IMPROVEMENTS IN STEAM ENGINES
Year: 1859

page_text: LETTERS PATENT to Jules Engelmann, of the City of Mulhouse, in the
Department of the Haut Rhin, France, Civil Engineer, for the Invention
of "IMPROVEMENTS IN STEAM ENGINES."
Sealed the 13th March 1860, and dated the 28th December 1859.
PROVISIONAL SPECIFICATION left by the said Jules Engelmann at the
Office of the Commissioners of Patents, with his Petition, on the
28th December 1859.
I, JULES ENGELMANN, of the City of Mulhouse, in the Department of the
Haut Rhin, France, Civil Engineer, do hereby declare the nature of the
Invention for "IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
Heretofore in what is known as the link motion and in other motions for
working the slide valves of steam engines a sliding piece has been employed,
the position of which has governed the amount of traverse of the slide valve,
and also the direction in which the engine moved; now in place of employing
this sliding piece, I transmit motion to the slide valve through a system of
levers and connecting rods simply jointed together; this may be effected in a
variety of ways.
For example, the slide valve may be worked by a system of levers and
connecting rods, to which motion is communicated from the connecting rod
which transmits the motion of the piston to the crank shaft. For this pur-
pose a lever may be jointed at any point of the connecting rod. The other

page_text: end of this lever may be jointed to a radius rod or link, which turns at its
other end on a fixed centre. At an intermediate point of this lever may be
jointed the end of another shorter lever, which at an intermediate point of its
length is supported by another link turning at its other end on a fixed centre.
The end of this second lever is caused to move up and down at the same time
that it is moved backwards and forwards by the motion of the connecting rod.
At this end of the lever is jointed a link, the other end of which is supported
by another link from one arm of a bell crank lever, the other arm of which is
connected by a rod to a lever similar to the ordinary reversing lever. This
same end of the link (opposed to that jointed to the lever) is jointed to another
link, the other end of which is supported by a radius rod (turning at its
other end on a fixed centre), and jointed also to a rod connected with the
slide valve rod. By this means when the reversing lever is moved so as (by
turning the bell crank lever on ils centre) to cause the link jointed to the
end of the second shorter lever to extend in a direct line with the rod con-
nected with the slide valve rod, the stroke or traverse of the slide valve will
be sufficient only to uncover the ports so as to correspond with the lead of
the slide, and the engine cannot be moved either in one direction or the other;
but when the link jointed to the slide valve rod is moved by the reversing lever,
either upwards or downwards, so as to be out of the direct line with the rod, a
greater and greater amount of motion is transmitted to the slide, and the
.direction in which the engine is caused to move will depend upon whether the
link on the end of the shorter lever inclines upwards or downwards. Or
motion may be transmitted to the slide valve through a system of levers and
connecting rods to which motion is communicated by an excentric. For this
purpose the excentric rod may be supported at any point in its length by a
radius rod or link which turns at its other end on a fixed centre, so that the
end of the excentric rod is caused to move up and down at the same time
that it is moved backwards and forwards by the excentric. The end of the
excentric rod has jointed to it a link which extends backwards towards the
excentric or in the opposite direction. The other end of this link is supported
by another link from one arm of a bell-crank lever, the other arm of which is
connected by a rod to a lever similar to the ordinary reversing lever. The
link jointed to the end of the excentric rod is jointed to another link of which
the other end is jointed to a radius rod turning at its other end on a fixed
centre, and which is also. jointed to a rod connected with the slide rod. By
this means, when the reversing lever is moved so as (by turning the bell-crank
lever on its centre) to cause the link jointed to the end of the excentric.rod to
'extend backwards or forwards in a direct line with the slide, rod, the stroke of

page_text: the slide valve will be sufficient only to uncover the ports so as to correspond
with the lead of the slide, and the engine cannot be moved either in one
direction or the other. But when the link jointed to the slide rod is moved
by the reversing lever either upwards or downwards so as to be out of the
direct line with the rod, a greater and greater amount of motion is transmitted
to the slide valve, and the direction in which the engine is caused to move
will depend upon whether the link of the end of the excentric rod inclines
upwards or downwards; or motion may be transmitted to the slide valve
through a system of levers and connecting rods, to which motion is commu-
nicated by two excentrics.
:
When two excentrics are employed the ends of the excentric rods are
connected together by a link. This link is jointed at one end or at an
intermediate point to one end of a link, which is connected at its other end to
one arm of a bell crank lever, the other arm of which is connected by a rod to
the reversing lever, so that the link connecting the two excentric rods may be
raised or lowered by the reversing lever. The link which unites the two
excentric rods is jointed at its two ends to two other links, which at their
other ends are jointed at a distance apart from each other to one end of a
lever, the line connecting the two centres being at right angles to the length of
the lever; the lever is jointed at its other end to a radius rod (turning at its
other end on a fixed centre), and also to a rod which at its other end is
connected to the slide valve rod. By this means when the reversing lever is
caused to move the link uniting the ends of the two excentric rods into such
a position that the two links connected to it are at equal angles to the lever
with which they are jointed (the piston being at the end of its stroke), the
stroke of the slide valve will be sufficient only to uncover the ports so as to
correspond with the lead of the slide, and the engine cannot be moved either
in one direction or the other. But when the reversing lever is caused to
move the link connecting the two excentric rods so as to bring either of the
links jointed to it more into a straight line with the lever to which it is
jointed, a greater and greater amount of motion will be given to the slide
valve, and the direction in which the engine is caused to move will depend
upon which of the links jointed to the link connecting the excentric rods is
brought into a line with the lever. In place of the link connecting the ends
of the eccentric rods being jointed by a link to the bell crank lever it may be
jointed to a rod turning on a fixed centre, and the amount of motion
communicated to the valve may be regulated by the end of the lever
(which is connected by links to the link connecting the excentric roils).
being connected by a link to the bell crank lever in connection with:

page_text: the reversing lever. The link connecting the two excentric rods may
also be dispensed with, the ends of the two rods being connected to
two arms of a lever turning on a centre at the end of a rod, which at its other
end turns on a fixed centre at right angles; to the two arms of the lever there
is a third arm; the end of this arm is jointed to a link, the other end of which
is connected by another link to the bell-crank lever in connection with the
reversing lever. This same end of the link is jointed to a second link,
supported at its other end by a radius rod (turning at its other end on a fixed
centre), and is also connected by a link with the slide valve rod. By this
means when the junction point of the two links is moved by the reversing
lever (by turning the bell-crank lever on its centre), so as to be in a line with
the slide rod, the slide valvo will receive a motion just sufficient to uncover
the ports, so as to correspond with the lead of the slide only, and the engine
cannot be moved in either direction. But when the junction point is either
raised or lowered, a greater and greater amount of motion will be transmitted
to the slide valve, and the direction in which the engine is worked will depend
upon whether the junction point is raised or lowered. In place of motion
being given to the system of levers by an excentric or excentrics, motion may
be given to them from a crank or cranks. For engines that are only required.
to turn in one direction, the levers may be arranged so as only to be capable
of varying the amount of motion given to the slide valve, without being able
to vary the direction of the rotation of the engine.
Another part of my Invention consists in arranging the valve gear of steam
engines in such manner that the amount of motion given to the valve and the
direction in which the engine is caused to rotate, is governed by causing the
eccentric strap partially to rotate around the axis of the excentric. This I
effect by connecting the end of an arm on the eccentric strap to a system of
levers arranged in a suitable manner for giving the partial rotation to the strap.
When a strap capable of making a partial rotation is employed, as above
described, it is necessary that the mechanism for transmitting the motion of the
excentric to the slide valve should be so arranged that when the eccentric strap
is half way between the extreme points of its motion, but a very slight motion
shall be transmitted to the slide valve, but that greater and greater amount of
motion shall be given to the slide valve as the strap is moved to either of the
extreme points of its motion. For this purpose I connect the projecting arm
of the excentric strap to a lever which turns on a centre on the end of a link,
the other end of which is connected to a pin jointed by a bow to the eccentric
or to the crank shaft. The other arm of the lever is connected to a link, which
through other links transmits the motion of the eccentric to the valve rods.

page_text: The lengths of the levers and connecting rods, and the position of the pin being
suitably adjusted, so that when the eccentric strap is half way between the
extreme points of its rotative motion, the stroke of the slide valve will be
sufficient only to uncover the ports so as to correspond with the lead of the
slide.
The eccentric rod may also be supported at an intermediate point. The end
of this rod is then caused to move up and down at the same time that it is
moved backwards and forwards. This end will be jointed to a link, which
through other links and levers transmits the motion of the eccentric to the slide
valve rod. The partial rotation of the strap around the axis of the excentric
will be slighter than in the former case to obtain the same variations in the
motion of the valve.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Jules Engelmann in the Great Seal Patent Office on tho
28th June 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JULES
ENGELMANN, of the City of Mulhouse, in the Department of Haut Rhin,
France, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-eighth day of December, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-third year of
Ier reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Jules Engelmann, Her special licenco that I, tho said Jules
Engelmann, my executors, administrators, and assigns, or such others as I,
the said Jules Engelmann, 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 "IMPROVE.
MENTS IN STEAM ENGINES," upon the condition, (amongst others) that I, the
said Jules Engelmann, 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.

page_text: NOW KNOW YE, that I, the said Jules Engelmann, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
Heretofore in what is known as the link motion, and in other motions for
working the slide valves of steam engines, a sliding piece has been employed,
the position of which has governed the amount of traverse of the slide valve,
and also the direction in which the engine moved; now in place of employing
this sliding piece I transmit motion to the slide valve through a system of
Jevers and connecting rods simply jointed together, and thus dispense entirely
with the use of a sliding piece which heretofore has been employed, either
sliding in a groove or on a rod, either straight or curved. Movement may be
given to the system of levers and connecting rods either by two excentrics or
cranks, or by a single excentric or crank, of which the connecting rod or bar
is suspended by one or other of its extremities, or by a poiut intermediate of
its length, or motion may be given to them direct from, the connecting rod
which transmits the motion of the piston to the crank shaft of the engine.
When applied to steam engines, such as locomotives, engines for steamers,
&c., which are required to move first in one direction and then in the other,
this arrangement serves both for varying the expansion and for changing the
direction; applied to engines which they move in one direction it serves for
varying the expansion only. I will now describe several arrangements of
mechanism which may be employed.
I will first describe an arrangement of mechanism (shown at Figure 1,
Sheet 1,) for transmitting motion to the slide valves through a system of levers
and connecting rods to which motion is communicated by two excentrics; in
this arrangement the degree of expansion and the reversing motion is governed
by the position of the excentric rods. A, A', are excentric pullies, attached
to the crank shaft of the engine with a suitable lead corresponding respectively
to the forward and backward movement of the engine. B, B, and B', B',
excentric rods and straps; C connecting rod, uniting together the two excentric
rods; D and D', small connecting rods, jointed on the one hand to the
'excentric rods at the points 6 and 6', and on the other hand to the lever E, at
the points d and d¹; E lever suspended to the point I, and receiving the
movement of the excentric rods through the connecting rods D and D'; F, F,
is a rod jointed at one end to the connecting rod C at a point F intermediate
of its length, and at the other end to the lever H; G, axis of the bell-crank
lever H; H, bell-crank lever, supporting the suspending rod F, F'; I, I,
suspending rod of the lever E, and of the connecting rod K, of the slide valve

page_text: rod; K connecting rod of the slide valve rod; L, slide valve rod; M, bell-
crank lever united to the connecting rod of the reversing lever; N, connecting
rod of the reversing lever; 0, reversing lever. The Drawing represents the
mechanism on the dead point, that is to say, the reversing lever is central.
between the two extreme points of its movement, and consequently the.
excentric rods are at an equal distance above and below the lever E, when the
piston is at the end of its stroke. In this position the lever E is equally in-
fluenced through the two rods D and D', by the two excentric rods, and by
reason of this combined movement the point I (the limits of whose oscillation.
correspond, but in the reverse direction to the limits of the movement of the
piston) gives to the slide valve a movement equal to the lap augmented by
the lead. At this point the engine could not work in either direction, but it
will be seen that according as by the rotation of the axis G, the excentric rods
are raised or lowered, the lever E will be more or less influenced by the move-
ment of one or other of the excentric rods, and that the engine will be thereby.
moved in one or other direction, at the same time the expansion will be
greater or less according as the excentric rods are nearer to or further from
their position when on the dead point. When the piston is at one or other
extremity of its course, it is necessary, in order to obtain a good result, that,
the bell crank being moved, the slide valve should remain stationary or nearly
so, this is what is called a constant lead. In the apparatus above described
the lead cannot be absolutely constant on account of the respective positions of
the excentric rods, which are crossed when the crank is at one extremity of its
course, and uncrossed when at the other, but by suitably adjusting the length
of the excentric rods, that of the connecting rods D and D', the distance
between the points d and d', and the length of the lever E, the amount of
movement given to the slide valve when the piston is at the end of its course,
will be insignificant during the rotation of the bell crank. In the Drawing
the connecting rods D and D', are supposed to be on the side of the crank
axis, but they could be arranged on the opposite side, the lever E being then
brought back in a similar manner to that shown at Figure 2, Sheet 1).
I will now describe an arrangement of mechanism where the two excentrie
rods are suspended from a fixed point, the amount of expansion and the
reversing motion being regulated by the position of the lever E, Figure 2,
Sheet I. The same letters of reference indicate like parts to those shown at
Figure 1. The only alteration is that the rod C, uniting the two excentric
rods is suspended by the connecting rod F, F, from the fixed point F, and in
addition the lever E is suspended by the rod I, I', to the lever H, fixed on the
axis G. When, by reason of the rotation of the axis G, the lever E becomes

page_text: inclined either upwards or downwards, this lever is more directly subjected to.
the movement of one or other of the excentric rods, and by this means the
degree of expansion, and the direction of the movement of the engine, may be
varied. In this arrangement the lead may be always constant; in order to
obtain this result it is only necessary that the length of the rods D, D', the
distance between the points d and d', and the length of the lever E, should be
adjusted in such manner that the curve described by the point I, during the
movement of the bell crank, when the crank is at one or other end of its
course, should coincide with the arc of a circle of a radius equal to the length
of the connecting rod of the slide valve K. It is evident also that as in the
arrangement first described, the rods D and D₁ may be placed on the side
opposite the crank axis.
Figure 3, Sheet 1, shews another arrangement of mechanism in which the
excentric rods are suspended from a fixed point, the expansion and the
direction of the movement of the engine being governed by the raising or
lowering of two connecting rods. In this Figure the same letters of reference
refer to like parts to those shown in the former Figures. The variations in
the arrangement are, that the piece C uniting the two excentric rods in place
of simply being a connecting rod is made into a true lever, having jointed to
it at the point F the connecting rod F, F, which suspends the mechanism
from the fixed point F', and also having jointed to it at the point C¹ the con-
necting rod D. This connecting rod D is suspended at its other extremity
d to the lever H by means of the suspending rod P; to this same extremity d
is jointed a connecting rod E, suspended at its other extremity I to a fixed
point I by the connecting rod I, 1'. The connecting rod K of the slide
valve is also jointed to this same point I. By reason of the movement of the
excentric rods the points C¹ will describe an oval curve, of which the minor
axis will measure the horizontal oscillation and the major axis the vertical
oscillation. The horizontal oscillation will be equal to that of the point F; it
results from the combined movement of the two excentric rods, and varies
according to the position of the excentric pullies. The vertical oscillation
'results from the length of the arm of the lever F, C'; the connecting rod D
'will then be subjected at its extremity C¹ to the movement of this oval curve,
that is to say, to its vertical and horizontal oscillations, and will transform this
motion at its other extremity d into an alternating circular motion, the point d
being suspended by the connecting rod P from the axis G. The point d will
therefore transmit the movement by means of the connecting rod E (suspended
by the connecting rod I, I', to the fixed point I') to the connecting rod of the
slide valve rod K, and consequently to the slide valve itself; this latter will

page_text: then be subjected to the movements given to the point d; the point d being
capable of being displaced by the rotation of the axis G it is evident that the
area of the arc described by this point will be increased according as the axis
of the connecting rod D is brought nearer to the major axis of the oval
described, in other words according as for a like position of the excentrics a
greater length of a line drawn through the central line of the connecting rod D
is comprised in the area of the oval. The area of the are will be least when,
the piston being at the end of its course, the line of the axis of the connecting
rod D coincides with the minor axis of the oval. In this position the point d
will be but slightly influenced by the vertical oscillations of the point C'. In
addition the extreme points of the oscillations described by the point d will
correspond, but in a contrary direction, to the extremities of the stroke of the
piston, the excentrics being set symmetrically in respect to the central lino
X, Y, of the mechanism. In addition, the oscillation of the point d in this
position will be equal to twice the lead given to the excentrics. The slide
valve will then be on its dead point, and its stroke will correspond with the
lap augmented by the lead of the slide valve. When the point d is moved
either upwards or downwards by moving the reversing lever it will be more
and more influenced by the vertical oscillation of the point C', and the stroke
will be increased in proportion. The limits of these oscillations of the point d
corresponding more and more as it is removed from the central line X, Y, to
the centre of the stroke of the piston, the time during which steam is admitted
is increased at the same time that the ports are more and more uncovered.
Any degree of expansion may therefore be obtained by varying the position of
the point d. The lead will be constant when the connecting rod E is of the
same length as the connecting rod D, and when the suspension rods I, I', and
F, F, are arranged in such manner that at the extremities of the stroke of
the piston the point C' is on the same line as the point I. Lastly, it is evident
that the movement will be in one or other direction according as the point d
is above or below the central line X, Y, of the mechanism, so that the
engine may be caused to move in either direction at pleasure. It may some-
times be advantageous to place the connecting rods D and E on the same
side as the crank axis, as also to place the point C¹ towards the crank axis in
place of its being situated on the opposite side, as shown in the Drawing.
Figure 1, Sheet 2, shews an arrangement of mechanism for working a slide
valve to which motion is communicated by a single excentric, and when the
excentric rod is supported from a point intermediate of its length (in this Figure
the letters of reference before used indicate similar parts); this mechanism
differs from that just described in that the rod B, B', of the one excentric A,

page_text: is suspended at a point C intermediate of its length from a fixed point C¹ by
means of the connecting rod C, C', the centre of the excentric strap, describing
a circle and the point C being retained nearly on the central line X, Y, of the
mechanism by the suspending rod C, C', the extreme point 6 of the excentric
rod will describe an oval curve of a greater or less length according to the
proportions of the arms of the levers and according as they are symmetrical
with the central line of the mechanism. The portion of the line X, Y, com-
prised in the area of this oval, will be equal to the diameter of the circle des-
cribed by the centre of the excentric strap; the excentric A is fixed on the
crank shaft in such manner that the extremity of its forward movement corre-
sponds exactly with the extreme of the back stroke of the piston, and vice versa ;
its stroke is arranged to be equal to the length of the lap of the valve in addi-
tion to the lead. The extremities of the vertical oscillations of the point, will
correspond nearly (and even exactly if the lengths of the arms of the levers are
suitably adjusted) to the centre of the stroke of the piston. From the point b
the movement is transmitted to the slide valve rod by means of the connecting
rods D and E, the latter acting on the connecting rod K, of the slide valve
rod; in this, as in the preceding case, the constant lead of the slide valve will
be produced by the horizontal oscillation of the point b, to which oscillation the
connecting rod D is constantly subjected whatever be the position of the point
d. The variations in the length of the stroke for governing the amount of
expansion are governed by the vertical oscillations of the point the influenco
of which on the connecting rod D will be greater and greater according as
the point on this latter is further and further away from the central line X,
Y; the direction of the rotation of the engine is governed by the point d, being
moved either above or below the central line X, Y. By suitably adjusting
the different parts of the mechanism the length of the different levers and
suspension rods, as well as the position of the points at which they are jointed
together, it will be possible to admit steam for precisely the same length of
time on each side of the piston, and at the same time equally to uncover the
ports for all the variations of expansion both for the forward and backward
movement of the engine. According to the arrangements of the engine, the
different points of suspension, and the axis of the bell crank lever may be
placed either above or below the central line; the connecting rods D and E
may also be placed in front of the point b, and the equality of these two con-
necting rods, and therefore the constant equality of the lead may be sacrificed
to more advantageous working arrangements by making the connecting rods
of unequal lengths.
Figure 2, Sheet 2, shews an arrangement of mechanism where the excentric

page_text: rod is suspended by one of its extremities at the back of the excentric; the
same letters of reference indicate like parts to those shewn in the former
Figures. The description of this arrangement is the same as for the preceding
arrangement, and the observation as to varying the disposition of the different
pieces is also applicable in this case.
An arrangement of mechanism could also be employed where the excentric
rod is suspended at its end opposite the excentric strap. The point 6 will then
be an intermediate point, and the oval described by this point will, in all cases,
bave its major axis on the line X, Y. This reason would renler the arrange-
ment but little practical, the vertical oscillations being less than the horizontal
ones. It would be necessary to have resource in this case to levers, or to other
means for obtaining the degree of oscillation required, which would make this
arrangement very much resemble the arrangement shown at Figures 2 and 3,
Sheet 3, where the movement is given by the connecting rod of the piston.
For this reason I have not thought it necessary to show a Drawing of this
arrangement. In the three preceding cases the perfect regularity of the
mechanism for giving motion to the slide valve may be disarranged by move-
ments caused by the bending of the springs of the locomotive when in motion',
which movement would disarrange the respective position of the crank axle in
respect to the point C. This inconvenience would be remedied by rendering
the position of the point C dependent on the vertical position of the crank
axle.
Figure 3, Sheet 2, shews another arrangement where the excentric rod may
either be suspended from one of its ends, or from a point intermediate of its
length. The excentric rod B, B', is suspended by means of the connecting
rod C, C', not to a fixed point, but to the arm II of the bell-crank lever; the
point b will transmit the movement direct to the connecting rod K; and the
movement of this connecting rod will be greater or less, according as a
greater or less amount of a line drawn through the centre of the rod is
contained in the area of the oval described by the point b. The stroke of
the valve will, therefore, be a minimum equal only to the amount necessary
to produce a suitable lead of the valve with respect to the lap when,
the excentric being at the end of its stroke, tho excentric rod B, B', and
the connecting rod K are in a direct line with each other. The stroke will
be augmented according as the successive angles made by the centre lines of
.the excentric rod and of the connecting rod become less, and according as the
point b is above or below the central line X, Y, the engine will have a forward
or backward motion. In order to move the excentric rod around the pulley
this rod is suspended by the connecting rod C, C', to the arm H of the bell

page_text: crank lever. When the axis of this latter is the crank axis itself, the position
of the lever H will be dependent on the position of the crank axis, which will
cause the movement of the slide valve to be regular in spite of the bending of
the springs of the locomotive when in motion. By raising the excentric rod
the point b describing an are of a circle around the centre of the pulley A, the
extremity P of the connecting rod K would not remain immoveable when the
excentric being at the end of its stroke, the direction of the movement of
the engine should be changed, the lead will not therefore be constant. To
compensate for this movement resource is had to the lever Q, P, R, turning
on the point Q, and united at this point to the lever II, prolonged by means of
the connecting rod V. The arc of circle described by the point v during the
movement of the reversing lever is determined in such manner as to transmit
to the lever Q, P, R, a movement, such that the point R remains stationary
during the raising when the mechanism is in the position above mentioned.
This point R communicates the movement to the slide valve rod by means of
the connecting rod K'. It is evident that with this same arrangement tho
excentric rod could be suspended to any other point, either at the front or the
back of the pulley. In all the arrangements of mechanism above described a
crank or cranks may be employed in place of the excentric or excentrics.
Figures 2 and 3, Sheet 3, show an arrangement of mechanism where the
movement is derived directly from the connecting rod of the piston. A is
the crank axis; B, connecting rod of the piston; C, slide blocks on the end of
the piston rod; D, guides for the blocks C; E, lever jointed at a point B¹ to the
connecting rod B; F, F, connecting rod suspending the lever E from point I'
upon it to the fixed point F1; G, small lever jointed at the point e to the lever
E; H, H', connecting rod suspending the lever G from a point upon it to
the fixed point H'; I, connecting rod jointed on the one hand to the point g
on the lever G, and on the other to the point i on the connecting rod K;
K, connecting rod jointed on the one hand to the point i on the connecting
rod I, and on the other to the connecting rod R; L, rod suspending the
connecting rod K to the arm M of the bell crank; N, axis of the bell crank;
O, arm of the bell crank communicating with the reversing lever; P, bell
crank rod; Q, reversing lever; R, connecting rod of the slide valve rod;
'S, S', connecting rod suspending the rod R by the point S to the fixed
point S; T, slide valve rod. The point B' of the connecting rod B describes
an oval curve, the major axis of which corresponds with the central line X, Y,
of the mechanism, and is equal to the stroke of the piston. The amount of
vertical oscillation or the minor axis of the curve will depend on the distance
of the pivot B' from the end of the connecting rod. If the lever E is of a

page_text: suitable length this vertical oscillation will be transmitted nearly in an equal
degree to all points of the lever, whilst the horizontal oscillation will be
diminished according as the point F is approached. It will be seen from
this that it is possible to find on the lever E a point, the horizontal oscillation
of which shall be equal to the stroke of the slide valve when on the dead
point; the vertical oscillation, which is constant or nearly so, will be equal or
nearly so to that of the point B'. By having a lever E of great length, and by
prolonging it beyond the point F to obtain the reverse motion, the point
chosen may describe an oval curve sufficiently symmetrical in respect to the
minor axis to permit of motion being transmitted direct from this point to the
slide valve; this arrangement would be principally applicable to engines which
are only required to work in one direction, the perfect symmetry of the curve
in respect to the minor axis not being in this case absolutely required; but
in practice it will be more convenient for the lever. E to be very short relative
to the amount of horizontal oscillation. The curves will then be extremely
irregular, and it is necessary to have resourse to the second lever G to correct
them, diminish the stroke, and reverse the movement. The length of the
arm of the two levers E and G, the length of the suspending rods and the
position of the points at which they are jointed together being suitably chosen,
the point g describes an oval, the amplitudes of which are equal in respect
to the minor axis, the minor axis representing besides the stroke of the valve
on the dead point, that is to say, the lap augmented by the lead. The major
axis will be about equal to the vertical oscillation of the point B', which will
have been suitably chosen. The movement of this point g will then be
transmitted to the slide valve rod in a manner analogous to that described at
Sheet I, Figure 3, and at Sheet 2, Figures 1 and 2. By proportioning the
different parts of the mechanism it will be possible in this case also to obtain
introductions of steam into the cylinder exactly equal in respect to the stroke
of the piston for all degrees of expansion, and for both directions of the
rotation of the engine. The suspending and raising mechanism may be placed
either above or below the engine, and the suspending pieces either in the
front or at the back as most convenient. The point B₁ on the connecting rod
of the piston giving motion to the system of distribution is not necessarily a
point situated between the large and small head of the connecting rod.
When the arrangement of the engine permits of it this point may be chosen
on the extremity of the connecting rod, prolonged beyond one or other of its
heads. This point may also advantageously be placed either above or below
the longitudinal axis of the connecting rod, that is to say, of the line uniting
the centres of the two. leads of the connecting rod.

page_text: I will insert here a general observation; in the preceding instances I have
supposed, for the sake of simplifying the Drawings, that the connecting rods D
and E, Sheet 1, Figure 3, and Sheet 2, Figures 1 and 2, were suspended
from the points at which they were jointed together. It is not, however,
essential that they should be suspended from these points, and Figures 2 and 3,
Sheet 3, shew that this position may sometimes be varied. I would here
remark then that it is possible to place the point of suspension on any point
of either of the connecting rods K or I, Sheet 3, Figures 2 and 3, or on
one of them prolonged, and in any position in respect to the joints of these
connecting rods.
All the arrangements of mechanism which have been described are equally
applicable to fixed engines as well as to locomotives, and are equally
applicable to those engines which are required only to move in one direction,
as to those which are required to move in both directions, the mechanism in
both cases, being the same. Several Figures having shown the mechanism
specially applied to locomotives I think it advisable to shew at Sheet 3,
Figure 1, an application of the mechanism to a fixed engine. It will be seen
that this mechanism does not differ from that lastly described, except that the
variations of expansion are obtained by means of the screw N screwing in
the nut M, sliding in a groove in the framing and carrying two pins L', on
which the suspending rods L turn. The screw N is held to the framing
of the machine at the point O, and is worked by the hand wheel P. For
fixed machines, as for those for mines, where a rapid change in the direction
of the movement of the engine is sometimes necessary it will be preferable
to adopt a reversing mechanism similar to that shown at Sheet 3, Figures 2
and 3.
I will now describe the other part of my Invention, which consists in
arranging the valve gear of steam engines in such manner that the amount of
motion given to the valve, and the direction in which the engine is caused to
rotate, is governed by causing the single excentric, strap partially to rotate
around the axis of the excentric. By displacing by 60° either on one side or
the other an excentric strap on its pulley, a forward movement on the one
hand is obtained with a lead of 30°, and on the other a backward move-
ment with an equal lead, provided that the excentric pulley is fixed in
a suitable position on the crank axis of the piston, the intermediate position 3
corresponding to the dead point. Figures 4, 5, and 6, Sheet 2, shew
these three positions, but the stroke will necessarily be the same both for
the extrenie positions and for the intermediate one. To apply the principle to
the regulating the movement of a slide valve it is necessary that the stroke

page_text: should be a minimum when the excentric rod is in its intermediate position
corresponding to the dead point. To obtain this result recourse is had to a
cranked lever. C, Slicet 2, Figures 7, 8, and 9, turning on the centre C' receiv
ing the movement of the.excentric rod B at the point B', and transmitting it
to the slide valve rod through the connecting rod D. The position of the
point C' on which the lever C turns will be determined in such manner for
every position, that the stroke will be a maximum at its two extreme positions
and a minimum at its intermediate position. This point C' should also satisfy
this condition that the ends of the stroke at the two extreme positions cor-
respond with each other and with the central line of the slide valve, and also
that the extremities of its stroke at the intermediate point should correspond
rigorously with the lead. The mechanism shown in the. three. positions .at
Sheet 2, Figures 7, 8, and 9, satisfy the above-mentioned conditions. The
connecting rod E, E', attached to a fixed point: E' determines with certainty
the position of the axis of rotation C'. In the example shewn at Figures 7,
8, and 9, Sheet 2, the conditions are such that the lead is constant, but when
this condition would be difficult to obtain in practice by reason of the arrange-
ment of the parts, it might be obtained by means of an additional lever F, E,
Figure 10, Sheet 2. This lever attached to the lever turning on the centro
His prolonged beyond the point at which it is jointed to the cranked lever C,
and is jointed at the point F to the connecting rod D of the slide valve rod.
This lever, in addition to being employed for raising and lowering the mecha-
nism, is also capable of correcting the faults resulting from the point C', being
in a bad position. For this purpose the arc described by the jointed end of
the lever I should be such that the piston being at one end of its stroke the
slide valve remains stationary during the change of movement of the piston.
The mechanism shewn at Sheet 2, Figuro 10, is supposed to be applied to a
locomotive; it is for this reason that the point E' of the connecting rod E, E¹,
has not been connected directly to the framing, but is rendered dependent on
the axis of the wheel by means of the piece P. The connecting rod Q permits
this point to have a vertical movement. In this manner the oscillations of the
driving wheel will not sensibly affect the working of the slide valve.
addition it is evident that the application of this arrangement, as well as of the
preceding ones, is not limited to a locomotive, but may also be applied to all
kinds of steam engines. For engines which are only required to move in one
direction the mechanism may also be much simplified the excentric strap
having then to move through a much less angle around the pulley for causing
the variations of expansion, this angle not exceeding 30°, because in this case
it is useless to bring the slide valve to the dead point.
In

page_text: Having thus described the nature of my Invention and the manner of per-
forming the same, I would have it understood that my improvements consist
in replacing the ordinary sliding piece used in link and other motions by a
system of levers and connecting rods simply jointed. together.
1st, when
the movement is given by two excentrics or cranks, as shown at Figures 1, 2,
and 3 (Sheet I.); 2nd, when the movement is given by a single excentric or
crank, of which the rod is suspended at its end, or at a point intermediate of
its length, and whether the variations of expansion and the reversing motion
are obtained by utilizing either. a, the horizontal and vertical oscillations
only of a point of the rod, as shewn at Figures 1 and 2, Sheet 2; b, the hori-
zontal and vertical oscillations of the rod combined with displacing the
excentric strap on its pulley, Sheet 2, Figure 3; or, c, the displacing the
excentric strap on its pulley only, Sheet 2, Figures 4, 5, 6, 7, 8, 9, 10. 3rd,
when the movement is given from the connecting rod attached to the piston,
Sheet 3, Fig. 1, 2, and 3. The different arrangements of mechanism may
also be applied to all kinds of steam engines, either to produce variations of
the amount of expansion or to produce variations of the expansion, together
with a power of changing the direction of the rotation of the engine.
In witness whereof, I, the said Jules Engelmann, have hereunto set my
hand and scal, this Twentieth day of June, in the year of our Lord
One thousand eight hundred and sixty.
T. BASSETT.
JULES ENGELMANN. (L.S.)