IMPROVEMENTS IN STEAM ENGINES
Year: 1877

page_text: LETTERS PATENT to Walter Hunter, of Bow, in the County of Middlesox, for
the Invention of "IMPROVEMENTS IN STEAM ENGINES"
Sealed the 90th July 1877 and dated the 7th Fahmin 1877
PROVISIONAL SPECIFICATION left by the said Walter Hunter at the Office
of the Commissioners of Patents on the 7th February 1877.
WALTER HUNTER, of Bow, in the County of Middlesex.
STEAM ENGINES"
"IMPROVEMENTS IN
This Invention has for its object improvements in steam engines, and relates
especially to engines which are provided with three cylinders arranged side by side,
and taking steam only at their outer ends, whilst their inner ends are open to a
chamber through which the crank shaft passes Such engines are described in the
Specification of a Patent granted to Peter Wilham Willans, dated March 19th 1874,
No 974
The admission of steam to the cylinders is controlled by valves which are fixed to
the pistons, or the piston in one steam cylinder serves itself as the valve for another
cylinder. I arrange such engines in such manner that the steam from one cylinder,
in place of escaping by the exhaust pipe, may be worked expansively in the other
two cylinders of the set.
The cylinders may be all of the same size (or they may vary in size), and one
(preferably the centre cylinder) supplies steam to the other two. The exhaust from
the one cylinder is led into a chamber, from which the other two cylinders are
supplied, or, when it is desired to exert the full power, this chamber can be put
into direct communication with the exhaust, whilst at the same time a valve is
opened, by which boiler steam is supplied direct to the two cylinders, which other-
wise receive low-pressure steam, or steam which has already performed work in one
of the cylinders
The engine can be reversed by means of a three-way cock in the passages, by
turning which the valves are changed about, so that the valve which previously
supplied one cylinder is now made to supply another

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Walter Hunter in the Great Seal Patent Office on the 4th August
1877
WALTER HUNTER, of Bow, in the County of Middlesex.
STEAM ENGINES"
"IMPROVEMENTS IN
This Invention has for its object improvements in steam engines, and iclates
especially to engines which are provided with three cylinders arranged side by side,
and taking steam only at their outer ends, whilst their inner ends are open to a
chamber through which the crank shaft passes. Such engines are described in the
Specification of a Patent granted to Peter William Willans, dated March 19th 1874,
No 974
The admission of steam to the cylinders is controlled by valves which are fixed to
the pistons, or the piston in one steam cylinder serves itself as the valve for another
cylinde I arrange such engines in such manner that the steam from one cylinder,
In place of escaping by the exhaust pipe, may be- worked expansively in the other
two cylinders of the set
The cylinders may be all of the same size (or they may vary in size), and one
(preferably the centre cylinder) supplies steam to the other two The exhaust from
the one cylinder is led into a chamber, from which the other two cylinders are
supplied, or, when it is desired to exert the full power this chamber can be put
into duect communication with the exhaust, whilst at the same time a valve is
opened, by which boiler steam is supplied direct to the two cylinders, which other-
wise receive low-pressure steam, or steam which has already performed work in one
of the cylinders
The engine can be reversed by means of a three-way cock in the passages, by
turning which the valves are changed about, so that the valve which previously
supplied one cylinder is now made to supply another
In order that my said Invention may be most fully understood and readily
cariied into effect, I will proceed to describe the Drawings hereunto annexed
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a longitudinal section, and Figure 2 15 a transverse section of an
engine arranged according to my Invention.
a, b, and c, are three cylinders arranged side by side They have steam supplied
to them only at their outer ends, whilst then inner ends are open to the chamber d
through which the crank shaft e passes, the bearings for it being formed in the ends
of the chamber d The pistons are formed with trunks, and are each coupled by
a connecting 1od with one of the throws of the crank shaft. The pistons working
in these cylinders have in each case a piston valve attached by means of a rod, and
so controls the passage of steam to and from another of the cylinders, the pistor
valves are marked a², b¹, and c¹ The piston valve a regulates the passage of steam
to and from either the cylinder b on the cylinder c, according to the position of the
three-way cock, which serves as the reversing valve of the engine, and similarly
the valve b¹ seves for either the cylinder a or the cylinder c, and the valve c¹ for
either the cylinder a or the cylinder 6 In all these features the engine resemble
that described in the Specification of Willan's Patent, to which reference has already
been made, and as is set forth in that Specification, in place of the main piston
actuating piston valves they may themselves seive as valves Now in order tha
the steam may be worked first in one of the cylinders, and afterwards in the othe
two, I provide a chamber g to receive the steam discharged from the first cylinder, and
from this chamber, through an intermediate chamber h, I cause the other cylinder
to be supplied, and the steam from these escapes into the chamber k, which is 1
communication either with a condenser oi is open to the atmosphere. is the pip
by which boiler steam is supplied to the engine, and it passes diect into the smal

page_text: cylinder, in which the piston valve a¹ works, and the parts of the engine being in
the positions in which they are represented in Figure 1 it passes thence by the port
in the side of the valve cylinder into the central working cylinder b; when the
valve a¹ rises to uncover the port the steam returns from the cylinder b by the same
way that it came, and it passes into the chamber g The chainberg is in com-
munication by the passage g¹ with the chamber h, and this chamber is open to the
small cylinders, in which the piston valves b' and c¹ work, as is more clearly seen in
Figure 3, which is a sectional plan of the upper part of the engine
The valve c¹ regulates the steam to and from the cylinder a, and the valve b² acts
similarly in respect to the cylinder c, these cylinders, when the valves b¹ and c² 1180
above the ports in their cylinders, deliver the steam into the chamber k When,
however, it is not desired to expand the steam from cylinder to cylinder, but that
each cylinder should be supplied with boiler steam, the slide valve m is moved to
the position in which it is shown in plan in Figure 4, and in vertical section at
Figure 5, it then covers the passages g' and ', and the chambers g and I become,
for the time, practically one chamber Simultaneously the communication between
the chamberg and the intermediate chamber is closed, whilst the latter chamber
is put into duect communication with the steam supply by the opening of the
valve n, which, as is seen in the Drawing, is now thrust from its seat by a projection
upon the end of the valve m
In this position of the parts the engine works as an
ordinary Willan's engine, but the expansive working and the economy incident
thereto can be resumed at any instant when it may be desired
Having thus descubed the nature of my said Invention and the manner of per-
forming the same, I would have it understood that I claim the construction of steam
engines substantially as herein described
In witness whereof, I, the said Walter Hunter, have hereunto set my hand
and seal, this Fourth day of August, in the year of our Lord One thousand
eight hundred and seventy-seven.