IMPROVEMENTS IN HIGH AND LOW PRESSURE OR COMPOUND STEAM ENGINES
Year: 1872

page_text: LETTERS PATENT to Hans Wilhelm Caspersen, of Newcastle-on-Tyne,
for the Invention of "IMPROVEMENTS IN HIGH AND LOW PRESSURE
OR COMPOUND STEAM ENGINES." -A communication from abroad by
John Blair, of Aarhuus, in the Kingdom of Denmark.
Sealed the 5th March 1872, and dated the 4th January 1872.
PROVISIONAL SPECIFICATION left by the said Hans Wilhelm
Caspersen at the Office of the Commissioners of Patents, with his
Petition, on the 4th January 1872.
I, HANS WILHELM CASPERSEN, of Newcastle-on-Tyne, do hereby
3 declare the nature of the said Invention for "IMPROVEMENTS IN HIGH
AND LOW PRESSURE OR COMPOUND STEAM ENGINES," a communication to me
from abroad by John Blair, of Aarhuus, in the Kingdom of Denmark, to
be as follows:-
This Invention has exclusive reference to that class of steam engines
known as compound or combined high and low pressure engines, wherein

page_text: the high-pressure steam after doing duty in a small high-pressure
cylinder passes thence to a large low-pressure cylinder.
According to this Invention it is proposed to work high and low
pressure or compound steam engines with slide valves or piston valves
so arranged as to transmit the steam from the high-pressure cylinder to
the low-pressure cylinder by direct communication with the steam
passages or ports at the ends of the two cylinders, thereby insuring
the least possible loss of steam in its continuous expansion from the
high-pressure cylinder to the low-pressure cylinder, whilst at the same
time a more effective vacuum is maintained at the return stroke
of each piston by reason of the direct communication with the con-
dansen
In carrying out this Invention as applied to a continuous expansion
compound engine worked with slide valves, the engine consists of a
small high-pressure cylinder and a larger low-pressure cylinder, the
diameter of the latter being twice the diameter of the former. Both
these cylinders are connected together by two separate steam chests,
one being situate between the top end and one between the bottom end
of the two cylinders. Each of these steam chests contains two slide
valves working on the respective faces of the two cylinders at the top
and bottom. The two steam chests are connected by a third steam
chest containing a variable expansion valve worked by an adjustable
eccentric or otherwise, as is well understood, from the crank axle. By
means of this valve the steam may be cut off at any part of the stroke,
either up or down, in the high-pressure cylinder. When the piston in
the high-pressure cylinder has travelled from the top half way down, the
piston in the low-pressure cylinder being then at the top will by the
motion of the two slide valves in the top steam chest receive the
steam from the top of the small cylinder, and thus both pistons will
work in conjunction with that quantity of steam which is previously a
cut off by the expansion valve. The pressure of the exhaust steam in
both cylinders being of course in proportion to the cut off by the
expansion valve, the steam in both cylinders is cut off and opened for
the exhaust by the slide valves in due time. The up stroke in both
cylinders will of course be effected in the same manner by the motion of
the slide valves in the steam chest situate between the bottom ends of
the cylinders and by the expansion valve.

page_text: It is evident that by this arrangement steam at a very high pressure
may be worked expansively down to a very low degree in both cylinders,
and as both pistons are all the time working upon a vacuum the con-
sumption of coals will be considerably less than with the present
arrangement of ordinary high and low pressure or compound engines
worked with piston valves. The steam may, if preferred, be admitted to
the high-pressure piston from the inside by a pair of piston valves, and
when the high-pressure piston has travelled one-sixth of the stroke the
steam is cut off from the boiler. Then a second pair of piston valves
opens to the condenser, and when the high-pressure piston has arrived
at half stroke the low-pressure piston will be on the top centre, and
before the steam is admitted to the last-named piston; and when the
last-mentioned piston valve begins to open for the steam, then one of a
third pair of piston valves is closed for the vacuum side, and when the
low-pressure piston has reached the top centre the said piston valve
is just at the point of opening, and vice versa. It is to be understood
that the movements of the three sets of piston valves are produced by
eccentrics and links in the usual way.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Hans Wilhelm Caspersen in the Great Seal Patent
Office on the 2nd July 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HANS
WILHELM CASPERSEN, of Newcastle-on-Tyne, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourth day of January, in the year
of our Lord One thousand eight hundred and seventy-two, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Hans Wilhelm Caspersen, Her special
license that I, the said Hans Wilhelm Caspersen, my executors, adminis-
trators, and assigns, or such others as I, the said Hans Wilhelm
Caspersen, my executors, administrators, or 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

page_text: and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN HIGH AND LOW PRESSURE OR COMPOUND STEAM ENGINES,"
a communication to me from abroad by John Blair, of Aarhuus, in the
Kingdom of Denmark, upon the condition (amongst others) that I,
the said Hans Wilhelm Caspersen, my executors or administrators, by an
instrument in writing under my hand and seal, 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 calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Hans Wilhelm-Caspersen, 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
Drawings, and to the letters and figures marked thereon, that is to
say :-
The said Invention has exclusive reference to that class of steam
engines known as compound or combined high and low pressure engines,
wherein the high-pressure steam, after doing duty in a small high-
pressure cylinder, passes thence to a large low-pressure cylinder.
According to this Invention it is proposed to work high and low
pressure or compound steam engines with slide valves, piston valves,
double beat valves, or valves of any other form, so arranged as to
transmit the steam from the high-pressure cylinder to the low-pressure
cylinder by direct communication with the steam passages or ports at
the ends of the two cylinders, thereby ensuring the Icast possible loss of
steam in its continuous expansion from the high-pressure cylinder to the
low-pressure cylinder, whilst at the same time a more effective vacuum
is maintained at the return stroke of each piston by reason of the direct
communication with the condenser.
In carrying out this Invention as applied to a continuous expansion
compound engine worked with slide valves, the engine consists of a
small high-pressure cylinder and a larger low-pressure cylinder, the
diameter of the latter being twice the diameter of the former. Both
these cylinders are connected together by two separate steam chests, one
being situate between the top end and one between the bottom end of
the two cylinders. Each of these steam chests contains two slide valves,

page_text: working on the respective faces of the two cylinders at the top and
bottom. The two steam chests are connected by a third steam chest
containing a variable expansion valve worked by an adjustable eccentric
or otherwise, as is well understood, from the crank axle. By means of
this valve the steam may be cut off at any part of the stroke, cither up
or down, in the high-pressure cylinder. When the piston in the high-
pressure cylinder has travelled from the top half way down, the piston in
the low-pressure cylinder being then at the top, will, by the motion of
the two slide valves in the top steam chest, receive the steam from the
top of the small cylinder, and thus both pistons will work in conjunction
with that quantity of steam which is previously cut off by the expansion
valve, the pressure of the exhaust steam in both cylinders being of
course in proportion to the cut off by the expansion valve. The steam
in both cylinders is cut off and opened for the exhaust by the slide
valves in due time. The up stroke in both cylinders will of course be
effected in the same manner by the motion of the slide valves in the
steam chest situate between the bottom ends of the cylinders and by the
expansion valve.
It is evident that by this arrangement steam at a very high pressure
may be worked expansively down to a very low degree in both cylinders,
and as both pistons are all the time working upon a vacuum the con-
sumption of coal will be considerably less than with the present
arrangement of ordinary high and low pressure or compound engines.
The steam may, if preferred, be admitted to the high-pressure piston
from the inside by a pair of piston valves, and when the high-pressure
piston has travelled, say, one-sixth or any other fraction of the stroke, the
steam is cut off from the boiler. Then a second pair of piston valves
opens to the condenser, and when the high-pressure piston has arrived
at half stroke the low-pressure piston will be on the top centre, and
before the steam is admitted to the last-named piston, and when the
last-mentioned piston valve begins to open for the steam, then one of a
third pair of piston valves is closed for the vacuum side, and when the
low-pressure piston has reached the top centre the said piston valve is
just at the point of opening, and vice versa. It is to be understood that
the movements of the three sets of piston valves are produced by eccen-
trics and links in the usual way.
And in order that the said Invention may be fully understood, I shall

page_text: It will be observed that the cranks must be placed at right angles or
ninéty degrees, whereby a double-acting engine is obtained with only one
high-pressure cylinder and one low-pressure cylinder.
Figures 4, 5, and 6 (Sheet 2) of the Drawings illustrate the application
and use of piston valves in lieu of slide valves to and in a compound
engine constructed and worked according to this Invention.
In Figure 4 the piston valves G, E, and E' are perfectly cylindrical.
The piston valve G in the chamber or steam chest F regulates the steam
from the boiler entirely, and can be worked to any expansion up to half
stroke of the high-pressure piston A. The piston valves E and E' in the
steam chests or chambers C and D regulate entirely the communication
or exhaust between the pistons and the condenser, thus obtaining a
perfect vacuum, as in the arrangement with the slide valves.
steam passes from the high-pressure piston A to the low-pressure piston
B past the ends of the piston valves alternately. This arrangement
affords easy access to all the working parts, and is not so liable to
become disarranged by wear and tear.
The
Figures 5 and 6 are merely intended to show that the same object can
be accomplished by adopting two half round piston valves E, E', working
in one chamber C instead of using complete pistons as shewn in Figure 4
working in two chambers C and D. The half round piston valves in
Figures 5 and 6 are more liable to wear and tear and sooner become
disarranged, by having both steam and vacuum upon them as in
the slide valve arrangement, but in all three instances herein-before
described the object in view is the same.
Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider to
be novel and original, and therefore claim as the Invention secured to me
by the herein-before in part recited Letters Patent is,―
First. The combination of slide or other valves and steam chests
with the high and low pressure cylinders of a compound steam engine
in such a manner that the steam shall be transmitted from the high-
pressure cylinder to the low-pressure cylinder by direct communication
with the steam passages or ports at the ends of the two cylinders, sub-
stantially as and for the purpose herein-before described, and illustrated
by the Drawings hercunto annexed.

page_text: Second. The combination of two pairs of slide valves, each pair
working in a separate steam chest situate between the upper and lower
ends of the two cylinders of a compound expansion engine, and being
in communication with a third steam chest containing a variable
expansion valve, substantially as and for the purpose herein-before 5
described, and illustrated by Figures 1, 2, and 3, of the Drawings here-
unto annexed.
Third. The peculiar combination of piston valves, steam chests or
chambers, and steam ports or passages with the high and low pressure
cylinders of a compound expansion engine, substantially as and for the 1
purpose herein-before described, and illustrated by Figure 4 of the
Drawings hereunto annexed.
Fourth. The peculiar combination and arrangement of half round
valves, steam chests or chambers, and ports or passages with the high
and low pressure cylinders of a compound expansion engine, substantially 1
as and for the purpose herein-before described, and illustrated by Figures
5 and 6 of the Drawings hereunto annexed.
In witness whereof, I, the said Hans Wilhelm Caspersen, have to
this my Specification set my hand and scal, this Twenty-first
day of March, One thousand eight hundred and seventy-two.
2