IMPROVEMENTS IN STEAM ENGINES, PARTS OF WHICH IM- PROVEMENTS ARE APPLICABLE TO OTHER ENGINES AND MACHINERY
Year: 1871

page_text: LETTERS PATENT to Hamilton Ela Towle, of No. 20, Budge Row,
Cannon Strect, in the City of London, Civil Engineer, for the
Invention of "IMPROVEMENTS IN STEAM ENGINES, PARTS OF WHICH IM-
PROVEMENTS ARE APPLICABLE TO OTHER ENGINES AND MACHINERY." -A
communication from abroad by George Hermann Babcock, of the
City and State of New York, United States of America, Mechanical
Engineer.
PROVISIONAL SPECIFICATION left by the said Hamilton Ela Towle
at the Office of the Commissioners of Patents, with his Petition, on
the 27th May 1871.
I, HAMILTON ELA TOWLE, of No. 20, Budge Row, Cannon Street, in
5 the City of London, Civil Engineer, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN STEAM ENGINES, PARTS OF WHICH

page_text: IMPROVEMENTS ARE APPLICABLE TO OTHER ENGINES AND MACHINERY," a com-
munication, to be as follows:-
=
The first part of my said Invention consists (in respect to steam, air,
and other engines) in communicating by means of a single eccentric
or crank a varying motion or throw to the reciprocating parts of the
machinery, thereby effecting (in the application of the Invention to the
valves of steam engines, for example) a variable closing with a constant
lend. For this purpose in a steam engine, for example, I employ an
eccentric or crank fixed to the shaft in a plane with the main crank or
in such a position that it will pass its "dead centres" coincidently with
the centres of the crank. One side of the strap of this eccentric (usually
that opposite the steam chest) is compelled to vibrate in a right line
by means of a slide, the other side consequently describes an irregular
oval figure and carries a curved link or block which fits upon or into
a block or link connected with the valve stem, and is capable of adjust-
ment to different angles relative to the said stem. The eccentric
has a throw equal to the lap and lead of the valve, and if the link is
fixed at a right angle to the valve stem the valve receives a throw
only equal to that of the eccentric, but if the link is adjusted to any
other angle with the valve stem the valve receives a throw greater
than that of the eccentric, depending upon the amount of inclination
of the link. The centre of the link being in line with the centres of
the shaft and the slide which controls the eccentric strap, and the centre
of the eccentric always coming into this same line at each end of the
stroke of the piston, a constant lead is imparted to the valve under all
positions of the link. The direction of inclination of this link determines
the direction of rotation of the crank, the engine being reversed in its
movement by simply changing the inclination of this link.
In the application of my said Invention to such other machines as
require the motions of certain parts to be made in curves or irregular
oval figures, such as weaving and engraving machines, the desired motion
may be obtained by causing one side of the eccentric strap to slide
or move to and fro in a curved path, while at the same time on another
part of the eccentric a point may readily be found which will be
moving with the desired motion, and which point can be connected
by a pin joint to any working part of the machine.
Another part of my said Invention is also especially applicable to
steam and other engines, and consists in giving to the several governing

page_text: dimensions of the above described valve gear a proportion by which the
effect of the angularity of the connecting rod on the position of the
piston in different parts of the stroke is compensated for, and a square
cut-off attained at all points of the stroke.
Another part of my Invention consists in the combination of a parallel
motion with the aforesaid link, by which I not only cause it to oscillate
or vibrate in parallel lines, but am also enabled to vary its inclination
without interference with its motion.
Another part of my Invention specially adapted for the cut-off
mechanism of steam or other engines consists in giving to to the eccen-
tric which actuates the valves a differential velocity of rotation rclative
to that of the crank for the purpose of eliminating the effect of the
angularity of the connecting rod upon the point of cut-off. I accomplish
this object by means of a differential crank motion or by eccentric
gear wheels, or other equivalent means. Also in the combination of
the means for producing this differential velocity of rotation with an
eccentric or crank, which is adapted to have its centre shifted across the
plane of rotation for the purpose of varying the point of cut-off or the
direction of rotation of the engine.
Another part of my Invention consists in the use in a connecting rod
or shackle bar of brasses which allow of oscillation in the plane of the
rod in combination with a cross head, which will permit a partial rotation
of the rod upon its own axis, the two forming the means for a universal
adjustment of the bearing to suit the line of the pin or pins. One
method of allowing the partial rotation of the rod upon its own axis is
the employment of guides forming portions of a cylinder, and a cross
head turned to fit the same.
Another part of my Invention, also especially adapted for steam
engines, consists in the combination of the said connecting rod with
spherical or equivalent self-adjusting bearings for the main shaft; also
in the combination with self-adjusting bearings of an eccentric forming
a portion of a sphere and a corresponding eccentric strap. The several
parts prevent any cramping of the journals from incorrect alignment or.
settling of the foundation, or other similar cause.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Hamilton Ela Towle in the Great Seal Patent
Office on the 27th November 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HAMILTON
Ela Towle, of No. 20, Budge Row, Cannon Street, in the City of
London, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-seventh day of May, in the
year of our Lord One thousand eight hundred and seventy-one, in
the thirty-fourth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Hamilton Ela Towle, Her
special licence that I, the said Hamilton Ela Towle, my executors,
administrators, and assigns, or such others as I, tho said Hamilton
Ela Towle, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
" IMPROVEMENTS IN STEAM ENGINES, PARTS OF WHICH IMPROVEMENTS ARE
APPLICABLE TO OTHER ENGINES AND MACHINERY," a communication to me:
from abroad by George Hermann Babcock, of the City and State of
New York, United States of America, Mechanical Engineer, upon the
condition (amongst others) that I, the said Hamilton Ela Towle, my
executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seuls, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Hamilton Ela Towle, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, reference being had to the accompanying
Drawings forming a part of this Specification:-
The first part of my said Invention consists, in respect to steam, air,
and other engines. in communicating by means of a single eccentric

page_text: or crank a varying motion or throw to the reciprocating parts of
machinery, thereby effecting in the application of the Invention to the
valves of steam engines, for example, a variable closing with a constant
lead. For this purpose I employ an eccentric or crank fixed to the
shaft in a plane with the main crank, or in such a position that it will
pass its "dead centres " coincidently with the centres of the crank..
One side of the strap of this eccentric (usually that opposite the steam
chest) is compelled to vibrate in a right line by means of a slide; the
other side consequently describes an irregular oval figure and carries
a curved link or block which fits upon or into a block or link connected
with the valve stem, and is capable of adjustment to different angles
relatively to the said stem. The eccentric has a throw equal to the
lap and lead of the valve, and if the link is fixed at a right angle to the
valve stem the valve receives a throw only equal to that of the eccentric,
but if the link is adjusted to any other angle with the valve stem the
valve receives a throw greater than that of the eccentric, depending upon
the amount of inclination of the link. The centre of the link being in
line with the centres of the shaft and the slide which controls the
eccentric strap, and the centre of the eccentric always coming into this
same line at each end of the stroke of the piston, a constant lead is
imparted to the valve under all positions of the link. The direction
of inclination of this link determines the direction of rotation of the
crank, the engine being reversed in its movement by simply changing
the inclination of this link.
In the application of my said Invention to such other machines as
require the motions of certain parts to be made in curves or irregular
oval figures, such as weaving and engraving machines, the desired
motion may be obtained by causing one side of the eccentric strap to
slide or move to and fro in a curved path, while at the same time on
another part of the eccentric a point may readily be found which will
be moving with the desired motion, and which point can be connected
by pin or joint to any working part of the machine.
Another part of my said Invention is also especially applicable to
steam and other engines, and consists in giving to the several governing
dimensions of the above described valve gear a proportion by which the
effect of the angularity of the 'connecting rod on the position of the
piston in different parts of the stroke is compensated for, and a square
cut-off attained at all points of the stroke.

page_text: Another part of my Invention consists in the combination of a parallel
motion with the said link, by which I not only cause it to oscillate or
vibrate in parallel lines, but am also enabled to varyžits inclination
without interference with its motion.
Another part of my Invention especially adapted for the cut-off
mechanism of steam or other engines consists in giving to the eccentric
which actuates the valves a differential velocity of rotation relative to
that of the crank for the purpose of eliminating the effect of the
angularity of the connecting rod upon the point of cut-off. This I
accomplish by means of a differential crank motion or by eccentric gear
wheels, or by other equivalent meaus. Also in the combination of this
differential velocity of rotation with an eccentric or crank which is
adapted to have its centre shifted across the plane of rotation for the
purpose of varying the point of cut-off or the direction of rotation of the
engine.
Another part of my Invention consists in the uso in a connecting rod
or shackle bar of brasses which allow of oscillation in the plane of the
rod in combination with a cross head, which will permit a partial
rotation of the rod upon its own axis, the two forming the means for a
universal adjustment of the bearing to suit the line of the piu or pins.
One method of allowing the partial rotation of the rod upon its own axis
is by the employment of guides forming portions of a cylinder and a
cross head turned to fit the same.
Another part of my Invention also especially adapted for steam
engines consists in the combination of the said connecting rod with
spherical or equivalent self-adjusting bearings for the main shaft. Also
'in the combination with self-adjusting bearings of an eccentric forming
a portion of a sphere, and a corresponding eccentric strap. These several
parts prevent any cramping of the journals from incorrect alignment or
settling of the foundation, or other similar cause.
One form of the portion of my Invention which relates to imparting
a varying throw to the valve is shown in Figures 1 and 2, and consists
in an eccentric a having a throw equal to the lap and lead of the valve,
and which is fastened to the shaft in line with the crauk, or in such
a manner that its "dead centres" will be coincident in time with the
"dead centres" of the crank. On this eccentric is fitted a strap d in the
usual manner, but the side
embraced by a jaw
pivoted
of this strap carries a slido e which is
upon a stationary stud. The effect of

page_text: this is such that as the eccentric a revolves this slide e reciprocates in
the jaw and causes a point in the strap d to describe an irregular figure
differing in form for every different position of the generating point.
The jaw is shown detached in Figures 1, 1º. A point in the strap d
situated in a line drawn through the centre of the eccentric a and the
stud f¹ describes an irregular oval, symmetrical as regards the said
centre line shown in Figure 1 in dots g, g. At this point the strap d is
fitted to receive the shank of a curved link or jaw h, which in turn
embraces a curved slide hinged to the end of the valve stem i or to
the end of a radius arm * which imparts its motion to the valve stem i.
As the eccentric a revolves and the jaw ƒ pivoted thereto describes the
irregular oval g, g, it carries this curved slide with it the length of the
conjugate axis g¹, g', of the oval and slides thereon the length of the
transverse axis g³, g². This curved slide ¹ being struck with a radius
equal to its mean distance from the stud f¹ on the opposite side of the
eccentric a, it follows that when its centre is normal therewith the
transverse motion of the jaw ƒ causes no motion of the curved slide h¹
or its centre, but when it is turned at an angle the transverse motion
imparts more or less motion to its centre in proportion to the angle it
makes with the centre line.
We will consider the curved slide in Figure 1 to be attached directly
to the valve so as to have a motion coincident therewith, and that the
shaft is revolved. The eccentric a coming upon its centre at the
same time as the main crank the centres of the jaw fand of the curved
slide ' coincide, and the valve is thrown just the throw of the eccen-
tric a beyond the central position. As we made the throw of the
eccentric & equal to the lap and lead the valve is opened just the lead
when the crank is on the "dead centre," and the turning of the curved
slide upon its own centre will make no change in this lead as the
) centres coincide. But if the curved slide is turned to stand at an
angle to its normal position it will be seen that the turning of the
shaft in either direction will cause a more or less rapid movement of
the valve, owing to the rapid transverse motion of the eccentric strap d
at that point, and that the direction of revolution to cause the valve
to open will depend upon the way the curved slide h¹ is turned: The
amount of opening of the valve and the consequent time of closing
will depend upon the degree of angularity given to the curved slide.
In Figure 1 partial centre lines for the curved slide arc drawn in dots

page_text: passing through the closing points of the valve and different points
in the revolution of the eccentric strap jaw, showing the effect of
different degrees of angularity of the curved slide upon the closing
of the valve for effecting the "cut-off." It is evident that if these
centre lines were drawn at the reverse angle they would intercept
corresponding points in the reverse revolution of the eccentric strap
jaw and that therefore this motion operates the same for either
direction of rotation of the engine, the reversing of the inclination
of the curved slide or link being sufficient to reverse the engine.
It is evident that the form of the oval described by the eccentric strap
head d' depends upon the relative proportions of the throw, the distance
from centre of shaft b to the stationary stud f, and from the centre c¹
of the eccentric a to the centre of the jaw which embraces the curved
slide, and that the shape of this oval has a controlling effect upon
the motion of the valve. I take advantage of this fact to eliminate to
a greater or lesser extent the disturbing effect of the angularity of
the connecting rod upon the movement of the piston, so as to give an
equal amount of steam to opposite ends of the cylinder. I employ the
following formula for this purpose in which R= the ratio of the
connecting rod crank, a=throw of eccentric= lap and lead of valve,
x=distance from centre of shaft to stationary stud, and m= the ratio
between this distance and that from the centre of eccentric to the centre
of jaw in head of eccentric stran.
Rand a being known, m may be assumed, and then the value of x 2
may be readily found. As × depends upon the value of m, by varying
the latter a value of × may be found to suit the convenience of different
constructions.
Another form of construction of this motion consists in causing a
point in the back end of the eccentric strap to reciprocate in a right 3
linc in contradistinction to causing a line in the eccentric strap to
reciprocate over a stationary point, as described above. In this modi-
fication the angularity of the connecting rod is climinated by making
the distanco from centre of eccentric to this point to bear the same ratio
to the throw of the eccentric as the length of the connecting rod bears 35
to the crank. In this form the value of me is immaterial except as it
influences the angularity of curved slide required for the greatest throw

page_text: of the valve. The greater the value of m in either form of construction
the less the angularity required. But it will be found that owing
to the ratio usually existing between the throw of the eccentric and
the size of the shaft the latter form of construction is rarely admissible,
except the connecting rod be more than six cranks long.
The third part of my Invention, which relates to the combination
of a parallel motion with the said curved slide or link, is shown in
Figures 3 and 4. In these Figures the parts above described are similar
to those shown in Figure 1, but the curved slide or link ' is carried on
a pin a fitted on the end of an "idle lever" ³, and passing through the
end of the valve stem i, or rather through a turnbuckle attached
thereto. An arm /* fixed to the curved slide h¹ and a reversing handle j
is hinged upon the stud ³ of the "idle lever" h³, a link k of the same
length between centres as the "idle lever" joining these two so as to
form a parallelogram. It is evident that the arm attached to the curved
slide remains always parallel to the reversing handle, and that the latter
may be shifted at any time without in any way impeding the freedom
of motion of the valve stem or its attachments.
The fourth part of my Invention, which relates to giving the eccentric
which actuates the valves of a steam or other cugine a differential
velocity of rotation relatively to that of the crank, according to one
method is shown in Figure 5, in which the eccentric a is mounted
upon a supplemental shaft l, the centre of which is not in line with
the centre of the crank shaft b, and which receives its motion from
the crank through a block m sliding in a slotted crank m' attached to
the supplemental shaft. When the parts are made in the following
proportions the effect of the angularity of the connecting rod is prac-
tically climinated, and the action is the same as if the connecting rod
had an infinite length.

page_text: It will be seen that as the throw of the eccentric does not enter into
the above formula this throw may be varied indefinitely without
altering the result; I therefore combine with this differential motion
a shifting eccentric or crank (which forms the fifth part of these
improvements) similar to what is commonly known as the "Dodd
motion," and thereby produce a cut-off entirely unaffected by the
relative length of the connecting rod to the crank. This is illustrated
in detail in Figures 6 and 7, which show one method of shifting the
eccentric by means of dovetail slides n, n, but any other method may
be used.
According to another part of this Invention I employ guides forming
portions of a cylinder, and a cross head turned to fit the same. Other
and equivalent means will readily suggest themselves.
One construction and adaptation of these adjustable bearings, shewn
as an example, is set forth in Figures 8 and 9, in which the connecting
rodo is shewn with the brasses p, p, in place. These are formed of
portions of a cylinder fitting into "chocks" 7, the whole fitting the
strap r sidewise and being adjustable for wear in any well-known
manner. This construction admits of a vibration in one direction
without interfering with the rigidity of the rod in all other directions.
I also use in combination with the above constructed rod spherical
or other adjustable bearings for the main shaft, and also an eccentric
composed of a portion of a sphere, all for the purpose of overcoming
any tendency to cramp the bearings consequent on want of accurate
alignment, or subsequent changes in the alignment due to wear or
settling of foundations. All these several features are shown in Figures 8
and 9.
Having thus fully described the said Invention, as communicated to
me by my foreign correspondent, I claim,—
First. The combination of an eccentric, eccentric strap, and curved
slide, substantially as described, for the purpose of imparting a variable
throw to a valve or other reciprocating part.
Second. In connection with a valve motion, substantially of the
character described, giving the parts such proportions as will
climinate or partially climinate the effect of the angularity of the
connecting rod, substantially as described.

page_text: Third. A parallel motion in combination with a valve motion, sub-
stantially of the character described, for the purpose specified.
Fourth: Imparting to the eccentric which actuates the valve or
valves of an engine a differential velocity of rotation relatively to that
of the crank, substantially as specified.
Fifth. The combination of an adjustable or shifting eccentric with
means for producing a differential motion of rotating, substantially as
described.
Sixth. A connecting rod having brasses which admit of vibration of
their axes relatively to the axis of the rod, in combination with a cross-
head which admits of a partial rotation around the axis of the rod,
substantially as specified.
Seventh. The combination of a connecting rod provided with brasses
as above and a cross head of the character described with spherical or
self-adjusting bearings for the main shaft, substantially as set forth.
Eighth. The combination of a spherical eccentric with self-adjusting
bearings for the main shaft of an engine, substantially as and for the
purpose specified.