
ports are made to communicate with a passage leading to the front end of the
displacement cylinder and this cylinder is furnished with a front cover with a
stulling box for the piston rod or trunk. There are also ports in the power
cylinder which are further out than the exhaust ports of that cylinder. When the
gases pass out of the power or ignition cylinder they have still more than
atmospheric pressure and this is utilised by then admitting them into the front
end of the displacement cylinder in which they expand whilst assisting in moving
the piston of that cylinder. The cranks of the power or ignition cylinder and of
tho displacement cylinder are so placed relatively to each other, as to cause tho
gases to be utilised as advantageously as possible in the displacement cylinder.
When the displacement piston moves forward again the gases exhaust from its
front end by the passage by which they entered and they pass through the ports
in the power or ignition cylinder, which ports then have the piston to the inner

page_text: side of them, whilst a cavity formed on the trunk of the piston is then opposite the
ports of the passage and puts them in communication with the outer ports which
lead into an exhaust pipe.
At the same time that the engine is modified in the manner just described the
operation of passing air unmixed with gas through the power or ignition cylinder
as described in the earlier Specification hereinbefore referred to, is dispensed with,
the liability to premature ignitions being absent, and the gases admitted into the
power or ignition cylinder consist exclusively of a practically uniform explosive
mixture. An additional valve the action of which depends on a speed governor,
is placed in the passage by which the explosive mixture passes from the displace-.
ment cylinder to the power or ignition cylinder, and the displacement cylinder is
made with a clearance space into which the explosive mixture is compressed when
the additional valve is closed. This arrangement not only conduces to a quicker
correction of the speed through the increased resistance opposed to the displacement
piston but also retains a charge of explosive mixture ready to act the moment the
speed becomes reduced and the additional valve is opened thereby diminishing or
preventing oscillations in the speed. A snifting valve fitted to the front end
of the displacement cylinder for the same purpose as in the first modification
hereinbefore described. A small reservoir is provided to facilitate the starting of
the engine, this reservoir receiving a quantity of the explosive mixture under
pressure through a check valve whenever the pressure in the displacement cylinder
happens to be sufficient in consequence of the additional valve being prevented.
from opening. Suitable passages and, hand valves are provided for admitting the
explosive mixture from the reservoir to the power or ignition cylinder when
starting the engine.
For the purpose of lubricating the interior of the displacement cylinder (or of.
the expansion cylinder of the first modification) there is provided an oil vessel
fitted with a gas-tight cover and having its top in communication by a passage
with the interior of the cylinder. A small passage leads the oil from the lower
part of the vessel past a screw valve to a passage extending straight down to the
cylinder; and in this passage there is a carefully fitted rod or needle which for the
purpose of keeping the passage clear is made to reciprocate by another rod
connected to its upper end and acted on by an inclined or cam surface or
indentation in the piston rod or trunk or other suitable moving part.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Dugald Clerk in the Great Seal Patent Office on the
17th April 1883.
DUGALD CLERK, of Glasgow, in the County of Lanark, North Britain, Engineer,
"IMPROVEMENTS IN MOTIVE-POWER ENGINES WORKED BY COMBUSTIBLE GAS OR
VAPOR "
My said Invention has for its object to improve the construction and action of
motive-power engines worked by, combustible gas or vapor. In somno existing gas
engines power is developed only at each alternate outstroke of the main piston,
and in others only at each outstroke, but in engines made according to my present
Invention power is developed during each instroko as well as during each outstroke,
which improved action involves various obvious practical advantages.
·
In carrying out my Invention the development of power during each instroke is
obtained by the continued expansion of the gases which have partly expanded
during the outstroke; and in one modification of my improved engines the gases
which have partly expanded in the main or ignition cylinder are led into another
cylinder which is in line with and behind the main cylinder and therein act on a
piston connected to the main piston or ram. The action is controlled by piston
slide valves working in passages situated between the two cylinders, the ignitions
being effected by means of parts substantially the same as those described in tlie
Specification of Letters Patent granted to me and dated 14 March 1881. N° 1089.
For engines of moderate and large powers, and when it is desired to ecomonise
gas as much as possible the parts are proportioned so that the explosive mixture
of combustible gas or vapor and air is forced into a reservoir under considerable
pressure, but for small powers the engine may be modified so as to work with
little or no compression; but in all cases the combustible gas or vapor and air are
drawn in so as to form a mixture which is practically uniform. In ongines con-
structed for large powers or so as to compress the explosive gaseous mixture to
a.high pressure there may be two cylinders besides the ignition cylinder arranged
so that there may be a third stage of expansion.
In another modification of my improved engines the compound or two-expansion-
stages feature of the engines hereinbefore described is adapted to an engine which
in other respects is constructed and operates like my engine described in the
earlier Specification herein before referred to.
For tlie purpose of lubricating the interior of the cylinder in which (in any of
the modifications) the second stage of expansion is effected I provide improved
apparatus of a kind hereinafter particularly described.
And in order that my said Invention and the manner of performing the same
may be properly understood I hereunto append two sheets of explanatory drawings
to be hereinafter referred to and representing examples of my improved motive-
power engines.
One modification is shown on sheet 1, of the accompanying drawings, figure, 1,
being a plan, and figure, 2, a longitudinal vertical section; whilst figures 3, and 4,
are transverse vertical sections of the part between the two cylinders, the former
as looking forwards and the latter as looking backwards. Figures 5, and 6, are a
sido elevation and a horizontal section of the same parts as are shown in figures, 3,
and 4. Figures, 7, and 8, on sheet, 2, are end and side elevations of a second
modification and figure 9, is a horizontal section. Figures, 10, and 11, are vertical
and horizontal sections of my improved lubricating apparatus. In these drawings
the same reference numerals are used to mark the same or like parts wherever
they are repeated.
In the modification of my improved engines shown on sheet, 1, of tho

page_text: accompanying drawings, a horizontal ignition cylinder, 12, has working in it a
plunger piston, 13, connected in the ordinary way to the crank of a first-motion
shaft, 14, carrying a flywheel, 15. At the back of the ignition cylinder; 12, but
separated from it by an intermediate casing, 16, there is a cylinder, 17, of larger
sectional area, having in it. a piston, 18, connected to the ignition piston, 13, by a
rod, 19, passing through a suitably packed passage, 20, formed through the inter-
mediate casing, 16, (or it might be by external rods or other suitable connections)
The larger cylinder, 17, hereinafter termed the expansion cylinder, acts as a
compressing pump at the end furthest from the ignition cylinder, 12 and forces an
explosive mixture of combustible gas or vapor into a reservoir, 21. The air and
gas are drawn into the compressing end of the cylinder, 17, through a check
valve, 22, and are forced through another check valve, 23, into the pipe, 24,
leading to the reservoir, 21. The valves 22, 23, are shown as of the kind
described in my earlier Specification hereinbefore referred to, but may be of any
other suitable kind. A stopcock, 25, is fitted to the reservoir pipe, 24, to allow of
pressure being retained in the reservoir when the engine is stopped and so as to
facilitate the restarting of it. From the reservoir the explosive mixture passes
to the ignition cylinder, 12, by a branch pipe, 65, connected to the reservoir
pipe, 24.
In the intermediate casing, 16, there are two transverse passages, 26, 27, having
valves in them, and also spaces, 28, for water to circulate through to prevent
overheating. The valve for controlling the admission of the explosive mixture to
the ignition cylinder and the ignition, and the valve for controlling the transference
of the gases to the expansion cylinder, 17, and their discharge therefrom, are piston
valves, and are worked by means of eccentrics, 29, 30, on the crank shaft, 14,
acting through röds, 31, 32, and bellcranks, 33, 34, connected to the valve rods,
35, 36. The admission and ignition valve is in the lower passage, 27, and being
substantially the same as the corresponding valve comprised in my earlier
Specification herein before referred to does not now require to be specially
described.
During the first part of the outstroke of the ignition piston, 13, the explosive
gaseous mixture enters into the ignition cylinder, 12, and, being cut off at a
variable point of the stroke, is ignited by preference when the piston reaches half
stroke or earlier. The increased pressure due to the ignition acts during the
remainder of the outstroke; and at the end of the outstroke the valve in the
upper passage, 26, of the intermediate casing, 16, opens a communication with the
near end of the expansion cylinder, 17, in which the heated gases act expansively.
during the instroke of the ignition piston, 13. By the instroke the gases are
expelled as completely as possible from the ignition cylinder, 12, and as any
remaining traces are expanded down to a low pressure and have their temperature
much reduced there is little or no liability to prematurely ignite the fresh charge.
of explosive gas entering the cylinder. The port, 37, from the ignition cylinder, 12,
into the valve passage, 26, is at about the middle of that passage, whilst the port, 38,
thence into the expansion cylinder, 17, is nearer the end of the passage which
communicates with the exhaust pipe, 39, so that when the piston valve is between
the ports, 37, 38, the latter will be open to the exhaust, and when the valve is to
the outer side of the port, 38, it will be shut off from the exhaust and in
communication with the port, 37.
"
For the purpose of regulating the speed of the engine there is an additional
valve, 40, in the passage, 41, by which the explosive gaseous mixture finds its way
to the passage, 27, and to the ignition cylinder, 12, this additional valve being
opened by connections deriving motion from a part working with the main ignition
valve, through an intermediate piece controlled by a speed governor. This device
is more fully shown in connection with the modification of my engine delineated.
on sheet, 2, of the drawings and is hereinafter particularly described. A snifting
valve, 42, is fitted in communication with the passage, 26, between the two.
cylinders, to admit air when the internal pressure is less than that of the atmosphere,

page_text: .
and to thereby avoid a loss of power which would otherwise occur when the
supply of explosive mixture has been temporarily shut off.
In the modification of my improved engine shown on sheet, 2, of the drawings
and which is in many respects like the; engine described in my earlier Specification
hereinbefore referred to, there is a displacement cylinder, 43, which was formerly
single acting, and there is an ignition cylinder, 12, from which the gases. formerly
exhausted through ports uncovered by the piston, 13, as it approached the end of
its outstroke. By my present Invention the exhaust ports, 44, of the ignition
cylinder, 12, are made to communicate with a passage, 45, leading to the front end
of the displacement cylinder, 43, and this cylinder is furnished with a front
cover, 46, with a stuffing box for the piston rod, 47. There are also ports, 48 in
the ignition or power cylinder, 12, which are further out than the exhaust
ports, 44. When the gases pass out of the ignition cylinder, 12, they have
still more than atmospheric pressure, and this is utilised by then adinitting
them into the front end of the displacement cylinder, 43, in which they
expand whilst assisting in moving the piston of that cylinder. The cranks of the
power or ignition cylinder,, 12, and of the displacement cylinder, 43, are so placed
relatively to each other as to cause the gases to be utilised as advantageously as
possible in the displacement cylinder. When the piston of the displacement
cylinder, 43, moves forward again the gases exhaust from the front end of
the cylinder through the passage, 45, by which they entered, and they pass through
the ports, 44, in the power or ignition cylinder which ports then have, the piston,
13, to the inner side of them, whilst a cavity formed on the trunk of the piston is
then opposite the ports, 44, of the passage, 45; and puts them in communication
with the outer ports, 48, which lead into an exhaust pipe. At the same time that
the engine is modified in the manner just described, the operation of passing air
unmixed with gns through the power or ignition cylinder, 12, as described in my
earlier Specification herein before referred to, is dispensed with, the liability to
premature ignitions being absent, and the gases admitted into the power or
ignition cylinder, 12; consist exclusively of a practically uniform explosive
mixture. An additional valve, the action of which depends on a speed governor, 49,
is placed in the passage, 50, by which the explosive mixture passes from the
displacement cylinder, 43, to the power or ignition cylinder, 12; and the
displacement cylinder, 43, is made with a clearance space into which the explosive
mixture is compressed whenever the additional valve is closed. This arrangement
not only conduces to a quicker correction of the speed through the increased
resistance opposed to the displacement piston, but also retains a charge of explosive
mixture ready to act the moment the speed becomes reduced, and the additional
valve is opened, thereby diminishing or preventing oscillations in the speed. The
additional valve is worked by a bellerank, 51, of which the vertical arm has
jointed to it a trigger, which is connected by a link, 52, to a bellcrank, 53,
arranged to be acted on by the governor, 49.. The inner end of the ignition slide
or valve, 54, has a projection or pin which acts through the trigger on the
bellcrank, 51, so as to open the additional valve at each stroke when the speed is
not above what it should be; but when the speed is too great the governor, 49,
so acts through the bellcrank, 53, and link, 52, as to move the trigger out of the
way of the projection on the valve, 54, and the additional valve consequently
remains closed until from the reduction of speed the governor moves back the
trigger into the position to be acted on. A snifting valve should be fitted to the
front end of the displacement cylinder, 43, for the same purpose as in the first
modification herein before described, but is not shown in figures 7, 8, 9. A small
reservoir is provided to facilitate the starting of the engine, this reservoir receiving
a quantity of the explosive mixture under pressure through a check valvo when-
ever the pressure in the displacement cylinder, 43, happens to be sufficient in
consequence of the additional valve being prevented from opening. Suitable pipes
and hand valves, 55, are provided for admitting the explosive mixture from the
reservoir to the power or ignition cylinder, 12, when starting the engine.

page_text: My improved lubricating apparatus shown in figures, 10 and 11, on sheet 2, of
the accompanying drawings comprises an oil vessel, 56, fitted with a gas-tight
cover, 57, and having its top in communication by a passage, 58, with the interior
of the cylinder to be lubricated. A small passage (seen only in figure, 11) leads
the oil from the lower part of the vessel, 56, past a screw valve, 59, to a passage, 60,
extending straight down to the cylinder; and in this passage, 60, there is a
carefully fitted rod or needle which for the purpose of keeping the passage, 60, clear
is made to reciprocate by another rod 61, connected to its upper end. This second
rod, 61, passes down a tube and has a small block fixed on its lower end to be acted
on by an inclined, or cam surface or indentation in the piston or trunk or other
suitable part working in the cylinder or in connection with the piston.
Having thus particularly described my said Invention and the manner of
performing the same I have to state that I do not restrict myself to the precise
details herein described or delineated but that what I believe to be novel and
original and claim as the Invention secured to me by and in terms of the herein-
before in part recited Letters Patent is :-
1. The improved construction of motive-power engine worked by combustible
gas or vapor in which the gases act with two or more stages of expansion in
separate cylinders, the parts being arranged and operating substantially in the
improved manner hereinbefore described.
2. The combination of parts constituting the improved motive-power engine
herein before described with reference to figures 1 to 6, of the accompanying
drawings.
3. The combination of parts constituting the improved motive-power engine
herein before described with reference to figures 7, 8, and 9, of the accompanying
drawings.
4. The improved lubricating apparatus for motive-power engines worked by
combustible gas or vapor and hereinbefore described with reference to figures,
10 and 11, of the accompanying drawings.
In Witness whereof I, the said Dugald Clerk, have hereunto set my hand and
seal this sixteenth day of April in the year of our Lord One thousand
eight hundred and eighty-three
Witness-
EDMUND HUNT-
Patent Agent-
Glasgow―
DUGALD CLERK. (L.S.)