Improvements in and relating to Apparatus for Compressing Air, Transmitting Power thereby, and Utilizing said Power in Operating Rock Drills and other Machinery.
Year: 1891

page_text: Date of Application, 4th Aug., 1891-Accepted, 19th Sept., 1891
COMPLETE SPECIFICATION.
Improvements in and relating to Apparatus for Compressing Air,
Transmitting Power thereby, and Utilizing said Power in
Operating Rock Drills and other Machinery.
We, CHARLES CUMMINGS, Mechanical Engineer, and EDWARD BROOKS
HINDES, Manufacturer, both Citizens of the United States of America, residing
respectively at No. 453 East Eleventh Street, in the City of Oakland, County of
Alameda and State of California, and at No. 411 Mission Street, in the City and
County of San Francisco and State of California, one of the United States of
America, do hereby declare the nature of this invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
This invention relates to machinery for transmitting power by means of com-
pressed air or other gas, the object of the invention being to provide better cheaper,
more compact and more efficient mechanism for the purpose indicated, whereby the
best results may be achieved in the application of energy to successful work at a
point distant from where the energy is generated, with the least possible percentage
of loss of energy in the transmission. And the invention consists essentially in the
construction, arrangement and combination of parts for carrying into practical
effect and operation, the underlying principle or method upon which the invention
is based, which is, to wit, the employment of two unequal pressures of air, both
above the normal atmospheric pressure, and maintained at a constant ratio to each
other, the air circulating through a system of pipes or conduits and other parts,
which system is closed to the external atmosphere after the apparatus has once
been charged, and said confined body of air being alternately expanded and com-
pressed during the circulation, all substantially as will be hereinafter fully described
and then more particularly pointed out in the subjoined claims.
In the annexed drawings illustrating the invention:
Figure 1 is a side elevation of our improved machine for transmitting power by
means of compressed air or other gas.
•
Figure 2 is a top plan view of the same.
Figure 3 is a right hand end elevation.
Figure 4 is an enlarged longitudinal section on the line w, w, of Figure 2.
Figure 5 is a cross section on the line z, z, of Figure 6.
Figure 6 is a longitudinal section on the line a, x, of Figure 7.
Figure 7 is a cross section on the line y, y, of Figure 6.
Figure 8 is a vertical section of the air governor or device for maintaining the
unequal air pressures at a fixed and constant ratio.
Figure 9 is a side elevation of the same.
Figure 10 is a longitudinal section of one form or example of driven machine
arranged to be operated by our improved means of transmitting power, said machine
being in the present instance a rock drill, and said figure showing the piston of the
drill near one end of its stroke.
Figure 11 is a similar longitudinal section, certain of the parts being removed
and showing the piston near the other end of its stroke.
Figure 12 is a horizontal sectional plan on the line u, u, of Figure 16.
Figure 13 is a sectional end elevation on the line a, a, of Figure 10.
Figure 14 is a cross section on the line y, y, of Figure 10.
Figure 15 is a cross section on the line z, z, of Figure 10.
Figure 16 is a cross section on the line w, w, of Figure 10.

page_text: Figure 17 is a cross section on the line », v, of Figure 10.
Like letters of reference designate corresponding parts throughout all the different
figures of the drawings.
The invention aims by novel means to practically embody a novel principle or
method which has never to our knowledge been carried into actual operation in a
practical machine. This principle or method consists in the use of two unequal
pressures of air, each above the normal atmospheric pressure and bearing to each
other a fixed ratio which is kept constant, the body of air which is held at these
two pressures being confined in a closed system. It will be remembered that in
the common and well known machine for transmitting power by means of com-
pressed air, the air is drawn into the compressing engine from the open atmosphere,
after which it is compressed until its expansive force is sufficient to perform the
intended duty where the power is required. The compressed air, after acting on
the motor or engine where the power is applied, is exhausted back into the
atmosphere, thus falling again to the normal atmospheric pressure.
In our
improved apparatus we employ two air pressures, both above the atmospheric
pressure, instead of one increased pressure. and the ordinary atmospheric pressure
as in the common machine. And in our apparatus the air used is not drawn from
the atmosphere or exhausted thereinto during the operation of the apparatus after
it has once been charged, except for the incidental purpose of supplying the slight
loss occasioned through leakage, but the operations of the apparatus are performed
on a confined body of air shut off from communication with the external atmosphere.
We have a suitable driving apparatus or power device which actuates the air
compressor. This compressor is so constructed and works in such a way as to
create two pressures of air, both above the ordinary atmospheric pressure, one
being, for example, one hundred pounds to the square inch, and the other for
example, two hundred pounds to the square inch, the high pressure in this case
being double the low pressure, or the ratio as two to one. There is a system of
pipes provided with valves which pipes carry the air to the driven apparatus where
the compressed air is to do its work. The air circulates constantly between the
compressor and the motor passing through reservoirs or receivers if desired, and
in this driven machine the unequal air pressures will be on opposite sides
of the piston, thus leaving the piston unbalanced, and permitting it to move
in the ordinary way..
Hence in one part of this circulating system the air
is at one pressure, while in another part it is at another pressure, the air thus
being subject to constant change from one pressure to the other as it circulates.
This change takes place alternately, the air when at high pressure doing its work
in the motor, and then exhausting into the low pressure air and so continuing until
it again reaches the compressor and is re-converted into high pressure air. This
change of volume takes place with but little loss of power through heat, so that
efficiency in the operation of the machine is promoted.
C, denotes the main frame or bed of the machine, which may be of any suitable
and desirable form to permit the convenient arrangement thereon and therewith of
the several mechanical parts.
B, B', designate the two parallel cylinders of the air compressor. We preferably
use two, although there may be any number. The air compressor is driven by any
suitable means. Steam is the motive power in the example of mechanism illustrated
in the drawings. A, and A', denote the steam cylinders which are of any usual
pattern. The piston of cylinder, A, has piston-rod, a. Cylinder, A, is for the
sake of convenience located in line with the air cylinder, B, of the air compressor.
This latter cylinder has its piston provided with piston rod, b, which is in line with
the piston rod, a. Between the piston rods, a, and b, is the yoke, c, which is
firmly connected to both rods. The piston of cylinder, A', has piston rod, a'.
Cylinder, A', is for the sake of convenience located in line with the air cylinder, B',
of the air compressor. This latter cylinder has its piston provided with piston
rod, ', which is in line with the piston rod, a'. Between the piston rods, a', and ',

page_text: is the other yoke, c, which is firmly connected to both rods. The main shaft, D,
of the steam engine is carried horizontally in suitable bearings, D¹, D¹, on the
main frame, C. At each end of this main shaft are the crank discs, d, d, having
their crank pins set at right angles so that the engine may start when the con-
necting rods are in any position, to which are pivoted the connecting rods, F, F,
which are connected at their other ends at points within the yokes, c, c, (see
Figure 1). On the drive shaft, D, are also the band wheel, E, governor pulley, E',
and eccentrics, e, e, said eccentrics having the eccentric rods, ff, that are connected
to the valve rods, f², f2, belonging to the valves within the valve chests, f³, f³, on
the sides of the two steam cylinders, A, and A
The belt, e, passing around the governor pulley, E', runs also over the pulley, g, on
the shaft of the ball governor, H, see Figures 1 and 2, which is of any common and
well known construction for a steam governor, and which serves the usual purpose by
controlling a valve in the steam pipe, H', which runs from the boiler to the steam
cylinders, passing on its way through the air governor as shown in Figure 1, the
construction of which air governor will be presently explained. The ball governor
is used to avoid accidents in case anything happens to the air governor, and is of
course properly adjusted for this purpose. We have thus given a summary
description of the steam engine which in the present example of our invention we
have arranged for driving the air compressor. It will be understood, and we here
emphatically state, that said compressor may be operated by any motor, if desired,
as well as by a steam engine. Therefore the engine herein shown and described is
simply given as one convenient type or form of mechanism for the purpose.
We will now proceed to describe the construction of the mechanism for com-
pressing the air in such a manner as to produce the two unequal air pressures, both
above the normal atmospheric pressure, which we have already above alluded to as
being the foundation idea of the invention. B, and B', represent as we have seen,
the two air cylinders within which are the pistons, B2, one of which has the piston
rod, b, and the other the piston rod, b'. By referring to Figures 4, 5, 6 and 7, the
construction of these air cylinders will he clearly seen. They are constructed
similarly. B³, denotes the bore of the cylinder within which the compressing
piston, B2 is fitted and wherein it operates. This bore is preferably surrounded
with a water jacket, h, for the purpose of keeping the parts from becoming heated
during the operation of compressing the air. The cylinders are provided at each
end with hollow heads, B, B, which are bolted or otherwise firmly secured to the
main body of the cylinder, as shown in Figure 6.
Each of the hollow heads, B', is divided by a vertical partition, I,-see Figure 5-
into two compartments, and in the main body of the cylinder above the water
jacket, h, are two horizontal channels, J, and J', divided by a longitudinal partition
or wall exactly in line with the partitions, I, I, in each head, so that the chambers
in the heads in conjunction with these channels, J, and J', which communicate
therewith, form two separate and distinct longitudinal compartments.
The bore, B³,
bas the heads, h', ', which constitute the inner vertical walls of the hollow
heads, B4, being an integral part thereof, each of which heads or walls, h', is
provided with four openings-see Figure 5-two of which lie on one side of the
partition, I, and two on the other side. At each of these openings a valve is
arranged. The hollow heads are of sufficient size to contain the mechanism of these
valves, as shown. There are therefore four valves at each end of the cylinder
bore, B³, and two of these four open inwardly into the bore, as suction valves, while
the other two open outwardly from the bore as discharge valves, a pair of suction
valves being on one side of partition, I, and thus between one of the longitudinal
compartments and the bore, B³, of the cylinder, and a pair of discharge valves being
on the opposite side of the partition and thus between the other longitudinal com-
partment and the bore of the cylinder, it being noted furthermore that one compart-
ment of the air cylinder, which we term the "low pressure compartment" because
it contains air at the lower of the two unequal pressures already spoken of, is
provided with four valves on the ends of the bore, which valves are all suction

page_text: valves; and also that the other compartment of the air cylinder which we term the
"high pressure compartment "because it contains air at the higher of the two
unequal pressures already mentioned, is provided with four valves on the ends of the
bore, which valves are all discharge valves, and permit the compressed air to be
discharged through them from the bore into the high pressure compartment; or, as
it may be otherwise stated, each end of the bore is furnished with four valves, two
suction and two discharge, the suction serving to admit air to the cylinder to be
compressed, and the discharge to allow the exit of the air after compression, all of
said valves opening so as to establish proper communication with the respective
compartments.
A
Proceeding now to describe more minutely the specific construction of these
valves so as to show one way in which they may be built, it being evident of
course that the structural details may vary greatly in practice, we see that at
each of the openings in the bore ends,, ', a valve casing, i, is screwed horizontally
into the head. The casings, i, which belong to the discharge valves are perforated
with a suitable number of openings,, . The casings, i, which belong to the suction
valves are preferably imperforate but open-ended. In the suction valves, one of
which is shown in detail at the left in Figure 4, a stationary tubular casting, j, is
supported by a vertical perforated diaphragm within the valve casing, i, in
such a manner as to leave an annular space between the casting and the casing.
k, indicates the valve having an inclined seat and adapted to open inwardly
into the bore, B³. The valve stem, k¹, of valve, k, lies horizontally within the
tubular casting, j. On the outer end of stem, k¹, is a nut, j', having a flange
thereon and likewise a jam-nut or collar, ³, secured in place by a pin.
coiled spring, ², surrounds the casting, j, and is tensioned between the flange on
nut, j, and the diaphragm which supports the casting in position. The spring is so
arranged as to normally keep the valve closed, but when the pressure on the other
side of the valve in the bore, B³, falls below the pressure in the valve casing, plus
the slight power of the spring, the valve will open, overcoming the resiliency
of the spring and compressing the same, and thus permitting the air to pass
through the valve. Air enters the suction valve as will be seen, through the
annular opening at one end of the valve casing. The discharge valves have a
slightly different construction. The casing, i, of these valves is perforated,
as we have seen. A casting, 1, lies within the perforated casing so as to leave
an annular space, the outer part of this casting being enlarged and screw-threaded
for screwing into the outer end of the valve casing. I, denotes the valve having
the stem,, which lies within a horizontal passage in the casting, ", the seat of
the valve being beveled, and the valve designed to open outwardly from the
bore. A spring, 12, is coiled around the casting, l, bearing at one end against
the valve, %, and at the other end against a shoulder on said casting. Hence,
when valve, l, opens, the spring is compressed, and said spring serves to close
the valve at the proper time. Obviously, when the pressure within bore, B³,
against the face of the valve, l, is greater than the air pressure within the valve
casing and adjacent compartment plus the slight power of the spring, the
discharge valve will open and allow the passage of air out of the bore, B³.
From the foregoing description of the construction and location of the suction
and discharge valves, it will be evident that when the piston, B³, moves to the
right in the direction of the arrow as shown in Figure 4, the two suction valves in
its rear which lead from the low pressure compartment of the cylinder, will in
consequence of the vacuum created in the rear of the moving piston, be opened to
permit air to flow in behind the piston, said inflowing air being either of atmospheric
pressure or of a higher pressure as the case may be. The two discharge valves
in the rear of the piston which communicate with the high pressure compartment
of the cylinder are at this time closed, while the two suction valves in front of the
moving piston will be closed, the air being compressed against them, but the two
discharge valves which lead into the high pressure chamber in front of the moving
piston, will, when the air is compressed against them, be opened, allowihe air

page_text: at a higher pressure to enter the chamber of higher pressure. When the compressing
piston reverses its movement, a similar operation will take place, the air now
entering through the other two suction valves, while the air in advance of the
piston is delivered in a compressed condition into the high pressure chamber through
the other pair of discharge valves.
The upper side of the air cylinder, B¹, is entered by a vertical pipe, K, which
discharges air into the channel, J, that connects the two head chambers, which
taken together and in conjunction with said channel, J, constitute the low pressure
compartment of the air cylinder. (See Figures 3 and 4.) The upper side of the
air cylinder is also entered by another vertical pipe, G, which receives air from the
channel, J', that connects the two head chambers, which, taken together and in
conjunction with said passage, J, constitute the high pressure compartment of air
cylinder, B. The pipe, K, has a short horizontal branch pipe, K', which is
The
provided with a valve, K³, said branch pipe, K', opening into the atmosphere.
pipe, K, is therefore an air induction pipe for delivering air to the cylinder, B', and
the pipe, G, an air eduction pipe for withdrawing and carrying air from the said
cylinder, the former being a low pressure pipe, so called, and conveying air of
atmospheric pressure (or of the lower of the two unequal pressures, as the case may
be) into the cylinder, while the latter is a high pressure pipe, so called, and conveys
compressed air away from the cylinder. When the valve, K2, is open, and the
apparatus is being charged, the function of pipe, K, is to deliver atmospheric air
to the cylinder, but after said valve has been closed and the valve, m, has been
opened, then the pipe, K, serves to deliver to the air cylinder, air at a certain
lower pressure, but above the atmospheric pressure, while the pipe, G, serves to
carry from the cylinder compressed air at a certain higher pressure than the
air in the induction pipe, the air in the two pipes being thus of unequal pressures.
The other cylinder, B, is suitably entered by induction and eduction pipes.
L, denotes the induction or low pressure pipe, situated vertically above cylinder, B,
and entering through the upper side of the cylinder into the channel that forms
a part of the low pressure compartment of the cylinder. M, denotes the eduction
or high pressure pipe located vertically above the cylinder, B, and entering through
the upper side of the cylinder into the channel that forms a portion of the high
pressure compartment of this cylinder. The pipe, L, has a short horizontal
branch, L', which is provided with a valve, L³, said branch pipe, L', opening into
the atmosphere in the same way as the pipe, K. It will be readily seen that the
The
function of the pipes, L, and M, is the same as that of the pipes, K, and G.
pipes, L, and K, having a similar function (being both low pressure pipes) are
connected together by the horizontal pipe, L³; and likewise the pipes, G, and M,
having a similar function (being both high pressure pipes) are connected together
by the horizontal pipe, G. The pipes, K, and M, being the main low and high
pressure pipes, extend upward vertically for some distance or as far as may be
necessary. They are connected together at one point by a horizontal pipe, N, see
Figure 3, having therein a valve, N', adapted to be operated by hand, and at a
point above pipe, N,, the pipes, K, and M, are connected by another horizontal
pipe, O, which is provided with an automatic valve, O'. The pipe, O, is only used
at certain times, as will be hereinafter related. At the upper end of the low
pressure pipe, K, a pipe, P, is connected thereto which runs from the motor or
driven apparatus where the power is applied to the work and also at the upper end
of the high pressure pipe, M, a pipe, P, is connected thereto, which likewise leads
to the driven apparatus, said pipe, P¹, conveying the high pressure air to said
apparatus, while the pipe, P, carries the low pressure or exhaust back from said
apparatus, and assists in returning it to the compressor. The low pressure pipe, K,
is provided at a suitable point with a gauge o, for indicating the pressure in the pipe,
and also with a safety valve, p, for relieving any undue or dangerous pressure, and
likewise the high pressure pipe, M, is provided with a gauge, o¹, and a safety
valve, p. In the low pressure pipe, K, at a suitable point above where the

page_text: horizontal pipe, L³, is coupled thereto is a valve, m, the function of which will
be stated in describing the operation.
In Figures 10, 11, 12, 13, 14, 15, 16, and 17, we have represented an example
of driven apparatus or machinery located at a point distant from the compressing
machinery, the pipes, P, and P¹, running between said driven machine and compressor.
This driven machine may obviously be of any kind and for any purpose or work,
such as a common engine, a rock drill, pump, or any other machine.
In the present
example the driven machine is a rock drill, and we will therefore proceed to
describe its construction and the way in which the two air pressures operate
thereupon.
A², denotes the cylinder of this drilling machine, B, the feed screw having the
operating crank handle, B, C³, a valve chamber on the side of cylinder, A²;
E³, the piston within the cylinder, A2, having piston rod, F³, which is adapted to
have the drill connected thereto, G³, a rod which carries at its outer end the ratchet
wheel, G, which is engaged by the spring pawls, g³, g³, said rod, G³, entering a
central longitudinal socket in the piston, E³, and being provided on its surface with
spiral grooves that are engaged by tongues on the nut, a', which is screwed into
the end of the piston, the said grooves and tongues being indicated in Figure 14,
and all of these parts being so arranged and related that on the down stroke of
the piston the ratchet will be fed forward while on the return or up stroke of the
piston the ratchet will stand still but the engagement of the nut with the spirally
grooved rod, G³, will serve to partially rotate the drill.
The high pressure conduit, P', which conveys air at the higher of the two
unequal pressures, and the low pressure conduit, P, which conveys air at the lower
of the two unequal pressures, which conduits we have seen are connected suitably
to the compressor, (see Figures 2 and 3) are likewise suitably connected at proper
points to the drilling machine-see Figures 10, 11, and 13-the pipe, P¹, entering
the side wall of the drill cylinder and the pipe, P, being connected to the valve
chamber, C³, and said pipes or conduits, P, and P₁, being provided respectively
at points near where they enter the drill mechanism with valves, P4, and P³, by
means of which the quantity of the air supply can be regulated. In the present
example of the invention we will suppose that the low pressure air has a pressure
of one hundred pounds to the square inch, and the high pressure air a pressure of
two hundred pounds to the square inch.
By referring to Figure 15, it will be seen that air enters through the high
pressure pipe, P', into the cross passage, 63, and thence into the high pressure
port, H, formed in the barrel of the cylinder, said port, H', having communication
at one end with the valve casing, C³, and at the other end with the bore of the
cylinder, as will be seen by observing the direction of the arrows in Figure 10.
Therefore the air on the right hand side of the piston as it appears in Figure 10
which in actual practice is the lower end of the piston, is always high pressure air.
By observing the piston, E³, it will be noted that the two ends thereof are of
unequal area. The right hand or lower end where the piston rod, F³, starts from
the piston is an annular surface, all the central portion of the piston end being
occupied by the rod, F³, so that the air can only act against the annular or rim face
of the piston surrounding the rod, F³. The left hand or upper end of the piston,
however, exposes its entire area to the action of the air, for although the rod, G³,
enters a longitudinal recess in the piston, yet said rod is rifled or spirally grooved
in such a manner that the air can get through between the joints and hence the
air is allowed to act upon the entire surface of that end of the piston. This
inequality of areas permits us to use high pressure air on both ends of the piston
to give the impulse thereto, for when the high pressure air is acting upon the
right hand or lower end of the piston--although the area of this end is less
than that of the other end-yet since low pressure air will at this time be upon
the other end, the high pressure air will overbalance the low pressure air and
- the piston will move towards the back end of the cylinder, and when high

page_text: pressure air is upon the left hand end of the piston rod to impel the latter, it
will be able to do so, since the area of that end of the piston is so much greater
than the area of the other end of the piston, although the other end of the
piston is likewise in contact with high pressure air.
In the wall of cylinder, A³, is likewise a low pressure port, I², which enters the
end of the cylinder bore opposite where the high pressure port, H°, enters, and
which enters the valve chamber, C³, at a point near the port, H³. The port, I³,
is clearly seen in Figures 10, 11 and 14.
The valve chest, C³, contains the piston valve D³, which may be of any suitable
and ordinary construction. Said valve, D2, is adapted to connect or disconnect
the ports, I, and H. The valve, D2, is provided with a longitudinal passage, d²,
extending from end to end. C4, C4, denote the heads of the valve chamber. The
longitudinal passage, d³, has a side opening, d³, through which air can pass in the
direction of the arrow, as shown in Figure 10, from the interior of passage, d³,
sidewise into the interior of the valve chamber occupied by the low pressure air.
The purpose of the passage, d³, is to prevent violent concussion between the end
of the piston valve, D, and the head of the valve chamber when the valve is
shifted. When the valve shifts, the air between the end thereof and the head of
the valve chest will be compressed sufficiently to form a cushion for the movement,
since the said air will enter but slowly into the small opening at the end of the
passage, d², after which it escapes through port, d³, into the exhaust.
In the wall of cylinder, A2, is a long port, K*, see Figure 12, one end of which
enters the cylinder bore at k³, while the other end enters the valve casing, c³,
at k', near one of the casing heads, C. LA, denotes another long port which
enters the cylinder bore at 10, and also the other end of the valve casing, C³, at 17,
near the other casing head, C.
The piston, E³, is provided with the longitudinal passage, ², extending inward
from the right hand end of the piston and communicating with the annular recess, ¿³,
formed in the piston. The points k, and 16, where the ports, K, and L*, enter the
cylinder bore are not exactly in line with each other, but are located as indicated
in Figure 12, so that when the piston is at the right hand end of its stroke, it
will cover the port, K', while the annular recess, 3, is opposite to the port, LA,
and in communication therewith, and in the reciprocations of the piston it will be
observed that the port, K4, only becomes uncovered so as to be in communication
with the interior of the cylinder bore when the end of the piston passes it, while the
port, L, is in communication with the interior of the cylinder bore through the
annular recess, is, and the longitudinal passage, h2, whenever the said annular recess
is opposite the point, 18, as is shown in Figure 12.
We will now proceed to describe the operation of the air pressures in producing
the reciprocations of the drill piston. When the piston is at the right hand end
of its stroke, as shown in Figures 11 and 12, then the valve, D2, will be at the
right hand position as indicated in Figure 11, in which position the ports, I2, and H³,
are cut off from each other, said port, I2, being filled with low pressure air which
likewise fills the space at the left hand end of the piston and also a portion of
the space within the valve chamber, C³, there being obviously a communication
between the low pressure pipe, P, and that portion of the cylinder bore at the left
of the piston. The port, H³, is filled with high pressure air which is acting upon
the right hand end of the piston, hence the longitudinal passage, 1, the annular
recess, is, and the port, L, are full of high pressure air, and hence the air acting
upon the left hand end of the valve, D2, is high pressure air.
Port, K, is now closed as the piston covers it. This being the condition of
the parts and of the air it is evident that the pressure on the right hand end of
the piston is greater than the pressure of the low pressure air on the left hand. end
of the piston, and hence the piston will begin its reciprocations and move to the
other limit of its stroke. On its way the end of the piston will uncover the opening
of the port, K', which will admit high pressure air into said port and conduct it to

page_text: the right hand end of the piston valve, D², thus shifting said valve so as to place
the ports, I, and Hs, into communication with each other and therefore causing
high pressure air to be introduced into the port, I2, so as to enter the left hand end
of the cylinder bore and act upon the left hand end of the piston. This will cause
the pressure on the left hand end of the piston-it having the greater area-to
overbalance the pressure on the right hand end of the piston, and therefore the said
piston will reciprocate to the right or in a downward direction, the reverse of the
former reciprocation, until as it nears the limit of its stroke it closes the port, K,
and brings its recess, 2³, into communication with the port, L', whereby high
pressure air is carried to the left hand end of the piston valve and the valve is
again shifted so as to separate the ports, I, and H³, and allow the pressure on the
right hand end of the piston to overbalance the pressure on the left hand end, the
air on this latter end of the piston now being permitted to exhaust into the low
pressure, and this reciprocation of the piston in each direction will take place
continuously.in the manner just described.
In order to govern the two unequal air pressures that are generated by the
compressor, keeping them regular and constant and maintaining a fixed ratio to
each other, we provide what we call an air governor. This governor has two main
functions, first, to regulate the speed of the compressor with relation to the work to
be done by the driven machine, i.e., to proportion the speed of the compressor so
that any amount of work may be done that is required (within of course the limit
of the capacity of the machine), and second, to maintain the desired ratio between
the pressures in the circulating pipes.
n, n', designate two pipes leading from opposite ends of the pipe, N, or one
leading from high pressure pipe, M, and one leading from low pressure pipe, K, said
pipe, n, being the one that leads from low pressure pipe, K, and is filled with low
pressure air, while said pipe, n', is the one leading from high pressure pipe, M, and
is consequently filled with high pressure air. The course of the pipes, n, and n', is
seen in Figures 1 and 2. The construction of the air governor is seen in detail in
Figures 8 and 9. At the upper end of the governor is a vertical cylinder, Q, con-
taining a trunk piston, Q', having a certain area. This cylinder we preferably term
the low pressure governor cylinder, because it is at that end of the governor where
the low pressure pipe, n, arrives, and hence low pressure air acts upon piston, Q. The
cylinder, Q, above the piston, Q', is filled with oil or some lubricant, and the upper
end of the cylinder is provided with a projecting pipe, n³, through which the
lubricant is fed into the cylinder when needed. This pipe, n³, is entered by the low
pressure pipe, n, and therefore, speaking in strictness, the low pressure air acts
against the lubricant instead of against the piston, but the surface is of the same
area and hence the result is the same. Between the upper head of cylinder, Q, and
the piston, Q¹, is a spring, g, immersed in the lubricant, which spring allows the
valve to open and close gradually and cushions the movement. Furthermore, it
will be noted with respect to cylinder, Q, that its lower end is provided with an oil
drip pipe, ², to receive any oil that may possibly leak between the piston and
cylinder. At the lower end of the governor is another cylinder, R, containing a
trunk piston, R³, having a certain area less than the area of piston, Q. This
cylinder we preferably term the high pressure governor-cylinder, because it is
situated at that end of the governor where the high pressure pipe, n', arrives, and
hence high pressure air acts upon the piston, R. The lower end of the cylinder, R,
is filled with lubricating liquid, inserted therein through the bent pipe, n², the upper
end of which is higher than cylinder, R. This pipe is entered by the high pressure
air pipe, n', and therefore speaking more accurately, the pressure of the air is
exerted directly upon the oil or lubricant, instead of upon the piston, R¹, but the
result is the same. Between the upper cylinder, Q, and the lower cylinder, R, is a
hollow valve chamber, H2, through which the steam pipe, H', passes. Said valve
chamber, H2, is secured to cylinder, Q, by the vertical bolts, r, r, passing through
flanges on the cylinder and on the chamber. It is also connected to cylinder, R,
:

page_text: by the vertical bolts, r³, r², which pass through suitable flanges on the valve casing
and on the cylinder, R. In this way the two cylinders and the valve casing are
firmly fastened together in such a manner as to leave a convenient space between
the valve casing and each cylinder, the bolts or rods, r, r, and ¹, r., being long
enough to permit of this.
S, indicates a yoke having a general oval form and surrounding loosely the valve
chamber, H2, the upper end of the yoke being in suitable proximity to the bottom
of the cylinder, Q, while the lower end of the yoke is near to the upper end of the
cylinder, R.
T, denotes a short bar or rod, the upper end of which enters loosely a socket in
the lower end of the piston, Q', said bar passing through the bottom of cylinder, Q;
while the lower end of the bar or rod, T, enters loosely a socket in the top end of
yoke, S. This rod, T, is held in place by the downward pressure of the piston, Q¹.
Another rod or bar, T', has its upper end received loosely into a socket at the
bottom of the yoke, S, while its lower end loosely enters a socket, in the piston, R',
belonging in the high pressure cylinder, R. The rod, T', is held in place by the
upward pressure of the piston, R. Near its upper end the yoke, S, is provided with
a cross connection, s, having a nut which holds the screw-threaded end of a valve
rod, s'. This rod carries the valve, H³, at its lower end within the steam pipe, H¹,
said valve being of any suitable and preferable construction, and arranged to
graduate the flow of steam through the steam pipe from the boiler to the engine in
proportion to the amount of work to be done, and also to control the flow whenever
it may be necessary to thus cut off or graduate the amount of steam and thereby
govern the speed of the engine and compressor. Said valve operates automatically.
We will now detail the operation of this governor device. It keeps the ratio of
the air pressures constant, and controls the speed of the compressor in proportion
to the amount of work to be performed. Its function is not to maintain a uniform
speed under all circumstances, as is the case with the ordinary steam engine
governor, but our air governor is designed to automatically vary the speed of the
compressor to suit the work being done by the driven machine, and the speed of
the compressor is of course controlled by varying the speed of the motor machine,
which in the present example is the steam engine. Thus one kind of driven device,
such as one rock drill, may require a certain number of revolutions of the steam
engine per minute to actuate the compressor sufficiently to transmit the required
power to drive said drill. Obviously two of these drills will require twice as many
revolutions of the actuating engine to drive them. The air governor automatically
varies the steam supply so as to control the speed of the engine and enable it to
perform the required duty. Likewise the said governor keeps the ratio of pressures
constant.
If at any time the compressor runs faster than is necessary so as to compress
more air than is required to drive the driven machine, the pressure in the high
pressure pipe will increase and that in the low pressure pipe will diminish and the
variation of pressures influences the air governor so that it tends to lessen the
speed of the compressor and restore the normal ratio of pressures.
On the other hand, if at any time the compressor is running slower than is
necessary to compress air as fast as the driven device requires, the pressure in the
high pressure pipe will decrease and that in the low pressure increase, and this
variation of the ratio acting on the air governor tends to increase the speed of the
compressor and restore the normal ratio of pressures. When the same conditions
of work to be done, obtain, the air governor keeps the ratio of pressures constant
by regulating the speed of the motive power and keeping it constant, so long as the
conditions of work do not change. When the conditions of work vary through
inequalities in the rock or a multiplication of the drilling devices (supposing the
driven device to be a drill) then the air governor operates upon the motor engine
and automatically changes and proportions its speed to conform to the change in
the work and make it capable of doing more or less work as may be required,
maintaining all the while a constant work. Evidently increase of work to be done
B

page_text: will lessen the amount of high pressure, air, thus causing the valve to open
wider and the engine to run faster to supply the required amount of high
pressure air.
The areas of the two pistons, Q1, and R', have the same ratio as the air
pressures. Thus, if the "high pressure" air is two hundred pounds to the square
inch, and the "low pressure" air is one hundred pounds to the square inch, the
area of piston, Q', will be twice the area of piston, R', since the pressures upon one
inch of surface of piston, R', will be balanced by the pressure upon two inches of
surface of piston, Q. In this case therefore, when the pressure in pipe, n, is one
hundred pounds and the pressure in pipe n', is two hundred pounds, these pressures
will exactly balance each other in the governor, and the pistons and other parts
will remain in equilibrium.
When the governor is in this condition the parts may be adjusted up or down by
hand and (but for the spring, 9) would remain in any position where they might be
placed. The spring, 7, however, is interposed above the piston, Q', so as to add a
little excess of pressure to that end of the governor and disturb what would
otherwise be an equilibrium sufficiently to keep the valve, H³, normally open,
although the spring, 7, is of slight power and readily overcome by any slight
increase in the high pressure air. The spring is further advantageous in allowing
a gentle motion in the parts of the governor. It cushions the end of the piston
and prevents the shock which might take place when a change of ratio suddenly
occurs and disturbs the equilibrium. The present example of governor is described
simply as an example. Especially is this true with respect to the areas of the
pistons, Q, and R'. These areas vary of course in different governors, where
different ratios between the air pressures than that of two to one are employed in
the apparatus.
In order to change the ratio of pressures without altering the pistons, weights
may be hung upon the yoke, S, at the perforations, S¹.
We will now explain the operation of the main compressing apparatus.
Referring to Figures 2 and 3, we will first describe the operation when cross
pipe, N, having valve, N¹, is used, and cross pipe, O, is supposed to lie idle or is
removed from the apparatus. First the valves, K2, and L2, will be opened to
admit atmospheric pressure air into the pipes, L', and K', and hence into the
compressing cylinders. The valve, N', will also be opened, usually by the hand of
the operator, it being non-automatic, and the valve, m, closed. Then the com-
pressor will be set to work and air will be drawn from the atmosphere into the
compressing cylinders, compressed therein, and sent through the pipes, G, M, N, K,
above valve, m, pipe, P and P¹. The compressed air in the entire system will of
course be now at the same pressure and a like degree of pressure will be indicated
on both gauges, that belonging to the high pressure pipe and that belonging to the
low pressure pipe. The operation of compressing will be continued until both
gauges register, say one hundred pounds, supposing this to be the amount of the
lower of the two unequal pressures. Then the operator will close valve, N'. This
will separate the system of low pressure pipes from the system of high pressure
pipes, leaving the pressure in the former system fixed permanently at one hundred
pounds. The operation of the compressor will continue until the air in the high
pressure pipes has attained a pressure of two hundred pounds, when the inlet
valves, K, and L², will be closed by hand, preventing the admission of any more
air, and the valve, m, will be opened by hand allowing air at a pressure of one
hundred pounds to be delivered to the compressor cylinders.
We have now our closed system wherein the air circulates between the compressor
and the drill or other driven machine. The air in one part of the apparatus is at
one hundred pounds pressure as will be seen from one of the gauges, and the air in
the other part of the, apparatus is at two hundred pounds pressure, as will be seen
on the other gauge. Here then are the two unequal pressures of air, both above
the atmospheric pressure, the ratio of the pressures being as two to one, which ratio
is kept constant by means of the air governor, and this governor is found in actual

page_text: practice to do its work so perfectly that hardly any fluctuation of the ratio is
perceptible upon the gauges or indicators with which the apparatus is provided.
It will be noted that no atmospheric pressure air is drawn into the machine during
its operation. The compressor always works upon air at one hundred pounds
pressure instead of upon air at atmospheric pressure. To supply any trifling
leakage that may take place we provide a little air pump, U, see Figure 1, which
may be of any suitable and ordinary construction and which delivers into the low
pressure pipes at some suitable point.
We will now briefly describe the operation when the cross pipe, O, having the
automatic valve, O₁, is made use of. In this case the pipe, N, serves no necessary
purpose, although the valve, N', might be left open until all of the pipes are filled
with air at one hundred pounds pressure, but lies idle with the valve, N', closed,
and also the air governor is not used, but the valves in the air pipes, n, and n¹,
In
running to the governor (said valves are shown in Figure 1) are closed.
starting the apparatus the valves, K2, and L2, will be open and the valve, m, closed.
The valve, will likewise be closed. This valve is constructed to operate
automatically, and is so arranged that it will open only when the pressure on one
side of it is one hundred pounds greater than the pressure on the other side. Of
course it may be adjusted for other pressures, but in the present example we
suppose it to open at one hundred pounds pressure on one side above that on the
other.
As the operation of compression proceeds the high pressure pipes will be filled
with air, having a pressure of one hundred pounds before any air will enter the low
pressure pipes. As soon as the pressure against the sides of the valve, O', attains
one hundred pounds, the valve will open and permit air to
pressure pipes. As the compression continues, the air in the sinto the low
pressure pipes
will finally stand at one hundred pounds and the air in the high pressure pipes at
two hundred pounds. The compression may continue beyond this if desired, but
probably it will not be. Then the valves, K² and L2 will be closed and the
valve, m, opened, and so we again have our closed system of pipes within which the
air circulates constantly, one gauge standing at one hundred pounds and the other
at two hundred pounds when the ratio is one to two.
This automatic valve arrangement which we have just described is used only in
certain cases, chiefly when the compressor is driven by a belt from some motor
shaft which actuates other machinery, which machinery it is necessary to drive
with a steady uniform motion and so the motor shaft cannot have its speed varied,
and hence an air governor cannot be used, and therefore the automatic valve
serves the purpose and keeps the difference of the pressures constant.
This
It will be noted that this arrangement with pipe O, having valve O',
accomplishes a different result from that accomplished by the air governor, in that
while the air governor serves to keep the ratio of the two unequal air pressures
constant, this automatically operating valve serves simply to keep the difference
of the pressures constant, in other words it may be said that the automatic valve
serves to regulate the arithmetical ratio of the two pressures while the air
governor serves to keep the geometrical ratio of the two pressures constant.
is an important difference when we come to look at the result that is accomplished.
Although this arrangement with pipe, O, is generally used with belt machines
and not in connection with the first arrangement, yet it may be made use of in
connection therewith if at any time the air governor should become disabled, and
we make no special claim to novelty in the arrangement of the pipe O, with its
regulating valve, but simply include the same herein to more fully explain the uses
and adaptation of our improved machine.
Numerous advantages accrue from the use of the invention herein described, a
few of which it may be well to enumerate here, in order that the importance of
the invention and the great utility in employing two unequal air pressures both
above the atmospheric, may be clearly understood and appreciated.
Among the resulting benefits we will first mention that our machine for

page_text: transmitting power by means of compressed air is much smaller and more compact
and therefore cheaper, easier of transportation and very much lighter in weight
than the machines now in use for doing a corresponding amount of work. This
statement is easily proved by a simple calculation. Suppose it is desired to
provide a cubic foot of air having a pressure of one hundred pounds, at one stroke
of the piston. Obviously if air at atmospheric pressure or fifteen pounds pressure
is to be compressed to this required pressure, the original volume of atmospheric
air will be seven cubic feet or thereabouts, i.e., seven times the volume of the
required volume at one hundred pounds pressure. If air at fifty pounds pressure
is to be compressed to the pressure of one hundred pounds two cubic feet of the
former will be required to make one of the latter.
In the ordinary air compressor, air is received into the machine at atmospheric
pressure, and hence the cylinder must contain seven cubic feet in order that the
atmospheric air may at one piston stroke be compressed to a cubic foot of one
hundred pounds pressure. Suppose it is desired to work the ordinary air
compressor with an unbalanced pressure of one hundred pounds. In order that it
may do this air must be compressed to one hundred and fifteen pounds on one side
of the piston and fifteen pounds or atmospheric pressure on the other side of it.
In our apparatus after it is charged, the air is delivered to the compressor at
one hundred pounds pressure. Therefore if it is desired to obtain a cubic foot of
air having two hundred pounds pressure which in our machine will give an
unbalanced pressure of one hundred pounds to work with, the cylinder needs to
contain only two cubic feet of one hundred pound air. Hence, where a cylinder
in our apparatus requires a cubical contents of two cubic feet, the cylinder in the
ordinary compressor apparatus requires a cubical contents of seven or eight cubic
feet in order to effect the same compression at one stroke.
This makes manifest
the essential difference in respect of size between the two machines, said difference
being dependent upon the fact that in one case the compressor operates upon
atmospheric pressure air, while in our compressor it acts upon air having already a
very high pressure, and this therefore demonstrates the value of our invention in
making a small, compact machine, which is found in practice to have less than
half the weight of certain other popular machines doing a similar work.
Another advantage accruing directly from our invention is an increase in
efficiency. This may be proved by another simple calculation, as follows:-When
a volume of air is compressed to one half, a certain amount of the energy
generated is lost through the heating of the air and the consequent dissipation of
energy in the form of heat.
When a volume of air is compressed to one-third, a
certain greater amount of power is lost through heat. When therefore, a volume
of air is compressed to one-seventh, as is the case when atmospheric pressure air is
converted into air having a pressure of one hundred and fifteen pounds to the
square inch so as to give an unbalanced pressure of one hundred pounds, a very
much greater amount of power is lost through the dissipation of heat energy than
is the case when the air is compressed to half its volume, as in our machine, where
air at a hundred pounds pressure is compressed to two hundred pounds so as to
give the same unbalanced pressure of one hundred pounds. Therefore it will be
seen that we lose very little power from heat and hence increase the efficiency of
the machine very greatly. It is found in actual practice which also is confirmatory
of theoretical calculations on the subject, that a very much greater per cent. of the
power generated at one end of the machine is applied to the work at the other
end of our machine than is the case with any other with which we are familiar.
Other advantages belonging to our invention might be referred to, but it is
deemed unnecessary as the two which have just been described are sufficient to
indicate the importance of our improvement.
Numerous details in the construction and relative arrangement of the parts of
the machine herein described, may be made without departing from the invention,
and we reserve the liberty of varying the same as experience may suggest within
wide limits..

page_text: 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 a machine of the class described in which the power is transmitted by
means of compressed air or other gas circulating in a closed system at two
unequal pressures both above normal atmospheric pressure, the combination of a
compressor, a machine to be driven by the power thereby generated, an air
conduit between the compressor and driven machine containing air at a certain
lower pressure and another air conduit between the compressor and the driven
machine containing air at a certain higher pressure, and means for keeping the
geometric ratio of the two pressures constant.
2. In a machine of the class described in which the power is transmitted by
means of compressed air or other gas or fluid circulating in a closed system at
two unequal pressures both above normal atmospheric pressure, the combination
of a compressor, a machine to be driven thereby, two air conduits between the
compressor and the machine containing air at the unequal pressures and a
governor for keeping the geometrical ratio of the two pressures constant and
regulating the speed of the compressor in proportion to the work to be done by
the driven machine.
3. In a machine of the class described in which the power is transmitted by
means of compressed air or other gas circulating in a closed system at two
unequal pressures both above normal atmospheric pressure, the combination with
a compressor, a driven machine, air conduits between the compressor and driven
machine, of an inlet valve for admitting atmospheric air to the compressor in
charging, a valve in the low pressure conduit adapted to be closed in charging
and a connection between the two conduits provided with a valve adapted to be
operated by hand to make, a temporary communication between said conduits
during the operation of charging.
4. In a machine of the class described in which the power is transmitted by
means of compressed air or other gas circulating in a closed system at two
unequal pressures both above normal atmospheric pressure, the combination of a
compressor, the driven element, air conduits between the compressor and driven
element, an inlet valve for admitting atmospheric air to the compressor in
charging, a valve in the low pressure conduit adapted to be closed in charging,
a connection between the two conduits provided with a suitable hand valve
whereby the operator in charging may temporarily establish communication
between the conduits and an air governor for keeping the ratio of the. two
pressures constant and for regulating the speed of the compressor in proportion
to the amount of work to be performed by the driven machine together with
suitable connections between the air conduits and the governor.
5. In a machine of the class described in which the power is transmitted by
means of compressed air or other gas circulating in a closed system at two
unequal pressures both above normal atmospheric pressure, the combination of
the compressor, a motor for actuating it, a driven element, two air conduits
between the compressor and the driven element containing air at two unequal
pressures, and a governor for keeping the geometric ratio between the two
pressures constant by regulating the speed of the motor which drives the com-
pressor and also for regulating the speed of the compressor in proportion to the
amount of work to be performed by the driven element.
6. In a machine of the class described in which the power is transmitted by
means of compressed air circulating in a closed system at two unequal pressures
both above normal atmospheric pressure, the. combination of a compressor, a
suitable steam engine for actuating the same, an element driven by the com-
pressed air, two air conduits or channels between the compressor and said
element containing air at unequal pressures, and an air governor for keeping the
geometric ratio between these two pressures constant, said governor controlling

page_text: a valve in the steam supply pipe of the engine, and thus regulating the speed of
the compressor so as to keep the ratio of pressures constant, sa'd governor
having also the function of proportioning the speed of the compressor to the
amount of work to be performed, substantially as herein described.
7. In a machine of the class described in which the power is transmitted by
means of compressed air or other gas circulating in a closed system at two
_ unequal pressures both above normal atmospheric pressure, the combination of a
compressor, an element to be driven by the compressed air, an air conduit
between the compressor and said element adapted to contain air at the lower of
the pressures, another air conduit between the compressor and the said element.
adapted to contain air at the higher of the two pressures, a suitable motor for
actuating the air compressor, an inlet valve for admitting atmospheric air to the
compressor in charging, a valve in the low pressure conduit adapted to be closed
in charging, a connection between the two conduits provided with a hand valve
whereby the operator during the process of charging up the apparatus may
temporarily establish a communication between said conduits, an air governor
containing two pistons whose areas have a ratio equal to the ratio between the
two air pressures, said governor controlling the speed of the motor which actuates
the compressor and discharging the double function of maintaining a constant
geometic ratio between the two air pressures and also proportioning the speed of the
compressor to the amount of work to be performed by the driven element, a low
pressure air pipe running from the low pressure conduit to the low pressure end of
the governor and a high pressure pipe running from the high pressure conduit to the
high pressure end of the governor.
.
8. In a machine of the class described in which the power is transmitted by means
of compressed air circulating in a closed system at two unequal pressures both above
the normal atmospheric pressure, the combination of a compressor, a suitable motor
for actuating it, an element to be driven by the power of the compressed air, two
air conduits between the compressor and the driven element containing air at
unequal pressures, an air governor having two pistons whose areas have the same
ratio as that between the unequal air pressures and having also a valve chamber
containing a valve which controls the supply pipe leading to the motor which
actuates the compressor, said valve being regulated by the movement of the
governor pistons, a low pressure pipe running from the low pressure conduit to
the low pressure end of the governor and a high pressure pipe running from the
high pressure end of the conduit to the high pressure end of the governor so that
the governor pistons may be balanced between the two pressures.
9. In a machine of the class described in which the power is transmitted by means
of compressed air or other gas circulating in a closed system at two unequal
pressures, both above normal atmospheric pressure, the combination of a compressor
having its cylinder or cylinders provided with a low pressure compartment and a
high pressure compartment, the low pressure compartment being provided with
suction valves which admit to the bore of the cylinder, and the high pressure
compartment being provided with discharge valves which lead from the bore of the
cylinder, an inlet valve for admitting atmospheric air to the compressor in
charging, a driven element, an air conduit between the compressor and the driven
element which contains air at the lower of the two pressures, another air conduit
between the compressor and said driven element which contains air at the higher
of the pressures, a valve in the low pressure conduit adapted to be closed in charging,
and a connection between the two conduits provided with a hand valve whereby the
operator during the process of charging up the apparatus may temporarily establish
a communication between the two conduits.
10. In a machine of the class described in which the power is transmitted by
means of compressed air or other gas circulating in a closed system at two unequal
pressures, both above normal atmospheric pressure, the combination of a compressor
having its cylinder or cylinders provided with a low pressure compartment having
suction valves leading into each end of the cylinder bore and provided also with

page_text: a high pressure compartment having discharge valves leading from each end of the
cylinder bore, a low pressure pipe entering the low pressure compartment of the
cylinder and running to the driven element, said pipe being provided with an inlet
valve to admit atmospheric air to the cylinder and also with a valve at a suitable
distance from the cylinder which is closed in charging, and a high pressure pipe
entering the high pressure compartment of the cylinder and running to the driven
element together with a connection between said pipes provided with a suitable
valve whereby the operator may during the operation of charging up the apparatus
temporarily establish a communication Letween the two conduits, and a governor
for keeping the ratio of the two unequal air pressures constant by regulating the
speed of the motor which drives the compressor and for proportioning the speed of
the compressor to the amount of work to be performed by the driven machine.
11. In a machine of the class described in which the power is transmitted by
means of compressed air, the herein described compressor consisting of a cylinder
or cylinders having the partitioned heads whose chambers are connected by channels
to form two compartments in the cylinder, a high pressure and a low pressure
compartment, both of said pressures being above normal atmospheric pressure,.
together with the suction and discharge valves at each end of the cylinder bore,
the suction valves entering the low pressure compartment and the discharge valves
entering the high pressure compartment said suction valves consisting essentially
of the cylindrical casing, the casting for supporting the valve stem, and the
spring, said suction valves opening inwardly into the cylindrical bore, and said
discharge valves consisting essentially of the cylindrical perforated casing, the
castings supporting the valve stem and the spring, and said discharge valves
opening outwardly from the cylinder bore, substantially as described.
12. In a machine of the class described in which the power is transmitted by
means of compressed air, the combination of the compressor having a cylinder or
cylinders provided with the partitioned heads, the channels communicating between
the chamber of said heads to form a low pressure and a high pressure compartment
within the cylinder, and the discharge and suction valves at each end of the
cylinder bore, said suction valves belonging to the low pressure compartment and
said discharge valves belonging to the high pressure compartment, said suction
valves having a casing, a casting supporting the valve stem and a spring, and said
discharge valves having a casing, a casting supporting the valve stein and a spring,
the suction valves opening inwardly into the cylinder bore, and the discharge
valves opening outwardly therefrom, a driven element, an air conduit running from
the low pressure compartment to said driven element, and the air conduit running
from the high pressure compartment to said element, the air in the two conduits
being of unequal pressures and maintained at a fixed geometric ratio by a governor
having the double function of keeping these pressures constant and of proportioning
the speed of the compressor to the amount of work to be performed by the driven
element.
13. In a machine of the class described in which the power is transmitted by
means of compressed air, the combination of a compressor consisting of a cylinder
or cylinders, having two longitudinal compartments a high pressure and a low
pressure the suction and discharge valves at each end of the cylinder bore, said
suction valves opening inwardly into the bore from the low pressure compartment
and said discharge valves opening outwardly from the bore into the high pressure
compartment, an element driven by the compressed air, an air conduit between
the compressor and said element containing air at a certain lower pressure, another
air conduit between the compressor and the element containing air at a certain
higher pressure, suitable valves for use in charging the apparatus and creating the
two unequal pressures and a device for keeping the ratio of the two pressures
constant and for proportioning the speed of the compressor to the amount of work
to be performed by the driven element.
14. In a machine of the class described in which the power is transmitted by
means of compressed air, the combination of the duplex compressor having two

page_text: cylinders, each provided with two compartments, a high pressure and a low
pressure, and suction and discharge valves on each end of the cylinder bore, the
discharge valves opening from the bore into the high pressure compartment, and
the suction valves opening into the bore from the low pressure compartment, low
pressure pipes entering the low pressure compartment of each cylinder, said
pipes being connected together, high pressure pipes entering the high pressure
_ compartments of each cylinder. said high pressure pipes being connected together,
one of said high pressure pipes being the main high pressure pipe and running to
the driven element, and one of the low pressure pipes being the main low pressure
pipe and running to said driven element, a valve in the main low pressure pipe,
and the connection between the main low pressure and main high pressure pipes
provided with a suitable valve adapted to be temporarily opened by the operator
during the process of charging up the apparatus so as to establish a communication
between the low pressure and high pressure air pipes, substantially as described.
15. In a machine of the class described in which the power is transmitted by
means of compressed air, the combination of the duplex compressor, the cylinders,
the engine for actuating the said compressor, low pressure pipes entering the low
pressure compartment of said cylinders, each of said low pressure pipes being
provided with an inlet valve to admit atmospheric air in charging up the apparatus,
the high pressure pipes entering the high pressure compartment of each cylinder,
one of said high pressure pipes being the main high pressure pipe and one of the
low pressure pipes being the main low pressure pipe, a valve in the main low
pressure pipe a driven element in communication with the main low pressure and
main high pressure pipes, a connection between these two pipes provided with a
valve, and a governor for keeping the ratio between the two unequal air pressures
constant at all times.
16. In a machine of the class described in which the power is transmitted by
means of compressed air, the combination of a compressor having a pair of cylinders,
a steam engine for actuating this compressor, a driven element adapted to be
operated by compressed air, the low pressure pipe, K, entering the low pressure
compartment of one cylinder provided with an inlet valve to admit atmospheric air
in charging, provided also with another valve and running to the driven element,
the low pressure pipe, L, entering the low pressure compartment of the other
cylinder, provided with an inlet valve for admitting atmospheric air and connected
with the low pressure pipe, K, by the pipe, L3, the high pressure pipe, M, entering
the high pressure compartment of one cylinder and running to the driven element,
the high pressure pipe, G, entering the high pressure compartment of the other
cylinder and connected with pipe, M, by the pipe, G', and the connection, N,
between the pipes, K, and M, provided with the inlet valve, N', substantially as
described.
17. In a machine of the class described in which the power is transmitted by
means of compressed air, the combination of a compressor having its cylinder or
cylinders provided with two longitudinal compartments, one of which is a low
pressure compartment and the other a high pressure compartment, the low pressure
compartment having suction valves at each end of the cylinder bore, and the high
pressure compartment having discharge valves at each end of the cylinder bore, a
driven element, two air conduits between the compressor and said element
containing air at unequal pressures and the governor for keeping the pressures at
a constant geometric ratio by regulating the speed of the motor which actuates the
compressor and for proportioning the speed of the motor to the amount of work to
be performed by the driven element.
18. In a machine of the class described in which the power is transmitted by
means of compressed air, the combination of a compressor, a driven element, an air
conduit in communication therewith and containing air at the lower pressure,
another air conduit containing the air at the higher pressure, a governor device for
keeping the ratio of these two unequal air pressures constant and for proportioning
the speed of the compressor to the amount of work to be performed by the driven

page_text: machine, together with an inlet valve for admitting atmospheric air to the
compressor in charging, a valve in the low pressure conduit adapted to be closed
in charging and a suitable hand valve in a connection between the two conduits.
whereby the operator during the process of charging the apparatus may temporarily
establish a communication between the conduits.
19. In a machine of the class described in which the power is transmitted by
means of compressed air, a compressor consisting of a cylinder or cylinders having
hollow heads, a water jacket surrounding the cylinder bore, two longitudinal
compartments within the cylinder, one adapted to contain low pressure air and the
other high pressure air, both pressures being above normal atmospheric pressure,
one compartment being entered by a low pressure pipe and the other by a high
pressure pipe respectively, which pipes communicate with a driven element and are
connected by a pipe provided with a suitable valve which is temporarily opened by
the operator during the process of charging up the apparatus and the suction and
discharge valves at each end of the cylinder bore.
20. In a machine of the class described, the combination of the drilling mechanism
with the two pipes or conduits containing air at two unequal pressures both above
normal atmospheric pressure, said air circulating in a closed system through said
pipes, the compressing device and the drilling mechanism and the two pressures
maintaining a fixed ratio to each other.
21. In a machine of the class described, a drilling mechanism operated by two
unequal pressures of air both above normal atmospheric pressure, a piston operated
by said pressures which maintain a fixed geometrical ratio to each other, and two
pipes or conduits containing the air at the two unequal pressures, the said air
circulating in a system closed against the external atmosphere through the pipes,
the drilling mechanism, and the compressing mechanism.
22. In a machine of the class described, the combination of the piston impelled
in each direction by the action of the higher of the two air pressures and two pipes
or conduits, one containing air at a certain lower pressure and the other air at a
certain higher pressure, the two pressures maintaining a fixed geometrical ratio to.
each other, both being above normal atmospheric pressure, and said air circulating
in a closed system through the conduits, the compressing mechanism and the drilling
mechanism.
23. In a machine of the class described operated by two unequal pressures of air
both above normal atmospheric pressure, a piston having high pressure air.
constantly on one end thereof and high pressure and low pressure air alternately
on the other end thereof, the impelling air on each end being always the high
pressure air.
24. In a machine of the class described operated by two unequal pressures of air
both above normal atmospheric pressure, a piston having unequal areas on each end
and having high pressure air constantly on one end thereof, and high pressure and
low pressure air alternately on the other end thereof, the impelling air on each end
being always the high pressure air.
25. In a machine of the class described operated by two unequal pressures of air,
both above normal atmospheric pressure, the combination of the cylinder, a piston
therein having unequal areas on its ends and having high pressure air constantly on
one end thereof, and high pressure and low pressure air alternately on the other end
thereof, the impelling air at each end being always the high pressure air, and a
suitable valve device for controlling the admission of high pressure air into that
end of the piston where the high pressure and low pressure air alternate.
26. In a machine of the class described operated by two unequal pressures of air,
both above normal atmospheric pressure, the combination of a cylinder having a
high pressure and a low pressure port therein, a piston having high pressure air
constantly on one end thereof and high pressure and low pressure air alternately
on the other end thereof, the impelling air at each end being always the high
pressure air, and the valve mechanism for regulating the inflow of air to that end
of the cylinder where the high pressure and low pressure air alternates.

page_text: 27. In a machine of the class described operated by two unequal pressures of
air, both above normal atmospheric pressure, the combination of the cylinder
having a high pressure and a low pressure port therein, a piston having unequal
areas on each end and having high pressure air constantly on one end, and high
pressure and low pressure air alternately on the other end, said piston having a
fongitudinal passage and an annular recess, and the valve casing and valve therein,
together with two ports leading from the cylinder bore to said casing and entering
the same at opposite ends.
28. In a machine of the class described operated by two unequal pressures of air
both above normal atmospheric pressure, the combination of the cylinder having a
high pressure port and a low pressure port, a piston in said cylinder having unequal
areas on its ends and having high pressure air constantly on one end thereof and
high pressure and low pressure air, alternately on the other end thereof, the impelling
air being always high pressure air said piston having a longitudinal passage
opening into the cylinder bore, and an annular recess with which said passage
communicates, the valve casing and the valve therein, and the two ports leading;
from the bore of the cylinder to the opposite ends of the valve casing.
29. In a machine of the class described, the combination of the cylinder having
high pressure and low pressure ports, a high pressure inlet pipe entering said
cylinder, a piston within the cylinder having high pressure air constantly on one.
end thereof, and high pressure and low pressure air alternately on the other end
thereof, said piston having a longitudinal passage and an annular recess, the valve
chamber and valve therein, the exhaust or low pressure pipe entering said valve
chamber and the two ports leading from the bore of the cylinder to the opposite
ends of the valve casing.
30. In a machine of the class described, operated by two unequal pressures of
air, both above normal atmospheric pressure, the combination of a cylinder having
high pressure and low pressure ports, a piston within said cylinder having.
unequal areas on each end and having high pressure air constantly on one end
and high pressure and low pressure air alternately on the other end, the valve
chamber and the valve device therein for controlling the admission of high
pressure air to that end of the piston where the high pressure and low pressure air
acts alternately, said piston having a longitudinal passage, substantially as described.
31. In a machine of the class described operated by two unequal pressures of
air both above normal atmospheric pressure, the combination of the cylinder
having the ports therein, the piston, the ports leading from the cylinder bore to
the valve chamber, the valve chamber and the valve within said chamber, said
valve having a longitudinal passage and a side outlet.
32. In a machine of the class described designed for operation by means of
two unequal pressures of air both above normal atmospheric pressure, the com-
bination of the cylinder having the ports therein leading into the cylinder bore
near opposite ends, the inlet pipe for admitting high pressure air to the cylinder,
the piston within the cylinder having a longitudinal passage and an annular
recess, the valve casing, the valve therein, the two ports leading from the cylinder
bore and entering said casing near opposite ends thereof, one of said ports being.
adapted to communicate with the annular recess of the piston at certain times
and the other port being adapted to be uncovered by the end of the piston at
certain times, substantially as described.
33. In a machine of the class described operated by two unequal pressures of
air, the combination of the cylinder having two ports entering the bore thereof
near opposite ends, the valve and its casing, the two ports leading from the
cylinder bore to the valve casing, and the piston with its longitudinal passage
and annular recess, together with the piston rod and the rifled rod entering the
longitudinal recess in the piston, the opposite ends of said piston being of unequal
areas and the high pressure air acting constantly on one end of the piston,
while the high pressure and low pressure air act alternately on the other end of
the piston.

page_text: 34. In a machine of the class described, the combination of the cylinder, the
feed screw and its handle, the valve chamber and its valve, the piston and its
piston rod together with the rifled rod entering the piston and carrying at its
other end a ratchet, the ends of said piston being of unequal areas and high
pressure air acting constantly on the end of lesser area and high pressure and
low pressure air acting alternately upon the end of greater area together with the
several ports and passages.
35. In a machine of the class described, the combination of the cylinder, the
piston having its ends of unequal areas, the valve chamber and its valves, the high
pressure air inlet entering the cylinder and the low pressure air inlet connected to
the valve chamber, high pressure air acting constantly upon the piston end of
lesser area, and high pressure and low pressure air acting alternately upon the
piston end of greater area, the impelling air being always the high pressure air,
together with suitable ports and passages, all arranged to accomplish the results,
substantially as described.
Dated this 4th day of August 1891.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.