Improvements in Steam Engines.
Year: 1895

page_text: Date of Application, 25th Jan., 1895
Complete Specification Left, 24th July, 1895-Accepted. 7th Sept., 1895
Improvements in Steam Engines.
THOMAS MUDD, Central Engine Works, West Hartlepool in the County of
Durham, Engineer do hereby declare the nature of this invention to be as
follows:-
It is proposed by this Specification to construct marine engines, electric light
engines and other steam engines on five cranks, which number of cranks distributed
round the circle gives exceptional advantages that will be referred to hereinafter,
especially in the case of engines of large size. The five cranks are preferably
distributed at equal angles round the crank-circle, but may for special reasons be
distributed unequally. The stages of expansion of the steam may be varied to suit
the boiler pressure used in each case, and will with the pressures now in use, and
probably soon to come into use, be either three stages (triple expansion), four
stages (quadruple expansion), or five stages (quintuple expansion).
In triple engines of large size built under this Specification it will generally be
convenient to have two low pressure cylinders to avoid the very large size of
In that case the triple engines would
cylinder necessary when there is only one.
preferably bave one high pressure cylinder, two second stage cylinders, and two low
pressure cylinders. They could in special circumstances have two high pressure
cylinders, one second stage, and two low pressure cylinders. In quadruple engines
of large size it will also for the same reason be generally convenient to have two
low pressure cylinders, and in that case the quadruple engines would preferably
have one high pressure, one second stage, one third stage and two low pressure
cylinders.
In quintuple engines there would be one cylinder for each stage of the
expansion.
The above relates to triple, quadruple and quintuple engines in which there is
only one cylinder to each of the five cranks, an arrangement that is preferable up
to as large sizes as possible, owing to the greater facility it affords for overhaul.
In engines of exceedingly large power, where it becomes desirable to further
sub-divide the cylinders, this may be done by placing the extra cylinders beyond
the number of five over one or more of the five forming the first row, the number
of these extra cylinders and the stages of expansion to which they belong being
determined by the circumstances of each case.
The positions of the cylinders in relation to each other may also be further
varied at will, inasmuch as the first or high pressure cylinder may be at one end,
working on the first crank on the shaft, and each succeeding cylinder may adjoin
thereto in regular order; or, the high pressure cylinder may be in the middle with
the others ranged on either side of it, this being a good arrangement for a five-crank
triple; or, the high pressure cylinder may be second along the shaft, the second
stage cylinder being fourth, the third stage cylinder in the middle, and the others
at the two euds, this being a good arrangement for a five-crank quadruple; or, any
other arrangement of the cylinders may be adopted to suit circumstances.
The sequence of the cranks when named after the cylinders to which they
belong, in their rotation after one another around the crank-circle can with five
cranks be considerably varied, but the sequence preferred when engines are
running "ahead" way is for the five-crank triple engine the order one, three, two,

page_text: three, two; for the five-crank quadruple engine, one, four, two, four, three'; and for
the five-crank quintuple engine, one, four, two, five, three.
Apart from any increased subdivision of the total range of expansion of steam
herein proposed, there are advantages of importance in the five-crank engine
peculiar to itself. When the change was made in marine engines from two-crank
to three-crank engines considerable advantage was found from the smoothness and
continuity of the effort on the shaft, and naturally so, for with a two-crank engine
with cranks at right angles, there cannot be more than four impulses in the
revolution, whereas with the three-crank engine there are six impulses. To adopt
four-cranks is a retrograde step in this particular, for with the cranks placed
at right angles so that they will balance each other the impulses fall again to four
in the revolution.
It will be seen therefore that there is exceptional value in having five cranks, as,
whilst preserving a perfect balance amongst the cranks at every position of the
shaft, the number of impulses rises to ten per revolution, a number that is a greater
percentage advance over the six of the three-crank engine than that was over the
four of the two-crank engine.
Also, as engines become larger it becomes more and more important to avoid the
consequent increase of initial stress and power passing through any individual
crank by the adoption of more crauks, resulting in greater sub-division of these
stresses and powers.
For a given power the parts are much lighter and more manageable in overhaul
and repair than in the ordinary compound or triple engine; and for a given size of
parts much greater power can be developed.
The advantages are such as to render the five-crank engine especially applicable
and desirable in the Navy and Mercantile Marine, where very great power is
required in the handiest possible form, and also for heavy electric power and
lighting plants, and heavy mill driving, where the steadiness of the engine due to
the power being applied by ten impulses to the revolution is of the very highest
importance.
Dated this 24th day of January 1895
Improvements in Steam Engines.
I, THOMAS MUDD, of the Central Marine Engine Works, West Hartlepool, in
the County of Durham, 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':-
-
It is proposed by this Specification to construct marine engines, electric light
engines, and other steam engines.on five cranks, which number of cranks distributed
round the circle gives exceptional advantages that will be referred to hereinafter,
especially in the case of engines of large size. The five cranks are preferably
distributed at equal angles round the crank-circle, but may for special reasons be
distributed unequally. The stages of expansion of the steam may be varied to
suit the boiler pressure used in each case, and will with the pressures now in use,
and probably soon to come into use, be either three stages (triple expansion), four
stages (quadruple expansion), or five stages (quintuple expansion).
In triple engines of large size built under this Specification it will generally be
convenient to have two low pressure cylinders to avoid the very large size of
cylinder necessary when there is only one. In that case the triple engines would
preferably have one high pressure cylinder, two second, stage cylinders, and two
low pressure cylinders.

page_text: They could in special circumstances have two high pressure cylinders; one second
stage, and two low pressure cylinders.
In quadruple engines of large size it will also for the same reason be generally
convenient to have two low pressure cylinders ; and in that case the quadruple
engines would preferably have one high pressure, one second stage, one third stage,
and two low pressure cylinders.
In quintuple engines there would be one cylinder for each stage of the
expansion.
The above relates to triple, quadruple and quintuple engines in which there is
only one cylinder to each of the five cranks, an arrangement that is preferable up
to as large sizes as possible, owing to the greater facility it affords for overhaul:
In engines of exceedingly large power, where it becomes desirable to further
sub-divide the cylinders, this may be done by placing the extra cylinders beyond
the number of five over one or more of the five forming the first row, the number
of these extra cylinders and the stages of expansion to which they belong being
determined by the circumstances of each case.
.
The positions of the cylinders in relation to each other may also be further
varied at will, inasmuch as the first or high pressure cylinder may be at one end
working on the first crank on the shaft, and each succeeding cylinder may adjoin
thereto in regular order; or, the high pressure cylinder may be in the middle with
the others ranged on either side of it, this being a good arrangement for a five-
crank triple; or, the high pressure cylinder may be second along the shaft, the
second stage cylinder being fourth, the third stage cylinder in the middle; and the
'others at the two ends, this being a good arrangement for a five-crank quadruple;
.or..any other arrangement of the cylinders may be adopted to suit circumstances..
The sequence of the cranks when named after the cylinders to which they
belong, in their rotation after one another around the crank-circle, can with five
cranks be considerably varied, but the sequence preferred when engines are running
"aheadway is for the five-crank triple engine, the order one; three, two, three,
two; for the five-crank quadruple, engine, one, four; two; four; three; and for the
five-crank quintuple engine, one, four; two, five; three:
t..
Apart from any increased. subdivision of the total range of expansion of steam
herein proposed, there are advantages of importance in the five-crank engine
peculiar to itself. When the change was. made in marine engines from two-crank
to three-crank engines considerable advantage was found from the smoothness and
continuity of the effort on the shaft, and naturally so; for with a two-crank engine
with cranks at right angles, there cannot be more than four impulses in the revolu-
tion, whereas with the three-crank engine there are six impulses. To adopt four
cranks is a retrograde step in this particular; for with the cranks placed at right
angles so that they will balance each other, the impulses fall again to four in the
revolution. It will be seen therefore that there is exceptional value in having five
cranks, as, whilst preserving a perfect balance amongst the cranks at every position
of the shaft, the number of iinpulses rises to ten per revolution, a number that is a
greater percentage advance over the six of the three-crank engine than that was
over the four of the two-crank engine:
Also, as engines. become larger it becomes more' and more important to avoid the
consequent increase of initial stress and power passing through any individual
crank by the adoption of more cranks,. resulting in greater sub-division of these
stresses and powers.
For a given power, the parts are much lighter and more manageable in overhaul
and repair than in the ordinary compound or triple engine; and for a given size
of parts much greater power can be developed.
is.
The advantages are such as to render the five-crank engine especially applicable
and desirable in the Navy and Mercantile Marine; where very great power
required in
d in the handiest possible form, and also for heavy electric power and
lighting plants and heavy mill driving, where the steadiness of the engine due to

page_text: :
+
the power being applied by ten impulses to the revolution is of the very highest
importance.
.
The cylinders of an engine built upon five cranks may be placed in a large
number of different ways in relation to each other, and it would be tedious and
useless to show drawings of every possible arrangement. To sufficiently illustrate
the intention of this Specification however, examples are given in the drawings
of a few arrangements for each of the three types of engine referred to above, viz.,
the triple, the quadruple and the quintuple engine.
In Sheet I are shown several methods of arranging the cylinders when the
engines are triple (or three-stage expansion engines).
In Fig. 1 the high pressure or first stage cylinder is in the middle, and there are
two second stage cylinders at the sides of it, and two third stage cylinders at the
outer ends.
In Fig. 2 the high pressure cylinder is at one end, and there. are two second stage
cylinders adjoining it, both on the same side, and two third stage cylinders following
these again on the same side.
In Fig. 3 there are two first stage cylinders, with a second stage cylinder
between them, and two third stage cylinders at the outer ends.
In Fig. 4 there are two first stage cylinders, one above the other in the middle.
of the engines, and two second stage cylinders, one on each side of the lower first
stage cylinder, and two third stage cylinders at the ends.
I
In Fig. 5 there are two first stage cylinders at one end of the engine, one above
the other, two second stage cylinders to one side of the lower first stage cylinder,
and two third stage cylinders adjoining these on the same side.
In Fig. 6 there are two first stage cylinders placed over two second stage
cylinders, and three third stage cylinders, one being between the two second
stage cylinders and the other two being at the outer ends.
In Sheet II are given a few examples of arrangement of cylinders on five cranks
when the engine is a quadruple, or four-stage expansion engine.
In Fig. 9 the first, second and third stage cylinders adjoin each other, and there
. are two fourth stage cylinders beyond the latter.
In Fig. 10 the first and second stage cylinders adjoin each other, and the third
stage cylinder stands between two fourth stage cylinders.
In Fig. 11 the arrangement is like Fig. 10, except that the first stage cylinder
is shown adjoining one of the fourth stage cylinders, and the second stage cylinder
is at the outer end.
In Fig. 12 the third stage cylinder is in the middle and stands between the first
and second stage cylinders, there being also two fourth stage cylinders at the outer
ends.
In Fig. 13 the first stage cylinder is in the middle, the second on one side of it,
the third on the other side, and, the two fourth stage cylinders at the outer ends."
In Fig. 14 the first stage cylinder is in the middle standing between two fourth
stage, cylinders, the second stage cylinder being at one end beyond one of the
fourth stage cylinders, and the third stage cylinder at the other end.
In Sheet III are given some examples of arrangements of cylinders when the
engines are quadruple (or four-stage expansion) engines on five cranks, but with
more than five cylinders.
In Fig. 17 there are two first stage cylinders standing over each other, a second
stage cylinder at the side of the lower first, a third stage cylinder adjoining the
second, and two fourth stage cylinders beyond the third.
In Fig. 18 there are two first stage cylinders standing over two second stage
cylinders, the third stage cylinder being between two fourth stage cylinders.
In Fig. 19 there is one first stage cylinder standing over a third stage cylinder,
which is in the middle of the engine, and which latter has on each side of it a
second stage cylinder, there being two fourth stage cylinders at the outer ends.
In Fig. 20 there is a first stage cylinder standing over a second sta
second stage cylinder

page_text: in the middle of the engine, the latter having two third stage cylinders, one on;
sach side of it, and two fourth stage cylinders at the outer ends.
In Fig. 21 there are two first stage cylinders standing over two second stage
cylinders, there being a third stage cylinder between the two latter, and two fourth,
stage cylinders at the outer end.
In Fig. 22 there are two first stage cylinders standing over two third stage:
cylinders, the latter having a second stage cylinder between then and two fourth,
stage cylinders at the outer ends. It is obvious that if in this arrangement it be
desired to have two cylinders to each stage a second stage cylinder may be placed.
as shown in dotted lines.
In Sheet No. IV are shown some examples of the arrangement of the cylinders.
when the engines are quintuple, or five-stage expansion engines.
In Fig. 23 the five cylinders representing the five stages of expansion are placed
in consecutive order.
:
In Fig. 24 the first stage cylinder is at one end adjoined by the second stage.
cylinder, the third stage cylinder being between the fourth and fifth.
In Fig. 25 the first stage cylinder is at one end, the second stage cylinder in
the middle, with the third stage cylinder on one side of it, the fourth stage
cylinder on the other side of it, and the fifth stage cylinler at the opposite end
from the first.
In Fig. 26 the first stage cylinder is placed between the second and fourth, and
adjoining the latter is the third stage cylinder, beyond which again is the fifth.
stage cylinder.
In Fig. 27 the first and second stage cylinders have the fourth between them,
and on the outer end beyond the first is the third stage cylinder, and at the other
end beyond the second is the fifth stage cylinder.
;
In Fig. 28 the first stage cylinder is in the middle, having adjoining it the third
and fourth stage cylinders, one on each side, and at the outer end beyond the third..
is the second, and at the other end beyond the fourth is the fifth.
In Sheet No. V are given some examples of the arrangement of the cylinders
when the engines are quintuple expansion engines on five cranks, but with more..
than five cylinders.
In Fig. 29 the first cylinder is shown over the second at one end of the engine,
and adjoining the second is the third, and then the fourth, and beyond that two
fifth stage cylinders. It is obvious that a slight modification of this arrangement
would be to place the first stage cylinder over the third, or over the fourth, as
shown in dotted lines. Or there might be two first stage cylinders in any of these
positions.
In Fig. 30 there are two first stage cylinders shown over the second and third
stage cylinders, and to one side of these the fourth stage cylinder stands between
the two fifth stage cylinders. Again, in this arrangement the two first stage
cylinders might be placed over the two fifth stage cylinders, as shown in dotted
lines.
In Fig. 31 the first stage cylinder stands over the fourth stage cylinder in the
middle of the engine, the latter having the second and third stage cylinders one on
each side, and the two fifth stage cylinders at the outer ends. In this arrangement
also there might be two first stage cylinders placed over the second and third, as
shown in dotted lines, instead of one over the fourth.
In Fig. 32 there are two first stage cylinders standing over the two fifth stage
cylinders at the outer ends, the fourth stage cylinder is in the middle, and between
these and the two fifth stage cylinders are two third stage cylinders, which have
two second stage cylinders over them.
The positions of the cranks in respect of their angular relation to each other
around the circle and in respect of their sequence may be varied at will to suit
5 circumstances. A few examples are given both of equal and unequal angles and
of sequences.
In Fig. 7, Sheet I, the five cranks are set at equal angles, the sequence shown

page_text: being one that is suitable for a triple five-crank engine, with one first, two second
and two third stage cylinders.
Fig. 8 represents also equal angles and shows an example for a triple engine
where there are more than five cylinders.
Figs. 15 & 16, Sheet II, show the five cranks at equal angles, the sequences
being examples suitable for quadruple engines having one cylinder each for the
first second and third stage cylinders, and two cylinders for the fourth stage.
Figs. 34 & 34, Sheet III, show examples of cranks set at unequal angles, the
sequences of the cranks being figured to suit triple engines on five cranks, with one
first, two second, and two third stage cylinders.
Fig. 35 is another example of the cranks set at unequal angles, the outside
figures representing the sequence in a triple engine, as in the two previous figures,
and the inside figures representing the sequence for a quadruple engine, with one
first, second and third stage cylinders and two fourth.
Fig. 36, Sheet IV, shows another example of the cranks set at unequal angles,
the inside figures showing a suitable sequence for a quadruple engine as in the last
case, and the outside figures showing the sequence for a quintuple engine with one
cylinder to each stage of expansion.
Fig. 37 is another example of the cranks set at unequal angles, the figures
representing a sequence suitable for a quintuple engine, as in the last case.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
(1.) In steam engines the employment of five cranks.
(2.) In steam engines, five cranks set at equal or at unequal angles with each
other, and in any order or sequence.
(3.) In steam engines the employment and disposition of five or more than five
cylinders in any order that is suitable to enable them to give motion through their
pistons, piston rods and connecting rods, or equivalent parts, to five cranks,
substantially as set forth, and of which some examples are shown in the drawings.
(4.) In steam engines the employment of five or more than five cylinders of such
relative sizes as to be adapted to triple, quadruple, or quintuple expansion of
steam, whilst being at the same time disposed in any relative order that is suitable
to enable them to work upon five cranks, substantially as set forth, and of which
some examples are given in the drawings.
Dated this 23rd day of July 1895.
THOMAS MUDD.