IMPROVEMENTS IN MOTIVE-POWER ENGINES
Year: 1876

page_text: LETTERS PATENT to Jeremiah Head, of Middlesbrough, in the County of York,
for the Invention of "IMPROVEMENTS IN MOTIVE-POWER ENGINES."
PROVISIONAL SPECIFICATION left by the said Jeremiah Head at the Oflice
of the Commissioners of Patents on the 9th March 1876.
JEREMIAH HEAD, of Middlesbrough, in the County of York.
MOTIVE-POWER ENGINES."
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IMPROVEMENTS IN
My Invention relates to motive-power engines to be driven by steam, air, water,
or other fluid pressure, and consists in the arrangement of four single acting cylinders
radially-round the shaft or axle to be driven in such a manner that
1st. The centre lines or axes of the said four cylinders shall lie in one plane (or
nearly so), which plane shall be at right angles (or nearly so) to the centre line or
axis of the shaft to be driven.
2ndly. The centre line or axis of cach of the said four cylinders shall form a right
angle (or nearly so) with that of the cylinders next on either side thereof, and shall
be in a line (or nearly so) with that of the remaining cylinder.
3rdly. The said four cylinders shall be open at their inner ends to a central
chamber, into which when in action the exhaust steam, air, water, or other fluid
shall be discharged from the distributing valve after having operated on the pistons,
and from which the exhaust pipe shall lead to the open air or elsewhere.
4thly. The steam, air, water, or other fluid under pressure shall be introduced
into each cylinder at or near its outer end, & shall act only upon that end of the
piston.
prefer to construct the central chamber in the form of a hollow cylinder con-
centric with the shaft to be driven, and open at each end. To a flange at one end
1 fasten a casting acting as a cover, and which contains the bearings of the shaft to
be driven, and forms the pedestal or frame of the engine. To a flange at the other
I secure a cylindrical flanged casting, forming the casing for the distributing
valve.
The shaft to be driven is furnished with a crank, which revolves inside the
central chamber, and to the crank pin of which the four connecting rods are secured
by any convenient joint. The connecting rods at their outer ends are severally
jointed to their respective pistons.
[Price Gd]

page_text: The distributing valve I prefer to make in the form of a hollow cylinder, having
ports for the incoming and outgoing steam, air, water, or other fluid, the portions of
the cylindrical valve containing the said ports being completely separated by a
diaphragm. I drive this valve by connecting it with the crank of the main shaft
by a trailing crank.
When it is desired to construct the engine so that it may be reversed, I introduce
a spindle (by preference composed of steel) through the centre of the valve and in a
line (or nearly so) with the axis of the main shaft, which spindle is capable of being
pushed in or drawn out by an external reversing lever. The spindle is provided at
one part with one or more spiral grooves, and at another part with an ordinary key-
way and bedded key, and corresponding spiral projections and keyways are made
in the central boss of the trailing crank and in the central hole of the valve respec-
tively. When by moving the reversing lever the central spindle is pushed in or
drawn out, it moves through the valve without turning it, but is compelled to rotate
in the trailing crank, whereby it changes the position of the valve with respect to
the crank, and in this way the entrance and exit of steam, air, water, or other fluid
is made to correspond with a right-hand or left-hand rotation of the shaft.
Where engines are not required to reverse, I sometimes attach a horizontal
governor having two revolving weights to a central spindle, such as that lastly
herein-before described. These weights by means of a spring are maintained close
to the spindle until an undue velocity is attained, when their centrifugal force causes
them to dilate. By suitable connections this motion is made to act (where steam or
other elastic fluid is employed) cither in moving round the distributing valve afore-
said with regard to the crank, as previously described, thereby controlling by varying
the expansion, or by a subsidiary cut-off or throttle valve inside the distributing
valve, and concentric with it.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Jeremiah Head in the Great Seal Patent Office on the 7th September
1876.
JEREMIAH HEAD, of Middlesbrough, in the County of York.
MOTIVE-POWER ENGINES."
"IMPROVEMENTS IN
My said Invention relates to motive-power engines to be driven by steam, air,
water, or other fluid pressure, and consists in the arrangement of four single acting
cylinders radially round the shaft or axle to be driven in such a manner that-
First. The centre lines or axes of the said four cylinders shall lie in one plane (or
nearly so), which plane shall be at right angles (or nearly so) to the centre line or
axis of the shaft to be driven.
Secondly. The centre line or axis of each of the said four cylinders shall form a
right angle (or nearly so) with that of the cylinder next on each side thereof, and
shall be in a line (or nearly so) with that of the remaining cylinder.
Thirdly. The said four cylinders shall be open at their inner ends to a central
chamber, into which when in action the exhaust steam, air, water, or other fluid
shall be discharged from the distributing valve after having operated on the pistons,
and from which the exhaust pipe shall lead to the open air or elsewhere.
Fourthly. The steam, air, water, or other fluid under pressure shall be introduced
into each cylinder at or near its outer end, and shall act only upon that end of the
piston.
The engine is generally similar in its construction and arrangement to the three-
cylinder engines upon what is known as Brotherhood's system, from which it mainly
This modification of
differs by the employment of four cylinders in lieu of three.
the multiple cylinder principle, vidclicit, the use of four cylinders, is however found
to possess advantages which are wanting in the three-cylinder engine, and to obviate

page_text: serious defects to which the latter is liable, as will be apparent from the particulars
herein-after given.
It will be unnecessary for me to describe in detail such of the parts and their
operation as are common to engines constructed according to my Invention and to
the three-cylinder engine. In order however that my Invention may be perfectly
understood I shall proceed to describe more particularly the features in which it
differs from engines of known construction on the same principle, and for that
purpose shall refer to the several Figures on the two explanatory Sheets of Drawings
hereunto annexed.
Sheet 1 of my Drawings illustrates the construction of my improved engine, and
Sheet 2 contains a series of comparative diagrams indicating the superiority in
efficiency and economy of my improved engine over engines on a similar principle
constructed with three cylinders.
Referring to Sheet 1 of my Drawings, Figure 1 represents a transverse vertical
section of an engine constructed according to my Invention; Figure 2 is a sido
clevation, and Figure 3 a plan, both corresponding to Figure 1; Figure 4 represents
a longitudinal section taken along the line A, A, Figure 1, of a portion of the
engine; and Figure 5 is a sectional elevation, the section being taken along tho
line B, B, Figure 4.
Figures 6, 7, 8, 9, and 10 are detached views representing the details of the con-
necting rods, and will be more fully herein-after described.
A, B, C, D, are the four cylinders arranged radially around the shaft or axle E to
be driven, and whence the motive power may be transmitted in any convenient
manner. This shaft is furnished with a crank E¹, which revolves inside a central
chamber F, and to the crank pin G of which are attached the inner extremities of
four connecting rods A, B, C, D, the latter being severally jointed at their outer
ends to the respective pistons A, B, C, D, of the four cylinders A, B, C, D. The
large ends a, b, c, d, of the connecting rods A', B, C, D', where they meet upon the
crank pin G, are notched, as shewn at.e in Figure 1, and more clearly in the
detached views of the connecting rods (see Figures 6 to 10) so as to provide for each
the maximum width of base where it bears upon the crank pin, and at the same
time admit by their interlacing one with another of the desired angular movements.
It will be seen from an inspection of the Drawings that the centre lines or
axes 1, 2, 3, 4, of the cylinders are in one plane, or nearly so (see Figures 2, 3, and
4, Sheet 1), and that this plane is at right angles, or nearly so, to the centre line or
axis 5 of the shaft E to be driven; also, that the centre line or axis of any one
cylinder (say, for example, the centre line or axis 1 of the cylinder A) forms a right
angle, or nearly so, with that of the adjacent cylinder on each side thereof, (say, tho
centre lines or axes 2, 4, of the cylinders B, D,) and is in a line, or nearly so, with
the centre line or axis of the remaining cylinder (the line 3 of the cylinder C).
The steam, air, water, or other fluid employed as the motive agent is introduced
from a distributing valve H through four passages f, g, h, i, into all the cylinders
A, B, C, D, in succession at their outer ends 6, 7, 8, 9, only, and acts only upon that
side of the pistons A, B, C, D, as in the case of the three-cylinder single acting
engine. The exhaust fluid, after having operated upon the pistons A, B, C, D², is
discharged through the distributing valve H into the central chamber F, to which
the whole of the cylinders at their inner ends are open, and is thence conducted by
an exhaust pipe I to the open air or elsewhere as required.
I prefer to construct the central chamber F in the form of a hollow cylinder con-
centric with the shaft E to be driven, and open at each end. To a flange 10 at one
end I attach a casting I', acting as a cover, and which contains the bearings of the
shaft E to be driven, and forms the pedestal or frame of the engine. To a flange 11
at the other end I secure a cylindrical flanged casting K forming the casing for the
distributing valve H.
The distributing valve H I prefer to make in the form of a hollow cylinder,
having ports 12, 13, for the incoming and outgoing fluid, the portions of the cylin-
drical valve containing the said ports being completely separated by a diaphragm 14.

page_text: I drive this valve by connecting it with tho crank E' of the main shaft E by a
trailing crank L.
When it is desired to construct the engine so that it may be reversed (as in the
case of the example shewn in the Drawing) I introduce a spindle M (by preference
composed of steel) through the centre of the valve H and in a line, or nearly so,
with the axis 5 of the main shaft E (as shewn clearly in Figure 4), which spindle is
capable of being pushed in or drawn out by an external reversing lever N. The
spindle is provided at one part with one or more spiral grooves 15, and at another
part with an ordinary keyway and bedded key, and corresponding spiral projections
are made in the central boss 16 of the trailing crank L, and also corresponding key-
ways 17 are formed in the central hole of the valve. When by moving the reversing
lever N the central spindle M is is pushed in or drawn out it moves through the valvo
without turning it, but is compelled to rotate in the trailing crank L, whereby it
changes the position of the valve with respect to the crank, and in this way the
entrance and exit of steam, air, water, or other fluid is caused to correspond with a
right-hand or left-hand rotation of the shaft.
When engines are not required to reverse, I sometimes attach a horizontal
governor having two revolving weights to a central spindle, such as that lastly
herein-before described. These weights by means of a spring are maintained close
to the spindle until an undue velocity is attained, when their centrifugal force causes
them to dilate. By suitable connections this motion is caused to act (where steam or
other elastic fluid is employed) either in moving round the distributing valve afore-
said in relation to the crank, as previously described, thereby controlling by varying
the expansion, or by a subsidiary cut-off or throttle valve inside the distributing
valve, and concentric with it. I have not considered it necessary to illustrate this
arrangement in my Drawings, as the manner in which it may be carried out will be
understood by practical men without further explanation.
Having thus described the construction of my improved engine, I shall now
proceed to demonstrate by the aid of the diagrams shewn in Sheet 2 of my
Drawings that with the four-cylinder engine the defects incidental to the use of the
three-cylinder engine are entirely obviated.
Figure 1, Sheet 2, shows outlines of the cylinders in a 4-cylinder single acting
engine, the cylinders marked a, b, c, d, being radially arranged round the shaft to be
driven. In one of the cylinders a the stroke is divided into sixteen parts, and the
corresponding positions of the crank pin are shewn on the circle which it describes.
The division is also made corresponding to the position of the pistons of each of the
other cylinders. In the cylinder a the expansion line of the steam is also shown
when the latter is cut off at 1,,, and of the stroke respectively.
Figures 3 to 7 inclusive arc diagrams showing the rotative force exerted upon
the crank pin throughout one revolution thereof. The length of the diagram in
each case represents the distance traversed by the crank pin in one revolution.
(Imaginary) ordinates are drawn at right angles to the base line at each sixteenth
of the stroke of each cylinder, and the length of these ordinates is the product of
the pressure of the pistons and their leverage at each position successively. The
upper curved line drawn through the ends of the imaginary ordinates from left to
right shows in each case the combined force upon the crank pin rising and falling
as the latter varies. The steam pressure is assumed to be 100 lbs. to the square inch
above vacuum.. Figure 3 represents the effect where there is no expansion; Figure 4
where the steam is cut off at the of the stroke; Figure 5, at 3/4, and the dotted lines
in the same diagram where it is cut off at 1 of the stroke; Figure 6 shows a cut off
at, and Figure 7 at of the stroke. In all these cases the upper curved line
represents the combined rotative force when the engine is going, and therefore has
the benefit of the expansion of the steam after it is cut off.
Figure 2 and Figures 13 to 17 inclusive represent in a similar manner the beha-
viour of a three-cylinder single acting engine under similar conditions.
On comparing the two sets of diagrams it will be seen that the 4-cylinder
engine of equal diameter of cylinders and equal stroke is more powerful than the

page_text: three-cylinder engine, whilst it occupies no more space, and is but slightly more
costly in construction. This of itself is an important advantage, but a comparison
of Figure 13, which gives greatest regularity with the 3-cylinder engine, with
Figure 6, which gives the greatest regularity with the 4-cylinder engine, will
show that a better result can be obtained in the latter case with a cut off at half
stroke than in the former case with no expansion at all. The proportion of steam
used would be obviously as two is to three in favour of the four-cylinder engine,
while the latter would produce the greatest power.
In many cases single acting three-cylinder engines have been applied where they
are required to reverse.
Sometimes, as in the case of a circular saw, a centrifugal pump, or screw pro-
peller, the full average resistance is not opposed to the engine at starting, and there-
fore a small proportion of the average rotative force is sufficient for starting, after
which the expanding steam assists over the dead points.
An examination of Figures 18 to 22 inclusive, and especially Figure 19, will show
that an earlier cut off than ths of the stroke is unattainable with the 3-cylinder
reversing engine, whilst a comparison of Figures 8 to 12 inclusive, and especially
Figure 10, will show that an equal facility for reversing is obtainable with the 4-
cylinder engine with a cut off at of the stroke. The steam used in these two
cases would therefore be as 44 is to 42, or about equal, whereas the relative power pro-
duced would be as the area of Figure 5 (dotted lines) compared with Figure 14, or
very much in favour of the 4-cylinder engine.
There are other purposes to which engines of this kind are applicable, such, for
example, as cranes or winches, rotatory furnaces, and small locomotives, where it is
of great importance that a reversing engine should have power to start at any part
of its revolution ageinst the full average resistance. In such cases it will be seen
from Figure 18 that there can be no expansion employed with the 3-cylinder
engines, whereas Figure 9 shews that the 4-cylinder engine will start with cut off
at nearly as well as the 3-cylinder engine without any cut off at all; and an
examination of Figure S will show that if expansion is sacrificed altogether with the
4-cylinder engine, a starting power is attained greater than is possible to the
3-cylinder engine, as well as a much superior average rotative power.
There are certain disadvantages attaching to a delayed cut off of the steam
besides the lack of economy.
-
Figure 23 shows the portion of a revolution through which it is necessary to shift
the steam distributing valve, whether in the 3-cylinder or the 4-cylinder
engine, if the steam is carried on to the end of the stroke; Figure 24 shows the
same for a cut off at of the stroke; Figure 25, where it is cut off at ; and
Figure 26 at
As the moving of the valve incident to reversing has to be effected by the longi-
tudinal motion of a worm (see Figure 4, Sheet 1) or other mechanical contrivance,
it is evident that the smaller the arc through which it has to be moved, the less
the motion of the worm, and the simpler and more compact the reversing gear
becomes.
It will thus be seen that the 4-cylinder engine is superior to the 3-cylinder engine
in every respect, vizt. :-
First (where reversing is not required). Equal regularity of rotative force with
equal compactness and greater power is attainable with greater economy of steam
(compare Figures 6 and 13).
Second (where reversing is required). Equal power of reversing against a minimum
resistance to start with and equal compactness are obtainable with about equal con-
sumption of steam, and far greater average rotative power; (comparo Figures 5 and
10) dotted lines) with Figures 14 and 19.
With about equal starting power and equal compactness superior average rotative
power is obtained for a less consumption of steam (compare Figures 4 and 9 with
Figure 18).

page_text: Fourth. With equal economy and superior compactness according to power pro-
duced, greater power of starting against the full average resistance is obtained.
Fifth. To produce equal starting power the reversing gear becomes simpler, at the
same time that greater economy is produced by the earlier cut off.
Having now described and particularly ascertained the nature of my said Inven-
tion, and the manner in which the same is or may be used or carried into effect, I
would observe in conclusion that what I consider to be novel and original, and
therefore claim as the Invention secured to me by the herein-before in part recited
Letters Patent is, constructing motive-power engines with four single acting
cylinders disposed radially round the shaft or axle to be driven, the pistons of
which cylinders are connected to a crank or its equivalent on the said shaft or axle
revolving in a central chamber, into which the exhaust fluid is conducted, the whole
being arranged so as to operate substantially in the manner herein-before described
and illustrated by my Drawings.
In witness whereof, I, the said Jeremiah Head, have to this my Specification
set my hand and seal, this Fourth day of September, One thousand eight
hundred and seventy-six.
JEREMIAH HEAD. (L.S.)