CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1854

page_text: LETTERS PATENT to James Ward Hoby, of Renfrew, in the County of
Renfrew, North Britain, Engineer, and John Milner, of Stanley Street,
Pimlico, in the County of Middlesex, Engineer, for the Invention of
"CERTAIN IMPROVEMENTS IN STEAM ENGINES."
PROVISIONAL SPECIFICATION left by the said James Ward Hoby and
John Milner at the Office of the Commissioners of Patents, with their
Petition, on the 10th May 1854.
We, JAMES WARD HOBY and JOHN MILNER, do hereby declare the nature
of the said Invention for "CERTAIN IMPROVEMENTS IN STEAM ENGINES" to be as
follows:-
The Invention relates to that class of steam engines known as "trunk
engines," in which the piston rod is replaced by a hollow pipe or "trunk,"
within which the connecting rod is jointed, and capable of vibrating to and fro.
We attach a cross-head to the top of the trunk, which cross-head is guided by
suitable guides, and has attached to it the rods of the air pump, feed pump,
and bilge pump, or other pumps which may be required. The piston and
cylinder cover may be dished, so as to enable the length of the trunk to be
reduced as much as possible. The connecting rod is jointed to the piston or
to the trunk at an intermediate point between the piston and the top of the
trunk, by which last arrangement the lateral pressure on the piston is partially

page_text: reduced, and the diameter of the trunk may also be diminished. In lieu of the
cross-head, we sometimes employ a short beam, connected to the trunk, from
which it receives its motion. This beam gives motion to the air pump and
other pumps, instead of their deriving their motion from the cross-head. We
also construct steam engines with a trunk or pipe attached to or forming part
of the cylinder cover, in lieu of or in combination with a trunk attached to the
piston. We construct such cylinder cover with a pipe or cylindrical trunk, as
part thereof, or suitably fixed thereto, to serve as a guide for the piston rod.
The piston may be concave, and the piston rod (or that portion of the piston
which performs the functions of a piston rod) may be either packed to work
steam-tight within the pipe or trunk aforesaid, or the said pipe or trunk may
be provided with a stuffing box, and packed so that the piston rod may work
steam-tight through it....The piston rod may be made hollow, so as to form
a trunk, and the joint of the connecting rod may be contained within it, as
in an ordinary trunk engine.
E
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Ward Hoby and John Milner in the Great Seal
Patent Office on the 7th November 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JAMES
WARD HOBY, of Renfrew, in the County of Renfrew, North Britain,
Engineer, and JOHN MILNER, of Stanley Street, Pimlico, in the County of
Middlesex, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tenth day of May, in the year of our Lord One
thousand eight hundred and fifty-four, in the seventeenth year of Her reign.
did, for Herself, Her heirs and successors, give and grant unto us, the said
James Ward Hoby and John Milner, Her special license that we, the said
James Ward Hoby and Jolin Milner, our executors, administrators; and
assigns, or such others as we, the said James Ward Hoby and John Milner,
our 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 "CERTAIN IMPROVEMENTS IN
STEAM ENGINES;" upon the condition (amongst others) that we, the said James
Ward Hoby and.John Milner, by an instrument in writing under our hands

page_text: and seals, or under the hand and seal of one of us, 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 John Milner, on behalf of myself and
the said James Ward Hoby, do hereby declare the nature of the said Inven-
tion, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement thereof, reference
being had to the accompanying Drawings, and to the figures and letters
marked thereon, that is to say:-
Figure 1, Sheet I., of the accompanying Drawings, is a front view, partly in
section, of a pair of steam engines constructed according to our Invention, and
fitted to a ship or vessel; Figure 2 is a side view of one of the same engines.
The same letters indicate similar parts in both Figures. In Figure 1, one of
the steam cylinders is shewn in elevation and the other in section. A is the
steam cylinder; B is the piston, to which is attached the trunk C, within which
the connecting rod D is jointed at E. The other end of the connecting rod is
connected to the crank F on the main shaft G. H is the slide valve, which is
worked in the ordinary manner. To the top of the trunk C is attached a cross-
head I, which works up and down on the guides J, J, which also serve to
connect the cylinder A with the frame Z, which supports the bearings of the
main shaft G. To the cross-head I are attached the air pump rod K and the
plunger L of the feed pump. The bilge pump. or other pumps may also be
worked by this cross-head. The lower end of the connecting rod D may be
jointed at the bottom of the trunk, or at some intermediate point between the
piston and the cross-head. In this latter arrangement, which is that shewn in
the Drawing, the piston is relieved from a portion of the lateral thrust of the
connecting rod, which is borne by the guides J, J. By means of the cross-
head I, we are enabled to work the pumps in a direct and simple manner, and
it is not necessary to employ a cranked intermediate shaft for that purpose.
The piston B may be made flat, as shewn in the Drawing, or concave, as in the
engines shewn in Figures 3, 5, 6, and 8.
Figure 3, Sheet II., is a longitudinal section of another of our improved
steam engines. A is the cylinder, and B is the piston; C is the trunk, within
which the connecting rod D is jointed at E. The other end of the connecting
rod is connected to the crank F on the main shaft G. The piston and cylinder
covers are made concave on the side next to the main shaft G, by which
arrangement the trunk is removed farther from the crank shaft, and may con-

page_text: sequently be made of smaller diameter, because less space is required for the
vibration of the connecting rod. The lateral thrust or pressure of the connecting
rod is in this arrangement chiefly borne by the piston, as in the ordinary trunk
engine, in which the trunk is on one side only of the piston.
Figure 4 is a longitudinal section of another of our improved steam engines.
A is the cylinder, and B is the piston; C is the trunk, and D the connecting
rod jointed to the trunk at E, and connected to the crank F on the main shaft
G; P is a cylindrical pipe or trunk attached to or forming part of the cylinder
cover, and forming the guide for the trunk C. a, a, is metallic or other
packing, fitted into a recess or recesses in the exterior of the trunk C. In this
arrangement the joint E is supported and guided throughout its course by the
pipe or trunk P. In lieu of the hollow trunk C, a solid rod of equal diameter
may be employed. This arrangement may be applied with a piston and
cylinder covers of concave form, and the pipe P will then be wholly or partially
contained within the concavity of the cylinder cover. Such an arrangement is
shewn in Figure 5, in which Figure the corresponding parts are marked with
the same letters as in Figure 4. By this arrangement a more compact form of
engine is obtained. In Figures 4 and 5, the joint E of the connecting rod is
at the extremity of the trunk C, which may be made solid, if preferred, and
which forms or acts as the piston rod; we, however, prefer to make this piston
rod hollow, for the sake of avoiding unnecessary weight. Figure 6 is a similar
arrangement to that shewn in Figure 5, excepting that the joint E is placed
within the trunk C, at some distance from its extremity, by which arrangement
the cylinder is brought nearer to the crank shaft, and the engine occupies less
space.
Figure 7 is a longitudinal section of another of our improved steam engines.
A is the cylinder, and B is the piston; C is the trunk, within which the
connecting rod D is jointed at E. The other end of the connecting rod is.
connected to the crank F on the main shaft G. P is a cylindrical pipe
or trunk attached to or forming part of the cylinder cover, and serving as
a guide for the trunk C. In lieu of applying the packing in a recess or
recesses in the trunk C, it is introduced at the inner end of the pipe or trunk
P, and is pressed up by another pipe Q, which is fitted between the pipe P
and the trunk C. The pipe Q thus acts as the gland of a stuffing box, as
well as serving with the pipe or trunk P to guide the trunk C. If other
descriptions of packing not requiring a gland be employed, the pipe Q
may be dispensed with, and the pipe P may be made to fit the trunk C. The
joint E of the connecting rod is thus well supported and guided, and the lateral
thrust of the connecting rod is borne by the pipe or trunk P. The joint E

page_text: may pass somewhat beyond the ends of the pipe P, as the lateral thrust of the
connecting rod diminishes towards the ends of the stroke.
Figure 8 is a longitudinal section of a steam engine, somewhat similar to
that shewn in Figure 7; the piston and cylinder covers are, however, made
concave instead of flat. The corresponding parts are marked with the same
letters as those in Figure 7. The pipes P and Q guide the trunk C, and sup-
port the lateral pressure of the connecting rod D, as in Figure 7. In both
these arrangements the joint E of the connecting rod is within the pipe or
guide when the connecting rod is at its greatest inclination, and the piston is at
or near to its half stroke, and also for a considerable distance on each side of
the position of greatest inclination. By prolonging the pipe P sufficiently, the
joint E may be made to work within the pipe during the whole of its stroke.
In no case should the length of the guide formed by the pipe P, or the pipes
P and Q together, be less than one-half of the stroke of the piston. The joint
E of the connecting rod may, if required, be placed at the extremity of the
trunk C, which may then be made solid, and the pipes P and Q are then
prolonged, to afford sufficient guide to the trunk or piston rod C. This
arrangement, however, occupies a greater space than that shewn in Figure 8.
In the various arrangements shewn in Figures 4, 5, 6, 7, and 8, the lateral
thrust or pressure of the connecting rod is borne entirely or to a great extent
by the pipe P, and the piston is thus relieved from the lateral pressure. In
constructing condensing engines according to these arrangements, the air. pump
may be worked by a cranked shaft, or directly by means of a piston rod
attached to the piston, near its circumference, and passing through a stuffing
box in the cylinder cover, or in any other suitable manner. The engines,
herein-before described in reference to Figures 1 and 2, are well adapted for
acting with their cylinders in a vertical position, and may be employed for
driving the paddle wheels of steam vessels. The engines shewn in Figures
3, 4, 5, 6, 7, and 8, are well adapted for acting in a horizontal or inclined
position, and may be employed for driving the screw propellers of steam vessels.
We do not, however, confine ourselves in either case to any particular position,
or to any particular application or use of such engines.
Having now described the nature of our said Invention, and in what manner
the same is to be performed, we wish it to be understood that we do not claim
generally the constructing of steam engines with trunks or hollow piston rods;
nor do we claim generally the constructing of steam engines with concave
pistons and cylinder covers; but what we claim is,-
£
Firstly, the constructing steam engines with the connecting rod working

page_text: within a trunk or hollow piston rod, to which is attached a cross-head which
works the air pump of the engine, as herein-before described.
Secondly, the constructing steam engines with the connecting rod working
within a trunk attached to or forming part of a concave piston, working in a
cylinder with covers of corresponding form, as herein-before described, in
reference to Figure 3.
.
Thirdly, the constructing steam engines with a flat or concave piston working
in a cylinder with covers of corresponding form, such piston being provided
with a solid or hollow piston rod or trunk furnished with suitable packing, and
working within a pipe or trunk attached to or forming part of the cylinder
cover, and serving as a guide and support for the joint of the connecting rod,
as herein-before described, in reference to Figures 4; 5, and 6.
Fourthly, the constructing steam engines with a flat or .concave piston
working in a cylinder with covers of corresponding form, such piston being
provided with a solid or hollow piston rod or trunk working through packing
contained within a pipe or trunk attached to or forming part of the cylinder
cover, which fixed pipe or trunk serves, either alone or together with an inner
pipe or gland, as a guide and support for the piston rod or trunk, and is so
arranged that the joint of the connecting rod may be within such pipe or pipes
when it is in its most oblique position, and for a space not less than half the
length of stroke of the piston, as herein-before described, in reference to
Figures 7 and 8.
In witness whereof, I, the said John Milner, have hereunto set my hand
and seal, this Fourth day of November, in the year of our Lord One
thousand eight hundred and fifty-four.
Witness,
CHARLES COWPER,
20, Southampton Buildings,
Chancery Lane,
London.
JOHN MILNER. (L.B.)-