Improvements in Steam Engine Valve-gears, such as Corliss Gears and the like.
Year: 1889

page_text: Date of Application, 22nd Mar., 1889
Complete Specification Left, 21st Dec., 1889-Accepted, 25th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in Steam Engine Valve-gears, such as Corliss Gears
and the like.
I, ROBERT MIDDLETON, of Sheepscar Foundry, Leeds, in the County of York,
Engineer, do hereby declare the nature of this invention to be as follows :-
This invention relates, primarily, to valve gears, such as work in connection with a
tripping or liberating catch controlled by the main governor, which have cylindrical
slide valves working in the arc of a circle on corresponding seats, receiving a rocking
motion from a central spindle-as in the well known Corliss valve gear; Secondarily,
it would be suited to any valve-gear of this description whether the valves worked on
circular or flat seats.
The object of my invention is (1) to produce a valve-gear whose tripping mechanism
shall act with greater promptness than heretofore when released by the governor.
(2) To produce the above (1) with a minimum movement of the valve which move-
ment shall be also constant and uniform in its length, to the extent of a full open
port; thereby enabling the length of the valve seat to be so proportioned as to allow
the valve to properly overlap at each end of its stroke, and thus cause the valve to be
continually bedding itself to its seat, without there being any chance of shoulder
being formed. (3) To allow the valve to be quickly opened to full port, leaving it
there ready to cover the port again immediately the release is arranged by the
governor.
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The nature of the alteration which my invention would make in an ordinary Corliss
valve-gear may be described as follows-The forward movement of the main valve-rod
which would ordinarily be capable of causing a steam valve to be opened and thrust
over to its furthest extent, holding it meanwhile until the trip gear released it,-is,
in my plan, arranged to rapidly carry the valve forward, but that only so far as 'to
fully open the steam port; at this point the main valve rod (whose movement need
not stop here) is caused to release. its hold on the valve, by the action of my
preliminary disengaging trip, and here the steam would be cut off, were it not that
I arrange another catch which engages and holds the valve at this "full open" point.
This second catch is afterwards released by a suitable trip or trigger, controlled by the
governer so as to cut off automatically in the usual way.
The rapidity of the cut off is self evident when the action of the valve 'is
noted; it is rapidly opened to "full port," and no further; and is there kept
ready waiting for the release to be given; the liberating action of the governor
producing an instantaneous commencement of the closing movement of the valve.
As already stated, the forward stroke of the main valve-rod need not stop when the
valve is released and left behind in the clutches of the second catch, as this will allow
greater freedom in giving a rapid movement to it.
Dated this 51 ham of touch 1000
WM. SNOWDON,
9, Beckett's Bank Chambers, Leeds, Yorks, Agent for the Applicant.,

page_text: COMPLETE SPECIFICATION.
Improvements in Steam Engine Valve-gears, such as Corliss Gears
and the like.
I, ROBERT MIDDLETON, of Sheepscar Foundry, Leeds, 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 :-
This invention relates, primarily, to valve gears, such as work in connection with a
tripping or liberating catch controlled by the main governor, which have slide
valves with cylindrical faces working in the arc of a circle on corresponding seats,
each receiving a rocking motion from its own spindle-as.in the well known Corliss
valve gear; Secondarily, it would be suited to any valve gear of this description
whether the valves worked on circular or flat seats.
The object of my invention is (1) to produce a valve gear whose tripping mechanism
shall act with greater promptness than heretofore when released by the governor.
(2) To produce the above with a minimum movement of the valve, which movement
shall be also constant and uniform in its length to the extent of a full open port;
thereby enabling the length of the valve seat to be so proportioned as to allow the valve
to properly overlap at each end of its stroke, and thus cause the valve to be continually
bedding itself to its seat, without there being any chance of a
"shoulder" being
formed. (3) To allow the valve to be quickly opened to full port, leaving it there
ready to cover the port again immediately the release is arranged by the governor.
The nature of the alteration which my invention would make in an ordinary Corliss
valve-gear may be described as follows:-The forward movement of the main eccentric
rod, or other such, used for actuating the valve-rod which would ordinarily be capable
of causing a steam valve to be opened and thrust over to its fullest extent,-holding
it meanwhile until the trip gear released it,-is, in my plan arranged to rapidly carry
the valve forward, but that only as far as to fully open the steam port. At this point
the valve rod (whose movement need not stop here) is caused to release its hold on the
valve by the action of my preliminary disengaging trip, and here the steam would be
cut off, were it not that I arrange another catch which engages and holds the valve at
this full open point. This second catch is afterwards released by a suitable trip
or trigger, controlled by the governor so as to cut off automatically in the
usual way.
The rapidity of the cut off is self evident when the action of the valve is noted :—
after being rapidly opened to "full port," and no further, it is there kept ready
waiting for the release to be given; the liberating action of the governor being
accompanied by an instantaneous commencement of the closing movement of the
valve.
As already stated, the forward stroke of the main eccentric rod (or other such)
used for actuating the valve rod need not stop when the valve is released and left
behind (full open) in the clutches of the second catch. This allows greater freedom
in giving the eccentric (or its equivalent) an extra length of stroke in order to get
greater rapidity of motion when the valve is being opened.
Referring to the drawings, which show a mode of using my double tripping
devices. Fig. 1 is a front elevation of the principal parts of the gearing required
for working two steam inlet valves-in this case, independently of the exhaust valves.
The gear may be taken as belonging to an engine whose piston is at about mid stroke;
the left-hand gear being in the position due to its having recently released its
valve and allowed it to close: the right-hand gear has about reached the limit of its
stroke and is preparing to commence its return stroke. The isolated portions in
figs. 2 & 3, are introduced to show & explain more clearly certain portions or posi-
tions of the gear drawn immediately beneath they also show how the valve seats
may be cut away to suit the definite stroke of the valves given by my plan of
working the lower portion of each of these figures may be taken as showing the

page_text: valves with their ports closed. Fig. 4, is a side elevation showing the near valve-
spindle or rod, its guide and gearing; whilst behind is the dash-pot and its sup-
porting bracket. Fig. 5, is an elevation showing a portion of the said dash-pot
bracket &c. Figs. 6 & 7 are respectively side elevations of the valve spindle and
gearing looking to the right and left hand from the centre of fig. 1. The same letters
refer to the same parts in all the figures.
A description of the parts and the modus operandi will best accompany one another.
Referring therefore to fig. 1, A and A', are the two valve spindles which can be
operated (when certain catches come into action) by the treble-eyed rocking levers or
wrist plates B, B, which receive a regular vibrating movement from the eccentric (or
other equivalent) rod C. The adjustable rod C connects together the two rocking
levers last mentioned. Each lever B, carries at its head a pawl D, which pivots
at D, and is arranged to engage with a projection E on a collar fixed to each valve
spindle (see figs. 2 & 3).
Each lever, B carries a stud F¹ on which rides (taking one thing at a time) a
tripping tongue F, (see fig. 3.) arranged to trip the pawl, D, off the projection E, as
soon as a certain position is arrived at, due to the upward movement of F (when the
lever B is rocked). For this purpose F is provided with a tail lever F which in
fixed
case is. connected through an adjustable rod F³ with a
each
as a centre.
stud G
From this it follows that each toe F can be so adjusted as to cause the trip to take
place as soon as the rocking lever, acting through the pawl D bearing on the
projection E, has pulled the valve as far over as to open its port fully.
Before this release, however, is effected, a second pawl H, pivotting on a fixed
stud H¹ (for the shape &c. see fig. 2) is so arranged that it falls over the edge of, and
engages with, the projection E, and thus continues to hold the valve in the "full
open" position.
The upward movement of F continuing (part of the rocking motion of B) another
toe J mounted also on the stud F is brought into contact with the pawl H which rides
on its own fixed fulerum ; and the action of this latter toe (regulated by the governor)
finally releases the valve at the requisite time. The tail lever J, in each case, is con-
nected, through its adjustable rod J with its own governor lever K. These levers K K
are geared together and are both worked from the governor rod L. The position L³.
is that demanding less steam, whilst 12 demands more.
There is only another toe that needs description and that is M; this forms part of
the toe piece J, and joins at the same tail lever J. Its use is as follows:-Suppose
the lever B to be at that end of its stroke which has depressed F¹ to its lowest position
then D will have fallen into gear with E, and will, when the return stroke commences,
carry the valve round to the position of "full open." Supposing further that the
governor is putting on so little steam that the valve does not require to get as far as
full open "evidently then the toe F will not be able to release D in time.
In such a case this toe M which stretches under D (see fig. 6,) raises that pawl and so
enables the final release to be given.
From
In fig. 4 &c. N, N, is the valve spindle guide, and O, O, the dash-pot and its
bracket; and in fig. 2, & 3, P, P, are the valves, & P1, P1, their seats.
what has been already explained it will be understood that the full arc, through
which the rocking levers B move, may with advantage exceed-and that in both
directions the movement required for the valve, as, by this means, the valve may be
moved to "full open more rapidly.
"
Other modifications to suit other arrangements of valve gears may easily be devised
when once my system of working with two tripping pieces is understood.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I declare that what
I claim is
(1.) The method of using double tripping devices on the Steam-inlet-Valves of a
Corliss or other such valve gear, a part of the gear-actuated from a fixed centre-

page_text: being used for bringing about the preliminary release and retention of the valve when
it arrives in its full open" position, whilst the other portion-actuated by the
governor is arranged to accomplish the final release and accompanying closing of
the steam port, for the purposes explained herein.
(2.) The valve gear with double tripping action, arranged, constructed, & operated,
substantially as described and shown.
Dated this 20th day of December 1889.
WM. SNOWDON,
9, Beckett's Bank Chambers, Leeds, Yorks, Agent for the Applicant..