Improvements in and connected with the Valves and Valve Gear of Steam Engines and similar Motors.
Year: 1898

page_text: Date of Application, 27th May, 1898-Accepted, 23rd July, 1898
COMPLETE SPECIFICATION.
Improvements in and connected with the Valves and Valve Gear of
Steam Engines and similar Motors.
We, WILLIAM DUNDAS WIGHT, of Pentre, Pontypridd, County of Glamorgan,
Engineer, and MATTHEW BROWN WILD, of 7, York Road, Erdington, Birmingham,
in the County of Warwick, Engineer, do hereby declare the nature of this inven-
tion, and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:―
Our present invention relates to improvements in and connected with that type
of valve and valve gear for engines and motors operated by expansible fluids
described in the Specification of Letters Patent No. 12496 dated the 28th day of
June A.D. 1895.
We will describe these improvements with reference to the accompanying
drawings which represent them as applied to a double acting steam engine having
separate valves and steam chests at opposite ends of the cylinder.
Figure 1 represents a partial side elevation, only one of the steam chests being
fully shewn with the cover removed.
Figure 2 is a sectional plan view of Figure 1.
Figure 3 illustrates one of the slide and cut-off valves, in longitudinal section,
drawn to a larger scale.
Figure 4 shews a cross section of the main valve.
Figure 5 is a side elevation of the trip gear shewn in Figures 1 and 2, drawn to a
larger scale.
Figure 6 shews a cross section of Figure 5.
Instead of arranging the trip gear between the main and cut-off valve spindles
we now arrange it upon the main spindle. As before, it consists of a toggle
joint 001 for each cut-off valve. As indicated by the drawings, these toggle
joints may be arranged together, or, particularly in short stroke engines, they may
be separated and be arranged at opposite ends of the cylinder as described in the
Specification No. 12496 of 1895, hereinbefore referred to. As shewn by Figure 5
of the annexed drawings, the centre pin of the duplex toggle joint, is secured
in a lug or lugs on a crosshead c, which also carries the duplex dash pot M.
The two pistons of this dash-pot are respectively fixed upon the corresponding
ends of the cut-off valve spindles ii. If however, the trip gear is separated as
already herein before referred to, to opposite ends of the cylinder, then, instead of
the duplex dash-pot, two separate dash-pots are required, one in connection with
each part of the trip gear, and each dash-pot will be carried upon a suitable part
of the main valve spindle in a manner corresponding to that shewn by Figures 2
1)
and 6. The crosshead c is secured upon the spindle 1 by means of a key such as d.
Those links ce of the toggle joints which are attached by the centre pin a,
are pivotted to the outer links ff by the pins gg below which there may be
formed upon one or other of the links ef a slight projection hh which can rest
upon the crosshead c as shewn by Figure 5, and thus prevent the downward bending
of the toggle joints. The outer ends of the outer links ff are pinned to a lug or

page_text: lugs on the slide blocks jj mounted upon the main valve spindle D. These blocks
have projections kk thereon which can, by the motion of the main spindle, be
brought into contact with the adjustable spring buffer blocks 11, Figure 1, fixed
upon a stationary rod m parallel with the valve spindles, for the purpose herein-
after described. The ends of the links ee are turned upwards above the centre
pin a to form the tail pieces nn. In the former Specification of Letters Patent
No. 12496/95 already referred to, the bending of the toggle joint at the proper
moment was effected by means of an inclined plane and traveller thereon, the
position of the inclined plane being determined by the governor. We may now
employ an equivalent arrangement. For example, we may arrange at about the
points oo Figure 1, two adjustable stops connected with the governor in such a
manner that with an increase beyond the normal speed of the engine, the stops are
brought nearer to the tail pieces nn¹ and the reverse. On the one side the tail
piece or pieces n¹ are brought into contact with the stop o', and on the other side
the tail piece n is brought into contact with the stop o. In either case the tail piece
is turned upon its pin and the toggle joint with which it is connected is bent.
The steam can have access to the steam end of the valve through one or more
ports pp, which can be opened or closed by the relative motion of the cut-off
valve q, Figure 3. It was explained in the former Specification herein before
referred to that the motion of this valve when permitted by the bending of the
toggle joint, is effected by the steam pressure in the steam chest acting upon the
inner part of the comparatively large diameter of the cut-off valve spindle. This
large diameter may be obtained by fixing a cylindrical casing F upon the spindle.
The motion of the cut-off valve in the opposite direction is obtained in the act of
re-straightening the toggle joint. This is ensured (as well as the opposite motion),
by the blocks jj being rigidly connected with the cut-off valve spindles at the
points rr.
The action of the apparatus is more immediate than, but resembles, that described
in the former Specification. That is to say, immediately upon the bending of the
toggle joint, the steam pressure forces the cut-off valve spindle outwards and thus
closes the ports Pp. But the re-opening of these ports is effected by the contact
of the projection & from the slide block j with the stop 1, whereby the motion of the
cut-off valve is delayed whilst the motion of the main valve continues.
Those parts of the engine and apparatus shewn in the drawings and not herein-
before described are:-the valve balance plate B, the steam inlet S, the exhaust
outlet Oc, the admission port P, the exhaust side E of the main valve, and the
cylinder C.
It will be understood that various modifications may be made in the arrangement
of the valve gear without departing from our invention. For example, instead
of attaching the duplex cylinder of the dash-pot to the main valve spindle, and its
pistons to the cut-off valve spindles, a piston block may be attached to the main
valve spindle and be common to two cylinders respectively fixed upon the ends of
the cut-off valve spindles. Or a simple spring buffer may be substituted for the
dash-pot, or the slide blocks jj may be stopped by coming into direct contact with
the crosshead c, intervening soft surfaces or packings being employed if desired.
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:-
1. In the valve gear of motors operated by expansible fluids, the construction
and arrangement of a duplex toggle joint mounted upon the main valve spindle
and connected with the cut-off valve spindle and a dash-pot; substantially as here-
inbefore described and as illustrated by the accompanying drawings.
2. In the valve gear of motors operated by expansible fluids, the combination
and arrangement of a duplex toggle joint with tail pieces, stops for displacing the
tail pieces and thus bending the joints, sliding blocks on the main valve spindle

page_text: connected to the toggle joints and to the cut-off valve spindle respectively, spring
buffer stops for re-straightening the joints, and a duplex dashpot the cylinder of
which is fixed upon the main spindle and the pistons upon the cut-off valve spindles
or the reverse, substantially as hereinbefore described and as illustrated by the
accompanying drawings.
3. In the valve gear of motors operated by expansible fluids, a toggle joint one
end of which is pinned upon the main valve spindle having a tail piece by means
of which the joint can be bent by contact with a stop, and the other end of which
is pinned to a block sliding upon the main valve spindle, this block being rigidly
connected with the cut-off spindle and having a projection capable of coming into
contact with a stop to produce the re-straightening of the joint, substantially as
hereinbefore described and as illustrated by the accompanying drawings.
4. In the valves of the type set forth, the construction and arrangement of a
port or ports in the main valve which are adapted to be simultaneously opened and
closed by the motion of the cut-off valve, substantially as hereinbefore described
and as illustrated by the accompanying drawings.
T1
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W. E. HEYS & SON.
Agents for the Applicants.