IMPROVEMENTS IN AND RELATING TO MINING MACHINES
Year: 1882

page_text: LETTERS PATENT to William Robert Lake, of the firm of Haseltine Lake
& Co., Patent Agents, Southampton Buildings London for an Invention of
"IMPROVEMENTS IN AND RELATING TO MINING MACHINES Communicated
to him from abroad by George Dexter Whitcomb, of Chicago, Illinois, United
States of America, Mining Superintendent
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 8th August 1882.
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake and Co., Patent
Agents, Southampton Buildings, London, "IMPROVEMENTS IN AND RELATING TO
MINING MACHINES [A communication to him from abroad by George Dexter
Whitcomb, of Chicago, Illinois, United States of America, Mining Superintendent]
33
This Invention relates to that class of machines for mining coal or ores, which
are operated by admitting steam or compressed air at the rear end and exhausting
it at the forward end of a piston cylinder, and vice versa alternately. In the
operation of these machines it has been found that the piston in its backward
movement, after each stroke, is thrust too violently against the rear head of the
cylinder, thereby producing a violent concussion and recoil which are excessively
fatiguing to the operator and unfavorably affect the durability of the machine.
The use of a cushion of india-rubber or like material has not been found a
sufficient remedy for this evil.
According to one part of the present Invention an air-cushion of adjustable
pressure is interposed for this purpose between the piston and the cylinder-head,
and devices are provided for regulating the pressure, as hereinafter described.
In carrying this part of my said Invention into practice I provide a piston
which works back and forth within the main cylinder and has a rod fixed to it
carrying the pick. The exhaust-port opens into the exhaust-passage which is
formed in the enlarged upper wall of the cylinder; the inlet port and exhaust port
are opened and closed by a sliding valve which is made to reciprocate by the
engagement of a slotted cap on its upper surface with a spiral wheel which turns

page_text: in a cavity of the auxiliary or valve motor cylinder, being on the same shaft with
an excentric cam, which turns in a cavity of the same cylinder.
At each end of the exhaust-passage I place a disc-valve of area sufficient to close
the passage, or nearly so. Its cylindrical stem has a bearing, partly in a groove out
in the outer surface of the piston cylinder, and partly in a heavy plate which is set
-close against the head of the cylinder. Passing through this plate, the stein carries
at its outer end a spring bar or handle the outer end of which is bent toward the
said plate so that the elasticity of the spring tends to force this end into one or
other of the sockets in the outer surface of the plate, which are arranged in the are
described by the outer end of the said spring bar or handle when the stem is turned
in its bearing. By drawing this end of the said spring-bar out of the socket the
stem may be turned so as to set the said disc at any desired angle to the base of the
cylindrical exhaust-passage and thus close that passage to a greater or less extent,
according to the greater or less angle to the horizon at which the cylinder is set
and the consequently varying momentum of the back stroke of the piston; but it
must never be entirely closed. When the disc has been set at the desired angle
the spring-handle is released, and immediately springs into the socket corresponding
with its position, and thus holds the disc at the angle to which it has been adjusted,
at the same time indicating what that angle is. By means of this device I provide
an elastic cushion of compressed air between the piston and the head of the
cylinder, whose resistance to the backward thrust of the piston is regulated by the
greater or less degree to which the said exhaust-passage is closed. I can thus
readily adapt this resistance to the varying force with which the piston comes
back. The appliances by which this is effected are not liable to get out of order,
and are obviously readily accessible for renewal in case of need.
In the end of the shell of the cylinder which contains the auxiliary motor
operating the aforesaid sliding valve I bore a hole or tube intersecting the exhaust-
outlet. This tube forms a seat for a cylindrical valve. The said valve and tube
are both screw-threaded, or not, as desired. For a part of its length about half the
thickness of this valve is cut away so that by setting this part at the intersection
of the exhaust-outlet and turning the valve the exhaust-outlet can be left wide
open or closed to a greater or less degree; or the said valve may be a tube with a
perforation capable of being turned into, or out, of correspondence with the exhaust-
outlet. The said valve is provided with a spring-handle substantially similar to
the aforesaid handle by means of which it can be turned, the outer end of the
handle springing into one of the sockets in the outer end surface of the auxiliary
cylinder. By thus regulating the degree of rapidity with which the air is exhausted
I am enabled to regulate the motion of the cams, and consequently the motion of
the sliding valve much more accurately than by means of a valve applied at the
necessarily smaller inlet-port; moreover a valve in the latter position is liable to
become obstructed by condensed water carried in by the air. This control of the
rate of reciprocation of the sliding-valve is of vital importanco since without it the
valve is liable to reciprocate too swiftly, so that the direction of the piston is
roversed before it has had time to make nearly a full stroke.
The said Invention further relates to an arrangement of the parts of the machine
whereby the exhaust ports are between the admission ports and the ends of the
cylinder. This arrangement of valves and ports relative to the cylinder causes
the rebound of the pick after making its blow, to aid in moving the valve and
opening the exhaust-port, thereby saving power and accelerating the action.
According to the said Invention I also make the piston-head and piston rod in
one piece to obviate the liability of breaking the fastenings of a joint where the
piston-head and piston-rod are made in two pieces, and 1 so construct the piston-
rod and its attachments that cushions can be inserted in the cylinder over that end
of the piston-rod not attached to the piston-head. And I construct cushions as
hereinafter described, and combine a cylinder-head having a flange or rim, and a
cylinder so constructed that the flange or rim of the cylinder-head passes over the
end of the cylinder to strengthen it; I also provide an inclined platform in

page_text: combination with the mining machine for the purpose of utilizing the weight of the
said machine to hold it to its work, as hereinafter described
The round part of the piston rod is made of the same diameter as the largest or
diagonal diameter of the square portion of the rod. Cushions are inserted in the
cylinder over the said square portion and fit closely the round portion of the piston-
rod, so as to serve as a packing to the front end of the cylinder, as well as a cushion
for the piston-head to strike against in case the pick does not hit the coal or other
material. There is also a cushion in the rear end of the cylinder for the piston-
head to strike against when it makes its back stroke. These are leather cushions;
one of which has a double erimp or fold, one crimp fitting against the interior of
the cylinder, and the other against the piston-rod which passes through it, thus
forming a packing between the piston-rod and the cylinder.
It is difficult to form two folds or crimps so near together from a single piece of
leather, I therefore make the outside fold of one piece, and the inner fold of another
piece, and overlap their edges. A ring is placed between the said folds and in order
to keep one fold in place, I rivet or sew through the pieces; this fastens the parts of
the cushion together and also keeps them in form.
In the other cushion one fold is made in one piece in the form of a disc with its
edges turned up to form the fold. A piece is set into the disc and a back plate
serves to keep the said fold from bending down, and the parts are fastened together
by a rivet or sewing, As the piston-rod does not pass through this cushion the
fold is made to fit against the cylinder only.
The exhaust-ports are between the inlet-ports and the ends of the cylinder, and
when the piston moves forward to strike the blow with the pick, the recoil of the
machine assists to move a valve forward to open the rear exhaust port and
the front inlet-port. I thereby utilize the recoil force to assist in moving the said
valve.
Upon an inclined portable platform the mining machine is placed when in
operation. It is made to slope toward the work of the machine, so that the weight
of the machine holds it to its work and assists to overcome the recoil from the blow
of the pick. The incline of the platform also enables the operator to give the
machine a downward pitch so that the weight of the piston and piston-rod assists
in giving force to the blow of the pick. This inclination of the platform operates
in this way to save power and assist in the working of the machine. I ordinarily
make the said platform double, with loose sections, and in such manner that the
machine is moved laterally from one platform to another, as it is moved from place
to place in its work,
The said Invention further relates to the construction and arrangement of devices
for controlling the supply of air to the small rotary engine which drives the valve.
The quantity of air required to operate this engine is always comparatively small;
and if the supply is regulated at one port only, (either the inlet or the exhaust) the
operation of the engine will be uncertain and unsatisfactory. If the supply is
regulated entirely at the inlet-port, it will sometimes reduce this opening so that it
will choke with dirt or congealed oil, and if the supply is regulated entirely at the
exhaust-port the back pressure will at times be so great as to nearly equalize the
pressure on the opposite side of the gate. I therefore provide means for regulating
at both the inlet and exhaust-ports. In regulating at the inlet-port it is necessary
to arrange the devices so that the supply of air will come in over the gate before
reaching the port, so that the pressure on the gate will always be sufficient to keep
it down in contact with the cam.
A revolving excentric is mounted on a shaft and arranged to revolve in a
chamber in the usual manner. The gate is also of the usual construction in rotary
engines of this description, arranged to rest at its lower edge on the excentric, and
moving up and down by the action of the latter thereon. The inlet-passage to the
engine is just in front of the gate, being cut down through from the top of the
chest; and the inlet, port is cut through a wall between this passage and the way
in which the gate moves up and down, opening into the upper part thereof. The

page_text: supply passage extends up from the air-chest to the upper end of the guide-way of
the gate and opens into the same. A small section is cut off from the upper edge
of the gate extending nearly across it, so that the air-supply is admitted directly
over the gate and exerts a constant pressure downward thereon, thus keeping it in
constant contact with the rotary excontric. As the gate drops, as soon as it reaches
the inlet-port, the air will enter to the engine. The movement of the gate is always
the same, opening the port to the same degree with every downward reciprocation.
In order to regulate the supply of air at this port I arrange a check-valve in the
top plate passing it down through a stuffing box into the upper end of the inlet
passage: this check-valve is screw-threaded so that it can be adjusted up and down,
and as it is turned down it will gradually close the inlet-port, thereby regulating
the supply of air to the engine. The exhaust-port is behind the gate; into this
port I insert a check-valve extending horizontally through the side of the chest into
the port opposite its outlet. This check valve passes through a stuffing-box and is
screw-threaded so that it may be adjusted back and forth, thus enabling me to
regulate the exhaust in the same way as the supply of air to the rotary engine.
By this system of regulation I am enabled to keep the pressure on the gate
substantially uniform, and by taking air in over the top of the gate the latter is
constantly held down to its work.
Another part of the said Invention relates to a peculiar mode of packing the piston-
rod where it passes through the cylinder-head. I apply the packing to the inner
face of this head. The packing is a ring of leather or other suitable material, the
outer edge of which is turned outward at right angles to form a projecting flange;
the inner edge is bevelled on the outside. The inner face of the cylinder head is
cut out to form a rabbet or seat on which this packing is placed, and a metallic ring
of suitable size embracing the main portion of the packing ring is set down over
the latter; this ring has a projecting flange extending outward from its outer edge
and resting upon a seat, also cut in the face of the cylinder-head, so that the face of the
ring will be flush with the main portion of the face of the head. A wedge-shaped
space is provided between the edge of the packing and the fastening ring; the air
admitted to the chamber in the end of the cylinder for the purpose of forming a
cushion, will force the edge of the packing ring tightly around the piston-rod and
so make a perfectly tight packing. This construction and arrangement in connection
with the peculiar packing in the cylinder, will make this air-chamber perfectly
tight and prevent the escape of air therefrom, which is absolutely necessary to
secure a satisfactory operation of the machine, for the whole beneficial result of this
cushion depends upon preventing the leakage of air therefrom.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Office on the
7th February 1883.
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, London "IMPROVEMENTS IN AND RELATING TO MINING
A communication to me from abroad by George Dexter Whitcomb, of
Chicago, Illinois, United States of America, Mining Superintendent
MACHINES"
This invention relates to that class of machines, for mining coal or ores, which are
operated by admitting steam or compressed air at the rear end and exhausting it
at the forward end of a piston cylinder, and vice versa, alternately. In the operation.
of these machines it has been found that the piston, in its backward movement
after each stroke, is thrust too violently against the rear head of the cylinder,
thereby producing a violent concussion and recoil, which are excessively fatiguing
to the operator and unfavorably affect the durability of the machine. The use
of a cushion of indin-rubber or like material has not been found a sufficient remedy
for this evil.
According to this part of the present invention an air-cushion of adjustable
pressure is interposed between the piston and the cylinder-head, and devices are
provided for regulating the pressure as hereinafter described
The said invention further relates to an arrangement of the parts of the machine
whereby the exhaust ports are between the admission ports and the ends of the
cylinder. This arrangement of valves and ports relative to the cylinder, causes the
rebound of the pick after making its blow to aid in moving the valve and opening
the exhaust-port, thereby saving power and accelerating the action.
According to the said invention I also make the piston-head and piston-rod in
one piece, to obviate the liability of breaking the fastenings of a joint where the
piston-head and piston rod are made in two pieces, and I so construct the piston-
rod and its attachments, that cushions can be inserted in the cylinder over that end
of the piston-rod not attached to the piston-head. And I construct cushions as
hereinafter described, and combine a cylinder-head having a flange or rim, and a
cylinder so constructed that the flange or rim of the cylinder-head passes over the
end of the said cylinder to strengthen it; I also provide an inclined platform in
combination with the mining machine, for the purpose of utilizing the weight of
the said machine to hold it to its work as hereinafter described
The said invention further relates to the construction and arrangement of devices
for controlling the supply of air to the small rotary engine which drives the valve.
The quantity of air required to operate this engine is always comparatively small;
and if the supply is regulated at one port only, (either the inlet or the exhaust) the
operation of the engine will be uncertain and unsatisfactory. If the supply is
regulated entirely at the inlet-port, it will sometimes reduce this opening so that
it will choke with dirt or cougealed oil, and if the supply is regulated entirely at
the exhaust-port the back pressure will at all times be so great, as to nearly
equalize the pressure on the opposite side of the gate. I therefore provide means
for regulating at both the inlet and exhaust-ports. I also have found that in
regulating at the inlet-port it is necessary to arrange the devices so that the supply
of air will come in over the gate before reaching the port, so that the pressure on
the gate will always be sufficient to keep it down in contact with the cam

page_text: мушрапушу шаишка.
Figure 1, is a rear elevation of a mining machine constructed according to thi
invention
Figure 2, is a section on the line XX figure 1, the wheels being removed and
the forward part of the machine being broken away. The excentric cam and spiral
wheel by which the sliding valve is operated are also removed
Figure 3, is a detail plan-section on the line Y Y figure 2 drawn to an enlarged
scale
Figure 4, is a detailed section on the line Z Z, figure. 2, showing the upper part
of the main cylinder.
Figure 5, is a section on the line V V in figure. 1, looking to the left, and
showing only the upper part of the auxiliary cylinder.
Figure 6, is a view of the valve for regulating the escape of exhaust steam or
air from the main cylinder, with its spring handle, drawn to an enlarged scale
Figure. 7, is a similar view of the valve regulating the escape of steam or air
from the auxiliary cylinder.
Figure. 8, is a section on the line W W figure. 7.
Figure 9, is a section similar to figure 5, but showing a modified form of valve
Figure 10, is a vertical central sectional view of a coal mining machine embodying
these improvements
Figure 11, is a plan view of one of the cushions.
Figure 12, is a central sectional view on the line. figure 11.
Figure 13, is a plan view of the other form of cushion
Figure 14, is a central sectional view on the line Y. Y. figure 13, and
Figure 16, is a perspective view of the double inclined platform.
Figure 16, is a detail longitudinal section of the valve-engine drawn to an
enlarged scale.
Figure 17, is a transverse section of the same on the line X X figure. 16.
Figure. 18, is a plan of the top plate of the same
Figure. 19, is a detail section on the line y y figure. 17, drawn to an enlarged scale,
Figure. 20, is a detail section on the line V V figure. 17, showing the exhaust
Figure 21, is an elevation of the inner end of the main forward cylinder head.
Figure 22, is a detail section of the same, on the line Z Z. figure 21.
Referring to figures 1 to 9, A, denotes the main cylinder of the machine ;
A', the piston which works to and fro within the main cylinder and a', the rod
fixed to the piston and carrying the pick. The exhaust-port B', opens into the
exhaust-passage C, which is formed in the enlarged upper wall of the piston
cylinder; the inlet port and exhaust port are opened and closed by the sliding
valve D, which is made to reciprocate by the engagement of the slotted cap d
on its upper surface with a spiral wheel which turns in the cavity E³, of the
auxiliary or valve motor cylinder E, being on the same shaft with the excentric
cam, which turns in the cavity E¹, of the same cylinder. As the construction of
this wheel and cam has nothing to do with the present invention, they are omitted
from the drawings. F represents the wheels on which the frame of the machine
rests. All these parts are of a construction already known.
At each end of the exhaust passage C, I place a disc valve, G, of area sufficient
to close the passage, or nearly so. Its cylindrical stem (³, has a bearing partly
in a groove cut in the outer surface of the piston cylinder and partly in the heavy
plate H, which is set close against the head of the cylinder. Passing through this
plate the stem carries at its outer end a spring bar or handle, G³, the outer end of
which is bent toward the said plate H, so that the elasticity of the spring tends to
force this end into one or other of the sockets h in the outer surface of the plate,
which sockets are arranged in the are described by the outer end of spring bar or
handle G³, when the stem G is turned in its bearing. By drawing this end of the
said spring bar G' out of the socket, the stem G¹ may be turned so as to set the
disc G at any desired angle to the base of the cylindrical exhaust-passage C, and

page_text: thus close that passage to a greater or less extent, according to the greater or less
angle to the horizon at which the cylinder is set, and the consequently varying
momentum of the back stroke of the piston A'; but the exhaust passage must
never be entirely closed. When the disc has been set at the desired angle, the
spring-handle G³ is released and immediately springs into the socket corresponding
with its position, and thus holds the said disc at the angle to which it has been
adjusted, at the same time indicating what that angle is. By means of this device
I provide an elastic cushion of compressed air between the piston and the head of
the cylinder, whose resistance to the backward thrust of the piston is regulated by
the greater or less degree to which the exhaust-passage C is closed. I can thus
readily adapt this resistance to the varying force with which the piston comes back.
The appliances by which this is effected are not liable to get out of order, and are
obviously readily accessible for renewal in case of need.
In the end of the shell of the cylinder E which contains the auxiliary motor
operating the sliding valve D, I bore a hole or tube I, intersecting the exhaust-
outlet K. This tube forms a seat for a cylindrical valve, L. As shown in the
drawings both the valve and the tube are screw threaded; but this will ordinarily
be found unnecessary. For the inner part of its length, about half the thickness
of this valve is cut away, as shown in Figures 5 and 8, so that, by setting this part
at the intersection of the exhaust-outlet K and turning the valve, the exhaust-
outlet can be left wide open or closed to a greater or less degree; or the valve L
may be a tube with a perforation l' capable of being turned into or out of corre-
spondence with the exhaust-outlet as shown in Figure 9. The said valve is provided
with a spring handle L', substantially similar to the handle G³, by means of which
it can be turned, the outer end of the handle springing into one of the sockets 6, in
the outer end surface of the auxiliary cylinder E. By thus regulating the degree
of rapidity with which the air is exhausted, I am enabled to regulate the motion of
the cams, and consequently the motion of the sliding valve, much more accurately
than by means of a valve applied at the necessarily smaller inlet-port; moreover a
valve in the latter position is liable to become obstructed by condensed water
carried in by the air. This control of the rate of reciprocation of the sliding-valve
is of vital importance, since without it the valve is liable to reciprocate too swiftly,
so that the direction of the piston is reversed before it has had time to make nearly
a full stroke
Referring to figures 10 to 15, A represents one of the wheels upon which the
machine is supported and B the cylinder; C C¹ are the cylinder-heads provided
with rims or flanges D, which pass over the ends of the cylinder as shown; E is a
valve; F F are inlet-ports; GG. are exhaust-ports; H is the piston head, and I is
the piston-rod, the two latter are made in one piece to obviate the difficulty
experienced by the use of a joint for joining them together. The round part of the
piston rod I is made of the same diameter as the largest or diagonal diameter of
the square portion J of the rod; K are cushions inserted in the cylinder over the
square portion J of the piston rod, and fitting closely the round portion I of the
said piston-rod, so as to serve as a packing to the front end of the cylinder as well
as a cushion for the piston-head to strike against in case the pick does not hit the
coal or other material. L is a cushion in the rear end of the cylinder for the
piston-head to strike against when it makes its back stroke. These cushions are
leather, the cushion K. has a double crimp, or fold one crimp fitting against the
interior of the cylinder, and the other against the piston-rod which passes through
it, thus forming a packing between the piston rod and the cylinder.
It is difficult to form two folds or crimps so near together from a single piece of
leather, I therefore make the outside fold a of one piece and the inner crimp or
fold b of another piece, and overlap their edges as shown in figure 12. o is a ring
placed between the folds a and b, and in order to keep the fold a in place, I rivet
or sew through the pieces, as indicated by the line d; this fastens the parts of the
cushion together and also keeps them in form

page_text: In the cushion L the fold e is made in one pieco, in the form of a disc with its
edges turned up. f, is a piece set into the disc, and g is a back plate which serves
to keep the fold e from bending down, and the parts are fastened together by the
rivet or sewing h. As the piston-rod does not pass through this cushion the fold is
made to fit against the cylinder only.
The exhaust ports G. are between the inlet ports F and the ends of the cylinder,
when the piston moves forward to strike the blow with the pick; the recoil of the
machine assists to move the valve E forward to open the rear exhaust port and
the front inlet-port. I thereby utilize the recoil force to assist in moving the
valve E
By this combination of inlet and outlet ports with the valves, I am able to
utilize the recoil from the force of the blow, to move the valve to open and
close the ports. The greatest recoil is occasioned by the forward stroke when the
pick strikes the coal.
M is an inclined portable platform upon which the mining machine is placed
when in operation. It is made to slope toward the work of the machine, so that
the weight of the machine holds it to its work and assists to overcome the recoil
from the blow of the pick. The incline of the platform also enables the operator to
give the machine a downward pitch, so that the weight of the piston and piston-
rod assists in giving force to the blow of the pick. This inclination of the platform
operates in this way to save power and assist in the working of the machine.
I ordinarily make the said platform double, with loose sections, and in such a
manner, that the machine is moved laterally from one platform to another, as it is
moved from place to place in its work
Referring to figures 16 to 20 the revolving excentric 1. is mounted on a shaft 2,
and arranged to revolve in a chamber 3. in the usual manner. The gate 4. is also
of the usual construction in rotary engines of this description, arranged to rest at
its lower edge on the excentric, and moving up and down by the action of the
latter thereon. The inlet-passage 5 to the engine is just in front of the gate,
being cut down through from the top of the chest, and the inlet-port 6 is cut
through a wall between this passage and the guide in which the gate moves up
and down, opening into the upper part thereof, as shown in Figure. 17.
The supply passage 7. extends from the air-chest to the upper end of the
guide-way of the gate, and opens into the same, as shown in Figure. 16. A small
Bection 8 is cut off from the upper edge of the gate extending nearly across it, ns
shown in Figure. 16 so that the air supply is admitted directly over the said gate
and exerts a constant pressure downward thereon, thus keeping it in constant
contact with the rotary excentric. As the gate drops, as soon as it reaches the
inlet-port, the air will enter the engine. The movement of the gate is always the
same, opening the port to the same degree with every downward reciprocation. In
order to regulate the supply of air at this port, I arrange a check-valve 9 in the
top plate 10, passing it down through a stuffing box 11 into the upper end of the
inlet passage; this check-valve is screw-threaded so that it can be adjusted up and
down, and as it is turned down it will gradually close the inlet-fort, thereby
regulating the supply of air to the engine. The exhaust-port 12 is behind the
gate, as shown in Figure 17, into this port I insert a check-valve 13, extending
horizontally through the side of the chest into the port opposite its outlet, as shown
in Figure 20. This check-valve passes through a stuffing-box 14, and is screw-
threaded so that it may be adjusted to and fro thus enabling me to regulate the
exhaust in the same manner as the supply of air to the rotary engine
By this system of regulation I am enabled to keep the pressure on the gate
substantially uniform, and by taking air in over the top of the gate the latter is
constantly held down to its work
Figures 21 and 22 show a peculiar mode of packing the piston-rod where it
passes through the cylinder head (these figures being enlarged views of the
head C, shown in Figure 10) I apply the packing to the inner face of this head.

page_text: The packing 15 is a ring of leather or other suitable material, the outer edge of
which is turned outward at right angles to form a projecting flange 16, the inner
edge is bevelled on the outside as shown at 17, in Figure 22
The inner face of the cylinder-head is cut out to form a rabbet or seat 18, on which
this packing is placed, and a metallic ring 19 of suitable size embracing the main
portion of the packing ring is set down over the latter, the ring 19 has a projecting
Bange 20, extending outward from its outer edge, and resting upon a seat 21 also
cut in the face of the cylinder-head, so that the face of the ring will be flush with
the plain portion of the face of the head as shown in Figure 22
It will be seen that a wedge-shaped space is provided between the edge of the
packing and the fastening ring; the air admitted to the chamber in the end of the
cylinder for the purpose of forming a cushion, will force the edge of the packing
ring tightly around the piston-rod and so make a perfectly tight packing. This
construction and arrangement in connection with the peculiar packing in the
cylinder, will make this air chamber perfectly tight and prevent the escape of air.
therefrom, which is absolutely necessary to secure a satisfactory operation of the
machine, for the whole beneficial result of this cushion depends upon preventing
the leakage of air therefrom
Having thus fully described the said invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim
First. In a mining machine, the main piston cylinder, provided with an air-
space between the piston and the rear cylinder-head, in combination with a sliding
valve, for regulating the admission and escape of air, or steam, an auxiliary engine
for operating the said valve, provided with the exhaust outlet K, and the valve for
regulating the escape of air or steam through this outlet, substantially as, and
for the purposes, described.
Second. The combination of the cylinder B, the valve E, and the inlet ports F
and G constructed and operating to utilize the recoil force, substantially as
specified.
Third. In a mining machine the piston-head H and the rod I made in one
piece, the piston-rod being so constructed, that the cushion discs can be passed
over the end of the piston-rod not attached to the piston head, substantially as
specified.
Fourth. The cushion packing having two folds or crimps made from separate
pieces of material substantially as specified.
Fifth. The backing plate of the packing in combination with the two folds
secured together by rivets or sewing to hold them in place, substantially as shown.
Sixth. The combination of the inclined platform M and the mining machine,
for the purpose of holding the said machine to its work, substantially as
specified.
Seventh. In a mining machine provided with an auxiliary engine for operating
the valve of the main engine, the inlet and exhaust-ports of the said auxiliary
engine, in combination with check-valves, one at each port, whereby the supply
of air to the engine is regulated at both the inlet and exhaust ports, substantially
as described.
Eighth. The gate 4 of the auxiliary rotary engine, in combination with the
supply passage 5, extending up to, and opening over, the said gate, the inlet-port 6,
and the inlet-passage 7, substantially as, and for the purpose, set forth.
Ninth. The gate 4, in combination with the inlet-port 0, the inlet-passage 7, and
the check-valve 9 arranged between the said gate and the rotary cam of the engine,
substantially as, and for the purpose, set forth.
Tenth The main forward cylinder head C, provided with the recesses 16,
aud 21, in combination with a packing ring 15, constructed as described, and the
metallic fastening ring 19, substantially as described.

page_text: Eleventh. The cylinder B, in combination with the piston-rod I, the packing K,
the forward cylinder head C', and the packing 15 at the inner face of the said
head, all arranged and operating substantially as described.
In witness whereof I the said William Robert Lake have hereunto set my
hand and seal this Seventh day of February in the year of our Lord one
thousand eight hundred and eighty three