Year: 1887

page_text: Date of Application, 29th Mar., 1887
Complete Left, 29th Dec., 1887
Complete Accepted, 16th Mar., 1888
We JOHN MAYNES, of 19 Myddelton Square Clerkenwell in the county of
Middlesex, and CHARLES LEESE WATCHURST, of 33 Blessington Road, Lee, in the
county of Kent, Engineers, do hereby declare the nature of this invention to be as
follows
Our invention relates to improvements in steam or other fluid engines by which the
mean effort exerted on the crank during any successive strokes may be increased or
decreased in exact proportion to the work required to be done, and to the volume of
steam or other fluid used, without requiring any alteration in the ratio of expansion,
in the pressure of the boiler or power generator, or any variation in the number of
strokes of the piston, or speed of the crank.
We accomplish this object by causing a variation in the ratio between the length of
the stroke of the piston and the length of the crank, that is, by increasing or
decreasing the length of the stroke of the piston, while the length of the crank
remains the same.
In carrying out our invention we arrange one or more steam or other fluid pressure
cylinders in any convenient or desired position in relation to the crank-shaft, and in
any designed combination of high or low pressure cylinders. Instead of conveying
the reciprocating motion of the piston to the crank directly through a connecting rod,
as is usual, we interpose between the piston rod and this connecting rod an
arrangement of a curved link and sliding block.
For convenience, we shall first describe the arrangement as applied to a single
acting cylinder engine. When a trunk piston is used in this case the outer end of
the piston rod is directly connected with the block in the link. When a piston rod is
used in the ordinary manner, passing through a gland and stuffing box in the
cylinder cover, a connecting rod is used to connect the outer end of the piston rod to
the block in the link. The piston being supposed to be at the commencement of its
stroke, the link is so placed that the centre line of its curved part will form a
portion of the circumference of a circle described from, the centre of the joint by
which the piston rod is coupled to the trunk piston, or from the centre of the

page_text: crosshead joint in the alternative arrangement above mentioned, using the length of
the piston rod, or connecting rod, as a radius, respectively. The link is suspended
from, or rocks on a centre which may be placed at any convenient point on either
side of a centre line drawn through the cylinder.
We couple the connecting rod, leading from the link to the crank, to a part of
the link at some distance from its centre of oscillation, and thus when the crank is
revolving, the chord of the are described by this point of the link will be equal to
twice the throw of the crank. By suitable means, controlled by governors or
otherwise, the block in the link, to which the piston rod end is connected, may be
moved to any position in the link.
These parts act together as follows:-The link being connected positively to
the crank will always oscillate through the same angle, but as the block in it
may be moved nearer to, or further from the centre of oscillation than the point
at which the connecting rod is coupled, therefore the piston rod with the piston
will have a shorter or longer stroke according to this position of the block. By the
arrangement of the link, however, as before described, the piston will always start
froni and return to the end of the cylinder, whatever may be the length of the
stroke.
We may, if preferred, form a double link, having two curved portions, with a
sliding block in each of the curved portions. One block will then be connected to
the piston rod, as before described, and the other one will be coupled to the end of the
rod connecting the link with the crank. Both blocks will be moved at the same time
by the controlling apparatus, but in opposite directions, the one being made to
approach the centre of oscillation of the link while the other is moved away from it.
By this means the ratio between the length of the stroke of the piston and the length
of the crank may be made to vary within greater limits than is the case in the
arrangement first described, but the principle governing the arrangement will be the
same.
When guide blocks and bars, or their equivalent are used, they may be placed
on either or both sides of the link, forming guides for the path of the piston rod, and
crank connecting rod, respectively.
To obtain the variation of piston stroke with a double acting cylinder engine, we
ase two pistons in the cylinder, which are able to move independently of each other.
The piston rod of the one may be tubular, and pass out through a stuffing box in the
cylinder cover, having a crosshead sliding in guide bars secured to its outer end.
The piston rod connected with the other piston is likewise tubular but of smaller
outside diameter than the first, so that it may be pushed within the first with a sliding
fit. This second piston rod is formed with an internal screw thread gearing with a
long screw which is secured to, and revolves in the piston rod crosshead as a bearing.
The outer end of this screw carries a spur wheel, which gears with another spur
wheel, carried, as to lateral movement, by brackets on the crosshead, but caused to
revolve by sliding on a shaft to which it is connected by a featherway or otherwise.
Motion is given to this shaft from the governing apparatus which regulates the
position of the blocks in the link, and thus, in the course of the travel of the cross-
head, motion is communicated to the long screw in either direction as required. The
curve of the link is struck from the crosshead joint when it is at the outer end of its
stroke, using the length of the connecting rod for a radius, and by the arrangement
above described the position of the pistons relatively to each other able to be varied
so as to give them their required positions in the cylinder when the length of piston
stroke is varied, that is, that the pistons shall always return to their respective ends of
the cylinders at the end of the strokes.
As an alternative arrangement the first piston rod may be made tubular and con-
nected to a crosshead sliding in guides as above described, but the second piston rod.
which may be solid, passes out through the first one, and is similarly connected to a
crosshead. These piston rod crossheads are each connected with a link mounted and
moving independently of each other. The curve of the one link is struck from the
centre of the one crosshead joint with its connecting rod as a radius when the piston

page_text: belonging to it is at the one end of the cylinder. The curve of the second link is
similarly struck from the centre of the second crosshead joint using its connecting rod
as a radius when its piston is at the other end of the cylinder. We may also, if
preferred take the piston rod of the second piston out through the back end of the
cylinder instead of through the first tubular piston rod, and connect it with the
oscillating link by suitable rods and guides. In these alternative arrangements
the movement of the sliding blocks in the links, and the communication of the motion
to the crank-shaft are similar to that before described in the case of the single acting
cylinder engine.
In controlling the motion of the sliding blocks we preferably make use of the
following arrangement, although we wish it to be understood that we may, where
convenient or necessary, use an equivalent. The sliding blocks are secured to toothed
racks which are able to slide in curved grooves formed in the links. Spur wheels
gear into these racks, and by their revolution, move them in either direction as
desired. A governor controlling a clutch in a system of epicyclic or differential
gearing, or other suitable mechanism, is used to control the direction of motion of
these spur wheels, according to the varying speed of the engine. At the same time
motion is given to the spur wheel on the crosshead in order to actuate the screw
moving the pistons in the arrangement above described.
The action of the steam, or other fluid, in the cylinder or cylinders is controlled by
means of valves and connections of the usual or any suitable character; and in other
respects we construct the engine with the ordinary and necessary parts and details
according to the purpose to which it may be intended to be applied.
Dated this MAL
1007

page_text: Improvements in Steam and other Fluid Pressure Engines.
We, JOHN MAYNES of 19 Myddelton Square Clerkenwell in the county of
Middlesex and CHARLES LEESE WATCHURST of 33 Blessington Road Lee in the
county of Kent Engineers 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:-
Our invention relates to improvements in steam and other fluid pressure Engines
by which the volume of steam or other fluid used in the cylinder during any
successive strokes may be increased or decreased in exact proportion to the work
required to be done or to the mean resistance to be overcome at the crank, without
requiring any alteration in the ratio of expansion, in the pressure in the boiler or
power generator, or any variation in the number of strokes of the piston or the speed
of the crank. An increase of the effort exerted in steam or other fluid
pressure
engines is now usually obtained by an alteration of the cut-off, that is, of the ratio
of expansion, by which the same rate of economy as before in the use of steam or
other fluid is not preserved. By our improvements we preserve always the same
ratio of expansion, and thus the rate of economy in the use of the steam or other fluid
is kept constant at all times.
We accomplish this object by causing a variation in the ratio of the length of the
stroke of the piston to the length of the crank, that is, by increasing or decreasing
the length of the stroke of the piston while the length of the crank remains the
same.
In order that our invention may be readily understood we have illustrated it in the
accompanying drawings in which
Figs. 1. 2 are the elevation and plan views respectively of a general arrangement
of an engine.
Fig. 3 is a section through the crosshead of the same, namely, through a line Y Z,
Figs. 1. 2,
Fig. 4 is a section of the valve controlling the supply to the water pressure
engine.
Figs. 5. 6 are two views in elevation of a single acting cylinder engine and con-
nections, shewing different positions of the moving parts.
Fig. 7 is the elevation of a single acting cylinder engine with the crank connected
to it through a double curved beam.
Fig. 8 is the elevation of an engine with the crank shaft placed under the
cylinder.
Figs. 9. 10 are the elevation and plan views respectively of a double acting cylinder
and double beam engine.
Figs. 11. 12 are the elevation and part plan views respectively of an alternative
arrangement of double acting cylinder engine to that illustrated in Figs. 1. 2.
In carrying out our invention we arrange one or more steam or other fluid pressure
cylinders in any convenient or desired positions in relation to the crank shaft, and
in any designed combination of high or low pressure cylinders. In order to

page_text: obtain the required variation between the length of stroke of the piston and
crank, we interpose an arrangement of a link or beam and sliding block between the
piston rod and connecting rod, instead of, as is usual, conveying the reciprocating
motion of the piston directly through a connecting rod to the crank.
For convenience we shall first describe the arrangement as applied to a single
acting cylinder engine. In Figs. 5 and 6, such a cylinder A is shewn, the piston B
being of the trunk class. The piston rod is connected to a block D sliding in
the link or beam E which is suspended on the fixed centre F, which may be
placed on either side of a centre line drawn through the cylinder. A lifting link G
attached to the block D can cause it to move up and down to any position in
the link E, carrying the outer end of the piston rod with it; this lifting move-
ment being effected by any suitable means controlled by a governor or otherwise.
The connecting rod leading from the link E to the crank I is coupled to a
part J of the link at some distance from its centre of oscillation F, and thus when
the crank is revolving the chord of the arc described by this point of the link will be
equal to twice the length of the crank. The piston B being supposed to be at the
commencement of its stroke the link E is so placed that the centre line of its curved
part will form a portion of the arc of a circle described from the centre of the joint B²
by which the piston rod is coupled to the piston, using the length of the piston
rod C as a radius. When a piston rod fixed to the piston is used in the ordinary
manner, passing through a gland and stuffing box in the cylinder cover, a connecting
rod is employed to connect the outer end of the piston rod to the block in the link
or beam and in this case, the curve of the link is described from the centre of the
crosshead joint, using the length of the connecting rod as a radius.
;
These parts act together as follows: First, let the block D and piston rod end bo
placed at the top of the link E as in Fig. 5. Pressure being applied to the piston B
will cause it to move the end of the link from J to J' according to the length of the
crank, the piston B and block D at the same time moving to the positions B and D¹
respectively. Second, let the block D and piston rod end be placed at the bottom of
the link as in Fig. 6. When the piston is moved, the link will move from J to J¹ as
before in Fig. 5, but the piston B and block D will in this case only move to B and D¹
Fig. 6, respectively; and thus in consequence of the movement of the block !)
from top to bottom of the link, the piston will have varied its stroke by the
difference in length between the positions B2 and B₁ in Fig. 5, and the similar
positions in Fig. 6, the length of the crank remaining the same. Also if the block D
be moved to any other part of the link between these two extremes, the piston stroke
will be varied proportionately. By the arrangement of the curved part of the link E,
however, the piston B will always start from and return to the end of the cylinder A
whatever may be the length of the stroke.
We may, if preferred, as in Fig. 7, form a double link or beam E having two
curved portions E¹ E with a sliding block in each of them. One block Ď will
then be connected to the piston rod as before described, the length of the piston
rod forming the radius of description of the curved part E' from the centre B
when the piston is at the back end of the cylinder; and the other block D¹ will
be coupled to the end of the rod C₁ connecting the link to the crank, through the
medium of a crosshead joint C2 as in Fig. 7, or otherwise as convenient, the length
of the rod forming the radius of description of the curved part E from the
crosshead joint C2 as a centre when the piston is at the back end of the cylinder.
Both blocks D, D₁ will be moved at the same time by the controlling apparatus, but
in opposite directions, the one being made to approach the centre of oscillation of the
link while the other is moved away from it. By this means the ratio of the length
of stroke of the piston to the length of the crank may be varied within greater limits
than is the case in the arrangement illustrated in Figs. 5, 6; but the principle
governing the movement will be the same. When guide blocks or crossheads K, and
guide bars KK' or their equivalent, are used, they may be placed on either or both
sides of the link E, forming guides for the path of the piston rod, and crank connecting
rod, respectively.

page_text: To obtain the variation of piston stroke with a double acting cylinder engine, we
use, in conjunction with the link or beam E, two pistons in the cylinder which are
able to move independently of each other. Figs. 9 and 10 show the elevation and
plan views respectively of such an arrangement. In this case two links E E' are
mounted so as to oscillate independently of each other, each having two curved
portions, formed parallel, one on either side. The piston rod C of one piston B is
made tubular and after passing through the front cylinder cover is connected to a
crosshead K sliding in guide bars K¹ K. The piston rod C₁ of the other piston B¹
is made to pass out through the first one, and is likewise connected to a crosshead K²
sliding in guide bars K³ K³. From both these crossheads, connecting rods (C³ are
coupled to blocks in the outer curved portions of each of the the two links. The curve
of the link E' is described from the centre of the crosshead joint K2, using the con-
necting rod C³ as a radius when the piston B₁ is at the back end of the cylinder. The
curve of the link E is similarly described from the centre of the crosshead joint K,
using the connecting rod C² as a radius when the piston B is at the front end of the
cylinder. The blocks in the links coupled to these rods C C are moved together,
and by the above arrangement, at whatever point in the links they may be, whether
placing the pistons nearer to, or farther from each other, the pistons will always
bottom on the ends of the cylinder at the end of each stroke respectively. We may
also, if preferred, take the rod C₁ of the piston 13¹ out through the back cylinder
cover, instead of through the first tubular piston rod B, and connect it with the
link by suitable rods and guides. Connecting rods CC, coupled at one end to
the blocks in the inner curved portion of each link respectively, are jointed to a cross-
head K sliding in the guide bars K K³, from which another connecting rod C is
coupled to the crank I, and imparts circular motion to it. The ends of the connecting
rods C C are moved up and down together in the inner portions of the links E E
but in an opposite direction to the movement of the ends of the rods C C³ with
the same effect as in the arrangement shewn in Fig. 7, but with the addition in the
present case that pressure is exerted on the pistons from both ends of the cylinder.
In Figs. 1. 2. 3 is shown an arrangement of double acting cylinder engine with means
by which the slide blocks in the link or beam E may be moved as required as above
described, and by which the pistons may be altered in position in relation to each other
so as to correspond with the variation of the stroke. The piston rod C of the front piston B
in the cylinder A is led out through a stuffing box in the front cover and connected
to the crosshead K. The other end of the piston rod U is passed through the piston B
and a screw thread is there formed upon it. The crosshead K slides in the inner
surfaces of two guide bars K' K' placed on either side of it, and a connecting rod C
is coupled at one end to the gudgeon pin K2 in the crosshead K, and at the other end
to two blocks D D sliding in the inner curved portions of the link or beam E. An
outer crosshead formed in two parts K³ K³ connected together by tie bars K* K*,
Fig. 3, is made to slide upon the outer surfaces of the guide bars K' K'. In each
section of this crosshead K³ two connecting rod ends C³ C+, C³ C, respectively are
coupled to the gudgeon pins K. K. The connecting rods C3 C3, at the sides in
contact with the link, are connected to blocks D D sliding in the outer curved
portions of it. The blocks D₁ D' are connected together by a bridge piece D² and by
this means the connecting rods 03 C³ may be moved together as if they formed parts
of one rod. When the variation of the stroke is made the end of the rod C and
blocks D D sliding in the inner curved portions of the link are moved at the same
time with, but in the contrary direction to the rods (303, and blocks D D. The
reciprocatory motion from the piston conveyed through the link to the connecting
rods C³ ³, is then conveyed through the gudgeon pins K K to the connecting
rod (, and then to the crank I, which thus receives circular motion in the usual
manner,
The connecting rod ends in the link or beam E are moved up and down in the fol-
lowing manner: The metal of the blocks D D in the inner curved portions is continued
round the end of the connecting rod C² so as to connect the two together, and from
the central part a tail piece is extended with a toothed rack L formed on its outer

page_text: surface. In a similar manner a tail piece is extended from the central part of the
bridge piece D which moves the two blocks D¹ D¹, and toothed racks LLP are formed
on each side of it. The two racks L, I each gear into a pinion L³. The outer rack L
is formed with worm teeth into which gears a worm pinion N mounted on a shaft N¹
revolving in bearings N2 N2 fixed to the back of the link E and moving with it. When
the shaft N is turned, the worm pinion N moves the two racks L' L up or down as
determined, and therefore also the blocks D' D1 and connecting rods (3; and at the
same time, through the medium of the pinion L³, the rack L with the blocks D D and
connecting rod C³ are moved similarly but in a contrary direction.
In order to turn the shaft N¹ we employ, by preference, a water pressure engine N³
with three single acting oscillating cylinders arranged to work onto cranks formed on
the shaft N, and driven by hydraulic pressure obtained from pumps and accumulators
in any usual or convenient manner. One end of the shaft N is placed in a fixed
bearing F near the centre of oscillation F of the link E, and from there is connected,
and motion of revolution is transmitted to the shaft N¹ by a flexible shaft N, or by a
universal joint coupling as preferred. The power transmitted through the water
pressure engine, and therefore the movement of the blocks D D' in the link E, is
controlled by a suitable governor acting upon a valve (one form of which is shewn in
Fig. 4) which regulates the supply, and the direction of the current of water to the
engine N³.
O is a pipe, leading from the pumps or accumulator for the supply of
water 0 is the exhaust or discharge pipe for the water after use in the cylinders.
The chamber in which the valve 82 works is divided into two parts 03 0₁, com-
municating with the pipes 0° 0° respectively, which lead to the cylinder valves. The
extent of opening of the valve 02, which is actuated from the governor, regulates the
amount of water passing to the engine N³, and therefore the extent of movement of
the blocks in the link E; and according as the valve 02 places one or other of the
pipes OO in communication with the chambers 03 04, that is, with the pipes 0° 0°,
so is the direction of the current going to the engine reversed, and the revolution of
the shaft N and its connections may be thus also reversed as required.
In order to accomodate the position of the pistons relatively to each other so that they
may at the end of the strokes always bottom on the ends of the cylinders respectively,
whatever variation of the stroke may be made, we cause the piston B¹ to be moved
lengthways on the piston rod C. A disc P able to be revolved is mounted in the
piston B as a bearing, and has connected to it a sleeve P with a screw thread formed
in its interior working on the screw formed on the end of the piston rod C. The end
of the sleeve P1 is closed, and a hole P2 is bored in it which slides along a fixed
shaft P3, a feather fitted in the sleeve end P2 making contact with a feather way on
the shaft. The shaft P³ is turned from the shaft N through the medium of the
geared wheels P P ; and when it is turned the feather above mentioned causes the
sleeve P and disc P to revolve on the piston rod screw, and thus the piston B' is
moved as required in either direction by the water pressure engine N³, proportionately
and simultaneously with the motion of the blocks in the link E.
Figs. 11. 12 shew an alternative means to the above for moving the pistons
relatively to each other in the cylinder, while preserving the same arrangement
as before for moving the blocks in the link or beam E. The piston rod C,
attached to the piston B, is made tubular, and its outer end is secured to the
crosshead K which is connected with slipper blocks sliding in the inner surfaces
of the guide bars K¹ K'. The connecting rod (2, preferably made forked, is coupled
to the blocks D D in the inner curved portions of the link or beam E. The
outer crosshead K³ K³ and connecting rods 030, are coupled to the beam E and
crank respectively in the manner before described. The piston B' has its rod C¹
passed out through the tubular rod C, and a screw thread is formed on the end
of it. A collar or bush P, to which is attached the spur wheel P¹, has a screw
thread in its interior working on the screw on the piston rod C₁, the collar P
being placed in bearings QQ forming part of the crosshead K. The wheel P1 gears
with another spur wheel P² attached to the crosshead K; and when the crosshead

page_text: is moved the wheel P2 slides along the shaft P' to which it is attached by a feather
and feather way. The shaft N is made to revolve by a water pressure engine as
before described, and through the medium of the gear wheels P P it turns the
shaft P³ and therefore the spur wheels P¹ P². The collar P, which preserves a
constant position in relation to the piston B, is thereby turned, and the screw in it
causes the piston rod C¹ and piston B₁ to travel lengthways as required for the
purpose afore mentioned.
Fig. 8 shews the elevation of an engine in which similar means to those above
described are used to obtain the variation of piston stroke, but in which the crank shaft
is placed under the cylinder. In this case the form of the curved portion E of the
link or beam E, in which the blocks D' D¹ and connecting rod end C slide, is
obtained by taking the centre of the crosshead K³ as a centre (when the latter is at
the end of its stroke as shewn in the drawing) and describing a circular arc
therefrom, using the length of the connecting, rod as a radius. The effect on piston
and crank will be the same as in the arrangements above described.
:
We may, if preferred, make use of an arrangement of epicyclic gearing (commonly
known as a differential governor) to control the motion of the sliding blocks D DY,
racks L L', and pistons B B¹; although we wish it to be understood that we do not
confine ourselves to the use of such racks and screws in the manner and for the
purposes as described, but that we may where necessary or convenient make use of
any mechanical equivalent. In the above case, the system of epicyclic or differential
gearing is suitably placed in connection with the shaft N³, and a clutch, moved from
a governor, is made to regulate the direction and extent of motion of the wheels
forming the aforesaid system, in proportion to the varying resistance to be overcome
by the engine.
The action of the steam or other fluid, in the cylinder or cylinders, is controlled
by means of valves and connections of the usual or any suitable character; and in
other respects we construct the engine with the ordinary and necessary parts and
details according to the purpose to which it may be intended to be applied.
Having now particularly described and ascertained the nature of our said Inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is
1. The use of a link or beam and sliding blocks placed at an intermediate
point in the connections between the piston and crank of steam and other fluid
pressure engines, or their equivalents, and in combination therewith, constructed and
connected in the manner as herein substantially illustrated and described; by
means of which the piston stroke may be varied while the length of crank is
maintained the same with the purpose of ensuring a constant ratio of expansion in
the cylinders, and an expenditure of the steam or other fluid in direct proportion
to the resistances to be overcome by the engine.
2. The use of two links or beams moving independently of each other, in conjunc-
tion with two pistons in a double acting cylinder engine, substantially as described,
and illustrated in Figs. 9. 10.
3. The method of moving the sliding blocks in the links or beams by means of
racks connected to them, and the manner of moving these racks by the use of a worm
pinion, gearing into a rack, made to revolve by connections, through flexible shafting
or a universal joint coupling, from a water pressure engine or system of epicyclic
gearing substantially as illustrated and described.
4. The manner of imparting motion to one of the pistons relatively to the other in a
double acting cylinder engine, proportionate to the motion of the sliding blocks in the
links, by mounting one piston on a screwed sleeve able to be revolved on a screwed
extension of the piston rod of the other piston, when turning motion has been
imparted to the sleeve by suitable connections from any convenient apparatus: or
alternatively; the manner of imparting the aforesaid motion to the pistons by mounting
a screwed collar on the crosshend able to be revolved, through the medium of geared

page_text: wheels or equivalent connections, upon a screwed extension of the piston rod of one of
the pistons all substantially as described, and illustrated in Figs. 1. 2 and 11. 12
respectively.
5. The arrangement of an engine, with a double curved link or beam, with the
crank shaft placed under the cylinder, substantially as described, and illustrated
in Fig. 8.
6. The use of a valve for regulating the supply of water to a water pressure engine,
substantially as described, and illustrated in Fig. 4; and the employment of hydraulic
pumps or accumulators for obtaining the said supply of water; all in combination
with the use of a link or beam and sliding blocks, as described, in steam and other
fluid pressure engines.
Dated this Twenty-ninth day of Dacamban 1007
CHARLES WATCHURST,
Agent for the Applicants.