Improvements in Valve Gear for Operating Corliss and other Types of Valves.
Year: 1894

page_text: Date of Application, 24th Nov., 1894
Complete Specification Left, 21st Aug., 1895-Accepted, 5th Oct., 1895 i
PROVISIONAL SPECIFICATION.
Improvements in Valve Gear for Operating Corliss and other Types
of Valves.
We JOHN COCHRANE of Grahamston Engine Works, Barrhead in the County
of Renfrew and WILLIAM CAMERON of Maryport in the County of Cumberland
Mechanical Engineer do hereby declare the nature of this invention to be as
follows:-
This invention relates to the release mechanism and arrangement of the same of
that type of gear in which the steam and exhaust valves are operated from one
eccentric with or without the intervention of a wrist plate.
The object being to ensure an automatic or variable release & closure of the steam
valves varying from zero to of the engines stroke.
Part of this invention relates to the means whereby the detent edges which bear
at certain periods on projections securely fixed to the steam valve spin lles are
caused to describe variable closed curves. The variability of the said curves
in relation to the edges of the beforementioned projections depending upon the
action of the governor.
In order to attain this; levers, which are rigidly attached to the detents, are,
connected by suitable rods to bellcianks or levers hung on a horizontal oscillating
lever, this horizontal lever may be oscillated by an eccentric suitably set in relation
to the main eccentric or it may be oscillated from a suitable point located in the
main eccentric or in its rod i.e. the rod of the main eccentric. The lever hung
on the oscillating lever besides being connected to the detents are also coupled to
the governor balls in a suitable manner. The detents are hung on levers and are
in this case operated from a wrist plate.
On release of the projection from its detent the valve is closed by a spring or by
any suitable means and is cushioned in the ordinary way.
This part of our invention is applicable to Corliss Cornish or double seated valves
sliding grid valves or any type valve operated directly or indirectly by the partial
revolution of a spindle.
In cases where we do not use a wrist plate and when we use the gear just
described we drive the steam valves by means of a link from pins located in the
exhaust valve levers; by correctly locating these pins the detent edges describe
curves similar to those obtained by the nse of a wrist plate.
Another part of this invention relates to a combination in which the detents are
not directly coupled to the governor controlled bellcranks or levers that are hung
on the horizontal oscillating lever. The detents are in this case operated by trip
levers hung on the same levers as the detents, one arm of each trip lever being
connected to the governor and to the horizontal oscillating lever in the same
manner as in the positively controlled gear. The other arm of each trip lever
bears on a suitably formed arm of the detent. On the release of the detent the
valve closes in the usual manner and on the arrival of the detent and trip lever at a
predetermined position the detents fall into gear with their projections which are
secured to the valve spindles. The detents may be caused to gear by the action of
a spring or by the action of gravity. The amount which they gear with their
projections is determined by the trip levers which are controlled by the governor.
The levers which carry the detents and their trip levers may be operated by either¨™

page_text: of the methods described in connection with the positively controlled gear and this
combination may be used to operate any of the type of valves described in connection
with the positively controlled gear.
Dated this 22nd day of November 1894.
JOHN COCHRANE.
WM. CAMERON.
Improvements in Valve Gear for Operating Corliss and other Types
of Valves.
We JOHN COCHRANE of Grahanston Engine Works, Barrhead in the County
of Renfrew, Engineer and WILLIAM CAMERON of Maryport in the County of
Cumberland Mechanical Engineer, do hereby declare the nature of this invention
and in what manner the saine is to be performed, to be particularly described and
ascertained in and by the following statement :-
This invention relates to the release mechanism and arrangement of the same of
that type of gear in which the steam and exhaust valves are operated from one
eccentric with or without the intervention of a wrist plate.
The object being to secure an automatic and variable release and closure of the
steam valves varying from zero to of the engine stroke.
Part of this invention relates to the means whereby the detent edges, which bear
at certain periods on projections securely fixed to the steam valve spindles, are
caused to describe variable closed curves. The variability of the said curves in
relation to the edges of the before-mentioned projections depending upon the action
of the governor.
In order to attain this, levers, which are rigidly attached to the detents, are
connected by suitable rods to bellcranks or levers hang on a horizontal oscillating
lever. This horizontal lever may be oscillated by an eccentric suitably set in
relation to the main eccentric. We prefer to oscillate it from a suitable point
located in the eccentric or in its rod, that is, in the rod of the eccentric used for
operating the steam and exhaust valves. The levers hung on the oscillating lever,
besides being connected to the detents, are also coupled to the governor balls in a
suitable manner. The detents are hung on levers that are hung on the valve spindle
brackets, and are in this case operated by a wrist plate.
In cases where we do not use a wrist plate, we get all the advantages of the gear
before described. by driving the steam valves by means of a link from pins located
in the exhaust valve levers. The links couple the exhaust valve levers to the
levers on which the detents are hung. These detents engage with and are released
from projections securely fixed to the steam valve spindles at certain periods. By
correctly locating the position of these pins, the detents engage quickly with their
projections, and their edges describe closed curves similar to those obtained when
when we use a wrist plate. The detents are rigidly attached to their levers, which
are connected to the bellcranks hung on the horizontal oscillating lever, in precisely
the same manner as in the arrangement with the wrist plate.
It is to be noted that in both arrangements, the detents are mechanically or
positively engaged with and released from their projections, and consequently we
are enabled to run the engines to which our invention is applied at a much greater
number of revolutions per minute than would be possible if the detents were not
positively engaged and released. Owing to this, and to the certainty of the action,
the engines are especially adapted for electric light installations, also for driving
electric transmission plant.
Another part of our invention relates to combinations in which the detents are
not directly or positively coupled to the governor controlled bellcranks or levers

page_text: that are hung on the horizontal oscillating levers. In this case the detents are
operated by trip levers which are not rigidly attached to the detents. We prefer
to hang these levers on the same pin on which the detents are hung. They may
be, however, hung on pins located on any suitable part of the levers which carry
the detents. The trip levers are coupled to the bellcranks in exactly the same
manner as in the beforementioned combinations, but owing to the trip levers not
being rigidly attached to their detents. the curves described by the detent edges
are not closed. The governor in this instance merely determines the amount which
the detents engage with their projections, and the point at which they are released.
The detents fall into gear with their projections by gravitation or by the action of
a spring. In this case the extent of automatic release can be extended beyond ot
the piston's stroke, but the speed at which the engine can be run must be less than
when fitted with the positively controlled detent. The levers which carry the
detents and their trip levers may be operated by either of meth ads described in
connection with the positively controlled gear. On release of the detents from
their projections, the valves in all cases are closed by spring, or atmospheric
pressure by means of a vacuum dash pot, and are cushioned in the usual manner.
Our invention is applicable to Corliss, Cornish, or double-seated valves, sliding
grid valves, or any type of valve operated directly or indirectly by the partial
revolution of a spindle.
As the valves are operated by one eccentric, and the range of automatic expansion
is from zero to of the pistons stroke, the release of the detents may take place
either during the opening or closing periods of the steam valves travel. This is
attained by giving the detents two movements, one directly from the eccentric
which opens and closes the steam valves; the other, hereafter called the secondary
movement, at right angles to the first, determines the engagement and release of
the detents with their projections. This movement is given to the detents by the
bell cranks and horizontal oscillating lever, which receives its movements from any
suitable moving part of the engine. We prefer to operate it, as before stated, from
the eccentric rod. In order that the detents may be released automatically at any
point of the pistons stroke, according to the load on the engine, we place the bell
cranks under the control of a governor The governor thus controls the amount of
overlap with which the detents engage with their projections, and therefore
determines the point of release. As the secondary movement given to the detents
by the oscillating lever is a constant, the resultant movement of the detent edge is
a close cut ve. The variability of the release point depends upon the amount of
overlap the detents have at the instant of engagement for any given point of
release, that is, the path described by the detent edge leaves the projection earlier
the less the amount of overlap.
In order that our invention may be better understood, we herewith proceed
to describe the accompanying drawings. Similar letters indicate similar parts
throughout the drawings.
Fig. 1 Sheet 1 illustrates the positively controlled gear, the valves being operated
by a wrist plate.
a a¹ are the detents with the rigidly connected levers bb and hung to the levers ce
operated from the wrist plate, the levers coupled to the bellcranks e e by rods.
The bellcianks ee are hung on the horizontal oscillating lever f which is oscillated
by the 1od g from the eccentric rod ; the bellcranks are connected to the
governor by the rod i. The left hand detent a' is engaged with its projection d",
the left hand steam valve being opened the amount of lead, the right hand steam
valve is closed, the right hand detent a being clear of its projection d*.
Fig. 2 Sheet 1 shews the bellcranks and horizontal oscillating lever with the
connection to the governor to a larger scale.
Figs. 3 and 4 Sheet 1 shews the arrangement we prefer of detent and lever when
they are not rigidly connected together. They are hung on the pin which is
secured to the lever c, the detent a is formed with a finger k armed with a steel
face, a similar finger is also formed on the lever b so that the movement of the

page_text: belleranks is communicated to the detent a through the lever by the steel faces on
the lever and detent a. The movement so communicated is such that will only
release the detent a from its projection d2 and determine the extent of their
engagement.
It will be obvious that the detent a and lever b may be hung on different pins
secured in the lever c, the finger being so formed to give the same movement to the
detent as when hung on the same pin.
The projection d' is secured to the valve spindle m.
Fig. 1 Sheet 2 illustrates a combination in which the wrist plate is dispensed
with. The levers cc, on which the detents a a with their rigidly attached levers b b
are hung, are driven by means of links from the exhaust valve levers n n. By
correctly locating the centres of the steam and exhaust valves and the points on
the exhaust valve levers from which the levers c c are driven, the detents a a are
brought quickly into contact with their projections *d*. The levers bb are
operated in precisely the same manner and by the same means as described in
connection with the drawings in Sheet 1.
Figs. 2 and 3 Sheet 2 shew the release mechanism in a larger scale.
The detent a and trip lever shewn by Figs. 3 and 4 Sheet 1 can also be applied
to the arrangement just described in connection with Sheet 2.
Fig. 1 Sheet 3 shews a modification of that shewn on Sheet 2. The horizontal
oscillating leverf with its belleranka e e being placed equidistant from each of the
detent levers and is driven from the eccentric rod by means of a bellcrank o.
This arrangement is a convenient one when the cylinders are arranged tandem.
Fig. 1 Sheet 4 shews a combination which the horizontal oscillating lever
is equidistant from each of the detent levers. the valves being operated by
a wrist plate. The action and description given above holds good for this
combination.
Fig. 2 Sheet 4 shews another modification; the detents a a in this case take the
form of a hook. The parts and action in this are similar to the preceding com-
binations. It will also be obvious that the horizontal oscillating lever f may be
transferred to the position shewn in Fig. 1 Sheet 1.
Fig. 3 Sheet 4 illustrates a combination in which the steam valves are of the
Cornish or double-seated type, and are operated by a wrist plate. The levers e c
are hung on the spindles and receive their movement from the wrist plate, the
detents a with their rigidly attached levers bare hung on c, the projections d² d*
form levers and are hung on the spindles r r, one end of the projections being
suitably coupled to the valve spindles pp, thus the movement of the wrist plate is
communicated to the valves through the detents. The left hand detent a' is
engaged with its projection d and the valve is open the amount of the lead. The
secondary movement of the detents is given by a horizontal oscillating lever
precisely the same manner as in the other combinations, and on release of the
detent from its projection the valve is closed by a spring and cushioned by a dash-
pot. It is obvious that the governor and oscillating lever with its bellcranks may
be removed to a position similar to that shewn in Fig. 1 Sheet 1, and the
Oscillating lever driven. directly by the link g without the intervention of the
bellcrank o.
in
It is to be understood that the release gear shewn by Figs. 3 and 4 in Sheet 1
may be applied to any of the combinations in place of the rigidly attached detent
and lever.
It will also be apparent that the governor may be replaced by a hand-wheel
and suitable mechanism by which the release may be controlled by hand instead of
automatically.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what we
claim is ;-
T
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page_text: under the control of a governor or other regulating device substantially as and for
the purpose set forth.
2nd. The combination of a horizontal oscillating lever and two bellcranks
substantially as shewn and described in connection with the annexed drawings.
3rd. The combination of a horizontal oscillating lever, two bellcranks, coupling
rods, and detents with their rigidly connected levers, substantially as shewn and
described in connection with Fig. 1 Sheet 1 and Figs. 1, 2 & 3 Sheet 4 of the
annexed drawings.
4th. In a release gear or escapement, the combination of two levers, a coupling
link, a detent with a lever rigidly attached thereto, and a projection or lever securel
to the valve spindle, substantially as and for the purpose set forth.
5th. In a release gear or escapement, the combination of two levers, a coupling
link, a detent with a lever rigidly attached thereto, and a projection or lever secured
to the valve spindle, substantially as shewn and described in connection with
Figs. 2 & 3 Sheet 2 of the annexed drawings.
6th. The combination as in the 4th claiming clause with a horizontal oscillating
lever, hellcrank and coupling rods substantially as shewn and described in connection
with Fig. 1 Sheet 2 and Fig. 1 Sheet 3 of annexed drawings.
7th. The combination of a horizontal oscillating lever, two bellcranks, coupling
rods, and detents with their levers free, substantially as shewn and described in
connection with Figs. 3 & 4 Sheet 1 of the annexed drawings.
8th. The combination as in the 6th claiming clause but with the detents free
from their levers substantially as shewn and described in connection with the
drawings annexed.
JOHN COCHRANE.
WM. CAMERON.