A New or Improved Rotary Motive Power Engine or Pump.
Year: 1885

page_text: A New or Improved Rotary Motive Power Engine or Pump.
I JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this Invention which has been com-
municated to me from abroad by Valentine G. Bell of the Jamaica Government
Railways Kingston Jamaica Engineer to be as follows:-
This Invention has for its object to provide a cheap, simple and efficient rotary
engine applicable for use either as a motive power engine or as a pump. I will
describe the Invention as used for a motive power engine by which its application
as a pump will also be understood.
The engine constructed according to this Invention consists of three principal
parts.
1° A shaft having rigidly attached to it, or forming part of it, a crank by which
the shaft is caused to revolve on its axis.
2º A piston, against which the pressure of the steam (or water or whatever fluid
is employed as the motive power) acts-The crank pin works in a bearing in the
axis of the piston, and thus determines the path of its central axis in a circle whose
diameter is equal to twice the throw of the crank-The motion of the body of the
piston is further controlled, by the means hereafter described, so as to cause it to
make half a revolution round the crank pin during each complete revolution of the.
shaft-These revolutions are in the same direction relatively to fixed points, and
in opposite directions relatively to one another.
The exterior form of the piston in any planes passing through the axis of the
crank pin is a rectangular parallelogram divided by the axis of the crank pin into.
2 equal rectangular parallelograms.
The form of the piston in planes perpendicular to the axis of the crank pin will
be described further on.
3° A casing or cylinder, within which the piston and crank revolve.
The shaft passes through bearings formed in one or both of the ends of the
cylinder; which bearings may be provided with stuffing boxes to prevent the escape,
CD 037

page_text: of the fluid employed as the motive power. The internal form of the cylinder
should be that generated by the revolution of a rectangular parallelogram round
one of its sides, while that side moves in a cylindrical path whose axis is the axis
of the shaft-This form may be slightly modified to suit the details of the
construction of the ends of the piston.
By making the piston in such a manner that its form can change automatically
to suit the form of the cylinder, the form above described may be departed from
to some extent, but this is deprecated as giving no advantage and being open to
many objections.
If then there be perfect contact between the piston and the cylinder at all points
of a rectangular parallelogram passing through the axis of the crank pin, in every
position of the crank, there can be no leakage from one side of the piston to the
other, a fluid pressure between one side of the piston and that portion of the
cylinder opposed to it, in excess of the pressure on the other side of the piston, will
tend to cause the crank to revolve; excepting when the piston is at right angles,
with the arm of the crank, which occurs once in every revolution of the crank.
This is the dead point of the engine and when a single engine is employed, a fly
wheel must be attached to the shaft to carry it over this point. At this point the
crank pin and piston are in their nearest position to one side of the cylinder and at
their furthest position from the other side. This is therefore the end of one stroke
and the commencement of the next.
The larger space of the cylinder must now be open to the external air or to a
condenser and steam (or other fluid) admitted in the smaller space The Engine
being helped over the centre, the pressure between the cylinder and piston will tend
to increase the distance between their opposed surfaces which the motion of the
piston being confined can only take place by causing the crank to complete the
revolution. The correct motion of the piston relatively to the crank is determined
through the greater part of the stroke by the form of the cylinder but at the
middle point when the axis of the crank pin is in the central axis of the cylinder,
and the central planes of the piston and the crank coincide-the central plane of
the piston is perpendicular to the surface of the cylinder and cannot be guided by
it. To maintain therefore the correct relative positions of the piston and crank at
all points of the stroke, a guide may be fixed in one end of the cylinder at a point
opposite the centre of the crank pin when at the dead point, that is when the
central plane of the piston is at right angles with that of the crank and is at its
nearest point to the surface of the cylinder which guide must slide in a longitudinal
groove cut in the side of the piston. Another means of determining correctly the
motion of the piston is to have a spur wheel, whose diameter is equal to twice the
throw of the crank, fixed to the end of the cylinder concentrically with the shaft
and gearing into an internal wheel of double the diameter fixed in the side of the
piston concentrically with the crank pin.
There are other means by which the object may be obtained, but the above are
preferred as being the simplest and best.
The entrance and exit of the steam (or other motive fluid) may be regulated by
valves in the usual way, but the ports for the entrance and exit may be so
arranged in the surface of the cylinder that the piston shall act as its own valve.
The position of the ports may also be made adjustable or may be provided with
slides or valves to be worked by hand in such a manner that the steam (or other
motive fluid) shall be cut off at any part of the stroke and allowed to expand
through the remainder and the motion of the engine may by similar arrangements
be reversed at will.
For working with steam or any elastic fluid the form of the piston in planes
perpendicular to the axis of the crank pin should be such as to fill as nearly as
practicable the smaller space of the cylinder when the Engine is on its dead point
and the piston must of course be symmetrical on each side of its central plane.

page_text: This form is not of importance when the Engine is worked by water or any other
inelastic fluid. In order to insure contact between the extremities of the piston
and the curved surface of the cylinder rocking shoes may be fitted to the
extremities of the piston which will adjust themselves to the surface of the
cylinder at every point and be pressed against it by the pressure of steam at
the back of them. The motion of these shoes may modify slightly the form of the
cylinder as above alluded to.
If this engine be driven by a power externally applied to the shaft, it may be
used as a pump as will be understood without further description.

page_text: A New or Improved Rotary Motive Power Engine or Pump.
I, JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex,
Gentleman do hereby declare the nature of this Invention which has been commu-
nicated to me from Abroad by Valentine G. Bell of the Jamaica Government
Railways, Kingston, Jamaica, Engineer and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
This Invention has for its object to provide a cheap simple and efficient rotary
engine applicable for use either as a motive power engine or as a pump. I will
describe the invention as used for a motive power engine by which its application
as a pump will also be understood.
The engine constructed according to this invention consists of three principal
parts.
1° A shaft having rigidly attached to it or forming part of it a crank by which
the shaft is caused to revolve on its axis.
2° A piston against which the pressure of the steam (or water or whatever fluid
is employed as the motive power) acts. The crank pin works in a bearing in the
axis of the piston and thus determines the path of its central axis in a circle whose
diameter is equal to twice the throw of the crank. The motion of the body of the
piston is further controlled by the means hereafter described so as to cause it to
make half a revolution round the crank pin during each complete revolution of the
shaft. These revolutions are in the same direction relatively to fixed points and in
opposite directions relatively to one another.
The exterior form of the piston, in any planes passing through the axis of the
crank pin, is a rectangular parallelogram divided by the axis of the crank pin into
2 equal rectangular parallelograms.
The form of the piston, in planes perpendicular to the axis of the crank pin, will
be described further on.
3° The engine comprises a casing or cylinder within which the piston and crank
revolve.
The shaft passes through bearings formed in one or both of the ends of the
cylinder which bearings may be provided with stuffing boxes to prevent the escape
of the fluid employed as the motive power. The internal form of the cylinder
should be that generated by the revolution of a rectangular parallelogram round
one of its sides while that side moves in a cylindrical path whose axis is the axis
of the shaft. This form may be slightly modified to suit the details of the
construction of the ends of the piston.
By making the piston in such a manner that its form can change automatically
to suit the form of the cylinder, the form above described may be departed from
to some extent, but this is deprecated as giving no advantage and being open to
many objections.
If then there be perfect contact between the piston and the cylinder at all points
of a rectangular parallelogram passing through the axis of the crank pin in every

page_text: position of the crank, there can be no leakage from one side of the piston to the
other and fluid pressure between one side of the piston and that portion of the
cylinder opposed to it, in excess of the pressure on the other side of the piston,
will tend to cause the crank to revolve, excepting when the piston is at right
angles with the arm of the crank, which occurs once in every revolution of the
crank. This is the dead point of the engine and when a single engine is employed
a fly wheel should be attached to the shaft to carry it over this point. At this
point the crank pin and piston are in their nearest position to one side of the
cylinder, and at their furthest position from the other side This is therefore the
end of one stroke and the commencement of the next.
The
The larger space of the cylinder must now be open to the external air or to a
condenser, and steam (or other fluid) be admitted in the smaller space.
engine being helped over the dead centre the pressure between the cylinder and
piston will tend to increase the distance between their opposed surfaces which as
the motion of the piston is confined can only take place by causing the crank to
complete the revolution The correct motion of the piston relatively to the crank
is determined through the greater part of the stroke by the form of the cylinder,
but at the middle point when the axis of the crank pin is in the central axis of
the cylinder and the central planes of the piston and the crank coincide, the
central planes of the piston is perpendicular to the surface of the cylinder and
cannot be guided by it. To maintain therefore the correct relative positions of
the piston and crank at all points of the stroke, a guide may be fixed in one end
of the cylinder at a point opposite the centre of the crank pin when at the dead
point, that is when the central plane of the piston is at right angles with that of
the crank and is at its nearest point to the surface of the cylinder, the said guide
must slide in a longitudinal groove cut in the side of the piston. Another means
of determining correctly the motion of the piston is to have a spur wheel, whose
diameter is equal to twice the throw of the crank, fixed to the end of the cylinder
concentrically with the shaft and gearing into an internal wheel of double the
diameter fixed in the side of the piston concentrically with the crank pin.
There are other means by which the object may be obtained but those described
are preferred as being the simplest and best.
The entrance and exit of the steam (or other motive fluid) may be regulated by
valves in the usual way, but the ports for the entrance and exit may be so
arranged in the surface of the cylinder that the piston shall act as its own valve,
it is not convenient that these ports shall be made in the curved surface of the
cylinder they should therefore be made in the ends of the cylinder The position
of the ports may also be made adjustable or may be provided with slides or valves
to be worked by hand in such a manner that the steam (or other motive fluid)
shall be cut off at any part of the stroke, and allowed to expand through the
remainder and the motion of the engine may by similar arrangements be reversed
at will.
· For working with steam or other elastic fluid the form of the piston in planes
perpendicular to the axis of the crank pin, should be such as to fill as nearly as
practicable the smaller space of the cylinder when the engine is on its dead point,
and the piston must of course be symmetrical on each side of its central plane.
This form is not of importance when the engine is worked by water or any other
inelastic fluid. In order to ensure contact between the extremities of the piston
and the curved surface of the cylinder, rocking shoes may be fitted to the
extremities of the piston, which will adjust themselves to the surface of the
cylinder at every point and be pressed against it by the pressure of steam at
the back of them.
The motion of these shoes may modify slightly the form of the cylinder as above
alluded to.
If this engine be driven by a power externally applied to the shaft it may be
need as a
numa
as will be understood without other decorintion then that herein

page_text: And in order that the said Invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the annexed sheets of drawings the same letters of reference
indicating corresponding parts in all the figures.
Figures 1 and 2 represent respectively an interior view and a longitudinal
section of an engine constructed according to this Invention arranged to be
actuated by steam or other elastic fluid and supposed to be rotating in the
direction indicated by the arrows. Figure 3 is an interior view of the cylinder
cover which is removed to obtain the view shown in Figure 1. Figure 4 is a
view of the face of the piston opposite to that shewn in Figure 1. Figures 5 and 6
represent, respectively an interior view and a longitudinal section of a similar
engine with certain modifications in the details. Figure 7 shows a modification of
the details of the piston.
The shaft (1) having rigidly attached to it or forming part of it the crank (2)
.revolves in the bearing (8) which forms part of or is rigidly attached to the
cylinder cover (4). The pin of the crank (2) works in a bearing in the axis of the
piston (5) and thus determines the path of its central axis in a circle whose radius
is equal to the throw of the crank. Rigidly attached to the cylinder cover (4) and
connected with the shaft (1) is a toothed wheel (6) whose diameter at the pitch
line is equal to twice the throw or radius of the crank (2) The toothed wheel (6)
gears with an internal toothed wheel (7) of a diameter and number of teeth double
that of the wheel (6). The wheel (7) is formed with or rigidly attached to the
piston (5) concentrically with the crank pin (2) These wheels determine the
motion of the body of the piston (5) relatively to that of the crank (2) and
the shaft (1) and causes it to make half a revolution round the crank pin (2)
during each complete revolution of the shaft (1) these revolutions being in the
same direction relatively to fixed points, but in opposite directions relatively to
each other. Another arrangement for determining the same relative motions of
the piston and crank without the use of toothed wheels is shewn in Figures 5 and 6.
A slide block (9) is free to revolve round a fixed pin attached to the cylinder
cover (10) the axis of which pin is in a direct line with the axis of the crank
pin (2) when the piston (5) is at right angles with the arm of the crank. The said
slide block (9) works in a longitudinal groove (11) formed in the face of the
piston (5). Other equivalent arrangements may be employed for determining the
relative motions of the piston and crank but those described and illustrated are
believed to be the simplest and best for the purpose.
The exterior form of the piston (5) in a plane containing the axis of the crank
pin (2) being rectangular and symmetrical on each side of the crank pin (2) the
motion of the piston (5) as above described determines the internal form of the
cylinder (8) whose section on any plane containing the axis of the shaft (1) is
therefore rectangular and the section in any plane perpendicular to the axis of the
shaft (1) is a trochoidal curve the true form of which however may be modified to
suit variations in the length of the piston (5) due to the details of its construction.
The exterior form of the piston (5) in planes perpendicular to the axis of the crank
pin (2) is such that when the piston (5) is in its nearest position to the curved
surface of the cylinder (8) the space between the contiguous surfaces of the
piston (5) and the cylinder (8) is reduced to a minimum.
If there be contact between the piston (5) and the cylinder (8) at all points of a
rectangular parallelogram passing through the axis of the crank pin (2) in every
position of the crank (2) a fluid pressure in the space on one side of the piston (5) |
in excess of the pressure on the other side, will tend to make the crank (2) revolve
excepting when the piston (5) is at right angles with the arm of the crank (2)
which occurs once in every revolution of the shaft (1). To ensure a good contact
at all points between the extremities of the piston (5) and the curved surface of
the cylinder (8) the extremities of the piston (5) instead of bearing directly on the
cylinder, may be and preferably are provided with rocking shoes which are
inaintained in constant contact with the anwend inform of the lindas (0) h the

page_text: excess pressure on the one half of their interior surfaces over that on the other
half. One form of rocking shoe (12. 12) is shown in figures 1 and 5 an alternative
form in figure 7.
When the piston (5) is at right angles with the arm of the crank (2) the engine
is at its dead point, the space on the one side of the piston (5) is at its maximum
and that on the other side at its minimum; this is the end of one stroke and the
commencement of the next-The larger space of the cylinder (8) being now open
to the external air or to a condenser and steam or other fluid pressure being
admitted into the smaller space and the piston (5) being carried past the dead
point either by its own momentum or by other means, the excess pressure on the
one face of the piston (5) will tend to increase the space on that side from its
minimum to its maximum which as the motion of the piston is confined can only
take place by the completion of another revolution of the crank (2) and the
shaft (1).
The admission and exit of the steam (or other motive fluid) may be regulated by
valves operated by the Engine in the usual way, but the ports or passages for the
admission and exit of the steam may be and preferably are so arranged on the
interior surface of the cylinder, that the piston shall uncover and cover them at
the desired intervals and so act as its own valve. In the engine represented in
the accompanying drawings the steam entry ports (13, 13) figure 3 are so arranged
in the cylinder cover (10) that the piston (5) begins to open them to the smaller
space of the cylinder (8) immediately on the said piston passing the dead point
and completely closes them again at the half stroke, keeping them closed during
the remaining half. The exhaust ports (14, 14, 14) figure 3 are so arranged that
the piston begins to open them to the larger space of the cylinder and has
completely closed them to the smaller space, on passing the dead point the exhaust
ports (14. 14. 14) thus remaining open throughout the entire stroke. By varying
the arrangement of the ports they may be kept open during the whole or during
any desired portion of the stroke. The ports may also be made adjustable or they
may be provided with slides or valves worked by hand so that the periods during
which they are open to the cylinder may be varied at will. The ports may also
be arranged symmetrically on each side of the centre, and to communicate with
either the steam or the exhaust as is desired, by which means the engine may be
made to rotate in either direction at will,
It is advisable to attach weights to the shaft of the Engine in such a manner as
to counterbalance the momentum of the piston and crank for the purpose of
reducing the vibration of the engine and the consequent wear and tear.
Two or more engines of different dimensions working on the same shaft or upon
separate shafts coupled together so as to work synchronously, may be compounded,
that is the exhaust steam from a smaller cylinder may be passed into a larger
cylinder or cylinders and therein be utilized expansively. It will be understood
without further description that an engine made as described may be used as a
pump if driven by a power externally applied to the shaft.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that
what I claim is :-
First. In motive power engines and pumps the combination of a trochoidal or
approximately trochoidal cylinder and a piston which in its revolution generates a
trochoidal or approximately trochoidal curve substantially as described.
Second. The combination of a cranked shaft and a piston revolving upon the
crank pin thereof and making one half revolution thereon during each complete
revolution of the crank and shaft substantially as and for the purpose described.
Third. The combination of a cranked shaft and a piston as above described and
a trochoidal or approximately trochoidal cylinder substantially as described.
Fourth. The combination together of two toothed wheels one with external
teeth and of a diameter equal to twice the radius of the crank rigidly attached

page_text: to the cylinder cover the other being rigidly attached to the piston and having
internal teeth and being of twice the diameter and number of teeth of the first
whereby the true relative motions of the crank and piston are determined
substantially as described.
Fifth. The guide in the cylinder cover engaging with the piston whereby the
true relative motions of the crank and piston are maintained substantially as
described.
Sixth. The rocking shoes fitted to the extremities of the piston whereby contact
between the piston and the curved surface of the cylinder is at all times maintained
substantially as described and illustrated by way of example in Figures 1, 5 and 7
of the accompanying drawings.
Seventh. The combination of ports or passages in the ends of the cylinder and
a piston revolving in a trochoidal or approximately trochoidal cylinder in such a
manner that the piston acts as its own valve substantially as described.
Eighth. The combination in an Engine of the kind herein before described of
ports or passages with slide valves or other equivalent valves for reversing the
direction of rotation of the engine or varying the cut off at will substantially as
described.
Ninth. The combination of two or more engines of the kind herein before
described to form a compound engine substantially as described.
Tenth. The arrangement or combination of parts constituting the Engine (or
pump) substantially as herein described with reference to the accompanying
drawings.