Improvements in Releasing Gear, applicable to Corliss or Oscillating Circular and other Valves.
Year: 1893

page_text: Date of Application, 10th Mar., 1893
Complete Specification Left, 9th Dec., 1893-Accepted, 10th Feb., 1894
PROVISIONAL SPECIFICATION.
Improvements in Releasing Gear, applicable to Corliss or Oscillating
Circular and other Valves.
A communication from abroad by LOUIS IRVING SEYMOUR, of Kimberley, Cape
Colony, South Africa, Mechanical Engineer.
I, ALFRED GEORGE BROOKES of 55 & 56 Chancery Lane in the County of
London, Chartered Patent Agent, do hereby declare the nature of this invention
to be as follows:-
This invention relates to improvements in connection with or for operating the
mechanism of ordinary Corliss or other valve gears, used in rotative steam engines,
where the inlet valve is fitted with trip gear, and is closed by the action of a
vacuum dash pot, spring or other equivalent device, the exhaust valve being worked
with a positive motion from the engine in the usual manner.
These improved means enable the admission of steam to the cylinder to be con-
trolled with great accuracy, the cut off of the inlet valve in each end of the cylinder
being equalized and made capable of taking place, if necessary, at any point of
the engine stroke between zero and full stroke.
For whereas in ordinary Corliss gears worked by eccentrics, the angularity of
the connecting rod causes the variation of the cut off at one end of the cylinder
to differ from the variation at the other end, an unequal amount of steam is thereby
admitted to each end of the cylinder at any other point of cut off than that at
which the gear was set. Further, if a great range of cut off is required it is
necessary to drive the inlet valves by a separate eccentric from that by which the
exhaust valves are driven thus occasioning multiplication of parts.
This arrangement of the improved releasing gear may be applied to a reversing
engine for winding, in connection with the ordinary link motion and Corliss valve
gear, although it may also be extended to any valve gear having a releasing drop
valve, such as a stamper, or other valve.
Supposing there is a tail shaft forming an extension of the main crank shaft of
a winding engine (a winding engine being the device selected for illustration in this
particular case) to show with what facility the gear may be applied to reversing
engines as well as engines only required to run in one direction.
There is provided a small eccentric keyed on the said tail shaft in the same
plane as the main crank of the engine is keyed to its shaft, so that the motion of
the cross-head and its extension is exactly synchronous with the motion of the
piston in the cylinder.
This is accomplished by making the throw of the eccentric of the same ratio
to the length of its eccentric rod as the throw of the main crank is to its
connecting rod.
The cross head at its outer end carries a T lever pivoted in its end, which is
connected in this case by a rod to a bell crank lever coupled to the throttle valve
lever so that the T lever may oscillate in position within certain defined limits, or its
outer end may oscillate in a plane higher or lower than the normal at the will of
the engine driver.
This end of the T lever may in the case of an automatically controlled
engine, be attached directly to the ordinary governor by the rod connected to the
throttle valve lever provided for that purpose.
Two small cut off rods are attached to the upper and lower ends of the

page_text: The one, say of the upper one, forms the connection to the cut-off gear or
releasing mechanism on the front end of the cylinder, and the other, say the lower
one, by means of two small bell cranks and a connecting rod forms a similar
attachment to the releasing gear on the back end of the cylinder.
So far the motion of the upper rod and the connecting rod is synchronous with
the motion of the main piston, no matter in what direction it moves.
To the outer end of the spindle or stem of the usual cylindrical oscillating
Corliss inlet valve, is keyed a lever carrying a hardened (say) steel plate which
engages the usual crab claw, and at its outer end is connected to an ordinary
dashpot by rod in the usual way.
Riding loosely on the valve stem centre is a lever which carries the crab claw.
This lever being driven from a wrist plate.
So far there is no deviation from the ordinary Corliss valve gear as usually
applied in all its variations.
The valve spindle has a hole which is of suitable dimensions, say 1 inches
diameter bored longitudinally and in one side a portion of the spindle is removed
to allow a small lever to be inserted, so that the motion of the rod alluded to as
the upper one is transferred by means of the small lever of the bell crank to a
longitudinal motion of the cylindrical slide back and forth in the centre of the
valve stem synchronous with the piston in the cylinder, no matter what position the
valve stem may be in its oscillation.
The outer end of the cylindrical slide is bevelled off, and shoves a small
cylindrical pin against the crab claw, thereby releasing the lever keyed to the
valve stem, and allowing the dash pot to close the steam valve in the usual
manner. The said pin slides freely in the valve stem arm; is slightly rounded at
each end and is prevented from moving too far in or out by a second pin working
against a flat in the side of the first named pin or like device. When the small
lever stands in its mid position the cylindrical slide should just have pushed the
pin far enough out to disengage the crab claw.
Now if the T lever occupies the mid position, the small lever will vibrate equally
each side the centre line, and the releasing of the gear take place at the middle of
its travel, or in the middle of the stroke of the piston; if the rod connected to the
throttle valve lever is moved downward and retained at its lowest point, the rod,
called here the upper one, will cause the small lever to vibrate in an are extending
from the centre line of its motion to the extreme point of its travel in which case
the release takes place at the commencement of the stroke.
If the rod connected as aforesaid to the throttle valve lever be raised to its
highest position and retained, the lever will then vibrate from the centre line of its
motion to its uppermost position during one stroke of the piston and the release
will therefore not take place till the end of the stroke. The cut-off may thus be
varied from zero point to full stroke, and is equal in each end of the cylinder, no
matter at what point it is desired.
It will be understood that the connecting rod operates the back inlet valve in the
same manner as it operates the front valve, the cylindrical slide of one valve moving
in an opposite direction to the corresponding slide of the other valve.
One side of the said slide is cut away in order to allow the pin to return to the
position when cutting off at the earlier points in the stroke, otherwise the crab
claw could not engage the valve stem lever when cutting off very early in the
stroke.
According to a modification of my invention, the valves are worked from a lay
shaft which is driven from, and has the same motion as the main crank shaft. The
inlet and exhaust valves are placed in the cylinder heads in order to minimise the
effect of clearance as much as possible, and are not oscillating or semi-rotative as in
ordinary Corliss engines, but are gridiron slide valves, having a sliding motion
transversely across the face of the cylinder head.
Each exhaust valve has a direct and positive motion imparted to it from a cam
on the lay shaft.

page_text: Each inlet valve stem is not connected to its own head direct, the latter being
driven positively by the inlet valve cam, and the connection between the valve
stem and its head or slide block being made by means of the tripping mechanism.
The shape of each inlet valve cam is such as to move its slide block so as to give
equal points of opening and closing at each end of the cylinder in respect of the
stroke of the piston.
In other words the front end inlet cam is different from the back end inlet cam by
such an amount that the effect of angularity of the connecting rod on the motion of
the valves is neutralized and consequently the front and back valves have equal motions
with each other relatively to the piston of the engine. The releasing mechanism
consists of an eccentric on the lay shaft having the length of its eccentric rod from
centre to centre in the same proportion to the stroke of the eccentric as the engine
connecting rod bears to the length of stroke of the engine; attached to the eccentric
rod end is a sliding cross head fitted with a pin on which is centred a square block.
This block works in a diagonal slot which is contained in a sliding piece, the latter
being so guided as only to be able to move longitudinally in the direction of the
piston rod. The eccentric has, therefore, the effect of moving the sliding piece in
a direction at right angles to the plane of the motion of the eccentric or longitudinally
in the direction of the piston rod.
Resting in this sliding piece are two cut off rods which actuate the trips or detents
for releasing the inlet valves.
These cut off rods move with the same relative speed and in exactly the same
manner as the piston moves in respect of its stroke in the cylinder, due to the action
of the eccentric before mentioned; and by moving the cut off rods (either by hand
or by a connection from a governor) to or from the inlet valve heads, the cut off
will be made correspondingly earlier or later, and will be equalized at each end of
the cylinder and may take place at any point between zero and full stroke.
Having been released in the manner just described the closing of the inlet valve
may be effected by means of a vacuum dash pot, or by a spring, or by having that
part of the valve spindle which passes through the stuffing box nearest the lay
shaft larger than that passing through the back end stuffing box; and the steam
always pressing on the annulus formed by the difference of the two areas forms a
constant load forcing the spindle towards the lay shaft thus producing the motive
power requisite for closing the valve.
A dash pot is provided at the back end of the spindle merely to form a cushion
against too violent a motion of the spindle.
Dated the 10th day of March 1893.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Releasing Gear, applicable to Corliss or Oscillating
Circular and other Valves.
A. communication from abroad by LOUIS IRVING SEYMOUR, of Kimberley, Cape
Colony, South Africa, Mechanical Engineer.
I, ALFRED GEORGE BROOKES of 55 & 56 Chancery Lane in the County of
London, Chartered Patent Agent, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:---
This invention relates to improvements in connection with or for operating the
mechanism of ordinary Corliss or other valve gears, used in rotative steam engines,
where the inlet valve is fitted with trip gear, and is closed by the action of a

page_text: with a positive motion from the engine in the usual manner.
These improved means enable the admission of steam to the cylinder to b
controlled with great accuracy, the cut off of the inlet valve in each end of th
cylinder being equalised and made capable of taking place, if necessary, at an
point of the engine stroke between zero and full stroke by a motion synchronou
with that of the piston.
For whereas in ordinary Corliss gears worked by eccentrics, the angularity o
the connecting rod causes the variation of the cut off at one end of the cylinder t
differ from the variation at the other end, an unequal amount of steam is thereby
admitted to each end of the cylinder at any other point of cut off than that at which
the gear was set.
Further, if a great range of cut off is required it is necessary to drive the inle
valves by a separate eccentric from that by which the exhaust valves are driver
thus occasioning multiplication of parts.
DESCRIPTION OF THE DRAWINGS.
Fig. 1, Fig. 14, Fig. 1B shew a side view partly in section of the cylinder of a
winding engine with my invention applied thereto the drawing being divided on the
lines 1-1 and 2-2 for convenience in delineation and Figs. 2, 24 and 2" a corre-
sponding external side view of the winding engine with a reversing engine for
operating the link motion, the drawing being similarly divided on the lines 3-3
and 4-4 for like convenience. Figs. 3 and 34 shew a side view divided on the
line 5-5 and Figs. 4 and 4^ a plan divided on the line 6-6.
Fig. 5 is a front of the inlet valve bonnet and gear. Fig. 6 is a vertical section
of the same taken on the line A* A* of Fig. 5. Fig. 7 shews a plan view with the
left hand portion thereof in section taken on the line B* B* Fig. 5.
Fig. 8 shews vertical sectional views of detail portions taken on the line C* C* of
Fig. 6.
Fig. 9 is a partial sectional view of the rod L connected by the pipe S with the
dash pot.
This arrangement of the improved releasing gear may be applied to a reversing
engine for winding, in connection with the ordinary link motion and Corliss valve
gear, although it may also be extended to any valve gear having a releasing drop
valve, such as a stamper or other valve.
A is a tail shaft forming an extension of the main crank shaft of a winding engine
(a winding engine being the device selected for illustration in this particular case)
to shew with what facility the gear may be applied to reversing engines as well as
engines only required to run in one direction.
B is a small eccentric keyed on the said tail shaft A in the same plane as the
main crank of the engine is keyed to its shaft, so that the motion of the crosshead C
and its extension D is exactly synchronous with the motion of the piston in the
cylinder.
This is accomplished by making the throw of the eccentric of the same ratio
to the length of its eccentric rod as the throw of the main crank is to its
connecting rod.
The crosshead D at its outer end carries a T lever E pivoted in its end at E',
which is connected in this case by a rod F, to a bell crank lever coupled to the
throttle valve lever so that the T lever may oscillate in the position shewn in
Fig. 1, 14, 1B within certain defined limits, or its outer end may oscillate in a plane
higher or lower than the normal at the will of the engine driver.
When the handle lever F¹ is in its upright position, as shewn in Figs. 14 and 24
the lever F is in its horizontal position and capable of oscillating upon its fixed
centre within the distance allowed by the stops FF: the lost motion of the
rod F being taken in the slot Fº.

page_text: When the handle lever F' is pushed over, the pin F' is brought into operative
position against the end of the slot F and cut off commences: the further the
handle is pushed over the shorter being the cut off.
When the handle lever F is returned to its vertical position the lever F2 and its
attached parts are brought back to their normal position by means of the balance
weight F³.
The outer end of the T lever may in the case of an automatically controlled
engine be attached directly to the ordinary governor by the rod F connected to the
throttle valve lever provided for that purpose.
G. G' are two small cut off rods attached to the upper and lower ends of the
T lever E.
The one, the upper-G forms the connection to the cut-off gear or releasing
mechanism on the front end of the cylinder, and the other G' the lower one, by
means of two small bell cranks and a connecting rod G² forms a similar attachment
to the releasing gear on the back end of the cylinder.
So far the motion of the upper rod G and the connecting rod G2 is synchronous
with the motion of the main piston, no matter in what direction it moves.
As shewn in Figs. 5, 6, and 7 to the outer end of the spindle or stem H of the
usual cylindrical oscillating Corliss inlet valve, is keyed the lever I carrying the
hardened (say) steel plate J which engages the usual crab claw K and at its outer
end is connected to an ordinary dash pot T by the rod L in the usual way as is
shewn by Fig. 1, 1A 1B.
The pin M is connected to the wrist plate as shown in Figs. 1 and 14.
Riding loosely on the valve chest bonnet is a lever U which carries the crab
claw K. This lever U being driven from a wrist plate.
So far there is no deviation from the ordinary Corliss valve gear as usually
applied in all its variations.
The valve spindle H has a hole which is of suitable dimensions say 11 inches
diameter bored longitudinally as shewn and in one side a portion of the spindle is
removed to allow a small lever N to be inserted, so that the motion of the rod G
alluded to as the upper one is transferred by means of the small lever N of the
bell crank O to a longitudinal motion of the cylindrical slide P back and forth in
the centre of the valve stem H synchronous with the piston in the cylinder no
matter what position the valve stem may be in its oscillation.
The outer end of the cylindrical slide P is bevelled off as shewn and shoves a
small cylindrical pin Q against the crab claw K thereby releasing the lever I
keyed to the valve stem and allowing the dash pot T to close the steam valve in
the usual manner. The said pin slides freely in the valve stem arm I, is
slightly rounded at each end and is prevented from moving too far in or out by a
pin R working against a flat in the side of the first named pin Qor like device.
When the small lever N stands in its mid position the cylindrical slide P should
just have pushed the pin Q far enough out to disengage the crab claw K.
Now if the T lever E occupies the mid position shewn the small lever N will
vibrate equally each side the centre line, and the releasing of the gear take place
at the middle of its travel, or in the middle of the stroke of the piston.
If the rod F connected to the throttle valve lever is moved downward and
retained at its lowest point, the rod G, called here the upper one, will cause the
small lever N to vibrate in an arc extending from the centre line of its motion to
the extreme point N' of its travel in which case the release takes place at the
commencement of the stroke.
If the rod F connected as aforesaid to the throttle valve lever be raised to its
highest position and retained, the lever N will then vibrate from the centre line of
its motion to its uppermost position N2 during one stroke of the piston, and the
release will therefore not take place till the end of the stroke.
The cut off may thus be varied from zero point to full stroke, and is equal in
each end of the cylinder, no matter at what point it is desired.
It will be understood that the connecting rod G' operates the back inlet valve in

page_text: the same manner as the rod G¹ operates the front valve the cylindrical slide P of
one valve moving in an opposite direction to the corresponding slide P of the other
valve.
One side of the said slide P is cut away as shewn in order to allow the pin Q to
return to the position shewn in the front view Fig. 5 when cutting off at the earlier
points in the stroke otherwise the crab claw K could not engage the valve stem
lever I when cutting off very early in the stroke.
According to a modification of my invention the valves are worked from a lay
shaft which is driven from, and has the same motion as the main crank shaft. The
inlet and exhaust valves are placed in the cylinder heads in order to minimise the
effect of clearance as much as possible, and are not oscillating or semi-rotative as
in ordinary Corliss engines, but are gridiron slide valves, having a sliding motion
transversely across the face of the cylinder head.
Each exhaust valve has a direct and positive motion imparted to it from a cam
on the lay shaft.
Each inlet valve stem is not connected to its own head direct, the latter being
driven positively by the inlet valve cam, and the connection between the valve stem
and its head or slide block being made by means of the tripping mechanism to be
hereinafter more fully described. The shape of each inlet valve cam is such as
to move its slide block so as to give equal points of opening and closing at each
end of the cylinder in respect of the stroke of the piston.
In other words the front end inlet cam is different from the back end inlet cam
by such an amount that the effect of angularity of the connecting rod on the
motion of the valves is neutralized and consequently the front and back valves
have equal motions with each other relatively to the piston of the engine. The
releasing mechanism consists of an eccentric on the lay shaft having the length of
its eccentric rod from centre to centre in the same proportion to the stroke of the
eccentric as the engine connecting rod bears to the length of stroke of the engine;
attached to the eccentric rod end is a sliding cross head fitted with a pin on which
is centred a square block. This block works in a diagonal slot which is contained
in a sliding piece, the latter being so guided as only to be able to move longi-
tudinally in the direction of the piston rod. The eccentric has, therefore, the
effect of moving the sliding piece in a direction at right angles to the plane of
the motion of the eccentric or longitudinally in the direction of the piston rod.
Resting in this sliding piece are two cut off rods which actuate the trips or
detents for releasing the inlet valves.
These cut off rods move with the same relative speed and in exactly the same
manner as the piston moves in respect of its stroke in the cylinder, due to the
action of the eccentric before mentioned; and by moving the cut off rods (either
by hand or by a connection from a governor) to or from the inlet valve heads, the
cut off will be made correspondingly earlier or later, and will be equalized at each
end of the cylinder and may take place at any point between zero and full stroke.
Having been released in the manner just described the closing of the inlet valve
may be effected by means of a vacuum dash pot, or by a spring, or as is shewn in
the accompanying drawings by having that part of the valve spindle which passes
through the stuffing box nearest the lay shaft larger than that passing through the
back end stuffing box; and the steam always pressing on the annulus formed by
the difference of the two areas forms a constant load forcing the spindle towards
the lay shaft thus producing the motive power requisite for closing the valve. A
dash pot is provided at the back end of the spindle merely to form a cushion against
too violent a motion of the spindle.
Fig. 10 is a longitudinal section shewing the invention applied to the cylinder of
a horizontal engine taken through the cylinder, cylinder heads, and valves.
Fig. 11 is a transverse section through the cylinder looking toward the cylinder
head.
Fig. 12 is an elevational plan of the cylinder, lay shaft and gear.
Fig. 13 is a plan view partly in section to a larger scale showing the releasing or

page_text: trip mechanism and a sufficient amount of the inlet valve heads and stems to
indicate the connection between them and the trip mechanism.
Fig. 14 is a sectional view on the line X X of Fig. 13 shewing the eccentric,
and giving a section through the sliding crosshead and clearly showing the pin and
block which fit into the diagonal slot before mentioned.
a a are the inlet valves which are of substantially ordinary construction, and
b, b the exhaust valves also of a construction substantially ordinary both being of
the gridiron type, having a sliding motion in the direction of the axis of its valve
stem and both being placed in the cylinder heads c, c.
d is that part of the inlet valve spindle which, being larger than the back part e
forms the annulus caused by the difference of the two areas and on which the
steam acts, forcing the spindle continually towards the lay shaft t.
A dash pot, the outside configuration of which is shewn at but as the internal
construction is of the ordinary kind it is not shewn, is attached to the rod e for the
purpose of cushioning the motion of the valve spindle d. The inlet valve head g
is detachable from the spindle d being retained in position relatively thereto by
means of the sleeve g the detachment being effected by the trip gear h sliding
across the end of the spindle d, thus releasing it and allowing the steam pressure to
force it into the recess provided for it. i, j are respectively the inlet and exhaust
valve cams mounted on shaft t, and is the eccentric, the length of whose rod k¹
from centre to centre indicated by the dotted line r, is in the same proportion to
its radius s as the engine connecting rod is to the length of crank. The eccentric
actuates the sliding cross head which is fitted with a pin m and square block m'
shown in Figs. 13 and 14. This block m' by moving in the diagonal slot in the
sliding piece n converts the motion of the eccentric into a travel of the two cut off
rods oo which thus move synchronously with the piston in the cylinder w.
small bell cranks p, p are fixed in the sliding piece n for the purpose of varying the
position of the detents h by means of the cut off rods oo to which they are
attached. A light spiral spring o' is coiled around each cut off rod o lightly
pressing it against the inner bell crank arm p for the purpose of keeping it up to
its work, the outer arm of the bell crank p is actuated either by hand or by
connection from a governor.
Two
In Fig. 14 a hand lever g is shewn for the purpose of varying the position of
the bell cranks p, but if necessary this lever q may be replaced by one actuated
from the governor not shewn; and it is evident that any alteration in the position
of these cut off rods o, o, will cause a corresponding alteration in the point of
cut off.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I wish it to be understood
that I do not confine myself to the exact methods of construction shown on the
drawings as they may be modified to suit different circumstances, I declare that
what I claim is :-
1. In a rotative steam engine valve gear an eccentric or cam mounted on a shaft
moving in unison with the main crank shaft said eccentric or cam actuating cut off
rod and tripping mechanism connected thereto in the same relative speed and in
exactly the same manner as the piston moves in respect to its stroke in the cylinder
and thereby effecting an equalized cut off at each end of the cylinder and a range
of variation of cut off from zero to full stroke substantially as described and
illustrated.
2. In a valve gear for a rotative steam engine cams of such a shape as will give
equal motions to the front and back inlet valves relatively to the piston movement,
in combination with trip or releasing mechanism moving in the same relative speed
as the piston, substantially as described and illustrated.
3. The herein described improvements in valve gear of rotative steam engines;
whereby facility is attained for cutting off equally in each end of a cylinder and
at any desired range, from zero to full stroke by a cut off arrangement operated

page_text: synchronously with the motion of the piston substantially as described and
illustrated by the drawings.
Dated the 9th day of December 1893.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.