IMPROVEMENTS IN MACHINERY FOR COMPRESSING AIR AND IN ENGINES DRIVEN BY THE SAME, PARTS OF WHICH ARE APPLICABLE TO OTHER ENGINES.
Year: 1875

page_text: LETTERS PATENT to Henry Percy Holt, of Royal Insurance Buildings,
Leeds, in the County of York, Civil Engineer, for the Invention of
"IMPROVEMENTS IN MACHINERY FOR COMPRESSING AIR AND IN ENGINES
DRIVEN BY THE SAME, PARTS OF WHICH ARE APPLICABLE TO OTHER ENGINES.'
"
PROVISIONAL SPECIFICATION left by the said Henry Percy Holt
at the Office of the Commissioners of Patents, with his Petition,
on the 13th December 1875.
I, HENRY PERCY HOLT, of Royal Insurance Buildings, Leeds, in the
County of York, Civil Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN MACHINERY FOR COMPRESSING AIR AND
IN ENGINES DRIVEN BY THE SAME, PARTS OF WHICH ARE APPLICABLE TO OTHER
ENGINES," to be as follows:-
The first part of this Invention consists in using a series of separate.
cylinders for compressing air up to high pressures, in each of which
the pressure is increased only about from 1 to 2 or 2½ atmospheres,

page_text: according to the working pressure and the air passed into the top of
intermediate receivers, in which it is cooled (by means of water flowing:
through hanging tubes stopped at the low end, having internal circu-
lating tubes) to the external atmospheric temperature or thereabouts
before entering the next compressing cylinder (for which it leaves at the
bottom of the receiver), and having its pressure raised a grade higher;
or in lieu of these one cylinder may be used to compress into several
receivers alternatively, there being in each of these receivers a pressure
progressing one grade below the other from the initial to the final or
working pressure. In this case cocks having several ways are used to
connect the compressing cylinder progressively with the receivers, and a
gear is used to regulate the requisite number of strokes from each
receiver into the next above, according to the pressure. By this means
the necessary working pressure is attained at a temperature not much
exceeding that of the atmosphere..
The compressing cylinder and valve arrangement may be of any con-
venient kind, and be driven by compound or other engines in the usual
manner.
The second part of this Invention consists in heating the air (imme-
diately before it is admitted to the engine cylinder) up to any convenient
temperature by means of furnaces, stoves, superheated water, or steam,
as may be most suitable under various circumstances.
For locomotive purposes the compressed air is expanded from the
receiver through a self-acting reducing valve, composed of double beat
equilibrium valve and metallic diaphragm, into the heating chamber,
'where a pressure of from 1 to 2 atmospheres is constantly maintained,
from whence it is conveyed to the cylinder.
In some cases a part of the air is passed through a combustion
chamber in which ignited fuel is stored for combustion, and this air at a
high temperature is mixed with cold in the low-pressure receiver before
being admitted to the cylinder.
For locomotive purposes, such as on tramways, the high-pressure
receiver, reducing valve heating chamber, and low-pressure receiver may
be carried on a truck and coupled to the car by means of hose piping,
and the engines may be arranged under the car so as to gain adhesive
power from the weight of passengers and car.

page_text: The third part of this Invention consists in forms of valve for
admitting and exhausting from the cylinder, which are as follows:-The
admission valves (in large engines are situated at the ends of the
cylinder, and sometimes placed in the cylinder covers) are circular in
some cases, having india-rubber seats, and are opened by the pressure of
air in the chest. The closing is likewise performed in the same manner
by the air acting on a piston or diaphragm (connected with the valve
and of greater area) working in the chest cover, the space behind this.
piston or diaphragm being filled with a liquid or fluid at the same
pressure as the air in the chest at the time of admission, and at a lower
pressure at the cut-off, this being regulated by a small valve under the
control of the governor. The exhaust valves are worked in the same
manner.

page_text: In some cases the lubricants may be heated (that pass round the
piston), and thus keep hot the internal bore of the cylinder.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Percy Holt in the Great Seal Patent Office
on the 13th June 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
PERCY HOLT, of Royal Insurance Buildings, Leeds, in the County of
York, Civil Engineer, send greeting..
.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirteenth day of December, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Henry Percy Holt, Her
special licence that I, the said Henry Percy Holt, my executors, admi-
nistrators, and assigns, or such others as I, the said Henry Percy Holt,
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 the Isle of Man, an Invention
for "IMPROVEMENTS IN MACHINERY FOR COMPRESSING AIR AND IN ENGINES DRIVEN
BY THE SAME, PARTS OF WHICH ARE APPLICABLE TO OTHER ENGINES," upon the
condition (amongst others) that I, the said Henry Percy Holt, my exe-
cutors or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and ascertain
the 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 calender months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said Henry Percy Holt, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement:-

page_text: The first part of this Invention consists in using a series of separate
cylinders for compressing air up to high pressures, in each of which
the pressure is only increased from about 1 to 2 or 2½ atmospheres,
according to the working pressure and the air passed into the top of
intermediate receivers, in which it is cooled by means of water (flowing
through hanging tubes stopped at the low ends, and having internal
circulating tubes, by means of which the cool water is introduced and is
gradually heated as it rises in the external tubes, and finally escapes at
the top. By this means the hotest air is brought in contact with the
hotest part of the cooling surface (and vice versa) to the external atmo-
spheric temperature or thereabouts before entering the next compressing
cylinder (for which it leaves at the bottom of the receiver), and having
its pressure raised a grade higher. By this means the necessary working
pressure is attained at a temperature not much exceeding that of the
atmosphere.
The several compressing cylinders are arranged of suitable areas to
follow the grades of compressiom, and their number is determined by
the pressure that the air has to be compressed to; they may be driven
by compound engines in the usual manner. The inlet and outlet valves
may be of any convenient kind.
In some cases instead of passing the air through several cylinders, as
above described, I prefer to use only one compressing cylinder, and to
pass the air several times through the same cylinder, and alter the
number of strokes of the piston to suit the decreasing volume of the air
as the pressure rises each time it is passed through. In order to carry
out this I have a series of reservoirs or receivers, the connections or
passages between which and the inlet and outlet valves of the cylinder
are arranged so that during the first series of strokes of the piston the
atmosphere communicates with the inlet valves, the outlet valves.
communicate with the first intermediate receiver in which the
pressure is raised during the second series of strokes of the piston, which
of a less number than the first series, according to the decreased volume
of the air (from the first receiver) to be passed through, and still further
condensed in volume by compression. The number of series of strokes,
and also the number of intermediate receivers depends on the working
pressure required. After the working pressure is attained in the last
receiver (after having passed through the intermediate receivers), the
connections or ports work round again to the same position as at starting,

page_text: equilibrium; and the valve is closed by the air in the chest acting on
the greater area of the piston or diaphragm. The pressure is admitted
behind the piston or diaphragm at the commencement of every stroke
by means of a valve connected to the engine, but is released or regulated
by a valve controlled by the govenor. The exhaust is worked in the
same manner.
In small engines the admission and exhaust may be regulated by slide
valves worked in the above manner, or as usual.
The fourth part of this Invention consists in the addition of springs to
the old form of governor to assist the rising of the arms and balls, and
render the same more sensitive in its action when a longer travel is
required for timing the closing of the cylinder admission valves. These
springs, which are usually spiral, are arranged in pairs, attached one on
each side to studs in the centre of each ball at the low end, and at the
upper end to supports arranged above the fulcrum of the arms in line
with the longitudinal axes of the arms in their lowest position, conse-
quently the springs do not assist the rise of the balls in that position, as
the springs pull in the direct line of the arms against the top pin or
fulcrum, but the power of the springs to lift the balls and arms increases
as the balls rise. This part of the Invention is applicable to other
engines.
The fifth part of this Invention consists in a method of lubricating
the cylinder valves, pistons, and glands to prevent leakage, as follows: →
The valves are so constructed with bars and grooves in the valves
between the exhaust and steam edges that the bars in the cylinder face
are not entirely uncovered to the exhaust; in these bars channels are
formed, which are kept continuously supplied with lubricants forced in
to keep the faces in good order. The body of the piston between the
rings is likewise kept continuously supplied with lubricants in the same
manner, and in cases where piston valves are used this likewise applies
to them also.
In some cases the lubricant supplied to the pistons as above may be
heated, and thus maintain the temperature of the bore of the cylinder,
in lieu of a heating jacket.
In some cases the lubricant is omitted, and replaced by hot steam in

page_text: :
I will now refer to the accompanying Drawings, in which the figures
and letters of reference are as follows:-
DESCRIPTION OF THE DRAWINGS.
Fig. 1. Valve and intermediate cooling receiver arrangement for com-
pressing cylinder.-a, suction valve; b, delivery valve; c, rotating
lining with posts; d, ports in lining; e, e, ports in casing; f, external
casing; g,g,g, and 9', range of receivers, Nos. 1, 2, 3, and 4 successively;
h, hanging tubes having water flowing through them; i, internal cir-
culating tubes; j, j', j², j³, j', connections from receivers to the several
ports in valve casing; k, ratchet wheel for turning lining at each suc-
cessive series of strokes.
Fig. 2. Furnace heating arrangement.-a, external casing; b, fire-
grate; c, internal cover; d, hand hole for supplying fuel; e, ash hole
for removing waste; f.f, cramps for securing doors; 9, inlet for air;
h, outlet for heated air to regulating valve.
Fig. 3. Self-acting valve for admitting hot air or steam according to
the temperature of the exhaust.-a, valve casing; 6, inlet for hot air or
steam; c, regulating valve; d, chamber containing expansive fluid or
liquid; d, expansion rod in place of the chamber; e, exhaust pipe; f,
passage to cylinder valve chest.
.
Fig. 4. Admission and exhaust valves.-a, valve chest; b, admission
valve at one end of the cylinder c; c, engine cylinder; d, metal dia-
phragm or piston; e, chamber and passage behind same; f, valve
worked by the engine for admitting pressure from valve chest at the
commencement of each stroke of the engine; g, exhaust or escape valve
controlled by the governor; h, exhaust valve for the cylinder worked by
pressure from the arrangement; i, diaphragm or piston of exhaust valve,
which is of greater area than the admission valve. Note. The arrange-
ment shown is for only one end of the cylinder, the other end is simply
a duplicate of this. j, steam pipe; k, governor; 1, steam pipe for valve
worked by the engine,

page_text: Fig. 5. Governor springs.-a, spindle of an ordinary governor; 6¹, b²,
arms and balls; c'. c4, connecting links; d, bracket or cross head; e¹, e²,
studs for carrying top ends of springs; f', f³, studs for attaching springs
to balls; g, g, spiral springs; h¹, h², adjustments.
Fig. 6. Arrangement for lubricating valves, pistons, and glands.-
a, piston; b, ordinary rings; c, lubricating slots; d, communication
with slots.
Fig. 7. Arrangement for heating bore of cylinder and air for expan-
sion.-a, piston; b, ordinary rings; c, slot for heating medium; d,
passage for heating medium; e, vents for escape of heating medium to
heat air during expansion; f, f, self-acting valve for regulating the
vents (of a circular form); 9, 9, springs for adjusting the opening of
valve according to the pressure in the cylinder.
´Having now fully explained and illustrated the manner of carrying
out my Invention, I wish to be clearly understood that I claim,-
First. The use of intermediate cooling receivers for compressing air
through several cylinders up to high pressures, as described and illus-
trated, in order to avoid unduly raising the temperature of the air.
Second. The use and arrangement of compound valve chests for
passing air several times through one.compressing cylinder in connection
with several intermediate cooling receivers, as described and illustrated,
for the above purpose.
Third. Arrangements for heating the air just before admission to
cylinders for expansion by means of furnaces, stoves, or the admission
of superheated water or steam into the valve chest or cylinder by means
of a self-acting valve regulated by the temperature of the exhaust, as
described and illustrated.
Fourth. The arrangement for opening and closing the admission and
exhaust valves of cylinders by means of diaphragms or pistons in the
steam chest, actuated by pressure from the chest admitted at the com-
mencement of each stroke by a valve coupled to the engine, and
released by valves under the control of governor, as described and
illustrated.
Fifth. The arrangement and use of springs for assisting the arms and
balls of governors to rise, as described and illustrated.
Sixth. The method of lubricating the pistons, valves, and glands, as
described and illustrated, and thus preventing leakage.

page_text: Seventh. The use of hot lubricants or superheated steam passed round
the piston to heat the internal bore of the cylinder, as described, in lieu
of using a heated jacket.
Eighth. The arrangement of valves in the piston for supplying heat
to the air during expansion.
In witness whereof, I, the said Henry Percy Holt, have hereunto
set my hand and seal, this Tenth day of June, in the year of our
Lord, One thousand eight hundred and seventy-six.
HENRY PERCY HOLT. (L.S.)