IMPROVEMENTS IN COMPOUND EXPANSIVE STEAM AND OTHER ENGINES
Year: 1885

page_text: I JAMES MATTHEWS of 22 Ashfield Terrace Newcastle on Tyne, Engineer do
hereby declare the nature of said invention for "IMPROVEMENTS IN COMPOUND
EXPANSIVE STEAM AND OTHER ENGINES" to be as follows :—
The object of my invention is to simplify the construction of compound
expansive steam and other engines so as to advantageously use the expansive
force of the steam.
According to my invention I am able to accomplish this by one cylinder and a
convenient way of carrying the invention into effect is by the fitting of a tube or
trunk on the back of the piston; this tube is preferably telescopic in order to be
able to reduce as much as possible a case or prolongation of the cylinder into which
prolongation this trunk slides. By the use of this trunk I am enabled to decrease
the effective area on one side of the piston, which is acted on by the high pressure
steam from the steam chest; after the steam has done its work it is exhausted
through an ordinary slide valve into a passage which conveys it to a second steam
chest from which it is admitted to the front or low pressure end of the cylinder
where it acts on the full area of the piston, less the diameter of piston rod, after
which it is exhausted through a second ordinary slide valve either into another
larger cylinder, a condenser, or the open air as may be desired.
The two slide valves may be worked with one eccentric; there is a pro-
longation of the piston rod for keeping in position the back or sliding end of
the trunk.
The trunk may be made in one piece lengthening its case to suit or I may close
the end of the trunk and use it as a high pressure piston applying the steam to
its back end.

page_text: Improvements in Compound Expansive Steam and other
Engines.
I, JAMES MATTHEWS of 22 Ashfield Terrace, Newcastle-on-Tyne, Engineer 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:
The object of my invention is to simplify the construction of compound
expansive steam and other engines so as to advantageously use the expansive
force of the steam.
According to my invention I am able to accomplish this by one cylinder, and
a convenient way of carrying the invention into effect is by the fitting of a tube or
trunk on the back of the piston; this tube is preferably telescopic in order to be
able to reduce as much as possible a case or prolongation of the cylinder, into which
prolongation this trunk slides. By the use of this trunk I am enabled to decrease
the effective area on one side of the piston, which is acted on by the high pressure
steam from the steam chest; after the steam has done its work it is exhausted
through an ordinary slide valve into a passage which conveys it to a second steam
chest from which it is admitted to the front or low pressure end of the cylinder
where it acts on the full area of the piston, less the diameter of piston rod,
after which it is exhausted through a second ordinary slide valve either into
another larger cylinder, a condenser, or the open air as may be desired.
And in order that the invention may be easily understood and readily carried
into effect I will further describe the same with reference to the accompanying
drawings, Figure 1 being a section through the cylinder and valve chest of a
compound expansive steam cylinder constructed according to my invention.
Figure 2 a plan of the interior of valve chest; and Figure 3 shows the steam
and exhaust passages when arranged for two ordinary slide valves instead of the
compound valve as at Figure 1.
Figure 4 is a vertical section, and Figure 5 is a cross section showing an
application of a piston slide valve, and double pistons to compound expansive
steam engines constructed and arranged according to my invention. Figure 6 is
a section showing a similar construction of piston in combination with two
ordinary slide valves instead of the compound piston valve, and Figure 7 is a
plan of the interior of the valve chest, the slide valves being removed.
The same letters of reference refer to similar parts in the various figures.
A is the high pressure end of the cylinder, A¹ the low pressure end of same; B is
the piston, B its rod; B is the tube or trunk on the back of piston; C is the case
or prolongation of the cylinder; D is the slide valve; E is the steam inlet to high
pressure end A of cylinder; F is the inlet at low pressure end A¹; G is the
exhaust.
Referring to Figures 1 and 2; in the position shown in the drawings, steam at
high pressure has entered by ports marked E, and has acted on the high pressure
side A of piston, and has expanded the telescopic tubes B³ B³ (in this case two such

page_text: tubes are shown) By the employment of this trunk or tubes I am enabled to
reduce the effective area of this side of the piston. The compound slide valve is
now operated by eccentric or otherwise, and the port E' in same being brought
opposite port E the exhaust will take place by the steam passing through slide
valve D and ports F F and acting on the low pressure side A¹ of the piston, the
effective area of this side of the piston B being greater than the other by the area
of the trunk B. The exhaust from the side A¹ takes place by passages F G¹
and G; or in the arrangement of steam passages shown at Figure 3 two ordinary
alide valves may be used instead of the composite slide; in which case after the
steam has done its work it passes by passage E through an ordinary slide valve
working in the steam chest D¹, and by a passage D³ into the second steam chest D*
from which it is admitted by à second slide valve in the steam chest D' to the
front or low pressure end A¹ of the cylinder where it acts on the full area of the
piston and is then exhausted through the steam slide valve and port G. The two
slide valves may be worked with one eccentric. There is a prolongation of the
piston rod at B* for keeping in position the back or sliding end of the trunk. The
truak may be made in one piece lengthening its case to suit or I may close the
end of the trunk and use it as a high pressure piston applying the steam to its
back end.
The construction and arrangement of the cylinder shown at Figures 4 and 5 are
similar to those described with reference to Figures 1 and 2 excepting that a
double trunk piston B B¹ is employed, the cylindrical hollow space formed therein
fitting over a cylindrical prolongation C on the interior of the opposite cylinder
cover; the prolongation B* of the piston rod as well as the double telescopic
trunk B' being dispensed with. The prolongation C forms a convenient guide
for the piston rod B'. The slide valve is shown of the piston type. Figures 6
and 7 show a form of cylinder similar to that described with reference to Figures 4
and 5, the prolongation or interior fixed trunk C being here shown hollow instead
of solid, and the piston rod passing through the opposite end of cylinder. It is
also arranged for two ordinary slide valves.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:
In compound expansive steam and other engines, the single or telescopic tube
or trunk for reducing the effective area on one side of the piston or pistons, by
which each single cylinder may be made compound and expansive; substantially
as described and illustrated with reference to the accompanying drawings.
1000
BREWER & SON,
For the Applicant.