Improvements in and connected with Valves for Steam Engines, or like Engines, Operated by Expansible Fluid or Vapour.
Year: 1894

page_text: Date of Application, 17th Sept., 1894
Complete Specification Left, 3rd Dec., 1894-Accepted, 26th Jan., 1895
PROVISIONAL SPECIFICATION.
Improvements in and connected with Valves for Steam Engines, or
like Engines, Operated by Expansible Fluid or Vapour.
I COURTENAY WILLIAM THOMPSON of 5 Fair Street, Tooley Street, in the
County of Surrey, Mining Engineer do hereby declare the nature of my invention
to be as follows:-
My invention relates to slide valves, of steam engines or like engines operated by
expansible fluid or vapour which valves may be flat, piston oscillating or other
valves and it has for its object to obtain the greatest possible openings of the inlet
and exhaust ports to and from the engine cylinders for any given travel of the
valve rods and eccentrics and, coincident with this advantage, to permit of, and
facilitate a very large range in the regulation of the cut-off for expansion, the
moment for inlet of motive fluid and for opening the exhaust, the closing of the
exhaust ports for cushioning, the governing of the speed and the reversal of
the engine, to suit varying conditions of power speed and other requirements, a
further object of my invention being to provide efficient means for relieving the
pressure on and the friction in working slide valves all as hereinafter described.
I use a valve slide plate sliding on the fixed valve seating in the valve chest
which valve slide plate is hereinafter called the main slide, and another valve slide
plate (sliding on the back of the main slide) which is hereinafter called the cut-off
slide.
Two principal features of my invention are that I use the cut off slide not only
to cut off the inflow of motive fluid to the cylinder (for expansion) but I also use
it to operate the exhaust ports so as to regulate the cushioning of the main piston
and opening the cylinder to exhaust and to operate the inlet ports so as to regulate
the amount at which inlet of motive fluid to the cylinder is effected and that I set
the excentric operating the main slide, (which excentric is hereinafter called the
main excentric) at right angles to the main engine crank, and the excentric
operating the cut-off slide, (which excentric is hereinafter called the cut-off
excentric) in a line with the same crank, and I arrange the two slide plates
relatively to each other so that when the main slide has half completed its travel,
say from right to left, the cut-off slide is just about to commence its travel in the
same direction or from right to left, and so on with reciprocating action, the main
slide being always in advance of the cut-off slide.
In some cases, especially where no reversal of the engines is required, I may
slightly modify the relative angular positions, in the direction of the rotation, of
the excentrics to one another and to the main engine crank, but the greatest
advantage is obtained by placing the excentrics as nearly as possible as described.
By using the cut off slide as described there is no necessity to give lead to the main
excentric and consequently nearly the full length of travel of the main slide is
effective in creating large port openings.
In order to produce this effect the inlet and exhaust ports are so arranged that
they are uncovered as soon as, or before, the main slide has reached its central
position of travel, cut off may then be effected by the cut off slide and also the
exhaust ports may be arranged to be closed at the desired moment by the same
cut off slide so as to regulate the degree of cushioning, I also prefer to arrange the

page_text: cut-off slide to regulate the moment of inlet of motive fluid and of opening the
cylinder to exhaust.
The amount of cushioning of the piston and the moment of inlet of motive fluid
and of opening to exhaust can therefore be regulated at will according to the degree
of cut-off and engine speed and to suit other conditions are required.
I will now illustrate a few examples of the uses and working of my invention by
reference to the accompanying drawings as follows:-
Figures 1, 2, 3 and 4 represent longitudinal sections through the slide valves
and cylinder casings, and the lettering and numbering is the same in all the
figures.
A, B, shews part of the cylinder and the valve seat is on the surface at A. B.
Q is the main slide and R is the cut-off slide. The length and travel of the
valves and the length and position of the ports are indicated by the equal divisions
numbered 1, 2, 3 and so on.
The motive fluid occupies the space within the valve chest at the back of the
valves. The exhaust passages are at X X. C and D. are the ports leading to the
cylinder and E and F are the inlet ports and J and H are the exhaust ports in
the valve seating. In Figure 1 the main piston is presumed to be at the A. end of
the cylinder the main slide Q is in the central position of its travel in the direction
from B to A (that is the main eccentric is at right angles to the cut off eccentric
as is shown by the cut off slide being at the B end of its travel) and the total
travel of the main slide is equal to two of the divisions, the cut off slide R, is at
the B. end limit of its travel (that is the cut off eccentric is diametrically opposite
to, but in the same line as, the main crank) and its total travel is only equal to one
of the divisions (Figure 3 illustrates the general arrangement when the cut off
eccentric is coincident with the main crank). During the A to B stroke of the piston,
the main slide Q travels forward and back over one division and starts in the
direction from B to A and the cut off slide R travels forward through one division
(from B towards A). It will now be seen how the motive fluid port 3 Q in the
main slide opens and shuts the inlet port E to the A end of the cylinder and
how the exhaust port 12 Q opens and shuts the exhaust port H to the B end of
the cylinder. During the B to A stroke of the piston the reverse of these actions
takes place.
By varying the length of travel of the main slide Q so the moment at which
the cut off slide R will cut off steam may be varied from nothing to about seven-
eighths of the stroke.
The cut off of motive fluid can also be varied by altering the travel of the
cut-off slide R, but it must only be altered slightly (unless a different slide be
introduced) because of its connection with the exhaust. The more the travel of
the cut-off slide R is increased the sooner will it close the exhaust ports and cause
increased cushioning in the cylinder.
If the ports E and F be widened, say one quarter of a division into the
divisions 3 and 14 respectively, then the moment of inlet of motive fluid can be
controlled by slightly altering the travel of the cut-off slide R and the more the
travel of the cut-off slide R is increased the sooner it will open the cylinder to
motive fluid.
By altering the size and position of the ports and by adding on or taking off
inside or outside "lap" the conditions of the distribution of motive fluid can be
altered, for instance, if the exhaust port J be widened towards the division 5 then
the A end of the cylinder will be opened to exhaust earlier, and this can be done
without interfering with the closing of the said exhaust port J, because closing
may be effected and regulated by the cut-off slide R.
In Figure 2 the valve seat A B and the main slide Q are the same as in
Figure 1 but a different cut-off slide R is shewn it being one division longer
inside the exhaust chamber at X and with this alteration the length of its travel
can be doubled, namely to that of two divisions; this enables the main slide Q, to
effect a large movement and opening for about a half cut-off, or less, according to

page_text: its travel. All the other conditions are similar to those described in Figure 1.
Figure 3 shews how the ports and other parts may be arranged when the cut-off
eccentric is placed coincidently with the main crank, and consequently when the
cut-off slide R travels in the same direction as the main piston. In this arrange-
ment, as in the arrangement Figure 1, the cut-off slide has about half the full
travel of the main slide. The operation will be readily understood by reference
to Figure 3 and the other conditions are the same as those which apply to
Figures and 2.
The arrangement shewn in Figure 4 operates as does that shewn in Figure 1 and has
all the same properties except that there is a modification of the ports introducing
additional openings to the exhaust. m and are these additional exhaust openings
in the cut-off slide R operated by the inlet ports 2Q and 15 Q respectively in the
main slide Q for opening to exhaust in advance of the stroke.
The ports may be repeated so as to form grids to give more than one opening for
each port.
The valve gear (exemplified in the several figures) may be reversed by
diametrically reversing the main eccentric with the main slide alone (the cut-off
slide remaining unaffected) or an equivalent effect may be produced by means of
any convenient reversing link, or other motion, between the main eccentric and its
slide. When reversed this valve gear retains all the properties and advantages
described with regard to Figures 1 2, 3 and 4. In order to effect the alteration in
the travel of the main slide and cut-off slide with the objects already described, any
ordinary link-lever or other motion may be used and it may be operated either by
hand or regulated by any suitable governor mechanism.
I may also place two additional cut-off slide plates on the back of the cut-off
slide, one operating on each of two inlet ports which may be constructed at each
end of the cut-off slide before described. These additional cut-off slides may be
operated for variable cut-off in any ordinary or convenient manner; for instance, by
making them gear with right and left hand screws or by constructing the ports in a
diagonal position and by traversing the additional cut-off slides transversely across
the back of the cut-off slide. The advantage of introducing these additional cut-off
slides is that the cut-off can then be regulated without affecting the reversing or other
links. In order to relieve the pressure on and the friction in operating the side
plates I reduce the surface on the back of the cut-off' slide exposed to the pressure of
the motive fluid by converting such surface into the equivalent of a piston and over
this piston 1 fix a shallow piece or the equivalent of a cylinder communicating on
the inner side with the air or the exhaust. I may reverse the position of the
equivalents of the cylinder and piston with the same effect. If no cut-off slide be
used in the valves to which this is applied the arrangement will be applied to the
main slide valve the arrangement being always fitted onto the outer slide plate
where several are used. I will presume however that it is applied to the back of
the cut-off slide described. The motive fluid acts to press down the equivalent of a
cylinder in proportion to the size of the equivalent of a piston and the cut-off slide
is relieved in the same proportion. The cylinder-like piece will reciprocate with
the cut-off slide and in order to carry its weight I may employ rollers or their
equivalents which support the reciprocating cylinder piece and are fitted with any
suitable devices to keep them in their varying but correct positions as the cylinder-
like piece moves over them and they move over the surface on which their other
side bears. Such devices may be arranged in any way which will maintain the rollers
in proper relative position and allow of the proper relation between the movement
of the surface which runs on them and the surface upon which they run, for
example toothed portions or pinions on the rollers gear with corresponding toothed
racks both on the cylinder-like piece and on the supporting surface, such as the
surrounding surface of the valve seat and the diameter of the pitch circle of the
pinions or their equivalents may be the same as the diameter of the rollers or
instead of the racks on the cylinder-like piece independent rack rods may be used
reciprocated equally to the cylinder-like piece from without by means of attached

page_text: rods passing steam tight into the valve chest. Or the toothed pinions and all the
fixed and reciprocating racks may be manipulated outside and the resulting regulating
motion be transmitted to the rollers or the like by means of rods passing steam-tight into
the valve chest. All such devices however arranged have for their object to ensure
that the axes of the rollers shall move in the same direction at half the rate and
through half the distance that the cylinder-like piece moves at, and through, and
any arrangement which by levers or otherwise will produce this effect (when either
placed within the valve chest or placed without and communicated to within) may
be used. A spring buffer or its equivalent may be intervened between the regulating
device and the rollers.
I do not limit myself to the precise details of arrangement as described, for
example instead of the valve being arranged as one valve for the inlet and exhaust
for both ends of the cylinder it may be arranged as two valves to control separately
the inlet and exhaust for each end of the cylinder or the valvular arrangement may
consist in any other number of separate valves to give by their combined action the
operations which I have described and although I have described but one cut-off
slide to perform the functions in conjunction with the main slide the functions may
be performed by two or more cut-off slides operating in conjunction.
Dated this 17th day of September 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.
Improvements in and connected with Valves for Steam Engines, or
like Engines, Operated by Expansible Fluid or Vapour.
I COURTENAY WILLIAM THOMPSON of 5 Fair Street, Tooley Street, in the
County of Surrey, Mining 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 :—
My invention relates to slide valves of steam engines, or like engines, operated
by expansible fluid, or vapour, which valves may be flat, piston, or oscillating, or
other valves, and my said invention has for its object to obtain the greatest possible
openings of the inlet and exhaust ports to, and from the engine cylinder or cylinders,
for any given travel of the valve rods and eccentrics, and coincident with this
advantage, to permit of, and facilitate a very large range in the regulation of the
cut off for expansion, the moment for inlet of motive fluid, and for opening the
exhaust, the closing of the exhaust ports for cushioning, the governing of the speed,
and the reversal of the engine, to suit varying conditions of power, speed and other
requirements.
I use a valve slide plate sliding on the fixed valve seating in the valve chest,
which valve slide plate is hereinafter called the main slide, and another slide plate,
sliding on the back of the main slide, which is hereinafter called the cut-off slide.
It will be evident however from the following description that the valves which
have the particular relative functions as hereinafter described, are not necessarily
arranged with the cut off slide on the back of the main slide, as their positions may
be reversed whilst still operating relatively to each other according to my invention,
two principal features of my invention being, that I use the cut-off slide, not only
to cut off the inflow of motive fluid to the cylinder, (for expansion) but I also use
it to operate the exhaust ports, so as to regulate the cushioning of the main piston
and the opening of the cylinder to exhaust, and to operate the inlet ports so as to
regulate the moment at which inlet of motive fluid to the cylinder is effected, and
that I set the eccentric operating the main slide, (which eccentric is hereinafter

page_text: called the main eccentric) at right angles to the main engine crank, and the
eccentric operating the cut off slide, (which eccentric is hereinafter called the cut
off eccentric) in a line with the sanie crank; and I arrange the two slide plates
relatively to each other, so that when the main slide has half completed its travel,
say from right to left, the cut-off slide is just about to commence its travel in the
same direction, or from right to left, and so on with reciprocating action, the main
slide being always in advance of the cut off slide. In some cases, especially where
no reversal of the engines is required, I may slightly modify the relative angular
position in the direction of rotation of the eccentrics to one another, and to the
main engine crank, but the greatest advantage is obtained by placing the eccentrics
as nearly as possible as described.
By using the cut-off slide as described, there is no necessity to give lead to the
main eccentric (though the cut-off slide may have the functions, additional to those
of cutting off steam for expansion which are herein described, even when the
eccentrics have lead or when the valves operate in any ordinary way as in ordinary
gears) and consequently nearly the full length of travel of the main slide is effective
in creating large port openings, and the fact that, by so using the cut off slide,
there is no necessity to give lead to the main eccentric, permits of a great variety
in the choice of gear, from amongst eccentrics and other similarly acting and
controlled mechanisms for operating the valve slides, so that they perform the
functions and have the relative movements as herein described.
In order to produce this effect, the inlet and exhaust ports are so arranged that
they are uncovered as soon as, or before the main slide has reached its central
position of travel, cut off may then be effected by the cut off slide, and also the
exhaust ports may be arranged to be closed at the desired moment, by the same cut
off slide, so as to regulate the degree of cushioning. I also prefer to arrange the
cut-off slide to regulate the moment of inlet of motive fluid, and of opening the
cylinder to exhaust, and these operations for opening and closing ports, for inlet
and exhaust to the cylinder, are effected by the movements of these two valve
slides, relatively to each other, with or without reference to the movement of the
main slide relatively to the openings in the valve face, as hereinafter described
particularly with reference to Figures 4, 5 and 6 of the accompanying drawings.
The amount of cushioning of the piston, and the moment of inlet of motive fluid,
and of opening to exhaust, can therefore be regulated at will according to the
degree of cut-off and engine speed, and to suit other conditions as required.
I will now illustrate a few examples of the uses and working of my invention by
reference to the accompanying drawings as follows:
Figures 1, 2, 3, 4, 5 and 6 represent longitudinal sections through the slide valves
and cylinder casings.
A. B. shews part of the cylinder, and the valve seat is on the surface at A. B.
Q is the main slide, and R is the cut-off slide. The length and travel of the
valves, and the length and position of the ports, are indicated by the equal
divisions numbered 1, 2, 3 and so on.
The motive fluid is presumed to occupy the space within the valve chest at the
back of the valves. The exhaust passages are at X X. C and D are the ports
coinmunicating with the respective ends of the cylinder, and E and F are the inlet
ports, and J and H are the exhaust ports in the valve seating. In Figure 1 the
main piston is presumed to be at the A end of the cylinder, the main slide Q is in
the central position of its travel in the direction from B to A, (that is the main
eccentric is at right angles to the cut-off eccentric as is shewn by the cut off slide
being at the B. end of its travel) and the total travel of the main slide is equal to
two of the divisions, the cut off slide R is at the B end limit of its travel, (that is
the cut off eccentric is diametrically opposite to, but in the same line as, the main
crank) and its total travel is only equal to one of the divisions. (Fig. 3 illustrates
the general arrangement when the cut off eccentric is coincident with the main
crank.) During the A to B stroke of the piston, the main slide Q travels forward
and back over one division, and starts in the direction from B to A, and the cut off

page_text: slide R travels forward through one division, (from B towards A). It will now be
seen how the motive fluid port 3, Q, in the main slide Q opens and shuts the
inlet port E to the A end, of the cylinder, and how the exhaust port 12 Q opens
and shuts the exhaust port H to the B end of the cylinder. During the B to A stroke
of the piston the reverse of these actious takes place.
By varying the length of travel of the main slide Q, so the moment at which the
cut off slide Ⓡ will cut off steam may be varied from nothing to about seven-eighths
of the stroke.
The cut-off of motive fluid can also be varied by, altering the travel of the
cut-off slide R, but it must only be altered slightly, (unless a different slide be
introduced) because of its connection with the exhaust. The more the travel of
the cut off slide R is increased, the sooner will it close the exhaust ports and cause
increased cushioning in the cylinder.
If the ports E and F be widened, say one quarter of a division, into the
divisions 3 and 14 respectively, then the moment of inlet of motive fluid can be
controlled by slightly altering the travel of the cut off slide R; and the more the
travel of the cut-off slide R is increased, the sooner it will open the cylinder to
motive fluid.
By altering the size and position of the ports, and by adding on, or taking off
inside or outside "lap," the conditions of the distribution of motive fluid can be
altered; for instance, if the exhaust port J be widened towards the division 5, then
the A end of the cylinder will be opened to exhaust earlier, and this can be done
without interfering with the closing of the said exhaust port J, because closing
may be effected and regulated by the cut off slide R, (also see Figures 45 and 6
for other examples of this provision for modifying the ports). In Figure 2 the
valve seat A B and the main slide Q are the same as in Figure 1, but a different cut
off slide R is shewn, it being one division longer inside the exhaust chamber at X, and
with this alteration the length of its travel can be doubled, namely to that of two
divisions; this enables the main slide Q to effect a large movement, & opening for
about a half cut off or less according to its travel. All the other conditions are
similar to those described in Figure 1. Figure 3 shews how the ports and other
parts may be arranged when the cut off eccentric is placed coincidently with the
main crank, and consequently when the cut off slide R travels in the same
direction as the main piston. In this arrangement, as in the arrangement Figure 1,
the cut off slide has about half the full travel of the main slide. The operation will
be readily understood by reference to Figure 3, and the other conditions are the
same as those which apply to Figures 1 and 2.
The arrangement shewn in Figure 4 operates as does that shewn in Figure 1,
and has all the same properties, except that there is a modification of the ports,
introducing additional openings to the exhaust; m and n are these additional
exhaust openings in the cut off slide R operated by the inlet ports, 2 Q and 15 Q
respectively, in the main slide Q for opening to exhaust in advance of the stroke.
In such form of valve (Figure 4) all the operations for the distribution of
steam; viz. the opening and the closing of the cylinder to steam, and the opening
and closing of the cylinder to exhaust, are effected between the operating faces of
the two slides, the main slide and the cut off slide respectively, while the principal
duty of the fixed valve seating is that of regulating the communication of the
ports of the two valve slides respectively with the cylinder and exhaust passages as
required.
:
In Fig. 5 the parts O and P in the main slide vibrate opposite to the ports E
and respectively in the valve seating, and are always in communication with the
cylinder, and the port X in the main slide is always in communication with the
exhaust passage X" in the valve seating. In this valve, as in all the examples,
the principal features of my invention are realised; thus during the stroke of the
piston from A to B, the main slide Q travels from its central position forward and
back through half the length of its stroke, and starts in the direction from B to A,
and the cut off slide R travels forward through its total stroke in the sanic

page_text: direction as that in which the main slide Q started, or from B towards A, and so
on, with reciprocating and alternate action, so that the main slide Q is always in
advance of the cut off slide R, the cylinder being placed alternately in communi-
cation with steam and exhaust for its respective ends. By so modifying the ports
as in Figure 5, and as hereinbefore provided for, the mechanism for operating a
main slide, may be attached to the slide R and rice versa," the mechanism for
operating a cut off slide, may be attached to the slide Q, and the principal features
of my invention will be realized.
The ports may be repeated so as to form grids, so as to give more than one
opening (for each port). The valve gear (exemplified in the several figures) may
be reversed by diametrically reversing the main eccentric with the main slide alone,
(the cut off slide R remaining unaffected) or an equivalent effect may be produced
by means of any convenient reversing link, or other motion, between the main
eccentric and its slide. When reversed, this valve gear retains all the properties
and advantages described with regard to Figs. 1, 2, 3, 4, 5 & 6.
In order to effect the alteration in the travel of the main slide and the cut off
slide with the objects already described, any ordinary link, lever, or other motion
may be used, and it may be operated either by hand, or regulated by any suitable
governor mechanism. I may also place two additional cut off slide plates on the
back of the cut off slide, one operating on each of two inlet ports, which may be
constructed at each end of the cut off slide before described.
Figure 6 illustrates an example of the application of auxiliary cut off slides as
hereinafter mentioned, these are marked H and H¹, & as the cut off slide R moves
in its stroke in the direction from B towards A, it cuts off steam between its face
and that of the auxiliary slide H, and in proportion as the slides H & H¹ are
moved to and from the centre, (or to and from each other) so cut off of steam is
effected earlier or later respectively in the stroke of the main piston.
These additional cut off slides may be operated for variable cut off of steam, in
any ordinary or convenient manner, for instance, by making them gear with right
and left hand screws, or by constructing the ports in a diagonal position, and by
traversing the additional cut off slides transversely across the back of the cut off
slide. The advantage of introducing these additional cut off slides is, that the
cut off can then be regulated without affecting the reversing or other links.
I do not limit myself to the precise details of arrangement as described, for
example, instead of the valve being arranged as one valve for the inlet and exhaust
for both ends of the cylinder, it may be arranged as two valves to control
separately the inlet and exhaust for each end of the cylinder, or the valvular
arrangement may consist of any other number of separate valves, to give by their
combined action, the operations which I have described; and although I have
described but one cut off slide to perform the functions, in conjunction with the
main slide, the functions may be performed by two or more cut off slides operating
in conjunction.
I will now give a few examples by reference to Figs. 7, 8, 9 & 10 illustrative of
the attachment of some valve operating mechanisms to the valve slides, such as will
produce the required relative movements as herein before set forth.
In the several Figures 7, 8, 9, & 10 C is the cylinder, P is the piston, R is the
valve seating, H is the crosshead pin, D is the crank pin, S is the crank shaft, A is
the main eccentric or main slide operating mechanism, B is the cut off eccentric or
cut off slide operating mechanism, A¹ is the main slide rod, B' is the cut off slide
rod, A" is the "setting" of the eccentric A, B is the setting of the eccentric B,
other lettering will be described in connection with each figure.
Upon examining one of the principal features of my invention, it will be seen
that the relative positions and movements of the parts constituting the valve
operating mechanism, and which are there referred to as eccentrics, as embodying
the most usual method of obtaining the necessary movements for valve slides, of
the valve slides themselves, and of the main crank, all determine and regulate the
varying positions of the valve slides relative to the positions of the main piston, in

page_text: its varying movements, and the angular arrangement of the valve operating
mechanism must be so regulated as to determine such required position of valve
slides relative to that of the main piston at all times.
In Fig. 7 the main excentric A is at right angles to the main crank, but it is also
at right angles to its own valve connecting rod, (the cut off excentric B being in its
correct relative position to the main excentric) whereas in Fig. 8, the valve chest is
outside of the centre line of the crank shaft, consequently the line between the
main excentric A, and its valve slide, is at an angle to the line of reciprocation of
the main piston, and consequently this main excentric will require to be approxi-
mately at right angles to the line of rod, which connects it to its valve slide, when
it will be somewhat modified from the right angular relation to the crank, but thus
it will secure the required and specified positions for the valve slides, relative to
the main piston. In this Fig. 8, the cut off slide rod B¹ receives its motion from a
lever B, pivoted at L and connected to the cross head H. A", which is at right
angles to A', is the correct setting for the main excentric A, and not A which is
at right angles to the main crank. In Fig. 9 there are presumed to be two cylinders
side by side whose piston rods operate two cranks at right angles. The valve slides
are here illustrated as being operated by two levers pivotted at L L and connected to
the two cross-heads respectively, the two cross heads are controlled by their respective
cranks at right angles, which yields the mechanical equivalent of two excentrics at
right angles. The cylinder section shewn is presumed to be the left cylinder, and
the right cylinder is presumed to be on the far side. The lever B operates the
cut off slide rod B¹, and is connected to the left cross-head H. The lever A
operates the main slide rod A', and is connected to the right cross head H*. D is
the left crank pin, and Dx is the right crank pin. The right valve slides are
operated by the reverse levers; thus the right main slide rod is operated by the
lever B, and the right cut off' slide rod is operated by the lever A.
In Fig. 10, only one excentric (A & B) is used, this excentric (A & B)
operates a carrier at right angles to the direction of reciprocation of the main
piston, but by the invention of a bell crank rocking shaft, the correct movement
is given to the main slide rod A¹; the necessary movement for the cut off slide
rod B' is obtained from the excentric (A & B) in the correct direction as shown.
The main slide rods may be connected with any reversing or other links, and in
Figure 10 a reversing link and lever are shown.
In this figure the parts are in the positions which they assume when the piston
is at half stoke.
The valve operating mechanisms illustrated in Figures 7, 8, 9 & 10, are a few
examples of the way in which I may effect the operation of the valve slides in the
manner hereinbefore described, but I may use any other mechanism which will
produce the particular effects in the operation of the valve slides, as hereinbefore
explained.
I have presumed in the foregoing descriptions that motive fluid is admitted
from outside the valve, and exhausted through the inside, but I do not limit myself
to admitting and exhausting the motive fluid in this way-as valves arranged
according to my invention, generally speaking, can be adapted to any known or
required conditions of working as readily as can other valves."
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In engines operated by steam or other expansible fluid or vapour the
combination with the main slide of a cut off slide both receiving their operating
motion from the engine in such a way that as well as cutting off the inflow of
motive fluid to the cylinder for regulating expansion when required the said cut-
off slide performs one, or more, of the following functions viz. :-Operating the
exhaust ports so as to regulate the cushioning of the main piston; operating the
exhaust ports so as to open the cylinder to exhaust; controlling the inlet ports so

page_text: as to regulate the moment at which inlet of motive fluid to the cylinder is effected
substantially as hereinbefore explained.
2. In engines operated by steam or other expansible fluid a main slide and a
cut off slide so combined or arranged and operated relatively to each other and
to the main piston that when the main piston commences its travel in either direction
the cut-off slide commences its travel in either the same or the opposite direction to
that of the main piston at the moment that the main slide has half completed (or
thereabouts) its travel in the same direction as that of the cut off slide the main
slide therefore being always in advance of the cut off slide the operation of the said
slides being effected by eccentrics as hereinbefore described or by equivalent
operating gear.
3. In engines operated by steain or other expansible fluid or vapour the
combination with the main slide of a cut-off slide both receiving their operating
motion from the engine in such a way that as well as cutting off the inflow of motive
fluid to the cylinder for regulating expansion when required the said cut off slide
performs one or more of the following functions, viz.Operating the exhaust ports
so as to regulate the cushioning of the main piston, operating the exhaust ports so
as to open the cylinder to exhaust, controlling the inlet ports so as to regulate the
moment at which inlet of motive fluid to the cylinder is effected, the said cut-off
slide commencing its travel in either direction at or about the same moment that the
main piston commences its travel in the same or the opposite direction, and when
the main slide has half or about half completed its travel in the same direction as
that of the cut-off slide; the main slide being therefore always in advance of the
cut-off slide and the operation of the said slides being effected by eccentrics or
equivalent operating gear all substantially as hereinbefore described.
4. The several arrangements and combinations of parts constituting valves for
steam engines or other engines operated by steam or other expansible fluid and
means for operating the respective valve slides relatively to each other to the ports
in the valve seating and to the movements of the main piston all substantially as
herein before described and illustrated by the several examples given in the
accompanying drawings.
Dated this 1st day of December 1804
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.