Improvements in Valve Gear of the Corliss Type.
Year: 1899

page_text: Date of Application, 18th Jan.,
1899
Complete Specification Left, 18th Oct., 1899-Accepted, 18th Nov., 1899
PROVISIONAL SPECIFICATION.
Improvements in Valve Gear of the Corliss Type.
I, CHARLES DAVY, of 6, Severn Road, Sheffield, in the County of York,
Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to Corliss valve gear and has for its object to relieve
the valve spindle of all bending stress and leave it subjected only to the torsional
stress incidental to turning the valve in its seat. For this purpose the trip
lever (or other lever by which the valve spindle is turned) is not keyed upon
the spindle but is pivoted about a fixed bearing independent of, but concentric
with, the valve spindle and is coupled to the valve spindle by a clutch coupling
such as to permit a motion of translation of the one part relatively to the other
part in a plane perpendicular to the axis of the valve spindle so that no side
stress will be imparted to the valve spindle, the fixed bearing alone resisting
all bending stresses due to the force exerted in opening the valve and compressing
the dash-pot spring (or equivalent steam cylinder) or to the expansion of the
spring on closing the valve after the trip gear is released.
With this object the trip lever is pivoted upon the end of the fixed bracket
through which the valve spindle passes, the motion lever by which the trip lever
is operated being pivoted upon the boss of the trip lever (or it may be upon
the same fixed fulcrum) and the clutch coupling by which the trip lever is
connected to the valve spindle is formed by diametrical lugs on a face plate
keyed on the valve spindle and similar lugs on the boss of the trip lever, the
lugs on the one being diametrically at right angles to those on the other and
these lugs engaging in corresponding grooves in the opposite faces of an inter-
posed disc loose about the valve spindle.
In some cases, as for instance where it is possible to arrange the motion rod
and dash-pot rod parallel to each other, the coupling may be simplified by the
omission of the intermediate disc in which case the centre line of the driving
lugs and grooves should be parallel with the rods, as near as may be, at the
moment when the trip gear is released.
Dated this 18th day of January 1899.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
COMPLETE SPECIFICATION.
Improvements in Valve Gear of the Corliss Type.
I, CHARLES Davy, of 6, Severn Road, Sheffield, in the County of York,
Engineer, 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:-
My invention relates to Corliss valve gear and has for its object to relieve
the valve spindle of all bending stress and leave it subjected only to the torsional
stress incidental to turning the valve in its seat. For this purpose the trip
lever (or other lever by which the valve spindle is turned) is not keyed upon
the spindle but is pivoted about a fixed bearing independent of, but concentric
5071

page_text: with, the valve spindle and is coupled to the valve spindle by a clutch coupling
such as to permit a motion of translation of the one part relatively to the other
part in a plane perpendicular to the axis of the valve spindle so that no side
stress will be imparted to the valve spindle when, in consequence of the bearings
becoming worn or from other cause, the parts referred to assume positions
eccentric to one another; the fixed bearing alone resisting all bending stresses
due to the force exerted in opening the valve and compressing the dash-pot
spring (or equivalent steam cylinder) or to the expansion of the spring on closing
the valve after the trip gear is released.
Reference is to be had to the accompanying drawings forming part of this
specification wherein are illustrated three modes of applying the invention;
Figures 1 and 2 shewing in axial section and sectional end view respectively so
much of the spindle and adjacent parts pertaining to one of the steam-admission
valves of a Corliss engine as is necessary in order to explain the invention.
Figures 3 and 4 are similar views shewing one modification and Figures 5 and 6
are also similar views shewing another modification of the invention. Figure 7
is a perspective view of the disc forming the universal clutch coupling. Similar
letters of reference denote like parts in all the figures.
The valve spindle A is journalled in the bracket B which is bolted to the end
of the valve chest C. The motion lever D is not keyed on the valve spindle
but is mounted so as to be capable of oscillating concentrically therewith about
a fixed bearing formed by a cylindrical prolongation
of the bracket B.
In the example illustrated in Figures 1 and 2 the lever D) is coupled at one
end by pine and rod E to the driving and trip gear by means of which the lever
is oscillated in one direction for the purpose of opening the valve and released
at the moment of cut-off, and at the other end is coupled by pin f and rod F
to the dash-pot plunger and spring whereby the lever is oscillated in the other
direction for the purpose of closing the valve. Upon the outer end portion
of the valve spindle A is keyed a face plate G between which and the motion
lever D is interposed a clutch coupling such that any relative displacement of
the axes of spindle A and lever D resulting from wear of the working parts or
otherwise will not cause a bending stress to be thrown upon the spindle A. To
this end the coupling consists of a disc H having a central aperture whose
diameter is sufficient to leave a substantial clearance around the spindle A,
the disc H being maintained in driving connection on the one hand with the
lever and on the other with the face plate G (which virtually forms part of
the spindle A) by the engagement of a pair of diametrical lugs d on the outer
face of lever D and of a similar pair of lugs y on the inner face of plate G with
corresponding diametrical grooves h formed on the inner and outer faces of the
disc H respectively, the grooves on the one face being at right angles to those
on the other face (as indicated in the separate view of the disc shewn in Figure 7)
so that whatever the amount of eccentricity of spindle A and lever D relatively
to one another, the disc H will maintain a perfect driving connection between
them without transmitting any side stress from one to the other.
In the example illustrated in Figures 3 and 4 the motion lever D which is
duplex, oscillates upon a pair of bearings i i formed respectively on the inner
and outer ends of the boss I of the trip lever J which is mounted upon the fixed
bearing b. The lever D is coupled by pin e to the eccentric rod E whereby the
spindle A is rotated in a direction to open the steam valve, and the arm J¹ of
lever Jis coupled by pin f to the dash-pot rod F whereby the spindle A is
rotated in the opposite direction so as to close the valve. In this case the
coupling disc H maintains driving connection on the one hand with the face
plate G keyed on the end of spindle A and on the other hand with lever J, by
the engagement with diametrical grooves h (Figure 7) at right angles to one
another on the opposite faces of the disc, of pairs of diametrical lugs gon
plate G and on lever J respectively, the central aperture of disc H leaving as
before a substantial clearance / around the spindle A. In this case levers D

page_text: and Jare maintained in driving connection with one another through the medium
of a detent K mounted between the members of lever D so as to be normally
presented in the path of lever J whence it is withdrawn at the moment of cut-off
by means of cam gear or equivalent mechanism (not shewn) whereby the detent
is caused to partially rotate about the pivotal centre k.
The intermediate clutch disc H having grooves at right angles to one another
in its opposite faces as above described, forms a coupling adapted to transmit
rotary motion without side stress between revolving parts whose axes are parallel
but eccentric to each other, whatever may be the direction in which the side
stresses act. Hence in the arrangements above described and illustrated in
Figures 1 to 4, the rods E and F, although shewn parallel, might occupy any
angular position and pull in any angular direction relatively to one another.
It is permissible however to adopt a less perfect but more simple form of coupling
in some cases, as for instance where the side stresses act in directions coincident
or parallel with each other. Thus for example where it is possible to arrange
the motion rod E and dash-pot rod F parallel to each other, the intermediate disc H
may be omitted and the valve spindle A may be coupled to the motion lever D
(or to the trip lever J as the case may be) by means which whilst adapted to
transmit rotary motion, will admit of relative movement of the respective parts
in a plane perpendicular to their axes in one direction only. Such an example
is illustrated in Figures 5 and 6 wherein the motion rod E is connected by pin e
to the duplex lever D and the dash-pot rod F is connected by pin f to the arm J
of the trip lever J, rods E and F acting parallel to one another. The members
of lever oscillate upon bearings i formed at opposite ends of the boss I
of lever J, which is mounted directly upon the fixed bearing b the driving
connection between levers D and J being effected through the medium of a
detent K pivoted at to lever D) as in Figures 3 and 4. The boss I of lever J
extends outwardly and surrounds the end portion of the valve spindle A from
which it is separated by an annular clearance space 7, the boss I and spindle A
being keyed together by means of a cotter M which passes diametrically through
both and makes a sliding fit in notches or slots in the end of boss I. The
cotter M is preferably so set as to be parallel to the rods E and F when the
motion lever D and trip lever J, connected together by the detent K, are in
mid-position as shewn in Figure 6.
In the foregoing my invention has been described and illustrated as applied
to the steam admission valves of a Corliss engine but it is to be understood that
the invention is equally applicable to the exhaust valves in which case of course
the trip mechanism and dash-pot connection would as usual be omitted.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:
In valve gear of the Corliss type mounting the lever by which the valve
spindle is rotated to turn about a fixed bearing independent of but concentric
with the valve spindle and connecting said lever to the valve spindle by means
which whilst maintaining driving connection between the lever and spindle
will permit a motion of translation of the one relatively to the other in a plane
perpendicular to the axis of the valve spindle substantially as and for the
purpose specified.
11
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1.... 1900
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.