AN IMPROVED COMPRESSED AIR MOTOR
Year: 1872

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine,
Lake, & Co., Patent Agents, Southampton Buildings, London, for
the Invention of "AN IMPROVED COMPRESSED AIR MOTOR."-A com-
munication from abroad by Louis Mekarski, of Paris, France,
Architect.
Sealed the 2nd May 1873, and dated the 9th November 1872.
PROVISIONAL SPECIFICATION left by the said William Robert Lake
at the Office of the Commissioners of Patents, with his Petition, on
the 9th November 1872.
I, WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co.,
Patent Agents, Southampton Buildings, London, do hereby declare the
nature of the said Invention for "AN IMPROVED COMPRESSED AIR MOTOR," a
communication, to be as follows:-
:-
The object of the said Invention is the utilization of compressed air in
motor apparatus of any desired power, and without producing shocks or
dislocations, the air being confined under a high pressure in reservoirs.
It permits the delivery of the air at a low pressure, differing to any

page_text: desired extent from that of the reservoir, and the variation of this
pressure according to the circumstances under which the work is per-
formed. The said apparatus consists essentially, first, of a pressure
reservoir V of tubular construction, in which the air is first forced under
high pressure (say 30 atmospheres); second, of a delivery reservoir U
with a regulating gauge, as herein-after described; third, of motor
mechanism of any suitable construction.
The delivery reservoir U communicates with the pressure reservoir
through the medium of the regulating gauge, and with the cylinder by
means of the ordinary distributing contrivances.
The special object. of the regulating gauge is to obtain in the
reservoir U, at the commencement of each stroke of the piston, a
pressure absolutely independent of the pressure in the reservoir V, and
that may be regulated as required. This contrivance is composed
essentially of a conical valve S and a piston P, mounted on the same
rod. The valve, whose point is turned toward the delivery reservoir
opens or closes the communication between the latter and the pressure
regulator. The piston P moves in a cylindrical chamber attached to the
delivery reservoir, and wherein its movement is limited. Upon the
exterior face of the piston is secured a spiral spring r, whose tension
may be regulated at will by means of a plate guided by a screw,
which is controlled by a handle m. The nut is camed by the aforesaid
cylindrical chamber.
The said machine operates as follows:-At first the pressure being H
in the reservoir V and one atmosphere in the reservoir U, the spring
moreover being free, the valve S intercepts all communication between
the two reservoirs. If now by means of the handle m the spring is
sufficiently compressed the valve S opens, and the pressure in U is
raised to the moment when the effort exerted upon the piston P becomes
sufficient to drive back the spring and close the admission aperture.
At this instant there will be in U a pressure absolutely different to the
initial and final pressure of V. This pressure h depends only upon the
proportions of the apparatus and the tension given to the spring. At
the first stroke of the piston the pressure diminishes in the reservoir U,
the valve S rises, the compressed air passes from V to U until h has
recovered its primitive value, if in the interval the tension of the spring
has not been varied. The same operation is repeated automatically at
each stroke of the piston. If now it is desired to augment or diminish

page_text: the work of the apparatus the spring is compressed or released more or
less, its tension measuring so to speak the pressure h. The employment
of the delivery reservoir with the regulating gauge permits of having
in the pressure reservoirs air confined at any desired pressure, and
decreasing in proportion to the delivery without affecting the working
of the motor.
This apparatus may be applied to tramway cars, automater carriages
of all kinds, machine tools, elevators, and the like; and it permits of
utilizing conveniently the power of watercourses, of tides, and of the
wind, whereby the compression of the air may be obtained more cheaply
than by steam.
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 8th May 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM,
ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Ninth day of November, in the year
of our Lord One thousand eight hundred and seventy-two, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Robert Lake, Her special
Licence that I, the said William Robert Lake, my executors, adminis-
trators, and assigns, or such others as I, the said William Robert Lake,
my executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "AN IMPROVED
COMPRESSED AIR MOTOR," a communication to me from abroad by Louis
Mekarski, of Paris, France, Architect," upon the condition (amongst
others) that I, the said William Robert Lake, my executors or admini-
strators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly describe and ascertain the

page_text: nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said William Robert Lake, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by
the following statement, reference being had to the accompanying
Drawing forming a part of this Specification:-
The object of the said Invention is the utilisation in motor engines of
any power without producing either shocks or dislocations of air confined
at high pressure in reservoirs. It permits the escape of the air at a
permanent low pressure, differing to any degree desired from that of the
reservoir, and also permits the variation of this pressure according to the
circumstances under which the work is performed. The said engine
consists essentially of the parts as shewn in Figure 1, that is to say,
first, in a pressure reservoir V of a tubular form, into which the air has
been first forced at a high pressure (30 atmospheres, for example);
second, in a distributing chamber U with a regulator herein-after
described; third, in an ordinary motor mechanism of any suitable
kind.
The distributing chamber U communicates with the pressure chamber
by means of the said regulator, and with the motor cylinder by ordinary
distributing mechanism.
The special purpose of the aforesaid regulator is to obtain in the
space U at the beginning of each stroke of the piston a given
pressure absolutely independent of the pressure in the reservoir V, and
which can be regulated at will according to the requirements of the
distribution. This regulator is essentially composed of two pistons or
plungers P, p, of different diameters, mounted upon the same rod. The
piston p moves in a chamber of the form of a thimble D, of which it
traverses the bottom in a leather packing. The nozzle a establishes a
permanent communication between the chamber D and the chamber V3
a partition, whose thickness is calculated to resist the difference of the
pressures exerted upon its two faces separates this chamber from
the reservoir or chamber U. A conical aperture o is formed in the
middle of this partition for the admission of the compressed air. The

page_text: communication is rendered intermittent by the play of the piston p,
terminated for this purpose by a conical base adjusted to the aperture o.
The second piston P has a larger section, and moves in the cylindrical
body C adjusted to the distributing chamber; it passes also into a leather
packing. A spring R acts upon the external face of this piston; the
tension of the spring may moreover be regulated at will by means of a
plate and a screw controlled by a winch. The screw nut is carried by
the cylindrical frame.
The apparatus works under the following conditions:-At the com-
mencement the pressure being H in the pressure reservoir or chamber,
and one atmosphere only in the distributing chamber, the spring more-
over being free, the communication may be considered intercepted between
the two chambers. If now the spring R has sufficient tension the piston p
repulsed in the exterior opens the orifice o; the compressed air enters
the chamber U, and the pressure h rises until. under the action of this
pressure the piston P forces the spring back again, and again closes the
admission aperture. At this instant there will be in the chamber U a
pressure different from the initial pressure H, and final pressure H'.in
the chamber V ; this pressure h depends only on the size of the apparatus
and the tension given to the aforesaid spring. At the first stroke of the
piston the pressure decreases in the chamber U, the valve S rises, the
compressed air passes from V into U until h has regained its primitive
strength (unless in the interval the tension of the spring has been
varied). The same action is repeated automatically at each stroke of
the piston. If now it is desired to increase or diminish the work of the
apparatus, I bend more or less the spring R, whose tension will measure
the pressure . The employment of the distributing chamber with the
regulator permits of having a volume of air in the pressure chambers at
any desired pressure, and decreasing in proportion to the distribution
without affecting the working of the motor.
The above-described arrangement, combined in case of need with
the variable expansion in the cylinder, forms a very convenient motor
eminently fitted for all manufacturing purposes where the work is
susceptible of great variations, and in cases where the employment of
steam is especially inconvenient. It may be applied to tramways, to
self-acting carriages of all kinds intended for town traffic, to implements
and machines for domestic purposes, to elevating machines used in ship
building yards, and for other like purposes. It furnishes moreover a

page_text: practical solution of the problem of the substitution of forces naturally
permanent for those given by the combustion of coal when by con-
veniently utilizing the force of streams of water, tides, or winds,
compressed air shall have been obtained at a net cost less than that of
steam with an equally useful effect.
Having thus described the principle of my improved apparatus, and
indicated in general terms the applications of which it appears to me
susceptible, I will now describe the details of construction of the expan-
sion regulator as it may be in practice, and my means of which the
escape of the compressed air is regulated as required, and by which the
regularity of the work is maintained, notwithstanding the continual
decrease of the pressure in the air chamber.
Figure 2 is an end view of the said apparatus, and Figure 3 is a longi-
tudinal section of the same, modified as herein-after described.
The primitive arrangement of my apparatus, as shown in Figure 1,
should be modified in several of its parts. I have for instance substituted
for the metallic spring R, intended to maintain an equilibrium in the
internal actions, an air spring, that is to say, a chamber 1, containing air
compressed more or less by the aid of a piston or plunger 2, operated
by a screw 3, with a fly wheel 4; this plunger passes through a packing
of leather or india-rubber 5. I have also substituted for the piston P,
upon which the action of the spring was exercised, a simple movable
diaphragm 6 of india-rubber, separating the chamber of compressed air 1
from another chamber 7, which represents the distributing chamber U,
Figure 1, and into which the gas flows from the pressure chamber.
Held tightly between two metal discs, and fastened to the admission
valve 8 by a rod with a hollow screw 9, this diaphragm 6 produces the
alternate play of the valve by oscillating from one side to the other of its
normal position.
I have shewn this valve in two different forms, Figures 3 and 4, each
presenting different advantages; in each case the one must be chosen
which will best serve the required purpose. That shewn in Figure 3
suppresses completely the cause of variation introduced into the working
of the apparatus by the action of the pressure in the air chamber upon
the large base of the valve. For this purpose this base is prolonged by
a small cylinder 10 of brass of the same diameter which extends through

page_text: the bottom of the entrance chamber 11 in a packing 12. In return the
friction of the packing opposing a certain resistance to the displacement
of the rod determines in the interior of the distributing chamber a
periodical variation equal to double the resistance of this friction with
regard to the rigid surface of the diaphragm.
In the modification shewn in Figure 4 the valve 8 preserves the usual
form, and remains subject to the influence of the great pressure, whose
decrease produces but slowly a gradual augmentation of that of the
distributing chamber; but the leakage which the first-described arrange-
ment renders possible is avoided, and the outlet aperture is more perfectly
closed during the stoppage, the india-rubber washer of the valve being
then firmly pressed against the seat.
I have moreover formed between the two chambers 1 and 7 of the
regulator a contingent lateral communication 13, intercepted' generally
by a cock 14, whose object is to permit the second chamber to be filled
with air possessing already a certain tension. I thus avoid the necessity
of giving to this part of the apparatus the exaggerated dimensions
which would be necessitated by the high pressures that might be
required.
I have devised an efficient and economical compression engine for the
compression of the air. This question presents serious difficulties, but
partially overcome by the apparatus hitherto employed for this purpose,
and the unsatisfactory result obtained therefrom scarcely permits their
application to work of any great importance. On the one hand when
the gas is raised to a considerable pressure it is almost impossible to
avoid the leakage likely to be produced at the joints of the valves and
the packings of the pistons, moreover the rise of temperature which
accompanies the mechanical action exaggerates the elastic force of the
gas, which increases at a rate much more rapid than that given by the
rule of Mariotte, thus occasioning a perceptible loss of effect.
To remedy this inconvenience I use the isothermal compression pump,
represented in vertical section in Figure 5, in which the compression is
produced by means of a film of water alternately raised and depressed by
the action of a plunger which passes through the neck of the receiver in
a packing of leather or india-rubber. The air is thus in contact either
with the water itself or with metallic envelopes dipped at each stroke
of the piston, and presenting moreover relatively to the volume of
the gas a very large surface. The temperature then remains constant.

page_text: In order to avoid leakage from the joints of the valves I form them
like that of the regulator with an india-rubber washer 17, Figure 6, held
fast between two metallic discs, one of which is adjusted with the guides;
the other yields under great pressure, and presses against the seat the
clastic part of the valve, which then hermetically closes the aperture.
As to the packing of the plunger, that may be made to assure a
perfect tightness, more especially if made of india-rubber, which permits.
the necessary slowness of the movement. If it happens however that
this mode of sealing is found insufficient, the air chamber may be made
distinct from the body of the pump, which will be then completely filled
with water and will communicate with it by a lateral tube. The action
of the piston in causing a return into this receiver of a volume of water
equal to its effective capacity will produce the compression in the same.
manner.
I propose to provide the apparatus with two pump barrels 18, 19, of
different diameters; the final compression is thus obtained twice, which
diminishes still more the influence of the detrimental space already
much reduced. Two cocks 15, worked with a key, permit the intro-
duction into the pumps of the water necessary to maintain constantly
the volume of liquid, notwithstanding the partial evaporation which takes
place. The verification of the levels is easily effected by two glass
indicator tubes 20. Other cocks 16, placed on the lower part, serve for
the discharge.
In conclusion I will point out a very simple means for obviating
another inconvenience also very serious, viz., the lowering of the tempe-
rature which accompanies the expansion of the gas in the cylinder, and
which sensibly diminishes the power of the apparatus. It will not be
sufficient in this case to act upon the circumference by keeping up a
circulation of hot water upon the cylinder; the unavoidable rapidity of
the expansion will render this mode of rewarming very incomplete: The
desired result is obtained in a manner much more perfect by causing the
air to pass through between the regulator and the distributing chest, a
boiler in which the water is maintained at a medium temperature by a
slight calorific force. The gas is thus charged with a certain quantity of
steam, the liquefaction of which during the expansion restores the heat
absorbed by the mechanical action. The caloric expended in this way
being entirely transformed into power the consumption of fuel is very

page_text: small, and does not require a strong draught; consequently there is
nothing here analogous to the furnaces of ordinary steam engines.
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, the expansion regulator working
as herein described, and allowing in motor engines of any power, and
without producing shocks or dislocations, the utilization of air held under
a high pressure in reservoirs.
In witness whereof, I, the said William Robert Lake, have hereunto
set my hand and seal, this Ninth day of May, in the year of
our Lord One thousand eight hundred and seventy-three.
Witness,
JAMES EDWARDS,
8, Southampton Buildings,
London.
W. ROBT, LAKE. (L.S.)