IMPROVEMENTS IN STRAM ENGINES
Year: 1865

page_text: LETTERS PATENT to Edmund Hunt, of No. 87, St. Vincent Street, in
the City of Glasgow, and No. 1, Serle Street, Lincoln's Inn, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN STRAM
ENGINES"
Sealed the 22nd December 1865, and dated the 26th October 1865.
PROVISIONAL SPECIFICATION left by the said Edmund Hunt at the
Office of the Commissioners of Patents, with his Petition, on the 26th.
October 1865.
I, EDMUND HUNT, of No. 87, St. Vincent Street, in the City of Glasgow,
and No. 1, Serle Street, Lincoln's Inn, in the County of Middlesex, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN STRAM
ENGINES," to be as follows, that is to say:-
This Invention comprises various improvements in steam engines, and
has generally for its objects simplicity and compactness in construction and
efficiency in use, with reduced friction and lessened wear and liability to
derangement.
A modification of engines embodying some of the improvements is specially
adapted for driving the screw propeller, and in addition to possessing the
advantages herein-before mentioned is such as to impart much less vibration
Price 8d.1

page_text: or tremor to the vessel than ordinary engines. In this modification the
cylinders are parallel to a horizontal axial line, which is that of the main
shaft, and the pistons are connected to levers which are carried in fixed
bearings, and vibrate on axes at right angles to and cutting the main axial
line. For two or four cylinders the lever axes are disposed by preference at
right angles to each other, and for other numbers of cylinders at corresponding
angles. The main shaft is formed with a crank which has an oblique pin, but
which, except in so far as it is shaped to suit the oblique pin, is like an
ordinary crank. Each lever is connected to the crank pin by a connecting
rod, the joints at the opposite ends of which are at right angles to each other.
It is advantageous to give a particular angle to the crank pin, and in the case
of two or four cylinders the best angle is about three-eighths of a right angle,
as measured between the centre line of the pin and the shaft's axis. If the
pistons are acted on with full pressure throughout the greater part of their
strokes, the rotating effect on the crank pin will, if the pin have such
inclination, be much more uniform than in ordinary engines, and the improved
engines will consequently run with greater smoothness at high speeds. The
centre line of the crank pin, the axial lines of the levers, and the centre lines
of the connecting rod joints on the levers must all cut the main axial line as
nearly as possible in the same point. The air pumps, feed and bilge pumps,
and in the case of surface condenser engines the cold water pumps, can be
placed in various positions, and can be worked with the greatest possible
convenience by levers in connection with the main levers, or on rocking shafts
carrying the main levers.
In another modification the connecting rod forming a separate piece
between each lever and the crank pin is dispensed with, and a vibrating bow
is formed'in one piece with the lever. The bow acts on brasses on the crank
pin, and the relative motions of the bow and crank pin are such that the pin
slides backwards and forwards along the bow as the shaft revolves. Two
bows serve for two or four cylinders, and one bow vibrates within the
other.
The valve apparatus of these engines comprises important improvements,
and is applicable to all steam engines having two or more cylinders placed
near together; whilst it is susceptible of a great variety of modifications to
suit different positions of the cylinders and various requirements. The
improvements are also partially applicable to single cylinders..
In one modification adapted to the engines herein-before described there is
only one valve for the two cylinders, which are formed with a horizontal port
face about level with their top sides, and disposed centrally between them.

page_text: There is a single exhaust port in the centre of the face, and it is square or nearly
so with its diagonal parallel to the cylinders, whilst four rectangular ports for
the two ends of the two cylinders are disposed one at each side of the exhaust
port, the two ports of either cylinder being diametrically opposite each
other. The valve is square or nearly so, and is moved by a small revolving
crank, which may project up at the centre of the exhaust port, being on a
vertical shaft driven by means of a pair of bevil wheels from the main shaft
below; or if the main shaft proceeds from the engines in the opposite direction,.
it may be driven from a small shaft in the line of and coupled to the main
shaft. The valve, notwithstanding it is made to move in a circle, is kept
parallel by a guide frame, or by crank links, or otherwise, and its motion and
action relatively to each diametric pair of ports is the same as that of an
ordinary reciprocating valve, whilst its area is less than that of the two valves
ordinarily doing the same work, and its motion is perfectly uniform and
continuous instead of reciprocating, being therefore much less liable to wear
the port face untrue. The reversing of the engine is effected by setting round
the valve crank relatively to the main crank by means of a slide and key
acting on a helical groove, or by any of the various well-known contrivances
for effecting such an adjustment. When the valve is guided by crank links
or their equivalent, the driving crank may be arranged to act on any part of
Various contrivances in use with
it that may be considered convenient.
common slide valves, such as double, treble, or grating ports to reduce the
travel, and appliances to remove or reduce the pressure on the valve, are
equally applicable to the improved valve, whilst its peculiar form and motion
admit of simpler appliances for various purposes. Thus for reducing the.
pressure the valve shaft furnished with steel or other suitable bearing pieces
may be set up by a screw to all but lift the valve off the port face; or the
valve may be made with a cylindrical body to receive a disc internally or a
ring externally made steam-tight by a ring or rings like a piston,and working,
on a plate attached or connected to the valve chest cover or bearing on the
valve shaft, or on a steel ball or balls, or on cones; or the disc or ring may be
fixed or connected to a second disc or ring with packing rings working in a
cylindrical recess (or it might be an exhaust port) in the valve chest cover.
The pressure on the valve may be entirely obviated by having parallel faces"
on opposite sides of the valve, with duplicate ports (each half the size of the
single ports). The valve is in this case made in two parts socketed together
and packed steam-tight in any convenient way, or with the surfaces of the
sides adjacent to the joint made flush and covered by a belt of thin metal or
of rubber, or of metal and rubber combined. The valve is made in two parts

page_text: to insure contact with both port faces, and if the steam pressure on their
projecting flanges does not keep them close to the faces springs may be intro-
duced between them. Adjustable cut-off appliances can be very conveniently
applied to the valve without interfering with the exhaust action, and without
requiring additional driving gear in connection with the main shaft. When
the part of the motion of any side of the valve that opens the port is nothing
just after uncovering the port, and just before commencing to recover it, the
transverse motion of that side is at its quickest, and may be very advan-
tageously used for cutting off in various ways. According to one plan steam
passages are formed in the valve somewhat as in ordinary valves, which have
cut-off plates on the back, and the outer openings of these passages are closed
at the required periods by plates connected by links or otherwise to stationary
points, it being by the motion of the valve under the plates that the effect is
caused. The stationary points are adjusted for different grades of cut-off,
and a convenient way of arranging them is to have them upon the ends of
four arms upon a central spindle which passes out through a stuffing box in
the valve chest cover, and is externally fitted with a lever and handle or screw
adjusting details. In another plan the port face is recessed round each steam
passage, and port plates with openings are fitted in such recesses, and are
formed with their top surfaces flush with the port face. The cut-off is
effected by projecting pieces formed on each edge of the valve, and the port
plates, which are stationary when working, are shifted to obtain different
grades of cut-off. Or the shifting or adjustable plates may be upon the
valve, suitable openings being formed in the port face made without separate
port plates in this case.
In another modification of the valve apparatus there are two valves, but the
crank motion of the valve is retained and both valves act for both cylinders, one
for the one end of one cylinder and for the same end of the other cylinder,and
the other for the opposite ends of both cylinders. When there are more than
two cylinders two valves may still in some cases be arranged to serve for them,
each acting for the same ends of all the cylinders. In this modification the
port faces may be variously arranged, but are most conveniently disposed
parallel to each other, but facing opposite ways and at right angles to the
cylinder axes, and in this case one revolving shaft serves for working both by
separate cranks, which are by preference disposed at diametrically opposite
points, and in the case ofhorizontal cylinders with vertical port faces thereby
cause the weights of the two valves to counterbalance each other. With this
arrangement very short steam passages are obtainable, and the waste of
steam therein is much reduced. The passages and waste of steam therein

page_text: may be reduced to a minimum by making the port faces on the outer sides
of plates forming parts of the cylinder covers, in which case the passages will
not require to be longer than the thickness of the cover plate, whilst even that
amount of passage may be practically almost annihilated by putting pieces
on the piston to enter into the passages on the piston approaching the ends of
its stroke. This last-mentioned modification, however, involves the incon-
venience of interfering with the valve chest and both cylinders when it is
necessary to examine one of the pistons; but very short passages may be
obtained without intrenching upon the cylinder covers, and at the same time
the pressure on the valves may be very considerably reduced by forming short
passages in the sides of the cylinder, with an exhaust port in each passage
covered by a plate in the passage, and with an inlet for steam opposite the
exhaust port, and covered by a steam valve or plate outside in the steam
chest. The steam valves or plates are worked by the crank motion, and
may have cut-off plates on their backs, whilst the exhaust plates are attached
or connected to the steam plates by bars or studs passing through the
steam inlets. This last-mentioned contrivance is applicable, where one
valve is used for the two or more cylinders, and also to common slide
valves. Another way of counterbalancing the weight of the valve or valves
when working vertically or at an inclination, and which at the same time
reduces the travel, and is on that account also advantageously applicable to
horizontally working valves, consists in dividing each valve into two parts at a
plane parallel to the port face, steam passages being formed in the bottom
part, and in some cases in the top part also. The two parts are made as nearly
equal in weightas practicable or convenient, and contrary motions are imparted
to them by means of diametrically opposite cranks or eccentrics, such contrary
motions requiring only one-halfthetravel or eccentricity of an undivided valvė
having the same effect. This improvement is obviously applicable to ordinary
slide valves; and an equivalent improvement may be adopted in the herein-
before described arrangement with exhaust plates in the steam passages by
working those plates contrarily to the steam plates by means of diametrically
opposite cranks or eccentrics. In some cases the valve may have a circular or
curved outline, the ports being correspondingly curved instead of being straight
sided, and if the valve is circular it will not require to be guided, but may be
left free to turn on the crank pin. In applying the improved valve apparatus
to ordinary engines there will in general be required two pairs of bevil or
spur wheels, one pair communicating motion from the main shaft to an inter-
mediate shaft, and the second transmitting the motion from the intermediate
shaft to the valve shaft. In some arrangements, however, of the herein-before

page_text: describedengines with oblique crank pin,ifthe portfaces are at right angles to the
cylinders, and if the crank shaft proceeds from the cylinders instead of passing
close to them, the small crank shaft for working the valves may be in the line
of and coupled to the main shaft, and no wheels whatever will be required.
A cut-off action, precisely the same as that got with the ordinary link motion,
may be obtained by arranging the crank pin to shift in a guide in connection
with the crank head, so as to take proper intermediate positions when moved
partly round (relatively to the main crank) in the direction for reversing by
any of the reversing appliances herein-before referred to. Engines with an
oblique crank pin and embodying the principal improvements herein-before
described may be very conveniently arranged for working on the double
cylinder expansion system. Each high-pressure cylinder may be placed near
its low-pressure cylinder with the pistons working in opposite directions and
connected to the rocking levers on opposite sides of their axes; or each low-
pressure cylinder may be an annular one, having the high-pressure cylinder
centrally within it. In an important modification two cylinders, a small high-
pressure one and a large low-pressure one, are used, with three pistons in each
cylinder. Each cylinder has two ports admitting steam only into the four
spaces between the pistons, and the most convenient valve apparatus for them
is of the improved kind herein-before described. The outside pistons of each
cylinder move in opposite directions stroke for stroke, and the central pistons
move contrarily to each other, but so as to differ by half a stroke from the
outside pistons. The pistons may be connected in various ways to the main
shaft, and it is preferred to employ levers with bows such as are herein-
before described for that purpose. The nature of the present improvement
will; however, be more easily apprehended if the crank shaft is supposed to
have the ordinary position relative to the cylinders, in which case the two
middle pistons will be connected to one crank, one of. them directly and the
other through a lever which reverses its motion, whilst to a second crank at
right angles to the first will be connected the other four pistons, one of them
directly and the others through levers. The middle pistons near each end
of their strokes move over portions of the cylinders, over which the other
pistons also move, but at different times, the strokes not being simultaneous,
and in consequence of this and of the described connection of the parts one
of the middle pistons is nearest one of the outside pistons, not at the end of
either piston's stroke, but ata point corresponding to one-eighth of a revolution
of the shaft, before the end of one piston's stroke and after the end of the
other's stroke. The valve is set to commence to admit steam between these
two pistons at about the period when they are nearest together as described.

page_text: The pistons then separate during one-half a revolution, and steam may be
admitted during the whole of this period, whilst the steam is exhausted from.
between the pistons during the next half of the revolution, when they will be
approaching each other. Precisely the same action takes place in the other
three spaces between the pistons, but with like phases,commencing at regularly
differing periods of the shaft's revolution. Each space in the small cylinder
decreases simultaneously with the increase of one of the spaces in the large
cylinder, and the steam after acting in each small cylinder space is transferred
to the corresponding large cylinder space to complete its expansion. The
result of this arrangement and action is to completely obviate and avoid the
injurious and ineffective strains which in ordinary engines act on the crank
pins and crank shaft bearings when any crank pin is passing what is termed
the "dead centre." This result arises from each piston as it were floating
with equal or nearly equal pressure on both sides of it whilst its crank is
passing the dead centre, and through one-eighth of the revolution on each side
of that centre. The cylinders may obviously be both of the same size and
work independently, and not on the double cylinder expansion system. The
four spaces may also be obtained in one cylinder, when one of the six pistons
will be dispensed with and the whole will be got into less space; or if the
pistons, instead of moving longitudinally in the cylinder, are constructed
and arranged to vibrate about the cylinder's axis, another piston cau be
dispensed with, and only four be used; whilst if a moving cylinder with
longitudinally moving pistons is used only three pistons will be required,
the cylinder ends acting as pistons. If the engine is arranged with three
spaces instead of four, with a corresponding number of pistons, these must
be connected to three cranks disposed at 120 degrees of the circle from
each other, or in an equivalent manner to one crank. The engine may
also be arranged with more than four spaces and corresponding crank con-
nections. The portion of the crank's path which is relieved of strain
increases with the number of piston spaces used.
In conclusion it may be stated that the great variety of modifications herein-
before indicated spring from a few simple elements, some of which happen to
be of very general applicability. The main features of the Invention are:-1,
the introducing of levers with connecting rods or bows, and carried in fixed
bearings in engines with oblique crank pins; 2, the working of two or more
cylinders with the same valve or valves; 3, the working of the valve or valves
with a continuous circularplane sliding motion insteadofa reciprocating motion,
and the availing of such circular motion to obtain a simple adjustable cut-off
action; 4, the dividing of the valve to reduce the passages and travel; and

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Edmund Hunt in the Great Seal Patent Office on
the 26th April 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDMUND
HUNT, of No. 87, St. Vincent Street, in the City of Glasgow, and No. 1,
Serle Street, Lincoln's Inn, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of October, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Edmund Hunt, Her special licence that I, the said Edmund Hunt,
my executors, administrators, and assigns, or such others as I, the said
Edmund Hunt, my 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 "IMPROVEMENTS IN
STEAM ENGINES," upon the condition (amongst others) that I, the said Edmund
Hunt, my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, 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 Edmund Hunt, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement in writing, reference being had to the accompanying
Drawings, that is to say:-
My said Invention comprises various improvements in steam engines,
and has generally for its objects simplicity and compactness in construction
and efficiency in use, with reduced friction and lessened wear and liability
to derangement.
The main features of my said Invention are, first, the introducing of levers

page_text: with. connecting rods or bows, and carried in fixed bearings in engines with
oblique crank pins; second, the using of one valve movement (with one or
more valves) to work two or more cylinders, the strokes of which cylinders are
made at different times; third, the actuating of the valve or valves with a con-
tinuous circular plane sliding motion for working two or more cylinders by
one valve movement, or for obtaining a simple cut-off action, or for both
these purposes; fourth, the dividing of the valve and giving reversed motions
to its parts in order to reduce the travel; and, fifth, the causing of steam to
work between pistons performing their strokes at different times, in order, as
herein-after explained, to relieve the crank or cranks and other parts of
ineffective.and injurious strains when at or near the dead centre.
And in order that my said Invention, and the manner of performing the
same, may be properly understood, I have hereunto appended five Sheets of
explanatory Drawings, to be herein-after referred to,and representing examples
of the many modifications of which my improved arrangements are susceptible.
In these Drawings the same reference numerals and letters are used to mark
the same or corresponding parts in the various Figures and in order to render
it unnecessary to repeat the description of similar parts.
A modification of engines embodying some of my improvements which is
shown upon Sheet 1 of the Drawings is specially adapted for driving the screw
propeller, and in addition to possessing the advantages herein-before men-
tioned, is such as to impart much less vibration or tremor to the vessel than
ordinary engines.
Figure 1 is a plan, Figure 2 isa longitudinal vertical section, and Figure 3
is a transverse vertical section; Figure 4 is a view of the crank-pin joint and
connecting rods as seen when looking along the axis of the crank pin;
Figures 5 and 6 are a plan and section of the valve; Figure 7 is a diagram,
showing the rotating forces as compared with those of common engines; and
Figure 8 is a perspective view of a slightly different modification of the
engines. In these modifications the cylinders 1, 2, are parallel to a horizontal
axial line which is that of the main shaft 3, and the pistons are connected to
levers 4, 5, fast on rocking shafts 6, 7, carried in fixed bearings, and the axes
of which are at right angles to and cut the main axial line. For two
cylinders, as shown, or for four cylinders, the lever axes (6, 7,) are disposed,
by preference, at right angles to each other and in the same vertical plane,
and for other numbers of cylinders at corresponding angles. The main shaft 3
is formed with a crank 8, which has an oblique pin 9, but which, except in so
far as it is shaped to suit the oblique pin, is like an ordinary crank. Each
lever (4 or 5) is connected to the crank pin 9 by a connecting rod (10 or 11),

page_text: the joints at the opposite ends of which are at right angles to each other. As
when the engines are complete various parts are disposed obliquely to each
other, and as it is not easy to ascertain from a drawing the exact form and
dimensions of parts represented in oblique positions, it has been considered
best to avoid such oblique representations as much as possible in Figures 1, 2,
and 3, and to give a general perspective view separately in Figure 8. Thus,
in Figure 1 the levers 4, 5, and their shafts 6, 7, are omitted, but one lever 4
and its shaft 6 are represented in Figure 3 in the positions proper to them,
when the piston of the cylinder 1 acting on them is at half stroke, whilst in
Figure 2 the same lever 4 is shown as though it were turned up into the
plane of the Drawing, and as viewed at right angles to Figure 3. Similarly
in Figures 2 and 4, views at right angles to each other are given of one of
the connecting rods 10. At the crank-pin joint there are four brasses, one
diametrically opposite pair being acted on principallybyone connecting rod 10,
and the other by the other connecting rod 11. One connecting rod 10 has
its head and cap fitted to the brasses to bear principally on the part of the
pin 9 nearer the left in Figure 2, but the head and cap project under the bolts
connecting the cap and head of the other rod 11, which last are, however,
formed with horns which meet each other, entering between the flanges of the
brasses and the projecting parts of the rod 10. The corresponding parts of
the two connecting rods 10, 11, are reversed towards each other, but are
otherwise shaped alike. To provide against what are called "end strains,"
which may arise if the joints are slack, the brasses of the joint 12, which is
that uniting the connecting rod 10 or 11 to the lever 4 or 5, are divided across
their middles, and taper keys or wedges are introduced, so as on being
screwed up by means of external nuts to cause the brasses to bear against the
collars on the lever journal. It is advantageous to give a particular angle to
the crank pin 9, and, in the case of two or four cylinders, the best angle is
about three-eighths of a right angle as measured between the centre line of
the pin and the shaft's axis. If the pistons are acted on with full pressure
throughout the greater part of their strokes, or if the strain transmitted in the
direction of the piston's motion is uniform throughout the stroke, the rotating
effect on the crank pin will, if the pin has such inclination, be much more
uniform than in ordinary engines,and the improved engines will consequently
run with greater smoothness at high speeds.
In the Diagram, Figure 7, the rotating forces or strains are shown com-
paratively. The innermost circle represents the path of the crank pin, and
the tangential strain upon it at any point is laid down in a radial direction
therefrom, the variation in the strain being shown by the curved line bounding

page_text: the radial distances. If one piston, arranged as in comnion engines (but with
the connecting rod supposed to be of infinite length in order to simplify the
Diagram), moves in the direction A, A, the tangential strain due to it will vary
in the manner shown by the black curve C, and if a second piston moves at
right angles thereto, or in the direction B, B, the combined strain due to
the two pistons will vary according to the black curve D, E. The curves G
and H, in red, show the corresponding strains with my improved engines, and
it will be observed that the latter curve H very nearly coincides with a circlo
(shown by a dotted line), or in other words represents the strain as almost
uniform, whilst the strain of common engines has four points E exceeding
and four points D falling short of the mean strain, the difference between the
greatest and least strains being nearly one-third of the mean strain. This
Diagram merely shows the amount of strain, and not the method of deducing
or calculating it, which will present no difficulty to those familiar with
mechanical principles. If the curves C and D, E, were corrected to allow
for the connecting rods in common engines they would show a greater
irregularity in the strain, but no corresponding correction has to be made in
the case of the curves G and H. In these improved engines the centre line
of the crank pin 9, the axial lines of the levers 4, 5, (that is the centre lines
of the lever shafts 6, 7,) and the centre lines of the connecting rod joints 12
on the levers 4, 5, must all cut the main axial line or centre line of the main
shaft 3 in the same point. The air pumps (13), feed and bilge pumps (14),
and in the case of surface condenser engines the cold water pumps (15) can
be placed in various positions. In the modification shown in Figure 8 these
pumps are all worked by levers 16 on the lever shafts 6, 7, the cold water
pumps being situated at the after end of the engines (not seen in the Figure),
and being worked by return rods passing through pipes to the cross heads
on the air pump rods. In Figure 8 the engines face the opposite way io
those shown in Figures 1, 2, and 3, the main shaft passing aft between the
cylinders, whilst in the others it proceeds aft from the engines. In
Figures 1, 2, and 3 the air pumps 14 are situated centrally beneath the
cylinders, aud cold water pumps 15 are placed opposite to them beneath
the main bearing, and passages from the latter to the surface condenser 17
are conveniently formed in the sole plate 18, and usefully strengthen that
plate. The feed and bilge pumps 13 are worked by a crank 19 on the end
of an intermediate valve motion shaft 20, which is in the line of the main shaft 3,
and which is coupled to the forward end of the crank pin 9. It is unnecessary
to describe the minor details in connection with the pumps, as the present
Invention does not comprise any improvements therein.

page_text: In other modifications of my improved oblique crank engines the con-
necting rod (10 or 11) forming a separate piece between each lever 4, 5,
and the crank pin 9 is dispensed with, and a vibrating or rocking bow is
formed in one piece with each lever. The bow acts on brasses on the crank
pin, and the relative motions of the two bows and of the crank pin are such
that the pin slides backwards and forwards along the bows as the shaft 3
revolves. Two bows serve for two or four cylinders, and one bow vibrates
within the other. The principal parts of these modifications that differ
from the corresponding parts of the engines herein-before described are
shown upon Sheet 2 of the Drawings.
Figures 9 and 10 are a face and a side elevation of a frame containing a
central bearing for the main shaft 3, and two pairs of bearings 21, 22, for the
vibrating bows. The cylinders are indicated by dotted circles in Figure 9,
the bearing frame in that Figure being represented as viewed from them,
and they are connected to it by means of the sole plate 18 at the bottom,
and by a strong stay 23 at the top, and shown in Figure 10. Figures 11
and 12 are views at right angles to each other of one of the bows 25 com-
bined with its lever 5, and it is formed with two journals, one beyond each
end of the bow, which occupy the diametrically opposite bearings 21, 22,
Figure 9, when the bow is in its place, the lever part 5 being then just out-
side of the upper bearing. When the corresponding piston is at half stroke
the lever 5 is in a vertical plane, but inclined upwards at an angle of
45 degrees of the circle, and it vibrates through three eighths of a right angle
alternately on each side of that position. The part of the bow 25 which acts
on the crank pin 9 is deviated upwards from the centre plane at right angles
to the lever 5 to an extent to allow for the thickness of the crank pin and
of the brasses between the crank pin and the bow, so that when the two are
connected the crank pin is always in a plane at right angles to the lover. The
crank pin's revolving motion may be considered as compounded of a vibrating
motion of which that plane and the lever 5 partakes, and of a vibrating
motion in that plane, and this latter element of the crank pin's motion is
provided for by arranging the brasses to slide upon the bow. Figures 13 and
14 are views at right angles to each other of the other bow 24, combined
with its lever 4, and this bow is made larger to work outside of the one 25
already described. The bow 24 is formed with journals to occupy the
bearings 21, 21, Figure 9, the lever part 4 being then just outside the upper
bearing. In this case the increased size of the bow requires its connection
with the upper journal on the outer end thereof. The two bows when in
position extend over towards both the cylinders, and they both act in the

page_text: same manner on the crank pin 9, but in directions at right angles or nearly
so to each other, and in such a way that when one is at the middle of its
stroke the other is at the beginning or end of its stroke. The connection of
each lever 4, 5, with its piston rod is of a kind constituting a parallel
motion requiring neither trunks nor ordinary piston rod guides. Figures 15
and 16 are views at right angles to each other of a guide block 26 which in
Figure 16 is placed in the position it has relatively to the lever 4 when at
half stroke. Figure 17 represents a lever 30 with three equidistant bearings,
the middle one for a pin 27 on the lever 4, the outer one for the piu of the
guide block 6, and the inner one for a pin in the forked end of the
piston rod 28, a part of which is shown in Figure 17. Figure 18 is a
Diagram showing this parallel motion (which is of a well-known kind) in its
middle and two extreme positions. The short movement of the block 26 is
provided for by arranging it to slide in a guide 29 at the top of the bearing
frame, Figures 9 and 10. Figures 19 and 20 are an elevation and a transverse
vertical section of the box and brasses for connecting the inner bow 25 to the
crank pin 9, and Figure 21 is a view of the under side thereof. There are
four brasses, one pair for the top and bottom of the bow, and the other pair
for the top and bottom of the crank pin 9, and the latter are fitted cylindrically
above and below, as seen in Figure 20, to permit of their accurate adaptation
to the crank pin. The box containing the brasses and binding them together
consists of a wrought-iron structure 31, with a top and with sides shaped to
pass on each side of the crank pin, and having their bottom ends formed into
screwed studs for the attachment of the cap 32, for which last there is more
available space on the under side in the case of the smaller bow 25. In the
case of the larger bow 24 the cap may be fixed on the upper side if preferred;
in other respects the brasses and their box may be made like those for the
smaller bow. I prefer to arrange the air pumps and cold-water pumps so as
to be worked by levers fast on projecting ends on the lower journals of the
bow pieces 24, 25.
In another modification of the engines the bows may be arranged to lie in
opposite directions, that is, one towards the forward side of the bearing frame,
and the other towards the after side thereof. In this case the crank pin 9
must be continued on opposite sides of the axial line, and may be arranged
with bearings at each end as in the Z-crank engines described in the Speci-
fication of Letters Patent granted to Alexander Morton and myself, and dated
5th June 1855 (No. 1287).
The valve apparatus which I prefer to use with the improved engines
herein-before described, and of which a modification is shown on sheet 1 of

page_text: the Drawings, comprises important improvements, and is applicable to all
steam engines having two or more cylinders placed near together, whilst it
is susceptible of a great variety of modifications to suit different positions of
the cylinders and various requirements. My improvements in valve appa-
ratus are also partially applicable to single cylinders or to cylinders placed
apart, like those of an outside cylinder locomotive.
On Sheet 3 of the Drawings a modification is shown similar to that de-
lineated upon Sheet 1, but adapted to a pair of inverted cylinder marine
engines, and as engines of this class are in common use I will describe the
valve apparatus more particularly as applied to them. Figure 22 is a hori-
zontal section as taken across the cylinders 1, 2, at the top ports; Figure 23
is a side elevation with the valve chest cover and valve removed; Figure 24
is a vertical longitudinal section of the valve chest with the valve in position;
and Figure 25 is a transverse vertical section of the engines as taken between
the cylinders. In this modification there is only one valve V for the two
cylinders 1, 2, which are (in this example cast together and) formed with a
vertical port face about level with the sides of the cylinders, and disposed
centrally between them. There is a single exhaust port X in the centre of
the face, and it is square or nearly so, with one of its diagonals parallel to
the cylinders, whilst four rectangular ports P, P, p, p, for the two ends of
the two cylinders are disposed one at each side of the exhaust port X. The
two ports of either cylinder are diametrically opposite to each other, to obtain
which arrangement two of the port passages cross each other between the
port face and the cylinders. The valve V is square or nearly so, and is
moved by a small revolving crank K, which projects at the centre of the
exhaust port, being on a shaft 33 driven by means of a pair of bevil wheels
from an intermediate shaft 20, whilst the latter is driven by means of a pair
of bevil wheels from the main shaft 3. The valve, notwithstanding that it is
made to move in a circle, is kept parallel by a guide frame 35, Figure 24, or
otherwise, and its motion and action relatively to each diametric pair of ports
is the same as that of an ordinary reciprocating valve, whilst it may be made
of less area than that of the two valves ordinarily doing the same work, and
its motion is perfectly uniform and continuous instead of reciprocating, being
therefore much less liable to wear the port face untrue. The reversing of
the engine is effected by setting round the valve crank K relatively to the
main shaft 3 by means of a slide and key acting on a helical groove, or by
any of the well-known contrivances for effecting such an adjustment. In the
reversing arrangement shown in Figure 25 the intermediate valve shaft 20
is movable longitudinally by means of the reversing lever R, and the bevil

page_text: wheels at its ends are made with elongated tubular bosses, which are fitted
with keys, the lower one adapted to a straight groove on the lower end of the
shaft, and the upper key adapted to a helical groove near the top of the shaft.
With this arrangement the upper bevil wheel is moved round relatively to
the lower one when the shaft 20 is raised or lowered. The engines shown
on Sheet 1 require only one pair of bevil wheels, and the reversing is effected
by means of a tube 34 on the intermediate shaft 20, and between it and the
first bevil wheel, this tube 34 being shifted by a fork which is traversed by
a screw spindle and hand wheel. The valve V will work without a guide
frame 35 if the sides of the valve chest are suitably shaped, but if the parts
were too slack there would be knocking and noise, which is avoided by guiding
the valve.
For guiding the valve I prefer to use two small guide cranks 36,
shown in Figures 26 and 27, which represent a face view and section of the
valve as fitted with a modification of cut-off appliances. These guide cranks
are in this example formed with discs and centre pins, which turn in recesses
made for them in the port face, the crank pins projecting up into sockets in
the under side of the valve. They should be situated as nearly as s possible on
lines proceeding from the driving crank at right angles to each other. When
the valve is guided by cranks or their equivalent the driving crank may be
arranged to act on any part of it that may be considered convenient. The
guide frame 35, Figure 24, is simply a rectangular frame, having its ends
fitted to slide in contact with two opposite sides of the valve chest, and having
a rectangular opening fitted to the box part of the valve V, so that the latter
can slide within it in a direction at right angles to that in which the frame
itself can slide. These parts should be fitted to work easily, as a little angular
deviation from the exact position of the valve will do no harm. Various
contrivances in use with common slide valves, such as double, treble, or
grating ports, to reduce the travel, and appliances to remove or reduce the
pressure on the valve, are equally applicable to my improved valve, whilst its
peculiar form and motion admit of simpler appliances for various purposes.
Thus for reducing the pressure the valve shaft 33, Figures 26 and 37, furnished
with a steel or other suitable bearing picce 37, may be set up by a screw 38
to all but lift the valve V off the port face; or the valve may be made with a
cylindrical body (as shown in Figure 35 to receive a disc internally or a ring
externally made steam-tight by a ring or rings like a piston, and working on
a plate attached or connected to the valve chest cover or bearing on the
valve shaft, or on a steel ball or balls, or on cones; or the disc or ring may
be fixed or connected to a second disc or ring, with packing rings working in

page_text: a cylindrical recess (or it might be an exhaust port) in the valve chest
cover. The arrangement last indicated is shown in Figure 35, and is very
convenient for a pair of "inside" locomotive cylinders, the exhaust taking
place through the valve directly into the blast pipe 39.
Figure 32 is a plan, and Figure 33 is a section showing the application of.
cones for relieving the valve of pressure. A three-armed table 40 is suspended
from a cylindrically flanged disc 41, which works in a stuffing box in the
valve chest cover, and has its upper side communicating by a small pipe with
the condenser. The disc 41 is made of an area corresponding to the extent to
which it is wished to relieve the pressure on the valve V. A.plate 42,attached
by three stud bolts to the valve, is above the table 40, and .these have each
three conical recesses, between which three double codes 43 ofsteel are placed.
These cones sustain the pressure between the valve and the disc 41, and with
the motion of the valve they roll round their respective couical seats. "Balls
could be used in a similar manner instead of the coues, but would present less
bearing surface. The pressure on the valve may be obviated to any extent
that may be considered desirable by arranging the valve to work between
parallel and opposite port faces. With this arrangement I prefer to make
the steam passages with duplicate ports (each half the size of the single ports),
but the arrangement is also applicable with single ports. Several modifications
with this arrangement are shown upon Sheet 4 of the Drawings.
Figure 41 is a sectional side elevation of a pair of inverted cylinder marine
engines, and Figure 42 is a sectional end elevation; Figures 43 and 44 are
sections of the valve, and Figure 45 is a view of that side of the valve which
is in contact with the port face of the cylinder supposed to be removed in
Figure 42, that is, the one to the right in Figure 41.
The steam passages
of each cylinder communicate with ports in the valve face, which are disposed
at an inclination of half a right angle to the cylinders, and those of each
cylinder respectively being inclined different ways they are at right angles to
each other. The valve V is made in two parts socketed together, and packed
steam-tight in any convenient way, as, for example, by a common stuffing-box
joint, as shown in Figure 44; or the surfaces of the sides adjacent to the
joint may be made flush, and may be covered by a belt of thin metal or of
rubber, or of metal and rubber combined. In Figures 47, 49, and 52 a thin
metal band covers the joint, and is itself covered by a band of rubber 44,
which slightly overlaps its edges. The rubber band may be protected from
grease by a covering of canvas or cotton, whilst it can always be easily
renewed if required. The valve is made in two parts to insure contact with

page_text: the port faces, and if the steam pressure on the projecting flanges or other
parts does not keep the parts close to the faces springs may be introduced
between them.
Adjustable cut-off appliances can be very conveniently applied to my
improved valves without interfering with the exhaust action, and without
requiring additional driving gear in connection with the main shaft 3, the
movements for such cut-off appliances being derived from the motion of the
valve relatively to the stationary valve chest or cover, and being available at
any part of the stroke in consequence of the valve's motion being circular;
thus, for example, the component part of the valve's motion taken in the
direction across the ports of one cylinder, if considered at the period when it
has fully opened one steam port and is about to return to cover it again, is
obviously nothing, but the component of the valve's motion in the direction at.
right angles is then at its quickest. In one plan, taking advantage of this
peculiarity, steam passages are formed in the valve somewhat as in ordinary
valves which have cut-off plates on the back, and the outer openings of these
passages are made at right angles to the openings in the under side of the
valve (or in an equivalent manner), and are closed at the required periods by
plates connected by links or otherwise to stationary points, it being by the
motion of the valve under or relatively to the plates that the cut-off action
is effected.
In the modification shown in Figure 26, Sheet 3 of the Drawings, the back
of the valve is made circular, with four radial cut-off ports, the plates c, f, of
which are guided by being centred on a pin formed or fixed on the centre of
the valve. The stationary points to which the cut-off plates c, f, are con-
nected by links are upon the ends of four arms fast on a central spindle 45,
which passes through a stuffing box in the valve chest cover, and is externally
fitted with a lever and handle or screw adjusting details. The motion of
the valve causes the plates c, f, to reciprocate over their respective ports,
and different grades of cut-off are obtained by simply adjusting the spindle
45, whereby the stationary points are shifted.
A similar cut-off arrangement is shown in Figures 41 to 45 on Sheet 4,
but with the cut-off ports made in the cylindrically shaped sides of the valve,
and with segmental cylindrical cut-off plates c, f, whilst the fixed points to
which these plates are connected by links are upon a ring 46 encompassing
the valve, which ring is adjusted for different grades of cut-off by a tangent
screw 47. In Figure 41 the cut-off plates are supposed to be removed from
the right-hand half of the valve. In Figure 28, Sheet 3, there are substituted
for the, links eonnecting the cut-off plates to the stationary points or pins

page_text: blocks jointed on the pins, and working in guide grooves on the backs of
the plates c, f.
In Figure 29 is shown an example of another way of driving the cut-off
motion from the motion of the valve, and in this case there are three cut-off
plates c, f, for the four ports, which plates revolve upon the valve by the
action of an internally toothed ring 48 fixed to them, and in gear with a
stationary spur wheel fast on the adjusting spindle 45. Cut-off motions on
this principle may be arranged in a great variety of ways, and with various
proportions of the wheels and ports. The internally toothed ring may be
stationary, a spur toothed wheel or ring being on the cut-off plates, as shown
in Figures 16, 47, and in Figures 48, 49, Sheet 4, in the former of which
segmental cylindrical cut-off plates are shown, whilst segmental flat cut-off
plates are shown in the latter. In Figures 50, 51, and 52 straight cut-off
plates are shown, on the sides of the valve being connected by links to
stationary points which are upon two levers 50,adjusted by a third two-armed
lever 51 fast on a spindle 45 passing through a stuffing box. This spindle 45
has on it externally a weighted lever 52, and a rod 53 jointed thereto passes
down to and through a tubular screw adjusting piece 54. By screwing down
the piece 54 the grade of cut-off is adjusted for going ahead, and does not
require attention when reversing the engine, as a lever 55, actuated by
the main reversing lever R, then draws down the rod 53, which is raised
aguin by the weight on the lever R being returned to its position for going
ahead. In the same Figures the valve crank K is situated beneath the valve,
and acts on a frame which carries the valve, but which is shown without
the valve in Figure 51. The frame is guided by crank links 36, which turn
on studs fixed in the valve chest.
In the modification shown in Figures 41 and 42 the valve shaft 35 and
crank K are situated as in Figures 50 and 51, and the intermediate shaft 20
is placed at the after end of the engines, the parts in connection with it being
arranged in a manner that will be easily understood from the Drawing. The
circular plane sliding motion may be imparted to the valve by a crank (or
eccentric) quite external to the valve chest, in which case the motion is com-
municated through a joint of the kind shown in Figures 53 and 54, the
former being a section and the latter a side view. The valve or its frame is
formed with or has attached to it a bar b, which projects down into a cavity
or pocket formed in connection with a plate c, to be bolted to the under side
of the valve chest. The pocket is made with openings in its opposite sides,
with external annular surfaces made parallel and as smooth as possible. At
the sides there are cylindrically flanged discs d, on which there fit easily rings

page_text: which work on the annular surfaces round the openings. The rings are
covered with external glands e, furnished with packing, and formed with lugs
for bolts to screw them by towards and against each other.
The pressure or
strain on the opposite glands is thus equal, whilst the discs & can move across
without jamming. An external bar f forms a continuation of the internal
valve bar b, and it is made with forked ends, which are entered between pro-
jections on the outsides of the discs d, after which a strong bolt g is passed
through the forked ends, through the discs d, and through an eye in the
bottom of the valve bar 6, whilst the parts are prevented from turning round
upon each other by a key inserted at the upper side of the bolt. The friction
of this joint is not more than that due to the pressure that the glands e
require to keep the rings steam-tight, whilst the parts admit of easy adjust-
ment and renewal.
Figure 55 is a sectional plan showing another arrangement for a like
object as applied to one of the valves of a pair of outside locomotive cylinders.
The valve Vis seen cornerwise, and the two valves with their ports at right
angles to each other are actuated simultaneously by a bar bextending across
between them. The pressure is taken off the valves by means of a packed
ring at the back, of a kind in use in marine engines. Inside the ring there is
an opening in the cover at which the bar 6 enters, whilst a plate / with a
spring is applied loosely outside to keep out dust. It is an advantage of
this arrangement that leakage of steam can be easily detected and corrected.
A cut-off arrangement is.shown in Figures 30 and 31,Sheet 3, which, like
some already described, derives its motion from the action of a stationary
wheel 49 fixed to the adjusting spindle 45 on a wheel connected with the cut-
off plates c, f. There are several small toothed wheels in this arrangement,
and for the sake of simplicity they are represented in Figure 31 as discs of
the dimensions of the respective pitch circles, which circles are shown in
Figure 30. The stationary wheel 49 is internally toothed, and has gearing
with it a deep wheel 55 loose on a spindle projecting up from the centre of
the valve V. The wheel 55 gears with an equal sized wheel 56 loose on a
spindle fixed in an eccentric 57, which is indicated by the dotted circle in
Figure 30, and which is free to turn round the valve spindle, on which it is
centred eccentrically. In one piece with the wheel 56 is a wheel 58, which
gears with a wheel 59 fast on the valve spindle, and the wheel 58 has to the
wheel 59 the same ratio that the wheel 55 has to the wheel 49, that is, 1 to 2
in this example. With this arrangement the eccentric 57 will make one
turn round the valve spindle for every turn of the valve shaft; whilst by
turning the spindle 45 its position relatively to the valve at any point of the

page_text: valve's motion can be changed. If the cut-off plates c, f, are connected to a
frame 60 actuated by the eccentric, but guided parallel, they will have pre-
cisely the same kind of circular plane-sliding motion on the back of the valve
that the valve itself has on the port face, and will give a very quick cut-off
with extremely short steam passages in the valve. If an excessively rapid
cut-off is wished for, radial ports may be formed in the back of the valve, as
in Figures 26 to 29, and a single cut-off plate may be formed in one piece
with the eccentric 57, which revolving once for each turn of the crank shaft
will admit steam to and cut it off from each of the four ports in succession,
and which can be adjusted to cut off earlier or later by shifting round the
spindle 45.
face.
Another plan of cut-off is shown in Figures 38, 39, and 40 on Sheet 4,
these being respectively a face view of the under side of the half valve for
one of a pair of cylinders, a section, and a plan of the corresponding port
In this plan the port face is recessed on each side of the exhaust
port and over each steam passage, and port plates 61, with openings P, are
fitted in the recesses, and are formed with their top surfaces flush with the
port face. The cut-off is effected by projecting pieces 62 on the outer edges
of the valve V, and pieces 63 partly occupying the inner steam opening
when the arrangement is what is termed "double-ported" as shown. The
port plates 61, which are stationary when working, are adjusted for different
grades of expansion by levers, as indicated, or otherwise. The cut-off is
caused by the cross motion of the valve bringing the pieces 62, 63, over the
projecting parts of the ports P.
In another modification the port face is made with port openings like
those shown in Figure 40, but without movable plates; whilst the pieces
62, 63, on the valve are made adjustable instead. This adjustment may
be obtained independently of the valve's motion by connecting the pieces.
62, 63, to a ring on the valve, which ring is connected by crank links (like
those for guiding the valve) to a stationary ring or segment, this last being
adjusted by a tangent screw or otherwise.
An important application of my improved cut-off arrangements is that to
factory and other land engines requiring to maintain as uniform a speed as
possible, as the adjusting spindle 45 may be connected to the governor, the
corrective action of which can thus be availed of in the most direct and
simple manner.
In another series of modifications of my improved valve apparatus there are
two valves, but the crank motion of the valve is retained, and both valves act
for both cylinders, one for one end of one cylinder and for the same end of

page_text: the other cylinder, and the other for the ports at the other ends of both
cylinders. When there are more than two cylinders, two valves may still in
some cases be arranged to serve for them, each acting for the same ends of all
the cylinders. In this modification the port faces may be variously arranged,
but are most conveniently disposed parallel to each other, but facing opposite
ways, and at right angles to the cylinder axes; and in this case one revolving
shaft serves for working both by separate cranks, which are by preference dis-.
posed at diametrically opposite points, and in the case of horizontal cylinders
with vertical port faces thereby cause the weights of the two valves to
counterbalance each other. With this arrangement very short steam passages
are obtainable, and the waste of steam therein is much reduced. The passages
and waste of steam therein may be reduced to a minimum by making the
port faces on the outer sides of plates forming parts of the cylinder covers, in
which case the passages will not require to be longer than the thickness of the
cover plate; whilst even that amount of passage may be practically almost
annihilated by putting pieces on the piston to enter into the passages on the
piston approaching the ends of its stroke. This last-mentioned modification,
however, involves the inconvenience of interfering with the valve chestandboth
cylinders when it is necessary to examine one of the pistons; but very short
passages may be obtained without intrenching upon the cylinder covers, and
at the same time the pressure on the valve may be very considerably reduced
by forming short passages in the sides of the cylinder, with an exhaust port
in each passage covered by a plate in the passage, and with an inlet for steam
opposite the exhaust port, and covered by a steam valve or plate outside in
the steam chest. The steam valves or plates are worked by the crank motion,
and may have cut-off plates on their backs, whilst the exhaust plates are
attached or connected to the steam plates by bars or studs passing throughthe
steam inlets. This last-mentioned contrivance is applicable where one valve
is used for the two or more cylinders, and also to common slide valves.
A set of marine engines with valve apparatus arranged in this way is
shown upon Sheet 5 of the Drawings; Figure 56 being a plan, Figure 57 a
vertical section across the cylinders, and Figure58 anendelevation; Figure59
is a section as taken through the axis of one of the cylinders, and at the valve
shaft, and Figure 60 is an irregular section to show the manner of attaching
the piece containing the exhaust passage at the inner end of each cylinder.
These are horizontal screw propeller engines, with return connecting rodslike
a kind in common use, and the parts on the side of the main shaft opposite to
the cylinders are not shown, as no novelty is proposed in their arrangement.
For working the valves there is an intermediate shaft 20, carried in bearings..

page_text: parallel to and above the main shaft 3, and driven from the latter by a pair
of spur wheels, and the valves are reversed by moving this shaft longitudi-
nally, it being formed with a series of collar teeth, which are acted on by a
pinion on a shaft 77, turned by a hand wheel. The valve shaft. 33 is driven
from the intermediate shaft 20 by a pair of bevil wheels, and it is parallel to
the cylinders, being at the intersection of two planes inclined up towards each
other at angles of 45 degrees of the circle from the cylinder's axes. The
cylinders are cast separately with one-half of the valve chest 73 upon each.
The arrangement of the ports is best seen in Figure 59. The passages 70,
at the two ends of the cylinder, have each an opening at their outer sides
leading into the exhaust passages X, and these openings are closed by plates
in the passages. At the outer end of the cylinder, where the cylindercoveris,
the exhaust passage X is cast with the cylinder, and a face plate is inserted
from the inside of the cylinder for the exhaust plate or valve to work on. At
the inner end of the cylinder the exhaust passage is in a separate casting, and
has the face formed on it for the exhaust plate to work on. Passages 71 are
formed along the tops of the cylinders, into which the end passages X lead,
and from which pipes 72 pass over to condensers on the other side of the
main shaft. The steam enters the passages 70 by openings on their inner
sides, with port faces in the valve chest 73 facing each other and at right
angles to the cylinders, as are also the exhaust port faces in the passages.
There is in this example a separate steam valve V for each end of each
cylinder, the pair of valves at one end being worked by one crank K, and
those at the other end by a diametrically opposite crank K. Each crank
actuates a triangular frame 74, each lower angle of which is jointed, not
directly to the valve, but to a cut-off plate c, f, on the back of the valve.
The angles of the frame 74 are made to move circularly parallel to the
driving crank by small guide cranks 36 carried at the ends of a segmental
bar 46 held in a grooved seat cast or fixed inside the valve chest (but not
shown in the Drawing, as it would hide and confuse more important details).
This segmental bar, ordinarily stationary, is adjusted to vary the grade of
cut-off by a lever 75 on a spindle 45, which passes through a stuffing box to
an external hand wheel or lever. The cut-off plate c, f, moves between
guides on the back of the valve V, which are curved circularly, and the
motion which the frame 74 imparts to it divides itself into two components,
namely, a motion of the cut-off plate relatively to the valve, and a motion of
the valve towards and from the cylinder. The under side of the valve is
crescent-shaped, as is also the port, which is thus of considerable length, and
as close as possible to the cylinder, with a proportionately reduced travel.

page_text: The steam passage in the valve is fed by a number of openings on the back,
the cut-off plate having a corresponding number of openings, and the grade
of cut-off is altered by a very slight adjustment of the segmental bar 46, the
curvature of the cut-off plate and its guides being for the purpose of pre-
venting the adjusting for cut-off from injuriously affecting the motion of the
main valve. When working the curvature of the cut-off guides has the effect
of improving the motion of the main valve by causing it to open and close
more quickly with a slower or pausing intermediate motion. The exhaust
plates in the passage 70 are worked by bars fixed to the under sides of the
main valves, and passing through slots or grooves in the steam port face, the
main valves having extensions, as indicated at 76 in Figure 57, to keep the
slots covered when the steam ports are not open. When two valves are used,
one at each end of a pair of cylinders, they may be worked by a single long
crank or by two cranks on the same side of the shaft, so as to move together,
in which case they may be advantageously arranged in the manner shown in
Figure 61 on Sheet 2 of the Drawings, this Figure being a section similar
to that in Figure 59 (Sheet 5). There are separate exhaust passages X at the
ends, with a steam space 73 intermediately. One of the exhaust spaces is
enlarged and has in it one port face and one of the valves V, whilst the other
valve V and port face are in the steam space 73. The valve in the steam
space has the pressure outside of it, as with ordinary valves, whilst the pres-
sure is inside the other valve and in the opposite direction, so that the two
valves being connected, the pressure on one counteracts that on the other.
By suitably proportioning the areas of the valves any reasonable proportion of
predominant pressure to keep the valves to their faces may be obtained. The
two valves may be connected in various ways, for example, by a solid bar, to
which the requisite motion may be imparted by a crank at one side. In the
Figure a tubular connection is shown, through which the driving crank K
passes, being suitably elongated, and its shaft having an end bearing in one
exhaust passage, whilst it enters the other exhaust passage through a stuffing
box. One of the valves is provided with a stuffing box joint, which admits
of the two valves adapting themselves independently to their respective port
faces, and also affords a means of properly proportioning the pressure on each
valve. This arrangement may be modified by making the outer spaces steam
spaces, and the intermediate space the exhaust passage, which plan is con-
venient for inside cylinder locomotives, the exhaust then communicating
directly with the blast pipe. One of the outside spaces, whether for steam
or exhaust, may be dispensed with at the end, with the valve in the inter-
mediate space, and the hollow of this valve may communicate with the

page_text: remaining outside space by a tubular connection between the valves. A way
of counterbalancing the weight of the valve or valves when working verti-
cally or at an inclination, and which at the same time reduces the travel, and
is on that account also advantageously applicable to horizontally working
valves, consists in dividing each valve into two parts at a plane parallel to
the port face, steam passages being formed in the bottom part, and in some
cases in the top part also. This arrangement is shown in Figure 34 on Sheet.
3 of the Drawings, which is a vertical section or at right angles to the port
face. The two parts 78, 79, are made as nearly equal in weight as practicable
or convenient, and contrary motions are imparted to them by means of dia-
metrically opposite cranks or eccentrics, such contrary motions requiring
only one-half the travel or eccentricity of an undivided valve having the
same effect. This improvement is obviously applicable to ordinary slide.
valves, and an equivalent improvement may be adopted in the herein-before
described arrangement with exhaust plates in the steam passages by work-
ing those plates contrarily to the steam plates by means of diametrically
opposite cranks or eccentrics. In some cases my improved valve may have
a circular or curved outline, the ports being correspondingly curved instead
of being straight sided, and if the valve is circular it will not require to be
guided, but may be left free to turn on the crank pin.
In applying my improved valve apparatus to ordinary engines there will
in general be required two pairs of bevil or spur wheels, one pair communi-
cating motion from the main shaft to an intermediate shaft, and the second
transmitting the motion from the intermediate shaft to the valve shaft. In
some arrangements, however, of the herein-before described engines with
oblique crank pin, if the port faces are at right angles to the cylinders, and
if the crank shaft proceeds from the cylinders instead of passing close to
them, the small crank shaft for working the valves may be in the line of and
coupled to the main shaft, and no wheels whatever will be required. A
cut-off action, precisely the same as that got with the ordinary link motion,
may be obtained by arranging the crank pin to shift in a guide in connec-
tion with the crank head, so as to take proper intermediate positions when
moved partly round (relatively to the main crank) in the direction for
reversing by any of the reversing appliances herein-before referred to.
An arrangement of this kind is shown in Figures 36 and 37 on Sheet 3
of the Drawings, which Figures also show the application of the reversing
appliance directly to the valve shaft 33. The pin 80 is fixed to the valve
for the sake of steadiness, and it is entered into a brass bush 81 carried by
the valve shaft. The bush 81 is fitted so that it can be shifted across in a

page_text: frame formed partly on the end of the shaft and partly by a frame piece
bolted on.
These parts are shown in plan immediately above Figure 37,
whilst a little higher is a plan of a fork formed on the end of a tubular
shaft, and which acts on a pin formed on the under side of the bush 81
and shifts it across the frame. The tubular shaft is fast to the bevil wheel 82,
by which the whole is driven; and in a part of it extending below that
wheel there are cut two diametrically opposite helical grooves or slots. The
central shaft has a straight groove or slot cut through it, and a key passing
through all the slots is held in an external box 83, with a loose ring which
can be shifted by a lever. When the box 83 is shifted the central spindle
is turned relatively to the bevil wheel and tubular shaft, and the bush 81
is thereby moved across the frame. By suitably shaping this frame the crank
pin or its equivalent may be moved across through whatever path may be
considered to give the best intermediate positions for working expansively.
Engines with an oblique crank pin, and embodying the principal improve-
ments herein-before described, may be very conveniently arranged for
working on the double cylinder expansion system. Each high-pressure
cylinder may be placed near its low-pressure cylinder with the pistons
working in opposite directions, and connected to the rocking levers on
opposite sides of their axes, or each low pressure cylinder may be an annular
one, having the high-pressure cylinder centrally within it.
In an important modification shown in section in Figure 62 on Sheet 2
of the Drawings, two cylinders, a small high-pressure one h, p, and a large
low-pressure one 1, p, are used with six pistons, 85, 85, 86, 86, 87, and 88,)
three in each cylinder. Each cylinder has two ports admitting steam only
into the four spaces between the pistons, and the most convenient valve
apparatus for them is of the improved kind herein-before described. A suit-
able modification of port face is shown in Figure 63, and the corresponding
valve is shown in Figure 64. The outside pistons of each cylinder 85, 86,
and 85, 86, move in opposite directions stroke for stroke, and the central
pistons, 87, 88, move contrarily to each other, but so as to differ by half a
stroke from the outside pistons. The pistons may be connected in various ways
to the main shaft, and I prefer to employ for that purpose levers with bows
such as are herein-before described. The nature of the present improvement
will, however, be more easily apprehended if the crank shaft 3 is supposed to
have the ordinary position relatively to the cylinders as shown in Figure 62,
in which case the two middle pistons 87, 88, will be connected to one crank
89, one of them directly and the other through a lever or pair of levers, by

page_text: which its motion is reversed, whilst to a second crank 90, at right angles to the
first, will be connected the other four pistons, one of them directly and the
others through levers. The piston rods, guides, levers, links connecting the
piston rods and levers, and the connecting rods will all be constructed exactly
like similar parts of existing engines, and this being the case they are merely
indicated by colored lines in order to save labor on the Drawings already
sufficiently extensive and elaborate. The blue lines indicate the levers and
connections belonging to the central pistons 87, 88, whilst the red lines
indicate those belonging to the outside pistons 85, 86, 85, 86¹. The top
pistons 86, 851, are connected to levers centred in the vertical planes passing
through the axes of the cylinders by means of levers, the outer ends of which
work on short horizontal guides, as in the parallel motion arrangement
shown in Figure 18 on the same Sheet, and the first-mentioned levers are
connected by vertical rods to the lever shown in red below and connected
to the bottom pistons 85, 86. To get the levers at the top within the border
they are represented as being a little lower than they ought to be. The
middle pistons 87, 88, when near each end of their strokes move over portions
of the cylinders, over which the other pistons also move but at different times,
the strokes not being simultaneous, and in consequence of this and of the
described connection of the parts one of the middle pistons 87 is nearest
one of the outside pistons 86, not at the end of either piston's stroke, but at
a point corresponding to one-eighth of a revolution of the shaft, before the
end of one piston's stroke and after the end of the others stroke; this will
be understood from the Diagram, Figure 65, which applies to the two cylinders
combined (or to a single cylinder with four piston spaces). The vertical
lines mark equal periods of one revolution of the shaft, and the curved lines
show the successive positions of the pistons, the middle line representing
both the top piston 86 of the small cylinder and the bottom one 86' of the large
cylinder. The thicknesses of the pistons are omitted in this Diagram; and
whilst referring to such thicknesses it may be mentione. that those of the
outside pistons are represented in Figure 62 as considerably increased, in
order that their packing rings may not have to pass the ports. It may also
here be mentioned that the rods of the middle pistons 87, 88, pass through
stuffing boxes in the bottom pistons 85, 86, and that the cylinders do not
require steam-tight covers, although it may be desirable to enclose the end
spaces to prevent loss of heat by the circulation of the air.
It will be seen from the Diagram, Figure 65, that the several spaces
between the pistons are all at their smallest at points 91, 92, 93, 94, cor-

page_text: responding to one-eighth of a revolution in each case from the "dead centres;"
each space increases during half a revolution, and then diminishes during half
a revolution., The valve is set to commence to admit steam into the several
spaces at about the periods when the respective pistons are nearest together,
and to exhaust at about the periods when the pistons are furthest apart. Each
space in the small cylinder decreases simultaneously with the increase of one
of the spaces in the large cylinder, and the steam that has acted in the small
cylinder is by the action of the valve transferred to the large cylinder to com-
plete its expansion. The result of this arrangement and action is to com-
pletely obviate and avoid the injurious and ineffective strains which in ordinary
engines act on the crank pin, crank shaft bearings, and other parts when any
crank is passing what is termed the "dead centre ;" this result arises from the
fact shown by the Diagram, Figure 65, that each piston, as it were, floats
with equal or nearly equal pressure on both sides of it whilst its crank is
passing the dead centre, and through one-eighth of the revolution on each side
of that centre. The cylinders may obviously be both of the same size to work
independently, and not on the double cylinder expansion system. The four
spaces may also be arranged in one cylinder, when one of the six pistons will
be dispensed with, and the whole will be got into less space; or if the pistons,
instead of moving longitudinally in the cylinder, are constructed and
arranged to vibrate about the cylinder's axis, another piston can be dis-
peused with, and only four be used; whilst if a moving cylinder with
longitudinally moving pistons is used, only three pistons will be required,
the cylinder ends acting as pistons.
An engine on the plan referred to with vibrating pistons is shown in
Figure 66 on Sheet 2 of the Drawings, this Figure being an end view with one
of the end covers removed and some of the parts in section, whilst connecting
links and rods are indicated by blue and red lines. Two of the pistons 87, 88,
are fixed on short shafts, one 95 a tubular one, and the other 96 a solid one
inside the other, and these enter the cylinder by a stuffing box in one end
cover, whilst on similar shafts meeting these half way and entering by a
stuffing box in the other end cover are two other pistons 85, 86. The front
piston shafts have levers on them externally, with pins coinciding in position
with the pistons, as indicated by the blue circles (the dotted blue circles
showing the stroke of each piston). The lever pins are connected by links to
a vertical cross head which works between horizontal guides, and from the
centre of which a connecting rod passes to a crank on the main shaft 3 at the
other side of the cylinder, and lying parallel thereto. Beyond the back end

page_text: of the cylinder the shaft 3 has a crank at right angles to the first one, and it
is acted on through similar connections by the other pistons 85, 86; the levers
of these pistons have to be situated at right angles to the pistons. The pistons
87, 88, are at half stroke, whilst the others 5, 86, are at the ends of their
strokes, and steam is supposed to be acting on the left sides of the pistons
87, 88, whilst the other sides of these pistons are in communication with the
exhaust, and it follows from this that each of the other pistons 85, 86, has
equal pressure on both sides of it. There are four ports P, and one is shown
in section with its valve apparatus, which is of a kind like that shown upon
Sheet 5 of the Drawings, and herein-before described. Near one end the
cylinder has a passage 73 completely round it for steam, whilst a similar
passage X for exhaust runs round it near the other end. Each port is dis-
posed parallel to the axis on the outside of the cylinder, and las on one side of
it a space communicating with the steam passage 73, and on the other one
communicating with the exhaust passage X, and it has separate openings into
these two spaces covered by plates V connected together and worked by a rod
passing out through a stuffing box. The four valve rods are worked by an
external frame b, which is actuated by an eccentric on the main shaft 3, and
which is guided by two guide cranks 36 (or by more, if necessary), so as to
have a parallel circular motion. The pistons 85, 86, 87, 88, and their shafts
may be packed, as in existing engines, with vibrating or revolving
pistons, or they may be made without packing if accurately fitted, and if
constructed with broad contact surfaces which can be obtained by reducing
the stroke.
If an engine of this kind is arranged with three spaces instead of four,
with a corresponding number of pistons (either vibrating or longitudinally
moving), these must be connected to three cranks disposed at 120 degrees
of the circle from each other, or in an equivalent manner to one crank; the
engine may also be arranged with more than four spaces and corresponding
crank connections. The portion of the crank's path which is relieved of
strain increases with the number of piston spaces used.
Having thus particularly described and ascertained my said Invention, I
have to state that I do not restrict myself to the precise details which I
have herein described or delineated, as my improvements are susceptible
of a great variety of modifications without departing from the main
features of my Invention, herein-before particularly noted, and that I
claim as the Invention secured to me by the herein-before in part recited
Letters Patent the constructing, arranging, or combining together of the

page_text: parts of steam engines, substantially in the improved manner herein-before
described.
In witness whereof, I, the said Edmund Hunt, have hereunto set
my hand and seal, this Twenty-fourth day of April, in the year of
our Lord One thousand eight hundred and sixty-six.
EDMUND HUNT. (L.S.)