IMPROVEMENTS IN OR CONNECTED WITH MOTIVE-POWER ENGINES
Year: 1880

page_text: LETTERS PATENT to Graham Stevenson, of Airdrie, in the County of Lanark,
North Britain, Engineer, for an Invention of "IMPROVEMENTS IN OR CONNECTED
WITH MOTIVE-POWER ENGINES."
PROVISIONAL SPECIFICATION left by the said Graham Stevenson at the
Office of the Commissioners of Patents on the 15th April 1880.
GRAHAM STEVENSON, of Airdrie, in the County of Lanark, North Britain,
Engineer. "IMPROVEMENTS IN OR CONNECTED WITH MOTIVE-POWER ENGINES."
This Invention has for its object to improve the construction and action of
motive-power engines, some of the improvements being designed to diminish the
wear and tear, whilst the other improvements relate to the valves and other parts
of the engine, and are designed to economise steam or fuel and to regulate the
speed.
In carrying out the Invention in one modification, the steam cylinder is
horizontal and attached by its front end to a trunk framing which is made with
a foot extending under the cylinder to give additional support. The steam
passages are at one side of the cylinder each extending nearly to the middle of the
cylinder's length. Each cylinder passage communicates with two port faces, one
for the admission, and the other for the exhaust; and to minimise the width of
casing the two port faces are inclined to each other, with their outer longitudinal
sides more inwards than their inner adjacent sides. The two admission port
faces may be continuous as may also be the two exhaust port faces, and there
may be a single admission valve and a single exhaust valve for the two passages,
or there may be two admission valves with either one or two exhaust valves.
The admission valve is of the grating class with several ports requiring little
travel, and the exhaust valve may for the same purpose have two or more ports
for each passage. The exhaust valve is in one modification of a hollow form, and
made with a second face to work against a horizontal face having in it the exhaust
port which communicates with the exhaust pipe at the side; or the exhaust port
face may be inclined instead of horizontal, but making an angle with the port face
of the cylinder passages. In some cases the admission and exhaust valves are in
separate casings, the exhaust steam being on the back of the exhaust valve.
The small motion of the steam admission valve or valves admits of the application
of a simple and easily adjustable contrivance for diminishing the pressure on the
back of the valve. A rod of a helical or other elastic form connected to the back
of the valve passes through and is fixed to the outer end of a sleeve of thin
metal made slightly flexible by being corrugated. This sleeve is fixed to an

page_text: opening in the cover or back of the casing. The rod projecting beyond the end
of the sleeve has applied to it a spring which bears on a fixed bracket, and the
pressure of which can be adjusted by means of a screw nut on the rod, so as to
relieve the valve of more or less pressure as may be found desirable in practice.
This contrivance can be made applicable to a valve having more travel by giving to
the part on which the spring bears a positive motion, compensating for the different
angular positions assumed by the connecting rod.
The valves may all be worked from one eccentric; it is however preferred to
work the exhaust valves from a separate eccentric or from a cam-groove drum on
the crank shaft, or on a shaft actuated therefrom. The eccentric for working the
admission valve or valves acts on a rocking shaft; which has fixed on it what is
hereinafter termed a rocking block. In its middle position this rocking block is
between the inner ends of two catches, which are jointed to a lever or bar
connected to or forming part of the valve rod. When the rocking block moves
from its middle position it acts on one of the catches and thereby moves the
valve rod and valve; but its angular motion causes the rocking block to escape
past the catch after a certain movement, and then the valve rod is moved back
again to its middle position by a spring or springs. When the rocking block
returns it lifts the jointed catch against the resistance of a spring, and gets
between the two catches again. The same action takes place alternately in
opposite directions, the same valvo rod serving to admit steam alternately to
opposite ends of the cylinder. The bringing back of the valve rod to its middle
position in either direction cuts off the steam, and the period of cut off depends
on the greater or less distance of the engaging edges of the catches from the
rocking shaft. The cut-off distance of the catches may be adjusted or regulated
in various ways, either by hand gear or by means of a speed governor, a very
slight adjustment being required, and being obtainable by moving the catches
or the bar they are on transversely, or by adjusting the rocking block or catch
to or from the rocking centre, or by moving the bearings of the rocking shaft.
The catches and block may be transposed, the catches being in that case moved by
the eccentric and acting on the block. The valve rod or bar attached to it acts on
a lever fixed to a cross bar, to the ends of which springs are applied tending to
keep it parallel to the valve rod; and when the valve rod moves in either direction
it moves the lever and bar angularly so as to act on one of the springs. On the
valve rod being released the spring re-acts, and making the rod return quickly cuts
off the steam. To prevent concussion the lever and bar are connected through a
lover to a piston working in a cylinder, and acting like what is known as a dash
pot, but in both directions of its motion. The cut-off mechanism hereinbefore
described may be modified to suit cases in which the admission valves of opposite-
ends of the cylinder are worked by separate rods, and in some cases a rotating
shaft with one or moro catch projections or blocks on it may be substituted for the
rocking shaft.
In engines in which the periods of admission of the steam are regulated by the
well known cataract or equivalent arrangement, the valves are according to one
modification of the grating slide class bereinbefore described, and are actuated by
means of a helical rod moved by the piston-rod crosshead. The holical rod acts on
two discs, one at each end of the valve casing, and each disc is fitted with
adjustable inclines or tappets which act alternately on opposite ends of the exhaust
valve rod. There is a single exhaust valve but two admission valves, each of the
latter being acted on by one of the discs. An adjustable incline on each disc moves
the corresponding valve rod so as to shut off the steam at the proper periods, at the
same time acting on a spring or weight which tends to open the valve. A catch
temporarily prevents the opening of the valve, but is released afterwards by a
tappet on the disc, and then the valve is only held by the cataract apparatus, which
allows it to open at the proper time as in the ordinary arrangement with double
beat valves.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Graham Stevenson in the Great Seal Patent Office on the 14th-
October 1880.
GRAHAM STEVENSON, of Airdrie, in the County of Lanark, North Britain,
Engineer. "IMPROVEMENTS IN OR CONNECTED WITH MOTIVE-POWER ENGINES."
My said Invention has for its object to improve the construction and action of
motive-power engines, some of my improvements being designed to diminish the
wear and tear, whilst the other improvements relate to the valves and other parts
of the engine, and are designed to economise steam or fuel and to regulate the
speed.
My improvements and the manner of performing my Invention will be most
readily understood with the aid of explanatory Drawings, two Sheets of which aro
hereunto appended, and I at once proceed to particularly describe the same, using
the same reference numerals to mark the same or like parts wherever they are
repeated in the said Drawings.
'
One of my improvements is shown (with others) in Figures 1, 2, and 3, on Sheet 1
of the accompanying Drawings, Figures 1 and 2 being sido elevations, and Figure 3
a transverso vertical section. In carrying out this improvement the steam cylinder
21 is horizontal, and attached by its front end to a trunk framing 22, which is made.
with a foot 23 extending under the cylinder 21 to give additional support. The
bottom of the cylinder is fitted with a stud 24, which is entered into and keyed in
a socket formed for it on the foot 23.
One of my improved arrangements of the valves is shown in Figures 1, 2, 3,
already mentioned, and in Figures 4 and 5, which latter are horizontal sections
through the admission valve and ports and through the exhaust valve and ports
respectively. The steam passages 25 aro at one side of the cylinder 21, each
extending nearly to the middle of the cylinder's length, and cach passage com-
municates with two port faces, one 26 for the admission, and the other 27 for the
exhaust. To minimise the width of casing the two port faces 26, 27, are inclined
to each other, as shown. The port faces 26, 27, may be continuous for the two
ends of the cylinder, and there may be a single admission valve 28 and a singlo
exhaust valve 29, as shown; or there may be two admission valves, with either one
or two exhaust valves. The admission valve 28 and its port face 26 are of the
grating class, with several ports requiring little travel; and the exhaust valve 29
and its port face 27 may for the same purpose have two or more ports for each
passage. The exhaust valve 29 is of a hollow form, and made with a second faco
along its bottom to work upon a horizontal face 30, having in it the exhaust port
communicating with the exhaust pipe at the bottom (or it might be at the side) of
the valve casing; or the exhaust port face (30) may be inclined instead of hori-
zontal, but making an angle with the port face (27) of the cylinder passages.
In some cases, and as shown in Figures 6, 7, and 8, I arrange separate casings
31, 32, in connection with the admission and exhaust valves. Figure 6 is a trans-
verse vertical section, and Figures 7 and 8 are longitudinal sections, as taken through.
the two valve casings 31, 32. In this example the valves 33, 34, shown are single- .
ported, the steam valve 33 being in one piece, but consisting of end parts connected
by a middle part, which last is not subjected to pressure. There are two separate
exhaust valves 34, which are arranged to have the steam pressure upon them, being
worked by claws projecting through the ports from a bar 35 working inside the.
casing 32.
When the steam admission valves are of the grating class, as herein before
described with reference to Figures 1 to 5 of the Drawings, the small motion of.
each valve admits of the application of a simple and easily adjustable contrivance,
I

page_text: for diminishing the pressure on the back of the valve. This is shown in longi-
tudinal section in Figure 9. A rod 36 of a helical or other clastic forin is
attached to the back of the valve 28, and passes through a sleeve 37 of thin metal
made slightly flexible by being corrugated. The rod 36 may be fixed to the outer
end of the sleeve 37, in which case the inner end of the latter is to be fixed to the
casing.cover; or the rod 36 may be fixed, as shown, to the inner end of the flexible
sleeve 37, this sleeve being fixed by its outer end inside of a hollow cone 38 formed
on the casing cover. The rod 36 passes out through a hole in the casing cover, and
has applied to it a spring 39 which bears on the end of the cone 38 or on a fixed
bracket, and the pressure of which can be adjusted by means of a screw nut on the
rod, so as to relieve the valve 28 of more or less pressure as may be found desirable
in practice. This contrivance may be made applicable to a valve having more
travel by giving to the part on which the spring (39) bears a positive motion com-
pensating for the different angular positions assumed by the connecting rod.
The valves may all be worked from one eccentric; however prefer to work the
exhaust valves from a separate eccentric or from a cam-groove drum on the crank
shaft, or on a shaft actuated therefrom. The steam admission valves are worked
by means of variable release or cut-off mechanism, of which two modifications are
shown in Figures 10, 11, and 12, on Sheet 2; of the accompanying Drawings. In
the modification shown in Figure 12, which is a sectional sido elevation, the
eccentric gives a rocking motion to a shaft or stud 40, which has fixed on it what
is hereinafter termed a rocking block 41. In its middle position this rocking
block 41 is as shown between the inner ends of two catches 42, 43, which arc
jointed to a bar 44 connected to or forming part of the valve rod 45. The inner
ends of the catches 42, 43, are pressed outwards by adjustable springs 46, the
action of the springs being limited by adjustable screw stops 48 against which the
outer ends of the catches bear. When the rocking block 41 moves from its middle
position it acts on one of the catches 42 or 43, and through it moves the valve rod
and valve; but its angular motion causes the rocking block +1 to escape past the
catch after a certain movement, and then the valve rod is moved back to its
middle position by a spring or springs. When the rocking block returns it lifts
the jointed catch 42 or 43 against the resistance of the spring, 46 and gets between
the two catches again. The same action takes place alternately in opposite
directions, the same valve rod serving to admit steam alternately to opposite ends
of the cylinder. The bringing back of the valve rod to its middle position in either
direction cuts off the steam, and the period of cut-off depends on the greater or less
distance of the engaging edges of the catches 42, 43, from the rocking shaft 40.
The cut-off distance of the catches 42, 43, may be adjusted or regulated in various
ways either by hand gear or by means of a speed governor, a very slight adjustment
being required, and being obtainable by moving the catches 42, 43, or the bar ++
they are on transversely or by adjusting the rocking block or catch piece 41 to or
from the centre, or by moving the bearings of the rocking shaft 40. The jointed
catches 42, 43, and the block 41 may be transposed, the catches being in that case
moved by the eccentric and acting on the block. This modification is shown in
Figure 10; and in it the rocking shaft or stud 40 has on it a disc 49 carrying the
catches 42, 43, and their adjustable springs 46, the catches being both jointed on
one pin or stud, whilst the catch block 1 is fitted to the valve-rod bar 44. The
catch block 41 is fitted in guides in the bar 44, so as to be capable of adjustment
nearer to or further from the rocking shaft or stud 40, and it is formed with a screw
shank working in an internally screwed bush 50 fitted in a socket in the bar 44.
A cap 51 fixed on the bush 50 has a square hole to receive the squared end of a
spindle 52 carried so that it can turn on its own axis, and also swing sufficiently
from an upper centre 53 to accomodate the reciprocating motion of the valve bar 44.
The spindle 52 has on it a bevil pinion 54 gearing with a bevil wheel 55, which
last is movable by a lever 56 connected to the governor or to a handle, and by
these parts the bush 50 is turned so as to adjust the catch block 41 as required..

page_text: In the modification shown in Figure 12 the adjustment of the catches 42, 43, to
or from the rocking shaft or stud 40 is effected by moving the valve bar 44 by
ineans of a rod 57 jointed to it, the valve rod 45 and bar having as much play or
elasticity as will allow of sufficient adjustment in this way. In Figure 12 a
convenient arrangement of springs is shown for moving the valve bar 44 to its
middle position from either side whenever the release of the catches takes place.
A rod 58 passing through a bushed slot in the valve bar 4+ is fixed to the centre
of a cross bar or disc 59 which rests on a seat of rubber or other suitable elastic
material. The disc 59 is pressed down by two sets of springs 60 adjustably held
in a casing 61 (shown in sectional plan in Figure 11.) When the valve bar is
moved towards the right hand the disc 59 is tilted so as to compress the right-hand
set of springs 60, and the left-hand springs are similarly compressed when the
valve bar is moved from its central position towards the left hand. Whenever the
catch block 41 and catches 42, 43, become disengaged the springs 60 which were
compressed react on the disc 59, and making it return to its horizontal position,
thereby by means of the rod 58 make the valve bar 44 return to its middle position
The rod 58 is extended and formed with a pointed end to work over a scale 62 to.
show the points of cut-off. The disc 59 is cushioned by the rubber seat on which
it comes to rest, but, if preferred, it may be connected to a piston working in a
cylinder, and acting like what is known as a dasli pot, but in both directions of its
motion.
My improved cut-off mechanism hereinbefore described may be modified to suit
cases in which the admission valves of opposite ends of the cylinder are worked by
separate rods, and in some cases a rotating shaft with one or more catch pro-
jections or blocks on it may be substituted for the rocking shaft.
"
My further improvements, which are shown in Figures 13 to 16 on Sheet 2 of
the accompanying Drawings, are applicable to engines in which the periods of
admission of the steam are regulated by the well known cataract or equivalent
arrangement. Figures 13 and 14 are side and end elevations showing the valve
casings and cylinder; Figure 15 is a face view of a disc with inclines or tappets for
working the valves, and Figure 16 is a section showing one modification of the
steam admission valve. The piston rod crosshead has fixed to it and works a
parallel rod 63 which has a helical groove formed in it, and which, being herein-
after called the helical rod, passes through elongated bosses 64, 65, formed on dises
66, 67, carried by means of their bosses in bearings 68. The longitudinal recipro-
cations of the helical rod 63 causes the discs 64, 65, to turn alternately in opposito
directions, and by so turning to act by means of tappets or inclines 69, 70, on the
valve rods 71, 72. There may be separate admission valves and separate exhaust
valves for each end of the cylinder, or there may be a single admission valve
and a single exhaust valve for both ends, each valve being in the latter case
proportioned relatively to the ports it controls, so as to be capable of sufficient
movement in both directions from its middle position to open and close one port
independently of the other. In the modification shown in Figures 13 to 16 a
single admission and a single exhaust valve are used. The valve rods 71, 72, have
springs 73, 74, applied to both ends of each, each spring being for causing the
valve to uncover the port at the end nearest to it, and each spring being com-
pressed at the proper time by one of two inclined pieces 75, 76, on the edges of the
discs 66, 67. The inclines 69, 70, which act on the ends of the valve 71, 72, are
adjustable in arc-shaped slots in the discs 66, 67, and their action is to move the
valves so as to close the ports at the ends opposite to the respective inclines. Each
such action brings the valve acted on to its middle position, in which it is held by
one or other of two catches 77 (Figure 16) engaging with it. These catches' 77
are shown as fitted inside the casings and as being ou spindles 78, which pass out
through stuffing boxes and have cranks on their outer ends for moving them by.
After each valve has been moved into and is held in its middle position the proper
spring 73 or 74 is compressed by the incline 75 or 76, so as on. the catch 77 being
"

page_text: released to move the valve to the other end of its stroke, and thus open the port at
the opposite ond. For releasing the catches 77 cataract cylinders 79 of the ordinary
kind are employed, their plungers or pistons being connected by rods 80 to the
cranks on the ends of the catch spindles 78, and also to levers 81, which latter
raise the cataract plungers or pistons for each fresh action, and which aro them-
selves acted on by adjustable tappets 82, 83, on the discs 60, 67. In explaining
the action the ports may be distinguished as admission ports A, B, exhaust
ports C, D, ports at one end of the cylinder A, C, and ports at the other end B, D.
Then ports A and D are opened at the commencement of a stroke of the steam
piston by the action of springs 74, 73, on the cataracts releasing the holding
catches. On a certain part of the stroke being performed port A is closed by the
nction of an incline 69, and thereupon the admission valve is caught in its iniddle
position. During the completion of the stroke a spring 73 is compressed ready for
opening the port B; a similar action takes placo respecting port D, but at a later
part of the stroke. For the return stroke what has been described as taking placo
respecting ports A and D takes place respecting ports B and C, completing tho
cycle of movements. This valve mechanism is specially applicable for a pumping
or other engine which is not connected to a rotating shaft.
By the arrangements and contrivances shown in Figures 13 to 16, and herein-
before described, the actions of slide valves and of engines fitted therewith are for
certain purposes advantageously rendered similar to those of the well known
Cornish pumping engine.
Having thus particularly described my said Invention, and the manner of per-
forming the same, I have to state that I do not restrict myself to the precise details
herein described or delineated, but that what I believe to be novel and original,
and claim as the Invention secured to me by and in terms of the hereinbefore in
part recited Letters Patent is,-
-
1. The providing of a horizontal steam ongine cylinder fixed by its front end to
a trunk framing with a support upon a foot extending from such framing, sub-
stantially as herein before described, more particularly with reference to Figures 1
to 3 of the accompanying Drawings.
2. The combination of cylinder passages and separate admission and exhaust
valves, constructed and arranged substantially as herein before described with
reference to Figures 2 to 5 of the accompanying Drawings.
3. The constructing of a separate hollow exhaust valve and parts in connection,
with one face working on the cylinder port face, and with a second face inclined
to the former, and working on a separate exhaust port face, as hereinbefore
described.
4. The combination of separate admission and exhaust valves and casings, and
single cylinder passages, arranged substantially as heroinbefore described with
reference to Figures 6 to 8 of the accompanying Drawings.
5. The combination of parts for diminishing the pressure on a slide valve, and
the external means of adjustment, heroinbefore described with referenco to Figure 9
of the accompanying Drawings.
6. The arranging of an admission slido valve to return to its middle position by
the sudden action of a spring or springs, and thereby cut off the steam at each end
of the cylinder alternately, the valve being moved from its middle position by a
rocking piece acting through catches, which are adjustable so as to be released at
an earlier or later period through the angular motion of the rocking piece, all
substantially as heroin before described with reference to Figures 10 to 12 of the
accompanying Drawings.
7. The combination of parts constituting the valve moving mechanism, herein-
before described with reference to Figures 13 to 16 of the accompanying Drawings.
8. The arrangement of inclines or tappets deriving motion directly or indirectly
from the piston rod for moving the valves to close the ports, and for.compressing
or straining springs, which will move the valves to open the ports when holding

page_text: catches are released by cataracts or equivalent apparatus, substantially as herein-
before described with reference to Figures 13 to 16 of the accompanying Drawings.
In witness whereof, I, the said Grabam Stevenson, have hereunto set my
hand and seal, this Thirteenth day of October, in the year of our Lord One
thousand eight hundred and eighty.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
GRAHAM STEVENSON. (L.S.)