IMPROVEMENTS IN THE CONSTRUCTION OF MARINE STEAM ENGINES WHICH AZE PARTICULARLY APPLICABLE TO STEAM ENGINES OF THE LARGEST CLASS
Year: 1839

page_text: MAUDSLAY & FIELD'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOSEPHI
MAUDSLAY and JOSHUA FIELD, of the firm of Maudslay, Son, and Field,
Engineers, of Lambeth, in the County of Surrey, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Seventh day of May, in the second year of Her reign, and in
the year of our Lord One thousand eight hundred and thirty-nine, did, for Herself,
Her heirs and successors, give and grant unto us, the said Joseph Maudslay
and Joshua Field, Her especial licence, full power, sole privilege and authority,
that we, the said Joseph Maudslay and Joseph Field, our exccutors, adminis-
trators, and assigns, and such others as we, the said Joseph Maudslay and
Joshua Field, our executors, administrators, or assigns, should at any time
agree with, and no others, from time to time and at all times during the term
of years therein mentioned, should and lawfully might make, use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed,
and also in all Her Majesty's Colonies and Plantations abroad, our Invention
of "IMPROVEMENTS IN THE CONSTRUCTION OF MARINE STEAM ENGINES WHICH
AZE PARTICULARLY APPLICABLE TO STEAM ENGINES OF THE LARGEST CLASS;" in which
said Letters Patent is contained a proviso obliging us, the said Joseph
Maudslay and Joshua Field, by an instrument in writing under our hands
and seals, or under the hand and seal of one of us, particularly to describe and
ascertain the nature of our said Invention, and in what manner the same

page_text: is to be performed, and to cause the same to be enrolled in Her Majesty's
High Court of Chancery within six calendar months next and immediately
after the date of the said in part recited Letters Patent, as in and by the same,
reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, we, the said
Joseph Maudslay and Joshua Field, do hereby declare the nature of our said
Invention, and the manner in which the same is to be performed, are particu-
larly described and ascertained in and by the following description thereof,
reference being had to the Drawings hereunto annexed, and to the letters and
figures marked thereon, that is to say :-
These improvements in the construction of marine steam engines are
particularly applicable to those of the larger class, and are designed principally
for the purpose of producing and applying a greater amount of steam power
than has heretofore been available within a given space or area on shipboard.
This is effected by different constructions, arrangements; and proportions of the
parts of a low-pressure engine, allowing a more perfect application of the expan-
sive force of steam without increasing the weight of the whole machinery.
The first feature of our improvements consists in adapting two steam
cylinders to one engine in such a way that the steam shall act simultaneously
upon both pistons, in order that they may be made to rise or fall together, the
piston rod of each being attached to one horizontal cross head, and thereby the
combined action of both pistons applied to one crank of the paddle shaft.
The second feature of our improvements applies more particularly to engines
for river navigation, and consists in the adaptation of a piston with two rods
working in a steam cylinder of large area, both pistons rods being connected
to one cross head above, which gives motion to the crank below it by a single
connecting rod.
The third feature of our improvements consists of a method of adjusting the
expansion valves of combined engines, by which the period for shutting off the
steam at any part of the stroke may be regulated in both engines at once by a
single movement whilst the engines are working.
The fourth feature of our improvements is, the peculiar construction of the
main beams of the framing that carry the plummer blocks of the main crank
shaft to which the paddle wheels are attached. These beams we form as
hollow trunks by the combination of wrought-iron plates attached to bars of
angle iron in the same way as ordinary boilers are made, and we are enabled
by that means to construct beams of the largest dimensions, of unlimited
strength, and of comparatively small weight. These improvements will be

page_text: more fully understood by reference to the accompanying Drawings, and the
following description thereof, in which Fig. 1 is an elevation, taken longitudi-
nally, representing an engine with two cylinders, constructed upon the plan
described as the first feature of our improvement. Figure 2 is a vertical
section of the same taken through the cylinders. Fig. 3 is a horizontal
section of a vessel, in which the situation of the engine shewn at Figure 1 is
seen as it would appear when looking upon it from above; and Fig. 4 is a
corresponding engine placed at the other side of the vessel, but represented in
section, cut horizontally through the cylinders. Fig. 5 is a vertical section,
taken transversely through a steam vessel, shewing the positions of two
engines, as in Figs. 3 and 4, the one engine being in section, the other an
external view, seen upon a plain in advance of the former; and Fig. 6 is a
plan or horizontal view of a portion of the steam vessel, with the engines and
their appendages, and also the frameing by which the crank shafts of the
paddle wheels are supported, similar letters referring to the same parts of the
machinery in all the preceding Figures. The two connected working cylinders
are shewn at a, a, their pistons at b, b, and the piston rod at c, c, the upper
ends of which rods are affixed by keys to the cross head d. Four vertical
rods e, e, e, e, affixed at top to the cross head d, are connected at the bottom
to a slider f, which slider is enabled to move up and down on the guide ribs g, g,
formed on the outer surfaces of the cylinders. To this slider f one end of a
connecting rod is attached, the other end of that rod being attached to the
crank i of the propelling shaft. From this arrangement it will be perceived
that by the simultaneous ascent and descent of the two pistons b, b, in their
working cylinder a, a, the rods c, c, will cause the cross head d to move per-
pendicularly up and down between its guide bars j,j, and in so doing to raise
and depress the slidef with the connecting rod h, which rod will, by that
means, be made to give rotary motion to the crank i, and thereby cause the
paddle wheel shaft k to revolve. A rod connected to the slide f will at the
same time work the lever m, to which the rod of the air pump n is attached.
The mode of adapting the steam valve of the combined cylinders a, a, is best
seen in Figs. 3 and 4. The steam is admitted to and withdrawn from the
cylinders by one slide valve, common to both, through a pipe n, seen in Fig. 5.
From this pipen the steam proceeds through a slide valve o of the ordinary
construction, and through the curved passages or tubes p, p, into both
cylinders. There is also a narrow passage of communication always open
at q, by which the steam is allowed to pass from one cylinder to the other,
for the purpose of keeping the pressure equal at all times in both cylinders.

page_text: The expansion valve is on the steam pipe n, at the entrance to the slide
valve. The slide is moved by an excentric in the ordinary way, and the
expansion valve is regulated by the means described hereafter under the third
feature of our Invention. The advantages proposed by this arrangement are,
simplicity of construction, more direct action on the crank, saving of space
and weight of material, offering easy means of giving larger area of
cylinder, whereby a given amount of steain can be used more expansively than
in former arrangements, and consequently yield more power and economise
fuel with the further advantage at sea, that when the engine is reduced in the
number of its strokes by deep lading with coal, as at the commencement of a
voyage, or by head winds, more steam may then be given to the cylinders, and
under such circumstances more speed to the vessel, all the steam generated in
the boiler being usefully applied.
The second feature of our Invention, viz, the improved construction of steam
engine having two piston rods working in one cylinder, is represented in the
accompanying Drawing at Figs. 7, 8, 9, 10, 11, and 12. Fig. 7 is an elevation
of the engine; Fig. 8, a section of the same, taken vertically through the
cylinder to the slide valve and the air pump. Fig. 9 is a horizontal view of
the top of the cylinder, valve, box, and air pump of these improved engines;
and Fig. 10 is a horizontal section taken through the cylinder of a similar
engine on the other side of the vessel. Fig. 11 is a section taken transversely
through a steam vessel, shewing the positions in elevation of the two engines
mentioned in the preceding Figure, the cylinder of one being in vertical
section, the other an external view taken upon a plain in advance of the
former with the crank shaft and paddle wheels; and Fig. 12 is a horizontal
view, as seen from above, of the two engines and their appendages,-the same
lotter of reference pointing out similar parts of the machinery in all the six
last-mentioned Figures. The cylinders of large area are shewn at a, a, and b
are their pistons; c, c, are two perpendicular rods inserted into each piston,
and working through stuffing boxes in the cylinder lid; d is a cross head to
which the two piston rods are keyed at top, and c, c, are the guide rods
fixed on cast-iron supports, upon which rods the cross head d slides up and
down. The connecting rod f is attached above to the cross head and below
to the crank g, g, on the paddle shaft. The other parts of the engines will
appear so obvious from inspecting the Drawings as not to require further
description. It will be perceived that by this arrangement of the parts of the
engine motion is given to the crank shaft below the cross head by a single
connecting rod. The advantages resulting from this improvement are, that a

page_text: paddle shaft placed at a given height from the bottom of the vessel will be
enabled to receive a longer stroke of the piston than by any other arrange-
ments now in use, a more compact and firm connection of the cylinder with
the crank shaft bearings is effected, and a cylinder of much greater diameter
may be applied, by which the principle of working steam expansively may be
more fully carried out, and a more direct action of the steam power on the crank
obtained, with a less weight of materials and a greater economy of space than
has heretofore been attained by any of the arrangements of marine engines in use.
The third feature of our Invention, viz, the method of adjusting the
expansive valves of combined engines, will be seen by reference to the Drawings,
Figs. 13, 14, 15, and 16. In these Figures 13 represents the central
portion of the double crank shaft of a steam vessel, with the parts appended by
which the above object is effected, as they would appear in elevation; Fig. 14
is a horizontal view of the same; Fig. 15 is an elevation taken at right angles
to Fig. 13, about the middle of the shaft, which is here shewn in section; and
Fig. 16 is an elevation also at right angles to Fig. 13, shewing one of the
cams upon the shaft in section, by which the lever and rod of the expansion
valve is worked, the respective letters referring to the same parts of the
machinery in these last-mentioned Figures. The central part of a double
crank shaft is shewn at a, a, supposed to be adapted to a pair of enginės; b, b,
is a tube or socket, sliding horizontally upon the shaft, but prevented from
turning upon it by a rib on the shaft taking into a long groove in the socket.
This tube or socket has two snail cams c and d affixed to it, or cast upon it,
and in the centre, between the cams, a series of rings or flutes e, e, are also
formed upon the tube. A spindle, placed at right angles to the main crank
shaft, has a pinion f, the teeth of which take into the rings or plates e, e, shewn
also detached at Fig. 15, and by turning this spindle and pinion f (which may
be done by a hand wheel g), the tube b, b, with its snail cans, will be slidden
upon the main crank shaft, to the right or left, as may be required. Upon
the periphery of the snail cams c and d, the antifriction rollers in the levers h
and i are intended to work (as shewn also in the detached Fig. 16). The
rods from these levers h and i are connected to the expansion valves of the
two engines below, and hence by the action of the cams c and d against the
levers h and i, as the main shaft a revolves, the expansion valves are opened
and closed. Let it be supposed that by turning the pinion f the tube or socket
b, b, (seen in Figs. 13 and 14,) has been slidden towards the left, as far as it
will
go, then as the main shaft revolves the uninterrupted circular periphery
of the cams c and d will act against the levers h and i, so as to keep them in

page_text: their elevated positions, consequently the expansion valves will, under those
circumstances, remain open. If, however, it is desirable to shut off the steam
during a part of the rotation of the main shaft, we turn the pinion f so as to
slide the tube b, b, with the cams c and d, toward the right in Fig. 13 and 14.
When this is done, only ค portion of the circular periphery of each cam will be
enabled to act in holding up the levers, for, as the main shaft with the cams
revolves, the roller of each lever h or i will, when the snail or curved edge of
the cam comes under the roller, allow the lever to fall, and by so doing to
close the expansive valve, and shut off the steam from the working cylinder,
until the roller rises again up to the opposite edge of the snail, and get on to
the larger radius of the cam, when, the lever will be raised, and the expansion
valve opened, allowing a free passage to the steam. In this way the cams may
be slidden still farther to the right, and cause so small a portion of the larger
radius of the cams to act against the levers as to shut off the steam during the
greater part of the rotation of the main shaft. By this apparatus we are
enabled to regulate the flow of the steam into both engines at once, by one simple
movement of the spindle and pinion, and without interrupting for a moment the
working of the engines; such a means of adjustment being highly important in
bringing into operation the full effect of steam applied upon the expansive
principle in economizing fuel, and adapting the power of engines to the varying
circumstces at sea, between light and heavy lading, and between strong head
wind and scudding before the gale. The peculiar construction of main beams
for supporting the crank shafts, mentioned as the fourth feature of our Inven-
tion, are formed by combining long flat plates of rolled iron, which we unite
to long bars of iron turned up at right angles, or what is commonly called
angle iron; the plates are firmly attached to these bars by rows of rivets in
the ordinary way of working wrought iron boilers. Such beams may be extended
to any length, and made into any form required and applied, as at m, m, m,
in Figs. 1, 2, 5, and 6, and the bearing and other parts of the engines may be
attached to these beams, as shewn in the Drawings. These beams may
be made of unlimited strength, and with a comparatively small weight of
material.
In witness whereof, we, the said Joseph Maudslay and Joshua Field,
have hereunto set our hands and seals, this Seventh day of November,
in the year of our Lord One thousand eight hundred and thirty-nine.

page_text: AND BE IT REMEMBERED, that on the Seventh day of November, in
the third year of the reign of Her Majesty Queen Victoria, the said Joseph
Maudslay and Joshua Field came before our said Lady the Queen in Her
Chancery, and acknowledged the Instrument aforesaid, and all and every
thing therein contained and specified, in form above written. And also the
Instrument aforesaid was stamped according to the tenor of the Statute
made in the fifty-fifth year of the reign of His late Majesty King George the
Third.