Improvements in or relating to the Distribution of Steam for Steam Engines and the like, and Apparatus therefor.
Year: 1890

page_text: Date of Application, 18th June, 1890
Complete Specification Left 18th Mar., 1891-Accepted, 25th July, 1891
PROVISIONAL SPECIFICATION.
Improvements in or relating to the Distribution of Steam for Steam
Engines and the like, and Apparatus therefor.
I, SPIRIDION PSAROUDAKI, of 95, Boulevard Beaumarchais, Paris, in the
Republic of France, Engineer, do hereby declare the nature of this invention to be
as follows:-
The distribution, for steam engines and the like, forming the object of this
invention comprises one or more drums, perforated with a certain number of large
or small ports or openings and revolving, or oscillating, between two flat circular
and symmetrical tables, one being the bottom plate of the cylinder itself, and the
other the superposed table. In the case of distribution by means of a revolving
drum for each cylinder, the under plate has four orifices or ports, at which the four
Steam circulating nines and namely
A circular opening made in the middle of this under plate serves as a bearing
for the axis of the drum, and a groove of 2 to 3 millimetres in depth serves to
produce, in the middle of the under plate, a larger circular space in the interior of
which there is no friction.
The distributing drum situated above this under plate is, in the case in question,
pierced by two large openings and four smaller ones situated quite near them.
This drum has a rotating motion half the speed of the main shaft.
The superposed table placed above the drum has four cavities situated
immediately opposite to the four orifices in the under plate, and the edges of each
one of these cavities are symmetrical to the edges of the corresponding aperture.
This superposed table has also, in the middle, an opening for permitting the passage
of the axle of the drum, and a circular recess of 2 to 3 millimetres in depth for
removing the friction surfaces from the centre. The two tables of the distributing
drum are in this manner entirely symmetrical.
The two large openings of the drum place in direct communication, on the one
hand, the various openings in the under plate (of the cylinder) and, on the other,
the corresponding cavities of the superposed table, acting in this way in a similai.
manner to the usual slide valve. Thus these openings can be narrower in the
middle, and, as the bars, which divide the large openings of the drum from the
little ones, must be of a small width, they can be strengthened by a sort of rib or
rather by making the inside surfaces sloping or bevelled.
The four small apertures in the drum serve to place in communication, or retain
in communication, each of the orifices of the under plate with the corresponding
cavity of the superposed table, and consequently these other openings must be a
No direct
little wider in the middle to further facilitate the passage of the steam.
communication between the openings of the under plate must be allowed by the
Sinall openings of the drum, so that these openings must have a rather smaller
breadth than the wall of the under plate of the cylinder which separates the orifices
which are the nearest.
The four small openings in the drum, and the four cavities of the superposed
table serve to double the sections presented to the passage of the steam, just as if
there were in front of the under plate of the cylinder another real plate.
The superposed table can be arranged in various ways. Therefore only one
advantageous method of arrangement will be described herein. In this mode of
arrangement the superposed table is composed of the following parts :-
1st. Of a circular cast metal plate traversed by four openings syminetrical to the
f the ....

page_text: 2nd. Of another flat plate having only a single opening in the middle for giving
passage to the axle of the drum.
3rd. Of four metal springs placed between the two preceding plates, and
surrounding the four openings of the cast metal plate, in such a way as to prevent
any passage of steam across these two plates, cither all round or from one aperture
to another, while at the same time tending to separate the two plates with a certain
elasticity. These springs are formed of a sheet of tempered steel or other clastic
metal, the rims of which are finished all round in such a way as to act as a spring,
and yet, at the same time, to be pressed by the pressure of the steam on the
contour of the openings of the cast plate and thus to completely prevent any escape
of steam.
4th. Of a box, covering the superposed table formed of the foregoing parts, and
also the distributing drum, and serving to facilitate the erection, and at the same
time preserve the distributing drum from the cold temperature of the outer air.
This box need not be air tight. On the contrary, it may be desirable to
establish communication between the interior of this box and the outside air or
the escape pipe, so that there is, over the cast metal plate, no other pressure
than that exercised by the steam which may be between the plates inside the
springs.
Four screw nuts, fixed on the upper part of this box, press on the flat plate, in
order to regulate the pressure of this plate on the four springs which can thus be
suitably compressed. Nevertheless, these springs must only be very slightly bent,
for the pressure, necessary for ensuring air tightness between the contact surfaces
of the drum and its two tables, will not be exercised by the springs, but by the
steam itself. Moreover, this pressure will only be applied on the side on which
there is steam to pass, and further, it will always be proportionate to the tension of
the same steam.
Thus when there is, on any side of the under plate of the cylinder, steam having
a tendency to lift the superposed table on this side, and escape by the contact
surfaces of the drum and its tables, there will be simultaneously above the cast
metal plate and from the same side another equal pressure exerted by the steam
and preventing any escape of steam through said contact surfaces; whilst, on the
side where there is no steam to escape, there will equally be no more pressure
beyond the cast metal plate; and further, as the speed of rotation of the distributor
is one half that of the main shaft, the power necessary for the transmission of this
motion, and also the wear and tear, will be quite insignificant. Thus this dis-
tributor is the best and the most perfectly compensated of all the equilibrium slide
valves ever used.
The following arrangements of details also form part of this invention :--
The distributing drum can be made in two parts surrounded by an exterior
circle, so as to allow of the end for the admission or discharge being changed either
by hand or by means of the regulator.
The distribution can be effected in a cylinder by means of several drums, or in
two cylinders by means of a single distributor, this distributor, or distributors
having, if desired, an alternative oscillatory motion instead of a rotary one, or a
rotary speed three or four times less.
The transmission of movement to the distributors can be effected by the help of
a single intermediate shaft, or, at most, by two, independently of the number of the
cylinders and of the distributors. This or these intermediate shafts can be divided
and their extremities screwed, and a union placed thereon having a corresponding
internal thread, in such a way as to enable this union to be adjusted and thus alter
the angle of position of the drum, either for the purpose of reversing its action or
for changing the expansion, by hand or by the regulator.
Dated this 17th day of June 1890.
WM. P. THOMPSON,
Of 6, Lord Street, Liverpool, Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to the Distribution of Steam for Steam
Engines and the like, and Apparatus therefor.
I, SPIRIDION PSAROUDAKI, of 95, Boulevard Beaumarchais, Paris in the
Republic of France, Engineer, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The superiority of steam engines of high speed and pressure having long been
generally admitted, and simple and plain slide valves being only suitable for both
these conditions to a very insufficient extent, especially in engines of considerable
dimensions, means of replacing such valves by other distributors have been tried,
but (in spite of more or less serious inconveniences) have soon ceased to be steam-
tight.
Endeavours have also been made to solve, in a more practical manner, the
question of the transmission of motion to the distributors, especially in reversing
engines, either for improving the condition of the distribution, or for diminishing
the shocks produced by the to and fro motion of the slide valves, or for doing away
with the slides ("coulisses"), very defective parts, or, finally, for reducing the
number of eccentrics, or dispensing with them altogether.
Further, all the systems of alternating and reversing movements have still several
defects, the principal of which are:-
1st. That when the expansion is increased the course of the slide valve is
diminished and the steam choked to a considerable extent; which is a very serious
drawback, especially in locomotives.
2nd. In order not to raise the slide valve and thus place in direct communication
the admission and the escapement, or for avoiding other still more serious incon-
veniences, it is necessary to make use of pressures too small for the usual expansion,
thus losing the great advantage of great compressions so necessary for avoiding
shocks, for diminishing the harmful effects and warming the internal walls of the
cylinder, and thus effecting a considerable economy of steam.
3rd. Of compelling the surfaces of the slide valves not only to be considerably
increased but also the travel of the valve, and thus causing either cylindrical slide
valves to be used or compensating systems, very inconvenient, both in construction,
and maintenance and in working.
4th. Not only of not permitting the independent arresting of the beginning or end
of the four communications which take place during one revolution of the motive
crank; but, on the contrary, of compelling some of these conditions to be sacrificed
for the benefit of the others, and of rendering the reverse action very defective,
and, finally, (not to mention other secondary drawbacks) not being suited for large
expansions, except by means of the most inconvenient complications.
The new system of distribution forming the object of this invention not only
remedies the above drawbacks but presents the following advantages :-
1st. The space occupied by the distributor and all the mechanism for transmitting
the movement in both directions is reduced by nearly one half. The advantage of
this for marine and locomotive engines, with inside cylinders, will be casily
understood.
2nd. The expenses of construction and maintenance are reduced in the same
proportion.
3rd. The speed of the engine and the atmospheric pressures can, without any
inconvenience, as regards the distribution, be increased as desired.
4th. The steam spaces are rendered perfectly tight and are better maintained
than in ordinary slide valves.
5th. In spite of the reduction in weight and volume, the sections presented to the
steam passages are larger. Thus, with a single distributor, expansion to one-

page_text: increasing the surface of the slide.
Choking the steam, and without very much
6th. The opening and closing of each communication can be regulated at will and
independently of each other during one revolution of the driving crank.
7th. The power developed by the engine is changed at the same time by
changing the expansion, the contraction and the lead for the admission and exhaust';
the two first within very wide limits, and the leads in such a manner that the
introduction always commences before the tension of the counter pressure is equal
to that of the boiler so as to avoid shocks, and so that the duration of the exhaust
shall be always the same. The unused steam is thus returned to the generator.
For instance, in a locomotive running down hill, the amount of coal consumed can
not only be reduced to the simple losses by radiation, but even the tension can be
stored up.
8th. The discharge pipe can be placed at the side of the upper bottom plate and
thus avoid the constant chilling of the walls of the cylinder by the contact of the
discharge with the said walls.
9th. Owing to the circular and continuous motion of the distributor, its speed
being two or three times less than that of the main shaft, and owing to the facility
with which it can be moved and its angle of keying changed during the working of
the engine, the greatest play can be had everywhere, and yet, at the same time,
the shocks of the transmitting parts (which the present systems produce) can be
avoided a very regular action can be constantly obtained, the direction or the
speed of the engine can be regulated with remarkable facility and rapidity, the
governing lever can be retained in any position without experiencing any resis-
tance, and the construction, erection and maintenance can be facilitated to the
greatest extent; the frequent repairs and derangements which characterise the
present systems can be avoided, and the engines can be very easily overlooked
without the necessity of having experienced mechanics.
The distribution comprises one or more drums, perforated with a certain number
of large or small ports or openings and revolving, or oscillating, between two flat
circular and symmetrical tables, one being the bottom plate of the cylinder itself,
and the other the superposed table. In the case of distribution by means of a
revolving drum for each cylinder, the under plate has four orifices or ports, at
which the four steam ways end, namely:
:―
The two channels for admitting steam to the two ends of the cylinder, ending
at A and B (Figure 1) on the accompanying drawings:
The tube or steam pipe coming from the boiler ending at C:
The exhaust pipe ending at D.
A circular opening O made in the middle of this under plate serves as a bearing
for the axis of the drum, and a groove m of 2 to 3 millimetres in depth serves to
produce, in the middle of the under plate, a larger circular space, in the interior of
which there is no friction.
The distributing drum situated above this under plate is, in the case in question,
pierced by two large ports A and B (Figure 2) and four smaller ones a bed,
situated quite near them. This drum has a rotating motion half the speed of the
main shaft.
Figures 2 and 3 represent the distributor, half in elevation and half in section.
The superposed table placed above the drum has 4 cavities A B C D',
(Figure 4), situated immediately opposite to the four orifices in the under plate,
and the edges of each one of these cavities are symmetrical to the edges of the
corresponding orifices. This superposed table has also, in the middle, an opening O
for permitting the passage of the axle of the drum, and a circular recess m² no
Fig. 4 of 2 to 3 millimetres in depth for removing the friction surfaces from the
centre. The two tables of the distributing drum are, in this manner, entirely
symmetrical.
The two large openings of the drum place in direct communication, on the one
hand, the various openings in the under plate (of the cylinder) and, on the other

page_text: the corresponding cavities of the superposed table, acting in this way in a similar
manner to the usual slide valve. Thus, these openings can be much narrower in
the middle, and, as the bars, which divide the large openings of the drum from the
small ones, must be narrow, they can be strengthened by a sort of rib, or rather
by making the inside surfaces sloping or bevelled, as shown in Figure 5, which
gives a section of this bar following the line L L, of Figure 2.
The four small apertures in the drum serve to place in communication, or retain
in communication, each of the orifices of the under plate with the corresponding
cavity of the superposed table. No direct communication between the openings
of the under plate must be allowed by the small openings of the drun, so that
these openings must have a rather smaller breadth than the partition in the under
plate of the cylinder, which separates the orifices B and D (Figure 1) which are
the nearest.
The four small openings in the drum, and the four cavities of the superposed
table serve to double the sections presented to the passage of the steam, just as if
there were in front of the under plate of the cylinder another similar plate.
In order to make it clear, let us suppose that the drum follows the direction
indicated by the arrow (Figure 1) and that one of its two large openings has
uncovered, at a given moment, the opening A* to a certain extent say eghl
Figure 1.
The opening C being at this moment almost uncovered by the same large orifice
in the drum which has already commenced to uncover the orifice A, it is evident
that the steam will only be limited in its passage by the section e 17. But this
same large opening in the drum, at the same time that it uncovered on one side the
orifice A of the plate to a certain extent, has also uncovered, on the opposite side
and to an equal extent, (Figure 4), the cavity of the upper table A' which
faces it.
And, as the cavity is, at the moment, in direct communication with the
orifice A of the bottom plate by the small opening of the drum which precedes the
large one, it follows that the steam will enter the orifice A (Figure 1) both by
the section eg, Figure 1, as well as by the section eg, Figure 4, of the
cavity opposite, and by the small opening in the drum which precedes the large
one. In this way, the section presented for the passage of the steam will be twice
as large.
What takes place at the beginning of the communication in question, takes place
also at the end, owing to the small opening which follows the large one, and the
cavity of the upper table which faces the orifice C at the moment when the
orifices A and C Fig. 1 are equally uncovered by the same large opening in
the drum, both the small openings of the drum, which are on each side of the large
one, and also the two cavities of the upper table which face the orifices A* and C,
Fig. 1 are also utilised. Thus the sections presented to the passage of the steam
are increased, not only at the commencement and at the end, but during all the
time of this communication.
What takes place as regards the orifice A, takes place also with orifice B, not
only for the admission but also for the exhaust. In this way, the sections for the
passage of the steam are doubled in the same manner as in bottom plates with
numerous openings and slide valves with several channels. Only in the latter case,
the sections for the passage of the-steam can only be doubled by a considerable
enlargement of the surface of the slide, whereas, by this new system, although the
sections for admission and exhaust are equally increased (which is not always the
case in slide valves with several channels) and, not only is the surface of the bottom
plate not increased, but, on the contrary, it is considerably diminished, simply
because the distributor has always the same position as if it remained perfectly
fixed, which constitutes a very great advantage. A certain number of cavities
must be made between the small openings a cb and d of the drum, the size of which
should equal or be slightly smaller than the above described openings of the drum
and of a shallow depth. These cavities can be placed either on one side or the
other of the drum, that is to say, on the four flat surfaces shown in Figure 2,

page_text: between the small openings. All these cavities must have no communication
between each other, they are not shown on the figures of the drawings hereto
annexed for the sake of clearness. In addition to these cavities, radiating and
very narrow grooves must also be made in all the partitions of the two lower plates
of the drum. The object of these cavities in the drum, and in the tables, is to
facilitate wear in the middle of these parts and thus increase the tight fitting of the
same and facilitate the movement.
The superposed table can be arranged in various ways. The most advantageous
method of arrangement will be that shown in Figure 6, which is a transverse
section of the cylinder K of the distributing drum A B and of its two tables. In
this mode of arrangement, the superposed table is composed of the following
parts:-
1st. Of a circular cast metal plate EE (Figure 6) traversed by four openings
symmetrical to the orifices of the under plate and shown separately on Figure 4.
2nd. Of another flat plate F F having only a single opening in the middle for
giving passage to the axle of the drum.
3rd. Of four metal springs G placed between the two preceding plates and
attached to the flat plate in such a way as to surround the four openings of the
other plate, and thus to prevent any passage of steam across these two plates, either
all round or from one aperture to another, while, at the same time, tending to
separate the two plates with a certain clasticity.
Figure 7 shows separately one of these four springs in plan view, and Figure 8 a
section across A B (Figure 7).
As seen by these figures, and also by Figure 6, these springs are formed of a
sheet of tempered steel or other elastic metal, the rims of which are finished all
round in such a way as to act as a spring, and yet, at the same time, to be pressed
by the pressure of the steam on the contour of the openings of the cast plate, and
thus to completely prevent any escape of steam.
4th. Of a plate H H (Figure 6) covering the superposed table formed of the
foregoing parts. This plate H H is tapped and is screwed on the upper part of
the box, which surrounds the drum, pressing it more or less and holding it firm
in the desired place, the pressure exercised by this plate on the four springs can be
regulated. Nevertheless, these springs must only be very slightly bent, for the
pressure, necessary for ensuring tightness between the contact surfaces of the drum
and its two tables, will not be exercised by the springs, but by the steam itself.
Moreover, this pressure will only be applied on the side on which there is steam to
pass, and, further, it will always be proportionate to the tension of the same
steam.
Thus, when there is, on any side of the under plate of the cylinder, steam having
a tendency to lift the superposed table on this side, and escape by the contact
surfaces of the drum and its tables, there will be simultaneously, above the cast
metal plate EE and from the same side, another equal pressure exerted by the
steam and preventing any escape of steam through said contact surfaces; whilst, on
the side where there is no steam to escape, there will equally be no more pressure
beyond the cast metal plate EE; and, further, as the speed of rotation of the
distributor is one half that of the main shaft, the power necessary for the
transmission of this motion and also the wear and tear will be quite insignificant.
Thus this distributor is the best and the most perfectly compensated of all the
equilibrium slide valves ever used.
The regulating device just described can be modified as shown in Figure 9.
The distributing drum and the superposed table are covered by a box H H, fixed
all around the plate. A number of screw bolts II press on the flat plate F F and
regulate the tension of the springs. In order to lubricate the surfaces of the drum
and of its tables, grooves or circular channels (Figures 1, 2 and 4) are made
round the drum and its two tables on their friction surfaces, in such a way as to
collect, by the contact of these parts, both the oil and steam which tend to travel
round in order to escape into the box of the drum. Two or more openings r

page_text: (Figures 2 and 3) made in the drunn connect the channels which follow both sides
of this distributor with another s (Figure 1) ending on the one side at the channel
of the under plate and at a tap, placed above the case in any suitable place to
ascertain on which side the escape is the greatest in order that the superposed table
may be further screwed down and the circulating and friction surfaces may be oiled
so as to diminish wear and facilitate their working.
As the interior of the box or case of the drum must be in constant communication
with the discharge, it is very easy to fix the escape tube above this box and
discharge thus from the side of the superposed table, in order to do this, the box is
constructed with an opening in the flat plate F F. If it be desired to do the same
for the entrance tube, it must be so arranged that the pressure of the steam can
only be exerted above the springs or on the flat plate F F.
The distribution by means of revolving drums is preferable, but an oscillating
drum can also be used, that is to say, having an angular alternating motion, in
numerous cases, and especially when it is desired to distribute in one cylinder by
two drums, one serving for the admission and the other for the exhaust, or fixed on
the two covers of the same cylinder in order to save space and each serving as one
of the two covers as well as for the admission and for the exhaust.
Figure 10 shows the lower plate, and Figure 11 the drum used when it is desired
to distribute separately in each of the ends of the cylinder, and Figure 12 shows
the under plate, and Figure 13 the drum used when it is desired to have one
distributor for the admission and another for the exhaust.
As seen in these two arrangements, the lower plate presents four openings, and
the drum three large and four small ones, the difference only consisting in the
relations between the various openings both of the under plate and of the drum,
and this relation must vary according to the conditions of the application.
Of the four orifices of the under plate, represented in Figure 10, two, A A,
conduct directly to the same end of the cylinder; the orifice C conducts to
the steam admission pipe, and the orifice B to the discharge pipe.
The distributor (Figure 11) which fits on this under plate has three large
openings A B C₁, and four small ones abc d.
The opening C always serves for the admission, and the opening B' for the
discharge, whilst the opening A' serves sometimes for the admission and sometimes
for the exhaust. The four small holes a bed serve to double the sections for the
passage of the steam, acting for this purpose in accordance with the cavities which
must always exist opposite the openings, as in the description of the revolving
drum.
Figure 11 shows the drum in the middle position in relation to the common axis.
Supposing that it be oscillating over the plate (Figure 10) it is easily seen that,
for a given movement of this drum, a section is presented for the passage of the
steam about 4 times greater than that which a simple aperture would present.
As the covers of the cylinders must be very thin, and the discharge pipe should
always have a large section, it would be preferable to make this pipe end at the
superposed table, there would then be, on the under plate, 3 openings, A, A and C,
and a cavity B, whilst the discharge pipe would end opposite this latter cavity.
A proportionate thickness could thus be given to the cover, and the chilling of this
cover by the discharge products could be avoided.
In the under plate shown in Figure 12, the openings C and C' open to the steam,
the opening A into one of the two ends of the cylinder, and the opening B into the
other.
If the drum serve for the exhaust, the ports C and C₁ conduct to the escape pipe
and are much larger. They can, if necessary, be replaced by cavities, and the
escape tube can be made to end opposite these cavities, that is to say, on the
superposed plate.
In the case of distributing by oscillating drums, these distributors must have
very little play on their axes and must be mounted very carefully so that they are
not hindered in their movement by pressing unequally on the plate of the cylinder

page_text: whilst, in the case of distribution by revolving drums, the central opening, through
which the axis of these distributors passes, can be made a little larger and thus
have a little more play without changing the conditions of distribution.
The distributing drum whilst preserving its shape could if desired be traversed
by large and small openings and revolve or oscillate between two plates, with the
following variations
1. Either one or both of the two under plates can be made more or less conical,
and, in that case, the flat surfaces of the drum must have a shape to correspond.
2. The superposed table may have a less diameter than that of the main under
plate, and, in that case, the external surface of the drum must be made conical and
not cylindrical.
3. The smallest partition of the superposed table may be made a little larger
than the corresponding partition of the under plate, and the section of the small
openings of the drum increased on the side of the superposed table.
The result of all these variations is that the two under plates of the drum will
not be entirely symmetrical, and, in appearance, will present some advantages, but,
in reality, none of these variations, are equal to the drum revolving or oscillating
between two flat under plates with entirely symmetrical edges, for all the
advantages of the other variations are insignificant and their defects are more
or less serious, and are not perfectly air tight.
The springs can be mounted on the side of the under plate of the cylinder, there
would then be on this side:-
1. A table presenting the necessary openings for the circulation of the steam
(the openings being a little rounded and presenting a section a little larger than the
under plate shown in the drawing):
2. The springs placed on this table having openings of a size at least equal to
that of the ports:
3. A plate, as shown in E E on Figure 6, placed on the springs and projecting
above the edges, as shown in drawing, in order to form the bedplate of the
cylinder.
On the side of the superposed table, there would be only a single plate
presenting cavities opposite the ports of the bed plate and the screw arrangement
(Figure 9) will press on this plate, or the screwed plate (Figure 6) for regulating
the pressure exercised on the drum.
Thus, as stated above, the superposed table can be still arranged in various ways,
as, for instance, in the following:
1. The springs can be made united so as to form a single plate, presenting its
cavities to the side where the steam tends to escape.
2. The inclined walls can be formed of these same springs in such a way that the
transverse section presents a sinuous line, in order thus to have a greater elasticity,
but, in that case, they must be placed in cavities made in one or other of the two
plates in such a way that the said sinuous walls press against the walls of these
cavities, and thus the pressure of the steam cannot displace them.
3. The plate F F of Figure 6 can be dispensed with, and the springs compressed
direct by the plate H H, but, in that case, the springs must be retained on the
plate E E in the same way.
4. All the metal springs may be replaced by a sheet of caoutchouc of asbestos or
other similar material, having the form of two circles of different diameters con-
nected by a number of ribs equal to that of the openings in the under plate. To
retain this fixed sheet in its place between the two plates, grooves of the same
shape, in which the elastic plate can, in large measure, rest, must be made in one of
the plates.
5. The entire superposed table could be made of a single plate, and it could be
held fixed in a suitable place without any clastic arrangement by taking other
precautions for diminishing escapes, or preventing them; these methods are,
however, less advantageous.
6. The interior of the box or envelope of the drum, instead of being in constant

page_text: communication with the exhaust, which is the more preferable, could also be made
quite tight, full of steam, or even full of oil. The pressure, then, would be much
greater or at least equal to that of the admission, the steam would tend rather to
enter the ports than to leave them, so that it would be necessary to turn the
concavity of the springs G and G (Figures 6 and 9) to the side where the steam,
which tends to escape, comes, or even to make these springs double, presenting
concavities both to the outside as well as to the inside. As the flat plate F F
must only exercise a slight pressure on the springs, it would then be necessary to
keep this plate fixed in a suitable place.
Finally, this table can be arranged in any suitable manner, either by diminishing
the number of plates or by fixing them differently, it is sufficient to present a cavity
opposite each orifice and to preserve, in the best way possible, the facility of motion
and to make it air tight.
The distributing drum described above is formed of a single piece, it can,
however, be constructed of several pieces, so that the size of the large opening may
be varied and the condition of the distribution thereby changed.
On
The mode of constructing this drum varies with the shape and method of
movement of this distributor. Thus, in the case of distribution by a revolving
drum having two large openings, this distributor is formed of two parts placed in
the shape of a cross surrounded by a circle and mounted on two axles, one of which
is solid and the other hollow, or held up externally in any suitable manner.
changing the relative position of these two parts, the size of the two large openings
would evidently be changed, and the end for admission or exhaust could thus be
altered whilst preserving suitable leads. This method of changing the work
performed by the engine is much inferior to that of changing the angle of the
keying of the whole drum by means of a helicoidal cylinder. Distribution can be
made in a single cylinder by means of two, three or four distributing drums,
independent of one another, or by means of two drums superposed. In this latter
case, these distributors will be separated by a special table having on both sides the
openings and necessary cavities for serving as superposed table for the lower drum
and as under plate for the upper or expansion drum. The entrance pipe opens
above the expansion drum, whilst the discharge pipe opens on the under plate of
the cylinder itself.
On the other hand, the distribution can be made in two tandem or compound
cylinders, with a single drum having three large equal openings, and also six small
equal ones, and having a speed of rotation three times less than that of the main
shaft. The two cylinders can be arranged side by side, end to end, or in any other
position. The distributor can be placed between the two cylinders, or on one,
preferably the large one. In all cases, the under plate will have six apertures,
namely
1. An opening serving for the admission of the steam:
2. Two openings placed on both sides of the steam admission opening, and
leading to both ends of the cylinder of admission:
3. Two openings placed beside the openings of the admission cylinder and
leading to the two ends of the expansion cylinder:
4. An opening placed between the two ports of the expansion cylinder and.
leading to the exhaust.
In front of each of these openings, there should be a corresponding cavity made
in the superposed table. Two special pipes conduct the steam from the openings
intended to bring the steam from the admitting cylinder to the two ends of the
cylinder.
The distributing drums can be equally well placed on the ends of the cylinders
as on the lateral sides, and, in different planes or positions as required.
The motion of the drum being rotary and uniform, and the different methods of.
transmitting this motion presenting nothing novel, there is hardly anything special.
to describe except the reversing device and altering the expansion by means of a
helicoidal cylinder.

page_text: The rotary motion can, however, be transmitter, to all the distributors,
by means of a single movement transmitted from the main shaft to the said
drums.
Thus, for instance, in a four cylinder machine actuating two rectangular cranks,
a single drum can be used for the two cylinders actuating the same crank, thus only
two drums will be required; and these two distributors can be mounted in planes
perpendicular to the main shaft in order to be simultaneously actuated by the same
axle and the same wheel, or in inclined planes selected so as to be capable of
actuating both wheels of these distributors simultaneously by a single wheel mounted
on the end of the intermediate shaft, which is easily done by making use of
helicoidal wheels which, as is well known, allow of the secondary shafts being
placed in different positions.
These helicoidal wheels must be placed in boxes full of oil for diminishing wear
and tear and preserving them from dust.
The drums can be thus distributed in such a way that the spur wheels (straight,
angle or helicoidal) turn each other either directly, or by intermediate wheels, or two
intermediate shafts can be employed where required.
The helicoidal cylinder, of which mention has been made above, is mounted on
the intermediate shaft or shafts, which transmit the rotary movement from the main
shaft to the drums. For this purpose, the shaft or shafts are intersected, their ends
are screwed in opposite directions with a very quick thread, and are connected by
a union having the same internal thread, so as to be capable of being moved longi-
tudinally, and thus the angle of the keying of the drum can be changed either for
reversing the action or for altering the speed of the machine, by hand or by a
regulator. Further, the rotary motion given to the drum need not be a uniform
one, but, in that case, the under plate must be designed in a suitable manner.
Where it is desired to place the distributors on the covers of the cylinders and
actuate them by an angular alternating motion, all the eccentrics, which are intended
to actuate these distributors, could be mounted on the same shaft parallel to the axes
of the cylinders, this shaft could be revolved by the main shaft direct, or by means
of helicoidal wheels, and could be intersected at any suitable point, and a helicoidal
union could be placed over the two ends, which could be capable of being displaced
longitudinally in order to change the expansion or reverse the action independently
of the number of the cylinders.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, declare that what I
claim is
1. The distribution of steam or other motive fluid in engines by means of
distributing drums placed between two circular and symmetrical flat plates which
present on the side adjacent to the under plate of the cylinder all the ports neces-
sary for the distribution of the steam arranged radially, and on the side adjacent to
the superposed table a cavity with symmetrical edges opposite each port therein, the
drums themselves being pierced by apertures which have no communication either
with one another or with the centre of the distributor, or with its periphery, but which
are of two different kinds, some of them serving to place the various ports in com-
munication in the same way as in the case of an ordinary slide valve, and the
remainder (the smaller ones) serving to place and retain in communication the ports
of the under plate of the cylinder with the cavities of the superposed table, which
thus act like other ordinary ports and thereby double the areas for the passage of
steam, substantially as described.
2. The formation, on all the flat surfaces of the drum, existing between the
smaller openings therein, of small shallow cavities, equal to, or rather less in breadth
than, the breadth of the said smaller openings and separated from each other by
means of strips of slight width, substantially as described.
3. The upper table composed of two plates separated by steel or thin copper
springs turned up all round in order to fit round above the openings of the cast

page_text: plate and thus form the cavities which the superposed table must have opposite the
ports of the under plate, substantially as described.
4. The modification of the arrangement described in Claim 3, in which the plate
and springs are placed on the side of the under plate of the cylinder, the superposed
table presenting in this case only simple cavities, substantially as described.
5. In engines having a rotary distributor, the reversing of the movement by
changing the angle of attachment of the distributor, this change being obtained
by means of one or more helicoidal sleeves placed on the shaft which drives the
distributor and fixed in such a way as to be capable of being shifted very easily,
substantially as described.
Dated this 17th day of March 1891.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.