IMPROVEMENTS IN STEAM ENGINES
Year: 1883

page_text: LETTERS PATENT to Herbert John Allison, of the firm of Allison Brothers,
Patent Agents, of 41 Southampton Buildings, Holborn, in the County of
Middlesex, for an Invention of "IMPROVEMENTS IN STEAM ENGINES."
Communicated to him from abroad by Elijah Frank Spaulding, John
Keese Hallock, and Elmer Stilman Smith, of Erie, Pennsylvania, United
States of America.
COMPLETE SPECIFICATION filed by the said Herbert John Allison at the
Office of the Commissioners of Patents on the 17th July 1883, i
HERBERT JOHN ALLISON, of the firm of Allison Brothers, Patent Agents,
"IMPROVE-
of 41 Southampton Buildings, Holborn, in the County of Middlesex,
MENTS IN STEAM ENGINES" communicated to me from abroad by Elijah Frank
Spaulding, John Keese Hallock, and Elmer Stilman Smith, of Erie, Pennsylvania,
United States of America.
This invention consists in providing new and useful improvements in steam
engines. The particular class of engines to which this invention relates are
automatic variable cut-off engines. The objects of the invention are:-
First, to provide new and improved variable cut-off valve-gear.
Second, improvements in the construction, generally, of the engine, and
particularly of the steam valve. Under the first head the improvements consist
in combining with any ordinary variable cut-off valve-gear, in which the regulator
is not on the shaft of the engine, with a dynamometrical regulator which is on the
driving shaft of the engine and is operated from the resistance of the load upon
the driving wheel of the engine.
Of the regulators which may be used off of the shaft of the engine in
conjunction with this dynamometrical regulator I do not intend to be limited.
They may be centrifugal, in any of the various forms or types of centrifugal
regulators, or they may be operated directly from the steam pressure taken from
the boiler or the steam-supply pipe.
The improvements under the second head will appear hereafter in the general
description.

page_text: There are only two forces to be considered in the government of a steam engine,
namely, the exertion or load upon the engine, and secondly, the energy of the
steam. In most cases both these forces are variable constantly, and in order to
govern the engine properly, that is to give it a perfect uniform or isochronous
movement it is necessary that the regulator of the engine shall take cognizance of
both these forces simultaneously and directly. Where an engine is regulated
wholly by a centrifugal governor operating upon the variable cut-off valve-gear,
whether that regulator is on the shaft of the engine or whether it is at some other
point, these two forces before named operate upon the valve-gear through the
medium of velocity, consequently their action is ultimate and not direct.
It has been attempted to overcome this by using the dynamometrical regulator
in conjunction with a centrifugal regulator in an integral device which is mounted
on the shaft of the engine, and the force of the load is made to oppose the
centrifugal force of the balls or weights of the centrifugal device. In such a
construction the load-force acts directly, but fluctuations in the pressure of steam
are only taken notice of through the medium of velocity.
It has also been attempted to govern a steam engine wholly from the variations
of the load, operating through a dynamometrical regulator, but it is obvious that
in that case there could be no government, for the reason that the fluctuations of
steam pressure are not taken notice of.
In pumping engines it has been attempted to use a centrifugal governor, and
also a dynamometrical regulator, which is operated from back pressure from the
receiver or mains. It is obvious that such a device can only be applied where the
engine is pumping into a receiver in such a way that there shall be back pressure,
and cannot be applied to all the various ordinary uses to which steam engines
are put.
From the following description it will be seen that I have so constructed my
device that I obtain direct government from both the forces named, when I use a
steam-pressure regulator off of the shaft of the engine, in conjunction with a
dynamometrical regulator on the shaft of the engine. I have shown a centrifugal
regulator used in conjunction with a dynamometrical regulator, but in such a
construction there is no direct regulation from the steam fluctuations, it being
necessary to wait for the changes in speed to effect the centrifugal regulator,
My invention is illustrated in the accompanying drawings as follows:-
Fig. 1 is a side view of the drive wheel, and shows the manner of constructing
the dynamometrical regulator and the connection of it with the other regulator
off of the shaft of the engine, which in this Figure is a steam-pressure
regulator.
Fig. 2 is a front elevation of the parts shown in Fig. 1, the drive wheel being in
section and the regulator off of the shaft being a centrifugal or speed regulator of
common type.
Fig. 3 is a perspective view of the parts shown in Fig. 1, the drive wheel being
broken away.
Fig. 4 is a plan view of the parts shown in Fig. 1 (the drive wheel being in
section), and also that portion of the valve-gear which is on the opposite side of
the engine bed (the bed being shown in fragments)..
Fig. 5 is a side elevation of that part of the valve-gear which is on the opposite
side of the engine-bed from the parts shown in Fig. 1.
Figs. 6, 7, 8, 9, 10, 15, 16, 17, 18, and 19 shown details of construction, and will
be fully explained hereafter in the proper place.
Fig. 12 is a side elevation and shows a different construction of the dynamo-
metrical regulator and a different type of valve-gear.
Fig. 11 shows my invention adapted to be applied to that type of valve-gear
known as the Corliss gear.
S
Figs. 13 and 14 show my invention applied to that type of engine or valve-gear
known as the Cummer.
9:

page_text: Fig. 20 is a horizontal, longitudinal section through the steam cylinder, and
steam chest, and shows the construction of the steam valves, ports, etc.
Fig. 21 is a back view of the cut-off valve.
Fig. 22 is a similar view of the exhaust valve.
Fig. 23 is an end view of the exhaust valve.
The construction shown in these various Figures is as follows: -
A, is the shaft of the engine; B, is the drive wheel of the engine, and is
mounted loosely on the shaft A; C, is the cross arm, which is fixed upon the said
shaft. The two parts B, and C, are connected together flexibly by the rods D,
and the springs Di, D', the said rods being connected with the arm C, and passing
through bosses b, on two of the arms of the drive wheel, and are secured by
adjusting nuts and washer d, and the springs D', D¹, which are interposed between
the washers and the bosses.
Full line arrows show the direction of revolution of the shaft, and dotted line
arrows show the direction of resistance of the load, or, in other words, the direction
of the strain of the belt. As the load increases the springs D¹, D¹, are compressed
and the wheel and the arm move apart. This movement is communicated to the
sliding collar E on the shaft by bell-crank levers F, F¹, F²; F, being the shaft and
F, F, the arms of said bell-crank levers. The bell-cranks are pivoted on to the
arm C, in bosses c', c¹, in the hub and lugs c, c, near the ends of the arms. The
upper arms F, are pivoted on the drive wheel by having their pivots set in sliding
pins ff, which are set in lugs b', on the inside of the rim of the wheel. The lower
arms, are pivoted to the links E', which are in turn pivoted to ears e, which
extend from the collar-core e³, and lie in recesses in the side of the hub of the cross
arm C.
By this device the collar E, is moved on the shaft one way or the other, as the
load on the engine is varied, and by the use of the bell-crank levers F, F1, F2, the
movement of the collar on the shaft may be as much in degree, or more if desired,
as the movement of the drive wheel at its periphery, which is very advantageous,
as there should be very little movement of the drive wheel, say not to exceed an
inch in all, from no load to full load. And it is desirable that the collar should
move about that distance laterally on the shaft.
It will be obvious that by having the arms F2, longer than F', movement on the
shaft will be greater than at the periphery of the wheel. From the sliding collar
the action of the dynamometrical governor is to be conveyed by gearing to the
variable cut-off valve-gear.
I have shown in the drawings several modifications of gears for doing this, but
they all operate on substantially the same plan, which may be stated to be a
rock-shaft or other pivoted lever, having a variable fulcrum or a varying arm
or an arm adapted to permit the point at which power is applied to be varied.
(This is also the case when the dynamometrical regulator acts through a shifting
eccentric, as in Fig. 12).
It is to this shifting arm or point of application of power (or fulcrum) that the
other regulator is applied. In fact both regulators are generally applied to it,
while either may be. The object of the shifting lever is to enable each regulator
to act on the gear at all times and always independently of the other.
In Figs. 13 and 14 this is not shown to be used, and there the two regulators
oppose each other.
In Figs. 1, 2, 3, 4, and 11 the construction is substantially the same, as to this
gearing, and in Figs. 12, 6, 7, 8, 9, 10, 15, 16, and 17 modifications are shown.
The construction in Figs. 1, 2, 3, 4, and 11 is as follows:-
In a slot or way in the face of the strap of the sliding collar is a sliding
block E², from which extends a pin e' (see Figs. 18 and 19 for detail).
On this pin is connected the stem or connecting rod of the other regulator, I'
or 12, as the case may be, as shown variously in the drawing. To a pin c¹, is also
connected the shifting or variable arm G³ of the rock-shaft G, which is sustained in
a horizontal position by a stud G¹, and has for its other arm the part G. The

page_text: .
shifting arm G³, is adapted to slide in a head G², on the shaft G, and is thus
variable in length. The stud G¹; is of such a length that it holds the rod or
shaft G, always at one side of the collar E, no matter what its position may be on
the shaft. Hence the arm G³, is always at an angle to the slot in the face of the
collar, (see Fig. 2) and therefore the said arm cannot shift without removing the.
shaft G, and it will of course be seen that the collar cannot move without moving
the shaft G. Now the position of the block E2; (and so, thereby, the arm G³, as
to its length) is varied, by reason of its connection with the regulator I, or I³:
Let us take it as in Fig. 2: any change in speed will change the position of the
weights of the governor I, and any change in their position will change the
position of the block E2, and to lengthen or shorten the arm G³, and any change in
its length will rock the shaft G, on account of the angle at which it, the arm G³,
sets to the slot in the collar E. The result is just the same where the regulator I³;
is used when any change in the steam pressure occurs. So it will be seen that
any change of speed (or steam pressure, if the regulator 1³ is used) will rock the
shaft G, and any change in the load will shift the collar E, and that will rock the
shaft G, proportionately to the length of the arm G³. It will also be seen that
either of these regulators can change its position and the position of the rock-
shaft G, and not interfere with or exert any appreciable power upon the other.
The movements of the rock-shaft G, are communicated to the valve-gear proper
from the arm G*, and the connecting rod g, and the rock-shaft H, H¹, H², and
rod H³.
In the construction shown in Fig. 11 the valve-gear is reached by a bell-
crank H, and rods H, and H, and it will be obvious that the connecting gearing
will be varied in various types of engines to suit the requirements.
In Figs. 15 and 16, which are respectively a plan and end view of the parts
shown, a modification of the rocking lever with shifting load-point or arm, is
shown. In this construction the rocking lever or rod G, is removed some distance
from the collar E, and a vibrating lever E, is interposed, and motion is communi-
cated to the arm G³, by the rod E, which connects with a sliding block in a
slot g³, in the arm G³, and the other regulator I, is connected with the rod E³, and
moves it up or down in the slot g³, as the conditions change.
It will be seen that any vertical or lateral movement of the rod E³, will move
the shaft G, and that the degree of movement will depend on the position of the
rod E, in the slot g³. The arm G³, is of variable length in result in this case,
while in the former construction it is so in fact, and in each case the movement of
the collar E, will move the shaft G, more or less, according as the other regulator
shortens or lengthens the arm G³.
In the construction shown in Fig. 12 the same effect is had by different means
somewhat. The varying or shifting arm G³, is in effect a link movement, and in
Fig. 12 I show it as such in fact, in the valve-gear. Here I have a slotted rock-
arm N', which is in fact a link, and the eccentric rod J, is moved in the link by
a governor I, to vary the cut-off; and the vibrations of the link Ni are also
varied by the dynamometrical governor on the shaft which shifts the eccentric.
So here again I have each governor operating wholly independent of the other,
and yet they co-act at all points of cut-off, and one is a dynamometrical governor
on the shaft and the other may be any type of governor, and is off of the shaft.
The manner of constructing the dynamometrical governor here shown, or the
means by which it shifts the eccentric, is of no consequence here, further than
I may say they may be greatly varied.
The application of the dynamometrical regulator to a wheel centrifugal regulator
not on the driving shaft is clearly shown in Figs. 13 and 14.
Here I apply the dynamometrical governor to the shifting collar E, and the
vibrating lever E, which takes hold of the counter-balance rod E and in effect
adds to or takes from the counter-balance weight W, as the conditions of the load
require. It will be observed that in this instance the two regulators do not act

page_text: independently, but that the centrifugal action of the weight is opposed by the
resistance of the load.-.
.:
In Fig. 17 still another modification of the variable arm of the rock-shaft G, is
shown. Here the arm G³, which is connected with the vibrating lever E, is not
variable, but that which takes the place of arm G, is. This consists of two
eccentrics, 1 and 2, of which 1, is fixed on the shaft G and the other 2 is placed so
'as to contain the first, and is connected so as to be moved by the regulator that
operates the rod I, and the connecting rod g, yokes over the eccentric 2:
It will at once be seen that this device is simply another means of changing the
length of the arms of the rock-shaft, or has the same effect, that each regulator acts
freely of the other, yet co-acts with it at all points.
The construction of the steam pressure regulator hear shown and the gearing by
which it operates upon the valve-gear is as follows:-
13, is the cylinder of this regulator and 12 is its piston stem, which connects
with the sliding block E2 in the collar E, on the shaft, or with such other part of
the regulator gearing as may be determined, as will be seen in the various forms
of construction here shown. This piston is weighted by a spring coiled around the
stem I, and by a tempering-nut i perfect adjustment can be had. The stem of
the piston is pivoted upon the piston, and can thus have a lateral movement,
which is necessary, as it connects with the rocking part of the gear. This will be.
seen in Fig. 2, in dotted lines.
This pressure device is acted upon from the steam in the boiler or the main
supply pipe, through the small pipe leading therefrom to this regulator, and always
registers the exact degree of boiler pressure. The pressure-cylinder and the pipe
leading thereto may contain water or other fluid, and be in effect a hydrostatic
press, but it will derive its power always from the boiler pressure of the steam.
This pressure-regulator operates in conjunction with the gearing G, G3, G4, precisely
the same as the speed regulator I, does, but it may be applied through gearing,
slightly different, in a manner which the speed regulator could not be applied, as'
for instance, in Figs. 9 and 10, where it is placed so as to operate horizontally, and.
varies the position of the fulcrum of the lever E¹.
In Figs. 6, 7, and 8 this steam-pressure regulator is shown applied in
substantially the same manner as the speed regulator is in Figs. 15 and 16, and it
may be applied to Fig. 17 without any change of construction whatever. Where
this steam pressure regulator is used the government of the engine will be direct
from the load, and the steam pressure, without the interposition of the medium of
velocity, and consequently the governinent will be instantaneous on any change in
the conditions of the pressure of the steam or the load performed by the engine, :
and without waiting for any change of velocity; and consequently the movements
of the engine will be isochronous.
In Figs. 4 and 5 the valve-gear proper is shown. Its construction is as
follows:-
L, is the eccentric on the shaft A. L¹ is the strap of the eccentric, and M is the
eccentric rod which connects with the rock-arm N. K is a link which is pivoted
upon a shaft by the side of the eccentric and is provided with a slotted arm k, by
which it is connected with the eccentric L, by a pin l, on the strap of the eccentric,
which moves in the slot . The rotative movement of the eccentric L, imparts to
Jink Ka vibratory or oscillating movement. The cut-off valve-rod J, connects
with the block j, which slides in the link K. Any variation of the position of
this rod, J, from or towards the shaft A, will vary the degree of reciprocation
which will be imparted to it by the link K. This variation is effected by the
rod J, being connected with the rocking-gearing H, H1, H2, by the rod H³, and as
we have seen before this gearing is rocked by the joint action of the two regulators
on the opposite side of the engine. The rods M, and M', operate the exhaust valve
of the engine. The rods J and J¹ operate the cut-off valve. The rods M, and M',
are jointed and supported upon the rocking-arm N.: On this rocking-arm N, is
:

page_text: also pivoted a guide-block m'. In the rod J¹, is a guide-loop J³, which embraces
this guide-block m', and thus is formed the guide for the cut-off valve rod.
Figs. 20, 21, 22 and 23 illustrate the construction of the steam valve. In these
Figures represents the cylinder of the engine; Q', the piston; P, P, are the
ports into the cylinder; R, is the main valve or exhaust valve; S, is the cut-off
valve or rider-valve.
The object of the construction is to properly balance both the main and the
rider-valve. The main valve R, is provided with ports r, r, which are branched or
delta-form. The rider-valve is provided with two ports on each end, 8, 8, and with
a cavity S. The steam is admitted to this valve through the opening T', in the
steam-chest T. The live steam does not enter the steam-chest but passes to the
piston through the valves. On the back of the rider-valve S, is a circular boss,
and within this boss is a balance-ring S2, which is kept in contact with the cover
of the steam-chest by a spring 82, thus making a steam-tight joint. The area of
this boss or ring is somewhat in excess of the area of the ports r, r, and s, s, for
the purpose of properly balancing the valves and leaving sufficient pressure to keep
them upon their seats.
The exhaust steam enters the steam-chest T, and from that passes out through
the exhaust pipe. The object of the delta-ports 7, 7, in the valve R, and the
gridiron ports s, s, in valve S, is to obtain a large port area, with small port
openings or mouths, thus enabling a cut-off to be made with a quick motion, and
at the same time have ample access to steam cylinder.
This is a much better construction than where the gridiron ports are in the side
of the cylinder, for the reason that I obtain the same advantages, with a much less
percentage of clearance space: that is to say, I am enabled to bring my valves in
very close proximity to the bore of the cylinder, thus leaving a very short port,
which of course means a small clearance space. It will be observed that both of
the valves are balanced, while ordinarily, where double valves are used, only one
of the valves is balanced.
On the right of Fig. 20 in the valve R, the ports 7, r, are indicated by dotted
lines, for the reason that the line of section passes through the valve stem, which
will be clearly seen by reference to Fig. 22, which is a back view of the valve R.
Fig. 21 is a back view of the valve S.
Fig. 23 is an end view of the valve R, and shows the lip or ledge at the bottom
of the valve, for the support of the rider-valve S.
The operation of the combined regulator is substantially the same in all the
Figures here shown (except in Figs. 13 and 14, which differs as before explained)
and is as follows:-
Any change in the load of the engine will affect the position of the collar, E,
which as it moves rocks the shaft G, from which the variable parts of the variable
valve-gear are moved. But this movement of the collar E, will be the same
always under like conditions of load, while the variations of the cut-off must not
be the same under all like conditions of load, for it must also be regulated with a
view to the energy of the steam. So the variable arm of the shaft G, is brought
into the construction. When the arm is short a given movement of the collar will
rock the shaft G, much further than when the arm is long; so by the secondary
governor, whether it is a speed governor or a steam-pressure governor changes
in the energy of the steam are made to vary the length of the arm, as follows:-.
High speed, resulting from high pressure, or high pressure acting directly
through the steam-pressure regulator will lengthen the said arm, and vice versa.
So it will be seen that the action of, like changes in load affect the movement of
parts in varying degrees, as regulated from the steam conditions. This is
absolutely essential, when the two governors are geared to act independent of each
other, and I consider it very desirable that they so act, unless it be in such a
construction as is shown in Figs. 13 and 14. And when these regulators do so act
independently they should act to affect the gear at all times. This is why the

page_text: shaft G, is set so that the arm G³, will always be at an angle to the plane of the
movement of the block E², as was above explained.
In all the Figures the same result is obtained, so that in every instance neither
regulator can act without moving the gearing. This prevents the steam pressure
changing under an even load without changing the cut-off; for, to refer to block E²,
it will be seen that at no point in the traverse of the collar E; can this block move
vertically without moving the shaft G, and in Figs. 8 and 16 the rod E³, cannot
move vertically without moving the shaft G. And so of the eccentric 2 in Fig. 17.
And in Fig. 12 the rod J cannot be moved by the regulator I (or 1°) without
affecting the cut-off.
What I claim as new is :-
1. In a steam engine, the combination, substantially as shown, of a dynamo-
metrical regulator on the shaft of the engine and some other regulator off of the
shaft of the engine, said regulators being geared together to co-act, substantially
as shown, in the automatic regulation of the variable cut-off valve-gear of said
engine.
2. In a steam engine the combination substantially as shown of a variable cut-off
valve-gear which is acted upon to automatically vary the cut-off, by two separate
regulators, one of which is mounted on the shaft of the engine and acts dynamo-
metrically to regulate from the changes in the load, the other is mounted off of the
shaft of the engine and is operated substantially as shown, to regulate the speed of
the engine.
3. In a steam engine the combination with a dynamometrical regulator on the
shaft of the engine, a rocking or pivoted part adjusted off the shaft of the engine,
and adapted, substantially as shown, to be actuated from said dynamometrical
regulator, a second regulator adjusted off of said engine shaft and in operative
connection with said rocking part, in a manner substantially as shown, whereby
both of said regulators shall be in co-active communication, and finally, a cut-off
valve for operating said engine, which is automatically varied in its action from
movements of both said connected regulators.
4. In a steam engine the combination of a dynamometrical regulator which
moves a shifting collar on the engine shaft, a rock-shaft or crank-shaft' adjusted
off of said engine shaft and connected, substantially as shown, to be operated
from said sliding collar, and finally, means substantially as shown for moving
the variable parts of the variable cut-off valve-gear of said engine from said rock-
shaft.
5. In a steam engine valve-gear a dynamometrical regulator consisting of a drive
wheel loose upon the shaft and flexibly connected with a fixed cross-arm on the
shaft, which cross-arm is provided with radially arranged rocking-shafts whose
outer arms are pivotally connected with the said drive wheel and whose inner
arms act to shift the collar on the engine shaft, substantially as shown.
6. In a steam engine the combination substantially as shown of two regulators
operating from different forces, which are connected together by gearing which is
variable from the action of one or both of said regulatora and is moved by the
action of either of said regulators, and is in operative connection with the variablo
cut-off valve-gear of said engine, in a manner substantially as shown, whereby the
action of said gearing will automatically vary the said cut-off valve-gear.
7. In a steam engine the combination, substantially as shown, of two separate
regulators operated by different forces, one of which acts dynamometrically, and
which are connected together by gearing which is variable from the action of one
or both of said regulators, and is moved by the action of either of said regulators
and is in operative connection with the variable cut-off valve-gear of said engine,
in a manner substantially as shown, whereby the action of said gearing will
automatically vary the cut-off valve-gear.
8. In a steam engine the combination substantially as shown of two regulators,
operating from different forces, one of which acts dynamometrically and the other
acts from the steam pressure and which are connected together by gearing which is

page_text: variable from the action of one or both of said regulators and is moved by the
action of either of said regulators and is in operative connection with the variable
cut-off valve-gear of said engine, in a manner substantially as shown, whereby the
action of said gearing will automatically vary the cut-off valve-gear.
9. In a steam engine the combination substantially as shown of a variable cut-off
valve-gear. which is acted upon automatically to vary the cut-off by two separate
regulators, which co-act to perform said office while each is free to act independently
of the other, one of which is mounted on the driving-shaft of the engine and acts
dynamometrically and the other is mounted off of the shaft of the engine and is
operated substantially as shown, to regulate the speed of the engine.
10. In a steam engine the combination substantially as shown of a variable
cut-off valve-gear which is acted upon to automatically vary the cut-off by two
separate regulators, which co-act to perform said office while each is free to act
independently of the other, one of which is mounted upon the driving-shaft of the
engine and acts dynamometrically and the other is mounted off of the shaft and is
operated directly from the pressure of the steam, substantially as shown, to regulate
the speed of the engine.
11. In a steam engine the combination substantially as shown of a dynamo-
metrical regulator on the shaft of the engine, gearing substantially as shown,
adjusted off of said shaft and connected to be operated from said dynamometrical
regulator and a steam pressure regulator mounted off of the shaft of the engine and
connected also with said gearing, in a manner substantially as shown, whereby a
movement of said second regulator will not only move said gearing but qualify its
movement from the other regulator.
12. In a steam engine the combination substantially as shown of a dynamo-
metrical regulator on the shaft of the engine, gearing substantially as shown
adjusted off of said shaft and connected to be operated from said dynamometrical
regulator, a second regulator which is operated directly from the steam pressure
and is mounted off of the shaft of the engine and connected also with said gearing,
in a manner substantially as shown, whereby a movement of said second regulator
will not only move said gearing but also qualify its movement from the other
regulator.
13. In a steam engine the combination substantially as shown of a dynamo-
metrical regulator which shifts a collar on the engine shaft, and a rock-shaft or
crank-shaft adjusted off of said engine shaft and having one of its arms variable,
substantially as shown, and connected by it to be operated from said sliding collar,
a second regulator mounted off of said engine shaft and adapted as shown; to vary
the said variable arm of said crank-shaft, and, finally, means substantially as shown
for moving the variable cut-off valve-gear of said engine from the said rock-shaft.
14. In a steam engine valve-gear the combination, with the eccentric L, strap L',
and pin l, of the link K, pivoted on the engine shaft and operated from the pin
working in the slot k, as shown, for the purposes mentioned.
15. In a steam engine valve-gear the combination of the valve-rods J, J¹, M, M¹,
jointed and supported in the manner shown on a single rock-arm N.
16. In a steam engine valve-gear the combination, with a rock-arm N, which is
moved by the exhaust valve-rod substantially as shown, of the pivoted guide-
block m and cut-off valve-rod J, J', embracing said guide-block as at J³, as shown,
for the purposes mentioned.
17. In a steam engine valve-gear the combination, with a cut-off valve-rod, of
the link K, pivoted on the engine shaft and rocked from the eccentric strap, and a
gearing substantially as shown for varying the position of said rod J, in said.
link K, from the action of the governing devices of said valve-gear.
18. In a steam engine valve-gear the combination with a cut-off valve-rod of a
pivoted link which is rocked by the action of the eccentric, in which link the said
rod is movable, for the purpose of varying the cut-off of the valve, and a gearing
substantially as shown, for varying the position of said rod in said link, which is
actuated from a dynamometrical regulator on the shaft of the engine, and a second

page_text: regulator which is adjusted off of the shaft of the engine, which two regulators act
upon the said gearing in a manner substantially as shown, whereby each acts
independently of the other, while one qualifies the effect of the action of the other.
19. In a steam engine the combination substantially as shown, with the
cylinder thereof, of two valves R, and S, of which S, rides upon R, and is provided
with an inlet-cavity for the steam and dual-ports 8, 8, which operate in conjunction
with delta-ports r, r, in the valve R, substantially as shown, for the purposes
mentioned.
20. In a steam engine the combination with the cylinder thereof of the exhaust-
valve R, and the cut-off valve S, superimposed upon said valve R, and adapted to
receive the live steam through the cavity S¹ therein, and provided with a balancing-
ring S2 upon its back; having an arca somewhat in excess of the sum of the area
of the ports in the valves, whereby the balancing of said rider-valve serves to
balance both valves, substantially as shown, and for the purposes mentioned.
In witness whereof, I, the said Herbert John Allison, have hereunto set my
hand and seal, this seventeenth day of July in the year of our Lord one
thousand eight hundred and eighty-three.
HERDERI. J. ALLISON. (L.S.)