IMPROVEMENTS IN ENGINES TO BE PROPELLED BY COMPRESSED ATMOSPHERIC AIR OR STEAM
Year: 1861

page_text: LETTERS PATENT to Francis Alton Calvert, of the City of Manchester,
Engineer, for the Invention of "IMPROVEMENTS IN ENGINES TO BE PROPELLED
BY COMPRESSED ATMOSPHERIC AIR OR STEAM."
Sealed the 28th March 1862, and dated the 21st October 1861.
PROVISIONAL SPECIFICATION left by the said Francis Alton Calvert
at the Office of the Commissioners of Patents, with his Petition, on the
21st October 1861.
:
I, FRANCIS, ALTON CALVERT, of the City of Manchester, Engineer, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN ENGINES TO BE
PROPELLED BY COMPRESSED ATMOSPHERIC AIR OR STEAM," to be as follows:-
The nature of my Invention consists in supplying compressed air or steam
from a reservoir or boiler to two cylinders, each cylinder containing two.
pistons, each lower piston containing one or more vacuum valves, to supply
the upper pistons with the air or steam when the expansive force of the
compressed air or steam is expended.
The valves and the air cushions for the two upper pistons are the same in
principle as those described in the Specification of Letters Patent granted to
me on the Fourteenth September, One thousand eight hundred and sixty,
No. 2218, with a slight difference in the construction of the admission valve,
which is annular, and fits on the exterior of the cylinder. The exhaust ports
consist of annular rows of holes for the escape of the air or steam; these

page_text: holes are placed at such a distance from the ends of the cylinder that the
requisite space may be left for the air cushions above referred to. The air
cushion is in communication with the reservoir or boiler, and when the air or
steam becomes compressed to a greater pressure than that in the reservoir or
boiler, the surplus pressure is forced back into the reservoir or boiler. The
lower pistons are actuated by toggle joints, and are balanced upon a beam;
they have a traverse of about one-fourth of the length of the cylinder, the
motion being imparted to them by a cam. The upper pistons are connected
to the beam or crank shaft of the engine.
During the commencement of the stroke, the two pistons in each cylinder
travel together, but when the lower piston has completed its stroke, the air or
steam is instantly admitted between the two pistons, and impels the upper one
forward until it arrives at the end of the cylinder. When the air or steam is
admitted between the pistons, the crank is at or near the point where the full
leverage is obtained.
The duration of the admission of the compressed air or steam is regulated
by a moveable inclined can, which gives a larger or smaller amount of the
compressed air or stean to the cylinder, but in every position of the inclined
cam the compressed air or steam enters at its full force.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Francis Alton Calvert in the Great Seal Patent Office on
the 19th April 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FRANCIS
ALTON CALVERT, of the City of Manchester, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of October, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Francis Alton Calvert, Her special licence that I, the said Francis Alton
Calvert, my executors, administrators, and assigns, or such others as I, the
said Francis Alton Calvert, 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
"IMPROVEMENTS IN ENGINES TO BE PROPELLED BY COMPRESSED ATMOSPHERIC AIR -

page_text: OR STEAM," upon the condition (amongst others) that I, the said Francis Alton
Calvert, my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe and ascer-
tain 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 calendar months next and immediately after the date of
the said Letters Patent.
NOW KNOW YE, that I, the said Francis Alton Calvert, 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 (that is to say):-
The nature of my Invention consists in supplying compressed atmospheric
air or steam from a reservoir or boiler to one or two cylinders, each cylinder
containing two pistons, each lower piston containing one or more vacuum
valves to supply the upper pistons with air or steam when the expansive force
of the compressed air or steam is expended.
The valves and the cushion chambers for the upper pistons are the same in
principle as those described in the Specification of Letters Patent granted to
me on the Fourteenth of September, One thousand eight hundred and sixty,
Number 2218, with the addition of means for conveying the compressed vapour
or air from the cushion chambers to the steam or air chest, and an alteration in
the construction of the admission valve, which is annular, and fits on the
exterior of the cylinder. The exhaust ports consist of annular rows of holes
for the escape of the air or steam; these holes are placed at such a distance
from the ends of the cylinder that the requisite space may be left for the
cushions above referred to. Each air cushion is in communication with the
chest containing the annular admission valve, the said chest being supplied by
the reservoir or boiler, and when the air or steam in the cushion chambers
becomes compressed to a greater degree than that in the chest, the surplus
pressure is forced back into it. The lower pistons are actuated by toggle
joints, and when a single cylinder is employed, the piston is counterbalanced.
The said lower pistons have a traverse of about one-fourth of the length of the
cylinder, the motion being imparted to them by a cam; the upper pistons
are connected to a crank shaft, or they may be connected by a beam.
During the commencement of the stroke the two pistons in each cylinder
travel together, but when the lower piston has completed its stroke, the
compressed air or steam is instantly admitted between the two pistons, and
impels the upper one forward until it arrives at the end of the cylinder. Each
cylinder is made to receive the compressed air or steam for propelling the piston

page_text: during its upward stroke. When the air or steam is admitted between the
pistons, the crank is at or near the point where the full leverage is obtained.
The duration of the admission of the compressed air or steam is regulated
by a moveable inclined tappet, which gives a larger or smaller amount of the
compressed air or steam to the cylinder, but in every position of the inclined
tappet the compressed air or steam enters at its full force, that is to say, so
long as the engine is driving its load; but supposing the load to be suddenly
thrown off, as in trip hammers and rolling mills, the lower end of the
táppet being bevelled off, the regulator would be moved to a greater height,
and would lift the tappet so that the admission valve would not be operated
upon.
And in order that my Invention may be fully understood and readily carried
into operation I will proceed to describe the accompanying Sheet of Drawings,
reference being had to the figures and letters marked thereon.
Figure 1 is an elevation in section of one of my improved engines with two
cylinders, which is intended to be worked by steam; Figure 2 is a plan also in
section through the steam chest and the parts on the same level; and Figure 3
is a plan of the cam for actuating the toggle joints and lower pistons.
a and bare the two cylinders; a' and 6 the two upper pistons fixed to the
piston rods a² and 62, which are connected in the ordinary manner to the con-
necting rods and crank shaft, the cranks of which are in line with each other
on opposite sides of the shaft; a3 and 63 are the two lower pistons, which are
constructed so as to act as exhaust and vacuum valves; that is to say, the body
of the piston is perforated, and upon it fits a plate marked c, c', mounted on a
centre stud, which passes through the centre of the piston, and projects under-2
neath for a spiral spring. The plate is about one-fourth of an inch less in
diameter than the piston to allow a supply of air or hot vapour to escape
around it when the plate is raised, and the pistons open and close the exhaust
ports, as will be described hereafter. The lower pistons are kept in line with
the cylinders by the cross heads a' and 6 and slides a and b, which are
provided with rests to support the pistons when down.
The admission valves d and d' are annular and perforated, and fit on the
exterior of the cylinders, which are also perforated. The valves are each made
in two parts for the convenience of putting together; they are contained in
the steam chests e and e¹, which are connected by suitable pipes with the 3
steam boiler. The upper rows of holes f, f¹, form the upper exhaust ports,
and the lower rows of holes 9, 91, form the lower exhaust ports; these exhaust
ports are placed at such a distance from the ends of the cylinders, that the
requisite space may be left for the cushion chambers, which are similar in

page_text: construction to those described in the Specification of Letters Patent granted
to me on the Fourteenth day of September, One thousand eight hundred and
sixty, Number 2218. The pipes h, h¹, form the connections between the cushion
chambers and the steam chests e, e¹, each cushion chamber being furnished
with a small flap valve i, ¹, the object of which is to allow the excess of
pressure in the cushion chambers to pass into the steam chest, and to prevent
its return when the action of the piston is reversed. The upper cushion
chambers are provided with conical vacuum valves, which are connected by.
pipes (not shewn in the Drawing) with the exhaust chamber or hot well r to
prevent the admission of cold air into the cushion chambers.
To the crank shaft is fixed a bevel wheel gearing into another wheel on the
hollow vertical shaft k, which carries the governor Z, the moveable inclined
tappet m for working the admission valves d, d¹, and the cam n, for actuating
the lower pistons a³ and 63. The governor is connected by the rod / with
the tappet m, which slides up or down on the hollow shaft k with the opening
or closing of the governor balls; the hollow shaft has slots through it to
allow the bush of the governor and the tappet m to rise and fall. The
tappet m, in revolving, acts alternately on two arms o, o¹, provided with anti-
friction rollers; these arms are respectively attached to the rods d³ of the
admission valves d, d¹, as shewn best in Figure 2. These valves are moved
about one-fourth of an inch, or more or less according to the size of the port
holes; each valve rod is provided with a spring d³, by which the valves are
instantly closed, when the tappet m ceases to act on the arms o, o².
The duration of the admission of the steam is thus regulated by the tappet m,
which gives a larger or smaller amount of steam to the cylinder, but in every
position of the tappet the steam enters at its full force, that is to say, so long
as the engine is driving its load; but supposing the load to be suddenly thrown
off, the lower end of the tappet being bevelled towards the centre of its shaft,
the regulator would be moved to a greater height, and would lift the tappet so
that the admission valve would not be operated upon.
r
The cam n acts upon antifriction rollers supported in the frame p, shewn
best in Figure 3, to which frame are jointed the links p² and p², each of which
is connected to the toggle joints 9, q', the upper links of which are jointed to
the under side of the lower pistons a³ and 63. The top flanges of the cylinders
are screwed to the upper part of the hot well or exhaust chamber r, which
should be sufficiently tight to hold the water of condensation, and which is
furnished with an aperture 7¹ open to the atmosphere. The water collected in
the chamber is removed at pleasure to the boiler, or otherwise disposed of.
2.1

page_text: The Drawing represents the pistons a¹ and a³ in the cylinder a in the
positions they occupy when steam is admitted and the lower piston 6 in the
cylinder 6 has just arrived at the bottom of its stroke, while the upper piston b₁
is descending. The mode of operation is as follows:-When the pistons are
near to each other, as shewn in the cylinder a, the crank to which the piston
rod a² is connected is thirty degrees below the horizontal line, or at about
fourteen-fifteenths of its full leverage, consequently the percussive action of
the steam is applied so as to produce on the piston a¹ a result similar to that
of a steam or air gun upon the ball. The inclined tappet m regulates the
duration of time for the admission of the steam; and I prefer to admit steam
during about one-twelfth of the stroke, but I would have it understood that a
greater or less amount of steam may be admitted.
During the admission of steam the lower piston a³ is stationary, and it
is supported by the toggle joints being in a vertical position; the upper
piston a¹ having acquired the requisite momentum, continues its ascent to the
end of the stroke. During the ascent of the piston a¹, should the expansive
force of the steam be reduced below the pressure of the atmosphere, then the
vacuum valve in the lower piston a³ is raised, and admits the vapour from
the hot well to preserve the equilibrium on the ascending piston until it passes
the upper exhaust ports f; the remainder of the stroke of the piston a' com-
presses the vapour in the upper cushion chamber until the pressure becomes
greater than that in the steam chamber e; the excess of compressed vapour is
then conveyed through the flap valve i and pipe h to the steam chest e.
While the piston a² is compressing the vapour in the upper cushion chamber
of the cylinder a, the piston bis performing the same office in the lower
cushion chamber of the cylinder b. The object of the cushion chambers is,
first, to return a certain amount of compressed vapour to the steam chest while
the cranks are turning their centre so as to be again applied to the piston
with the steam from the boiler; secondly, to check the momentum of the
piston; and, thirdly, to relieve the strain on the crank pin.
During the descent of the piston a¹, the upper piston b¹ and lower piston 6³
are ascending together, and when they arrive at the annular port holes, the
steam is admitted in the manner before described in reference to the cylinder a.
The object of the lower pistons is to obviate the necessity of filling the
cylinders with steam until the crank is in the position for receiving the full
force of the steam, and to increase its effective force by having a small space
to fill.
I have described my improvements as applied to an engine to be worked by

page_text: steam; but I wish it to be understood that compressed atmospheric air rarified
or otherwise may be used instead of steam.
Figure 4 is a section, and Figure 5 an elevation, partly in section, of my
improved admission valve, applicable to engines of the ordinary construction,
and working at the usual velocity, as the cushion chambers above referred to
could not conveniently be applied to such engines so as to increase their
velocity. s is the steam chest of a vertical or horizontal engine, and s¹ the
slide valve. The face of the steam chest lid is provided with a circular row
of holes; t is the valve seating, which has a series of circular rows of holes.
opening into the V-shaped chambers t¹, and u is the valve surrounding the
valve seating; the valve is furnished with holes corresponding with those
in the valve seating. When the holes in the valve and valve seating coincide,
the steam is admitted into the chambers t¹, and through the perforations in
the face s, to the ordinary steam chest, care being taken that the admission
port is at this time fully open, or nearly so, to convey the steam to the head of
the piston, and that the piston is in the position for acting on the crank when
at an angle of about forty-five degrees, this position being found advantageous
for applying the percussive action of the steam. The valve u is worked by
the moveable inclined tappet m, similar to that described in reference to the
preceding Figures 1 and 2.
Having thus stated the nature of my Invention, and described the manner
of carrying the same into operation, I declare that I claim,-
First, the general arrangement and combination of the improved engine to
be propelled by compressed atmospheric air or steam, as shewn and described
in reference to Figures 1, 2, and 3 of the accompanying Drawing.
Secondly, I claim the means of bringing the piston into the required position
in the cylinder previous to admitting the compressed air or steam.
Thirdly, I claim the application of the additional pistons marked a³ and b³ to
the cylinders of steam or air engines, and the mode of actuating the same
when used in the manuer and for the purposes described.
Fourthly, I claim the conveying of the compressed air or vapour from the
cushion chamber to the steam or air chest.
Fifthly, I claim the application of the admission valve direct to the circum-
ference of the cylinder.
Sixthly, I claim the moveable inclined tappet marked m, actuated by
the regulator or governor, as shewn and described, or any modification thereof,
whereby the compressed air or steam is directly admitted to the cylinder by
the action of the regulator or governor.

page_text: And, lastly, I claim the improved construction and arrangement of valves
for admitting steam to engines of the ordinary construction, as shewn and
described in reference to Figs. 4 and 5.
In witness whereof, I, the said Francis Alton Calvert, have hereto
set my hand and seal, this Sixteenth day of April, in the year of our
Lord One thousand eight hundred and sixty-two.
F. A. CALVERT. (L.S.)