IMPROVED MECHANISM FOR OPERATING THE CUT-OFF VALVES OF STEAM- ENGINES
Year: 1881

page_text: LETTERS PATENT to Henry Harris Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVED MECHANISM FOR OPERATING THE CUT-OFF VALVES OF STEAM-
ENGINES." A communication from abroad by Simeon A. Goodwin, of
Philadelphia, Pennsylvania, United States of America.
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at the
Office of the Commissioners of Patents on the 27th December 1891.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co. Patent Agents,
Southampton Buildings, London. "IMPROVED MECHANISM FOR OPERATING THE
CUT-OFF VALVES OF STEAM-ENGINES.' [A communication from abroad by
Simeon, A. Goodwin, of Philadelphia, Pennsylvania United States of America.]
"
This Invention relates to improvements in that class of steam-engines in which
a main slide-valve performs the functions of admission and release, while the
suppression is effected by an auxiliary or cut-off valve working upon the backs of
the main valve. In such engines the auxiliary valve is usually operated by a
separate eccentric on the engine-shaft, and the travel is somewhat greater than that
of the main valve.
According to the present Invention this eccentric is dispensed with, and the
cut-off valve is operated, as well as controlled, by the governor; and the governor
is driven by chain gearing, this being the cheapest and most easily applied means,
and sufficiently positive in motion to answer the peculiar requirements of
the case.
To reduce the travel to a minimum so as to put as little labor as possible upon
the regulating elements of the governor, the cut-off valve is made to ride upon, and
with, the main valve, so that, in relation to the former, the latter is at rest. To the
same end narrow multiple ports are employed in place of one wide port. These

page_text: ports are at right angles to the main or cylinder ports and the motion or travel
of the cut-off is across, or at right angles to, that of the main valve.
The cut-off valve, for reasons that will appear, is substantially in equilibrium
while moving to close, this being an important condition.
The object proposed by this Invention is to provide a simple and inexpensive,
yet efficient and durable, automatic valve gear that can be readily applied to old
or existing, as well as to new plain slide-valve engines.
In carrying the said Invention into practice the governor is fixed upon the
steam-pipe or upon another pipe on the steam chest. It is driven by chain gearing
consisting of a sprocket wheel on the main shaft of the engine, a chain having
links of equal length, and a sprocket wheel on the shaft of the governor. These
wheels are of the same size in order to give the governor-shaft the same speed as
the engine. This shaft is by preference tubular; it carries a movable cam which
imparts a reciprocating motion to a yoke, and through a rod and link the said
motion is communicated to the cut-off valve which works in grooves or guides on
the back of the main valve, which, in its turn, is operated by an eccentric in the
usual manner. The aforesaid rod passes through a stuffing box in the base-plate
of the governor, and the link is pivoted to the end of said rod.
The regulating elements of the governor are connected with the cam through a
bell crank and rod; this rod being loosely fitted within the hollow shaft, has near
its end a groove cut around its periphery, in which groove works the end of a steel
pin, which is screwed through one side of the cam and passes freely through a slot
in the hollow shaft which slot lies, obliquely to the axis of the shaft, being inclined
in the direction of its rotative motion. The bell-crank is connected with the lifting
sleeve of the governor, by a link.
The-main-valve has two independent series of narrow ports through its back,
each series uniting respectively in one port in the face of the valve.
The cut-off valve has corresponding ports through it so disposed in relation to
those in the main valve that while one series is open the other series is closed.
The cam is so shaped as to throw the cut-off valve quickly in order first to effect
a sudden suppression of the steam, and secondly to complete the throw before the
pressure of the steam in the cylinder of the engine and consequently under the
valve, has fallen off by expansion so as to accumulate an unbalanced pressure on
the top of said valve, and thereby to impose a heavy load upon the governor. For
it should be observed that when the cut-off valve commences to make its movement
there is no unbalanced pressure upon it on the end that is open because the steam
is passing freely through its ports and there should be none on the other end
because the main valve has already closed the main steam-port on that end before
the cut-off valve has to move. But during the interval between the suppression
by the cut-off and the suppression by the main valve in the previous movement,
the pressure in the port or mortise in the latter has been falling by expansion in
the cylinder, and to restore this before the next movement the main-valve seat is
recessed in order to admit steam from the chest into said mortise or port for the
purpose of restoring the equilibrium before the cut-off valve has to move. Tho
link operates perpendicularly to the line of motion of the main valve. The
vibrating motion of its lower end does not affect the motion of the cut-off valve.
The cam is recessed or made smaller behind its working face so as not to bind
between the points of its yoke in order that it may be freely moved on its shaft
by the governor.
Bearing in mind that the main valve which has an invariable positive motion,
admits and exhausts the steam and that the cut-off valve has nothing to do but to
suppress it, first on one end, and then on the other at variable times or points of
the stroke under control of the governor, the operation is readily understood.
When the speed of the engine increases, the balls of the governor fly farther apart,
the sleeve of the governor rises, causing the bell crank to move the rod to the
right and with it the cam, and as the cam moves horizontally on its shaft it is

page_text: caused to advance relatively in relation to the motion of the engine, by means of
the oblique slot.
This causes the cam to operate sooner and the cut-off to take place earlier in the
stroke of the engine, or, which is the same thing in effect, it reduces the quantity of
steam admitted to the piston and thus reduces the speed. When the speed falls
below its normal measure the operation of all these parts is reversed, the admission
is prolonged and increased, and the volocity restored. It is obvious that the
common gear-wheel and shafting may be employed to impart motion to the
governor-shaft without affecting the other parts of the Invention but the chain
gear is much the cheapest and most easily applied especially to old or existing
engines.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Harris Lake in the Great Seal Patent Office on the
27th June 1882.
"
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co. Patent Agents,
Southampton Buildings, London. IMPROVED MECHANISM FOR OPERATING THE
CUT-OFF VALVES OF STEAM-ENGINES." A communication from abroad by Simeon
A. Goodwin, of Philadelphia, Pennsylvania, United States of America.
This Invention relates to improvements in that class of of steam engines in
which a main-slide valve performs the functions of admission and release while
the suppression is effected by an auxiliary or cut-off valve working upon the back
of the main valve. In such engines the auxiliary valve is usually operated by a
separate excentric on the engine-shaft, and the travel is somewhat greater than
that of the main valve. According to the present Invention this excentric is
dispensed with and the cut-off valve is operated, as well as controlled, by the
governor, and the governor is driven by chain gearing, this being the cheapest and
most easily applied means, and sufficiently positive in motion to answer the
peculiar requirements of the case. To reduce the travel to a minimum so as to put
as little labor as possible upon the regulating elements of the governor, the cut-off
valve is made to ride upon, and with, the main valve so that in relation-to-the-
former the latter-is-at-rest. To the same end narrow multiple ports are employed
in place of one wide port. These ports are at right angles to the main or cylinder
ports, and the motion or travel of the cut-off is across, or at right angles to, that of
the main valve. The cut-off valve for reasons that will appear, is substantially in
equilibrium while moving to close, this being an important condition.
The object proposed by this Invention is to provide a simple and inexpensive,
yet efficient and durable, automatic valve-gear that can be applied to old or
existing, as well as to new, plain slide-valve engines.
In the accompanying Drawing
Figure 1 represents the governor with its chain gearing, the cam, the yoke and
connecting rods, the cylinder and valve-chest, with a plan of the cut-off valve on
the back of the main valve.
Figure 2 is a plan showing the cut-off ports in the back of the main valve.
Figure 3 is a vertical sectional elevation of the cylinder, steam-chest, and
governor taken at right angles to Figure 1.
Figure 4 is a vertical section of the main and cut-off valves and main valve seat
and cylinder ports, drawn to an enlarged scale.
Figure 5 is a sectional elevation, drawn to an enlarged scale, of the governor
shaft and cam to show the obliquo slot in the said shaft.
Like letters indicate the same parts throughout the Drawing.
The governor E is fixed upon the steam-pipe P as in common practice with
throttling governors. It is driven by chain gearing consisting of the sprocket-
wheel A on the main shaft of the engine, the chain D having links of equal length,
and the sprocket-wheel B, on the sbaft I of the governor. These wheels are of the
same size in order to give the governor shaft the same speed as the engine. This
shaft is tubular and carries a movable cam e which imparts a reciprocating motion
to the yoke d, and through the rod i and link h the said motion is communicated
to the cut-off valve n, which works in grooves or guides on the back of the main
valve m, which, in its turn, is operated by an excentric in the usual manner.
rod i passes through a stuffing box in the base plate of the governor, as represented
in Figure 1, and the link his pivoted to the end of the said rod. The regulating
The

page_text: elements of the governor are connected with the came through the bell crank x
and rod a, as plainly shewn in Figure 3. The rod a being loosely fitted within tho
hollow shaft I, has, near its end, a groove cut around its periphery, in which groove
works the end of a steel pin, which is screwed through one sido of the cam and
passes freely through a slot in the shaft I; this slot is seen at s in Figure 5, and
lies obliquely to the axis of the shaft, being inclined in the direction of its rotative
motion. The bell crank is connected with the lifting sleeve of the governor by a
link, as shewn in Figures 3 and 1.
The main valve has two independent series of narrow ports v, v' (Figure 2)
through its back, each series uniting respectively in one port l, l', (Figure 4) in the
face of the valve. The cut-off valve n, (Figure 1) has corresponding ports v, v²,
through it, so disposed in relation to those in the main valve that while one
series vis open, the other series v² is closed.
The cam e is so shaped as to throw the cut-off valve quickly in order first to
effect a sudden suppression of the steam, and secondly, to complete the throw
before the pressure of the steam, in the cylinder of the engine and consequently
under the valve, has fallen by expansion so as to accumulate an unbalanced'
pressure on the top of the said valve, and thereby to impose a heavy load upon the
governor. For it should be observed that when the cut-off valve commences to
make its movement there is no unbalanced pressure upon it on the end that is
open, because the steam is passing freely through its ports and there should be
none on the other end because the main valve has already closed the main steam-
port on that end before the cut-off valve has to move; but during the interval
between the suppression by the cut-off and the suppression by the main valve in
the previous movement the pressure in the port or mortise in the latter has been
falling by expansion in the cylinder, and to restore this before the next movement
the main valve seat is recessed at g, g' in order to admit steam from the chest into
the said mortise or port for the purpose of restoring the equilibrium before the
cut-off valve has to move.
The link h operates perpendicularly to the line of motion of the main valve, as
clearly indicated in Figure 1. The vibrating motion of its lower end does not
affect the motion of the cut-off valve.
The came is recessed or made smaller behind its working face, so as not to bind
between the points of its yoke, in order that it may be freely moved on its shaft
by the governor.
Bearing in mind that the main valve which has an invariable positive motion,
adinits, and exhausts the steam, and that the cut-off valve has nothing to do but
to suppress it, first on one end and then on the other at variable times or points of
the stroke under the control of the governor, the operation is readily understood.
When the speed of the engine increases, the balls of the governor fly farther apart,
the sleeve of the governor rises, causing the bell-crank to move the rod a to the
right, and with it the cam e, and as the cam moves horizontally on its shaft it is
caused to advance rotatively in relation to the motion of the engine by means of
the oblique slot 8. This causes the can to operate sooner and the cut-off to take
place earlier in the stroke of the engine, or, which is the same thing in effect, it
reduces the quantity of steam admitted to the piston, and thus reduces the speed.
When the speed falls below its normal measure the operation of all these parts is
reversed, the admission is prolonged and increased and the velocity restored.
I am aware that this gear would not be sufficiently positive to operate a cut-off
which is at the same time the admission-valve, for the last nained function must
be performed with great and invariable accuracy; but experiment has shewn that
it answers well for operating a slide valve that is substantially in equilibrium, and
that has only to perform the single duty of suppressing the steam on the back of
the main valve as herein described.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim-

page_text: First. The combination of the yoke, the cam adjustable by a governor or
otherwise, the stein or rod, the link, and the cut-off valve, substantially as shown
and described, and for the purposes specified.
Second. The combination of the sprocket-wheels and chain, with the yoke, the
adjustable cam, the link, the stem or rod and the cut-off valve, substantially as
shown and described and for the purpose specified.
Third. The link connected to the stem or rod and to the cut-off valve, and
moving freely within a space or connecting pipe between the governor and steam
chest, substantially as set forth, and for the purpose specified.
Fourth. The combination of the following elements viz-a main slido valve,
operated by an excentric and carrying upon its back a cut-off valve with multiple
or narrow ports, and mechanism operated directly by the governor to impart an
independent reciprocating motion to the cut-off valve by means of a pivoted link,
substantially as, and for the purpose described.
Fifth. The combination of the sprocket-wheels and chain, with a governor and
cut-off valve, substantially as set forth, and for the purpose specified.
In witness whereof I the said Henry Harris Lake have hereunto set my
hand and seal this Twenty seventh day of June in the year of our Lord One
thousand eight hundred and eighty-two.