provements in Gear for Operating Slide Valves of Steam Engines
Year: 1898

page_text: Date of Application, 6th June, 1898 -Accepted, 23rd July, 1898
COMPLETE SPECIFICATION
Improvements in Gear for Operating Slide Valves of Steam Engines
I, JAMES BARNES ALLFREE, of 21st Street and North West Avenue, in the City
of Indianapolis, in the County of Marion and State of Indiana, United States of
America, Manufacturer, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascei-
tained in and by the following statement -
My invention relates to certain new and useful improvements in valve gears for
steam engines, and consists of mechanism of peculiar construction, whereby two
modifying motions are introduced into the ordinary so-called slide valve movement,
in common use, one of said modifying motions being more rapid and the other
slower than the primary movement of the valve as ordinarily operated, one motion
the former providing for the more rapid opening and closing of the ports and the
latter providing a retarding movement permitting the valve to dwell or delay a
longer time, during which the actuating fluid is operating expansively and during
the exhausting period as will be more fully explained hereinafter
The objects of my invention are to so modify and regulate the movement of the
alde valve of an engine to conform to a variable velocity of travel at different
points of its path as are most favorable to the attainment of a free and rapid
induction port opening and a rapid closing of induction port so as to prevent wire
drawing, and to provide a rapid, free and extended eduction port opening to the
close of the period at which steam or other actuating fluid is working expansively
and to obtain thereby the maximum duty and economy and beyond that hereto-
fore attained by any type of automatic or high speed engine, or any low speed
engine, either of the Corliss type or any other high grade engine
I attain these objects by means of the mechanism illustrated in the accompany-
ing diawings throughout which similar characters of reference designate like parts
Figure 1 is a side view of an automatic balanced slide valve engine, having my
new valve motion applied thereto, parts of fly wheel being bioken away and cover
of steam chest removed;
Figure 2 18 an enlarged detail side view of the rocker arm and showing other
smaller parts attached thereto,
Figure 3 is an enlarged detail side view of a toothed_sector;
Figure 4 is an enlarged detail end and side view of an eccentric and pinion
shaft,
Figure 5 is an enlarged vertical side view of parts shown in Figures 2, 3 and 4,
Figures 6, 7, 8 and 9 are diagram views showing the relative positions of the
steam ports and the slide valve registering therewith, and the primary and auxiliary
moving and modifying mechanisms and the relative positions of their parts as coin-
pared with the different positions assumed by a piston starting at the point of
induction port opening.
Figure 10 is a fac-simile of indicator diagram taken from a high speed engine
equipped with my invention in valve modifying mechanism
Referring first to Figure 1, a is the main bed plate of any suitable form and
construction adapted to the requirements of high speed engines. b is a fly wheel

page_text: pulley. represents the main eccentric which is pivoted to the hub of said pulley
in this case by means of a wist pin c; to the said eccentric are attached or made
integial therewith arms supporting the inertia weights g of the automatic governor.
It will readily be seen that as the speed of rotation of engine varies in the least
degree to either a lower or higher speed than normal that a temporary change in the
position of the weights y will be effected, which will cause a movement of the
main eccentric c upon its pivoted axis o altering its throw, thus actuating the
valve more or less as the case may be by means of intervening mechanism. is
an ordinary strap mounted on said main eccentric and has secured to it a rod of
terminating at and being movably mounted on pin which is provided therefor
near upper end of rocker-arm. Arm is movably pivoted, sectors being in this
case provided with a short transverse shaft s extending from side to side of said
rocker-aim. Said sectors is provided with an adjustable wrist pin mounted in &
adial slot formed therein, on said wrist pin 18 pivotally secured a connecting
rod which is connected at opposite end to the eccentric strap mounted on
auxiliary eccentric d which is in this case secured directly to shaft of engine and
rotating therewith By means of this auxiliary eccentric an oscillating motion is
given to said sectors by which it is caused to partially rotate upon its axis, which
said axis has a variable lateral motion communicated to it by the main eccentric,
which motion 18 limited in extent and controlled by the automatic governor
mechanism before described.
The degree of oscillation of said sector upon its axis may be adjusted to a greater
angle by moving wrist pin nearer to the axis, and to a lesser angle by moving
said pin further from the axis; by this adjustment more or less rotation will be
given to the modifying eccentric described further on
Instead of a rocker-arm a sliding bar or bracket may be used providing mount-
ings for said sector and modifying gear
At the outer circular rim of sectors are provided a series of teeth * adapted to
mesh with teeth e¹ of pinion mounted on shaft e, said shaft being journaled at,
ina ocker-arm r; said shaft e is also provided with an eccentric pin e to which is
attached one end of a connecting rod, said rod being connected at opposite end
to valve stem v projecting from the slide valve which reciprocates within the
steam chest and is adapted to register with steam ports and *.
In the application of my invention, as shown in Figure 5, the rods and d
are both connected to the primary or main eccentric as the point is located on
the opposite side of axis s which axis in this case has no lateral motion, and the
angular distance between the points 3 and 18 thereby increased sufficiently to
ve the necessary advance movement to the modifying mechanism. The steam
chamber communicates with supply pipe h and the exhaust chambers k at each
end communicate with a suitable exhaust pipe.
I will now describe the modifying valve mechanism, which constitutes my m-
vention and will show the influence the same exerts on the movement of the
pumary eccentric and the character of the modified movement
What constitutes my invention is the introduction into the valve gear of a
modifying eccentric or means whereby the primary simple or compound movement
can be modified to accelerate the valve travel at certain divisions and to retard it
at certain other divisions of travel.
The throw or eccentricity of said modified eccentric here shown is proportioned
in accordance with the amount of travel of valve and degrees of acceleration re-
quired at the extremes of valve movement In operation the main eccentric c
actuates the rocker-aim giving to it a variable oscillation, regulated by the governor,
a movement such as ordinarily is given to slide valves, but between the rocker-arm
and valve I introduce said eccentric and when this eccentric is rotated during
the travel of the rocker arm it increases or diminishes the motion it transmits
from the rocker-arm to the valve thus causing an acceleration at one point and a
dwelling or a delaying at another point of its travel
The valve travel is made up of long and short motions, the beginnings from
each end being short movements just sufficient to close the induction port when

page_text: coming practically to a stop dwelling a short period, then the finishing movement
traveled at an equally high rate of speed but moving much further which completes
the travel in one direction, the next succeeding movement being the beginning of
the return stroke or travel, a short movement, a dwelling period, then the longer
finishing movement
In order to fully understand and appreciate the operation of my invention
reference will now be had more directly to Figures 6 to 10 inclusive. By directing
our attention first to Figures 6 and 10 and considering the relations or mechanism
corresponding to the position of the engine we will more readily trace and compare
the movements of the parts and comprehend the action of the different elements
and their succeeding motions through the complete cycle of operations.
In the diagiam Figure 6, o represents the position of crank corresponding with
the position of the piston Figure 10, when said crank is in this position the
valve v will be on the verge of port opening at to admit steam while the port 1
is still emitting exhaust steam from opposite end of cylinder. The crank moving
in direction of arrow till arriving at the position o¹ at which time the piston has
reached the position p¹ and the steam in the cylinder has reached its maximum
initial pressure
It will be observed that while the crank 18 moving from o to o
the modifying eccentric pin rotates in direction of arrow 1 Figure 6, which move-
ment is in the same direction as rocker-arm see arrow 3, thus accelerating the move-
ment of valve at the period of the cycle just being traversed till the crank reaches
said position o Figure 7 at which point the valve 18 practically at rest, as the
actions of the two eccentrics are practically equal and modifying eccentric has
reversed its direction of rotation as indicated by arrow 1 Figure 7 Arrow indi-
cates flow of steam into the cylinder and arrows f indicate the flow of exhaust
steam.
Referring next to Figures 8 and 10 the position of piston is seen to be at p³, at
which position of its stroke, corresponding with the steam 18 cut off and the
expansion begins Now note particularly the direction of motion of the modify-
ing eccentric and that the main eccentric is nearing its dead point where if unaided
by modifying eccentric the steam port would still be partially open but by the
quick reverse motion of modifying eccentric moving now in the duection of
arrow 1 closes the port very rapidly when the valve is again retarded in its move-
ment until it approaches the point of the release of steam as shown in positions p³,
Figure 10, and o' and by dotted lines ³, Figure 9, showing the beginning of
exhaust, and the crank being further notated till the piston reaches the position p
when the accelerated motion will again set in and the induction port at opposite
end of cylinder 19 rapidly opened beginning the next cycle of operation, the point
of compression shown by position of valve occurs practically at the end of the
stroke as seen at o, Figure 9, corresponding to p point of compression, while p
represents release It will be observed that the most efficient actions of the modify-
ing mechanisms are applied to increase the velocity of the valve when it approaches
the end portions and reversing of its travel and to decrease its velocity during the
middle or central portions of its movements, thus as the piston 18 traveling from
to the valve is traveling at its minimum or slower rate or at about one-half
the velocity at which it would be impelled if operated directly by the main
eccentric during this portion of its travel This retarded movement of valve per-
mits the free and unobstructed flow of exhaust steam and while the piston moves
successively from p to pl and p to 5 the valve moves very rapidly, that is
about twice the velocity that it would move were it being impelled directly by
the main eccentric only and this acceleration continues until the valve reaches to
position of full port opening as shown in Figure 7. in which position the valve
remains momentarily at rest till the movements of both main eccentric and modify-
ing eccentric again act simultaneously in the same direction and combine move-
ments to operate rapidly and close the ports with the same accelerated velocity
as that operating at port opening as a comparison of diagrams, Figures 7 and 8,
will show, and thus the opening and closing of the induction ports is accomplished
at about four times the velocity as that of the intermediate or retarded portions of

page_text: the travel of said valve It is obvious from the foregoing specifications that by
the use of this motion modifying gear I obtain a larger opening for the admission
of steam, whereby the initial pressure in the cylinder is brought up more nearly
to the boiler pressure and by reason of this and the rapid closing wire-drawing is
avoided, then also as a result of a slower or retarded movement during the period
of expansion the compression is delayed and the release will not occur until the
piston has practically reached the end of its stroke while by reason of the rapid
travel again setting in toward the end of the valve movement the exhaust port 18
thrown unusually wide-open, allowing a perfectly free and unobstructed exhaust
I do not confine myself to the use of the foregoing or any special form of construc-
tion of movable or automatically variable main eccentrics or to fixed eccentrics or
any of the well known means whereby the valves of an engine are caused to 10-
ciprocate or to alternately open and close the steam ports in connection with my
invention, as such means do not constitute or form a part of my invention but are
merely incidental elements employed to carry out the application of my invention,
neither do I confine myself to the particular means herein before described, whereby
the modifying eccentric may be rotated to produce the desired result as many and
various means may be resorted to, to rotate the same without departing from the
spirit and scope of my invention and I hold myself at liberty to make such altera-
tions as fall fairly within such scope
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed I declare that what
I claim 18-
1 In a gear for operating slide valves of steam engines a reciprocating slide
valve, means for producing motion to reciprocate said valve, means to convert said
reciprocation from a single impulse movement or stroke into a movement com-
prising three distinct divisions to each stroke, the first division being short and
rapid at the beginning of the stroke and the last being a longer, rapid movement
at the end of the stroke and an intermediate division being practically a cessation
of motion, said three divisions completing one stroke
2 In a valve gear operated by either a movable or fixed eccentric, and means
whereby the throw or movement of said valve is so influenced as to cause a rapid,
short movement at the beginning of the stroke, then a slow movement, then ter-
minating with a rapid and longer movement and continuing to reciprocate in this
manner through each successive stroke, finishing each stroke with a long rapid
movement and beginning the next stroke with a short, rapid movement, substan-
tially as set forth
3 In a valve gear for steam engines, the combinations of a slide valve, a primary
reciprocating motion, a modifying mechanism to modify said motion and means
to transmit motion so modified to aaid valve, all substantially as set forth
4 In a valve gear for steam engines the combination of an engine shaft, a regu-
lating eccentric mounted on said shaft, a rocker-arm or sliding bracket recipro-
cated by said eccentric, a modifying eccentric rotatively mounted on said arm or
bracket, a valve and means to connect said modifying eccentric to said valve
5 In a gear for slide valves of steam engines the combination of a main eccentric
producing a reciprocating motion, a modifying eccentric adapted to change the
effect of said reciprocating motion, means to support said modifying eccentric
1otatively, and adapted to reciprocate said modifying eccentric transversely across
its axis, substantially as shown
6 In a gear for slide valves of steam engines the combination with an engine
shaft, a regulating eccentric on said shaft, a rocker-arm or lever operated by said
eccentric, a modifying eccentric, means for supporting said modifying eccentric,
means for rotating said modifying eccentric and means for imparting thereto a
lateral motion across its axis; substantially as set forth
7 In a valve gear for steam engines, a valve, a main eccentric, an auxiliary
eccentric, means for combining the motions of both said eccentrics, substantially
as set forth.

page_text: 8 In a valve gear for steam engines, a reciprocating lever, a modifying eccentric
mounted in said lever, and means whereby a motion of alternate rotation 16 im-
parted to said modifying eccentric, a valve, and means for connecting said modify-
ing eccentric to said valve, substantially as set forth
The combination in valve gears for steam engines of a reciprocating rocker-
arm or lever, an eccentric shaft carried by said lever, means whereby motion of
1otation is transmitted to said eccentric, through and by said lever, substantially
as shown.
10 In a valve gear for steam engines the combination of a reciprocating lever,
an eccentric carried by said lever, means for rotating said eccentric alternately in
opposite directions simultaneously with the reciprocation of said lever, substan-
tially as shown.
11. In a valve gear for steam engines, the combination with a reciprocating
lever, a shaft journaled in said lever, an eccentric pin on said shaft, a pinion on
said shaft, a toothed sector meshing with the said pinion, pivoted on said lever,
a rod pivotally connected at one end to said sector and to an eccentric at its other
end to reciprocate said sector, substantially as shown
12. In a gear for slide valves for steam engines, the combination with a valve,
a modifying eccentric-pin, means for connecting said pin to said valve, means for
supporting and carrying said eccentric-pin, a main eccentric, an eccentric rod
extending from said main eccentric to said supporting and carrying means whereby
said means is reciprocated, and means whereby the said eccentric-pin is rotated, as
shown.
13 In a valve gear for steam engines, the combination with a valve, a modify-
ing eccentric-pin, a rod connecting said eccentric-pin to said valve, a lever or rocket-
arm, means on said rocker-arm whereby said eccentric-pin shaft is supported and
means to rotate said pin alternately in opposite directions, substantially as shown
14. In a valve gear for steam engines, the combination with a slide valve, a
rocker-arm, a modifying eccentric-pin, rotatively mounted on said rocker-aim, a
rod connecting said slide valve to said eccentric-pin, a toothed pinion on shaft of
said eccentric-pin, a toothed sector pivoted on said rocker-arm adapted to mesh
with said pinion and means for oscillating said rocker-arm and said sector, sub-
stantially as set forth.
15 In a valve gear for steam engines, a slide valve, a modifying eccentric-pin,
a rod connecting said eccentric-pin to said valve, a rocker-arm, a shaft carrying
said eccentric-pin rotatively supported on said 1ocker-arm, a toothed pinion on said
shaft, a toothed sector pivotally secured to said rocker-arm, adapted to mesh with
said pinion and means for oscillating said rocker-arm and said sector in opposing
directions; substantially as shown
16 In a valve gear for steam engines, the combinations with a slide valve, &
modifying eccentric-pin, a rod connecting said valve to said eccentric-pin, a rocker-
arm, an eccentric-pin shaft rotatively carried by said rocker-arm, a toothed sector
pivoted on said rocker-arm, and adapted to mesh with said pinion, a main eccenti1o
adapted to reciprocate said rocker-arm and means for oscillating said sector upon
its axis in directions going practically opposite to motions of said rocker-arm, as
shown.
17 In a valve gear for steam engines the combinations of a slide valve, a modi-
fying eccentric-pin, a rod connecting said valve to said eccentric-pin, a rocker-aim,
an eccentric-pin shaft carried by said rocker-arm, a toothed pinion on said shaft,
a toothed sector pivoted on said rocker-arm adapted to rotate said pinion, a main
eccentric adapted to oscillate said 1ocker-arm and an auxiliary eccentric adapted to
oscillate said sector in opposite directions, substantially as described.
18. In a valve gear for steam engines an eccentric located at an intermediate
point between the primary means for traveising the valve and means whereby the
said eccentric 18 caused to rotate causing a modification of the primary movement,
all substantially as shown
19 In a gear for slide valves of steam engines, a modifying eccentric located at
a point intermediate between the main or primary eccentric and the valve to be

page_text: operated and means by which the said intermediately located eccentric is caused
to rotate whereby a modified movement 18 imparted to the valve for the purposes
set forth.
20 In a valve gear for steam engines the combination of a valve, means for
producing a primary reciprocating motion, a modifying eccentric operating
between said primary motion and said valve and means for connecting said eccentric
to said valve, whereby a modified movement is imparted to the said valve, sub-
stantially as described.
21 In a valve gear for steam engines the combination of a valve, means for un-
parting motion to said valve, a modifying eccentric operating between said means
and said valve, a means for rotating said eccentric upon its axis, means for laterally
oscillating said axis simultaneously with action of rotation, resulting in a com-
pound motion and means for impaiting to said valve, latter said motion, whereby
the velocity of valve travel is accelerated at one point and retarded at another, sub-
stantially as set forth
22 In a valve gear for steam engines the combination of a valve, primary means
for imparting motion to said valve, a modifying eccentric placed between said
means and said valve, means for rotating said eccentric upon its axis and means
for laterally oscillating said modifying eccentric across its axis accelerating the
travel at the beginnings and endings of the valve motion and retaiding at the inter-
mediate portion of valve travel, as set forth and described.
23 In geais foi slide valves of steam engines the combination of a valve, suit-
able means for imparting motion to said valve, an eccentric between said means
and said valve, means for connecting said means to said valve, suitable means for
rotating said eccentric alternately in opposite directions, for the purpose of increas-
ing and diminishing the velocity of said valve at certain portions of travel, as
shown
24 In a motion for slide valves of steam engines, the combination with a valve,
means whereby an accelerated motion is imparted to said valve at the beginnings
and endings of its stroke and whereby the velocity of said valve 18 retarded at and
during the intermediate portions of its stroke
25 In a gear for slide valves of steam engines the combination of a primary oi
main eccentric, a 1ockel-arm operated by said eccentric, a modifying eccentric
mounted rotatively in said rocker-arm, a toothed pinion secured to said modify-
ing eccentric, means for connecting said valve to said modifying eccentric, a toothed
sector mounted movably on said aim, a secondary or auxiliary eccentric adapted to
operate said sector simultaneously in duections opposite from movements of said
1ocker-arm
Tad thin 6th law of June 1908
GEO. THOS HYDE,
No 1, Broad Street Buildings, Liverpool Street, EC
Agent for Applicant.