Improvements in Valves and Valve Mechanisms for Engines Operated by Steam or other Expansible Motive Agent.
Year: 1896

page_text: Date of Application, 16th Apr., 1896-Accepted, 4th July, 1896
COMPLETE SPECIFICATION.
Improvements in Valves and Valve Mechanisms for Engines
Operated by Steam or other Expansible Motive Agent.
I, COURTENAY WILLIAM THOMPSON, of 30 College Road, Bromley, in the
County of Kent, Mining 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 :-
The principal object of my invention is to provide valves whereby the exhaust
or cushioning conditions of the motive fluid (which I will hereinafter refer to as
steam) can be controlled or regulated independently of or suitably for the regula--
tion of steam cut-off and to provide valve mechanisms to increase the efficiency
of the exhaust conditions in relation to the distribution of steam in the engines,
and to suit the varying conditions of reversing or non-reversing engines.
In some instances I provide a separate exhaust valve, to be used as an auxiliary
to, and to be controlled independently of, the main valve, when such main valve
operates for both steam and exhaust; for instance in Figure 1 of the accompanying
diagrams the valve B represents the main valve (for simplicity and to reduce
clearance, the system is of inside steam type) controlling both steam and exhaust
in the ordinary way; whereas the valve A, only controls the exhaust, but it is
shewn with no inside lap so as to be open to the cushioning. The steam may also
be admitted to such a valve as A, when the greatest power is required.
1 will describe the nature of my invention and the manner in which it may be
performed by reference to the examples illustrated in the accompanying diagrams
but I wish it to be understood that these are only examples in elucidation of my
invention and that I do not limit myself to the particular devices shewn.
Figure 1 has already been described, but in connection with the operating
mechanism, the valve B will always operate best with more angular lead and less
travel than those of the valve A.
Any of the valves described in this specification may operate with any suitable
gears for instance the valve A, Figure 5 may be operated by any suitable main
valve gear and the valve B Figure 5 by any suitable expansion gear; and any
Imechanism herein described may operate with any suitable valve system, such for
instance as any ordinary and suitable expansion valve system.
The valve system shewn in Figure 2 is practically the same as that in Figure 1
but the mechanism is such that the spindles cannot pass directly to the centres of
the valve pistons. This valve system is only suitable to be used under the
conditions according to my invention for forward running, but it is shewn in con-
nection with reversing mechanism, such as a marine engine when the economy in
reverse running is of little or no importance and where this can be sacrificed for the
sake of economy in forward running.
I provide two blocks in the one controlling link; which give the valve B
more lead and less travel than those of the valve A. The reverse however is the
case when the engine is reversed. The forward half of a reversing link, for
example, (or its equivalent) may be used in this manner for non-reversing engines.
When such a mechanism, with two blocks or valve-pins, in the one link, is used
with such an engine as a locomotive where forward and reverse working are
important, then the ports and valve faces of the valve A must be the same as those
of the valve B, the one valve being for steam admission in forward and the other
in reverse running alternately; steam is then only admitted to one valve at any

page_text: one time, viz. that one having the most lead and the least travel; but when a
great quantity of steam is required, then such steam may be admitted to both
valves,
In Figure 3 the mechanism is equivalent to that shewn in Figure 2, the one block
with the two valve pins in it and in the one link producing equivalent effects on
the valves.
The principal duty of the valve A is to control the exhaust, but it also regulates
the moment for admitting steam, which is necessary as the steam controlling, or
expansion valve B, opens too early. This valve and gear may be used for example
for marine engines, but the most useful marine engine valve is that shewn in
Figure 4 operated by such a gear as that shewn in Figure 3. The steam
admission valve B may be of flat, piston or other form.
In Figure 4 likewise, the valve B must have more lead and less travel than those
of the valve A, whereas, unlike the valve B in Figure 3, the lap of the valve B
in Figure 4 is so proportioned that it regulates both the opening and closing to
steam. Both the valves A and B are shewn in the central position of their travel.
In this case the valve A may have no inside lap at all and consequently all the
clearance space may be in communication with the cushioning of exhaust prior to
opening to the steam. This is a very beneficial arrangement, as the clearance
space may be so proportioned in capacity as to regulate the intensity of the
cushioned or back pressure under the varying conditions of the cut off; this
arrangement is most useful in compound engines where the pressure of the
exhaust varies in proportion to the amount of steam used.
This beneficial effect is further increased and rendered applicable to both simple
and compound engines as shewn in the valve faces of the valve A in Figure 4
by slightly cutting out the inside or steam lap and by adding a slightly greater
amount of outside or exhaust lap relatively to the cylinder ports, so as to have
the clearance or cushioning space filled by steam just previous to exhaust and so
as to transfer this steam under such pressure to the other end of the cylinder.
This cushioning space is never open to exhaust but is always open to the steam end
of the cylinder so that, while it prevents any excessive cushioning, all the, work
done in cushioning is given back in full. This effect is produced by varying the
movement of the exhaust or cushioning valve as well as that of the steam valve
and in contradistinction to the ordinary expansion valve gear. The plates and ports
of the valve B may be doubled or trebled or further multiplied.
The valve B may be given precisely the same movement as that given to the
valve A when the clearance or cushioning space will require to be larger, than if
the valve B had more lead and less travel than those of the valve A, as in the
former case the compression will always be greater than in the latter case.
With such a valve as A in Figure 4 for example, when there is little or no
steam lap, the same size of steam opening can be effected with half the travel that
is necessary with an ordinary valve. The exhaust porta may then be doubled
while the steam port is only single without increasing the weight of the valve
when the travel is halved, and, retaining the diameter of the valve, equally full
port openings are obtained with half the travel of the heavy valve, whereas the
small valve B requires very little moving, and simultaneously the full advantage
of the suitably proportioned cushioning space is provided for the variable amounta
of steam consumed.
For very high speeds and powers the steam may be admitted directly to the
cushioning space between the two pistons of the valve A and in addition to the
steam admitted through the valve B.
The arrangement shewn in Figure 4 has another great advantage, as it entirely
provides against the trouble which exists with piston valves of so closing the ports
as to enclose condensed water and not permitting it to escape and the consequent
danger of knocking out the cylinder end. By the arrangement Figure 4, free
access is provided from the cylinder to the cushioning space and, if necessary,
thence into the valve chest through the expansion valve which rises readily off its

page_text: seat to any excess of pressure. The cushioning space can besides be readily
drained by a relief or other valve placed at its lowest point.
In this and other valve systems herein, the steam admission valve B may be
operated by a shaft governor. If the engine be reversed then steam may be
admitted directly into the steam or cushioning space of the valve A, and the
unreversed valve B rendered inoperative.
Or again for marine engines the shaft governor may control the main valve, as
in a non-reversing engine the high pressure cylinder valve is not reversed (the
other being reversed) but the steam is admitted into the exhaust passage and
passed to the next cylinder (the steam may be reduced in pressure first if desired)
the high pressure valve pistons, slide on the valve spindle and are kept in position
on shoulders by the pressure of the steam in forward running. In reverse running
the pistons are forced in the opposite direction and keep the cylinder ports open to
the exhaust passage continuously.
In like manner a double acting cylinder may be made single acting, to reduce
its power at will; the steam is, say, on the outside of the valve pistons, and if
the steam be withdrawn from one side, the pressure will be withdrawn from one
piston. This piston will then be pushed over to full exhaust and remain
stationary there while the valve spindle slides in and out of it, thus one end of
the cylinder will be constantly open to exhaust and the cylinder made single
acting. If the steam be returned to such side of the valve, then the cylinder
will be double acting again. In this arrangement the valve and mechanism may
be of any ordinary kind and any equivalent arrangement may be used and the
engine may be reversing or non-reversing; and may be of locomotive, marine,
stationary or other type.
The valve arrangement shewn in Figure 5 is the flat valve equivalent of that
shewn in Figure 4 and this invention includes slide valves whether of flat piston,
oscillating or other kind.
In Figure 5 the valves A and B, are equivalent to the valves A and B
respectively in Figure 4. X is the steam chest and Y is the clearance or
cushioning space.
When a clearance space is provided in the manner shewn in
Figures 4 & 5 there can be no knocking of, or enclosure of condensed water in
the cylinder and the bulk of the clearance space should be low down with a relief
or other valve at the lowest point.
The combination valve A'B shewn in Figure 6 gives the same results as those
given by the arrangements Figures 4 & 5 when the slide A (of Figures 4 & 5)
has the same movement as, those of the valve B (of Figures 4 & 5). Thus in
Figure 6 the passages in the valve between the faces A and B communicate with
the clearance space Y, and with the two ends of the cylinder, whereas the
faces BB control the steam distribution in the usual manner the faces A A
controlling the exhaust and cushioning in the particular manner according to this
invention. The valve A B may be fitted or balanced in the steam chest X in any
convenient manner; and this valve will be very beneficial when operated by a
shaft, governor, eccentric, or generally when there is only one slide both for
variable expansion and exhaust. Such a clearance space as is described in
Figures 4, 5 & 6 would perhaps be better described as a cushioning space simply.
The valve arrangement in Figure 6 may be modified by providing a port in the
face Z and an expansion valve to operate on the back of such port, and further by
providing more steam lap at B B. The auxiliary expansion valve will be operated
so as always to cut off the steam early (see Figure 8 for a suitable nature of
mechanism for this) whereas the modified faces B B would only operate for steam
admission and cut off for the later points of cut off. This modified form will be
most useful with a reversing mechanism in which both valves can be controlled by
one lever (see Figure 8).
This modified form Figure 6 is best seen in Figure 6-the lap is increased at
the faces B B, the expansion valve Z2 operates the port Z, on the back of the

page_text: In Figure 6 X is an auxiliary steam chest.
This expansion valve Z2 only operates for early cut off of steam whereas the
valve A B operates only for late cut off of steam consequently the valve A B
never has its travel so much reduced and never effects so heavy cushioning as
does an ordinary simple valve.
Equivalent arrangements, to those shewn in Figure 6 & 64 are for example as
follows:-
The valve in Figure 6 may enrry its own cushioning space, moving as a part of
itself, and further a steam admission valve may operate in connection with this
clearance space, as, for example, it does in Figure 6.
As illustrated in Figures 5, 6, 6, 7 & 9 for instance the various slides may be
interchanged and combined in any suitable manner that their particular properties
suggest.
The valve in Figure 7 is equivalent to the modified form of that in Figure 6
viz., Figure 6^, except that the cushioning space is not provided, that the valve A B
operates in contact with the plate Z which is here a floating anchor plate, that
there are two ports Z' Z, instead of one, and that the expansion plate 2' operates
for these two ports.
There may be lap, as shewn, between the faces of A. B and Z, or the steam or
cushioning passage in the valve A B may always be open to one or more ports
in Z, and the expansion plate 22 may consequentiy operate as does the plate B in
either Figure 3 or Figure 4. The faces B B may be given such additional lap
that they will not open to steam at all and the cushioning passages may be
enlarged with the result that either the auxiliary late cut off may be effected
equivalently between ports in and between A Band Z, or A B may form a
suitable expansion valve system, in which Z is an anchor plate and Z³, an
expansion valve, and in which the cushioning passage in A B, in addition to its
particular properties as before described, also constitutes the equivalent of the
ordinary steam ports in a main valve.
In describing mechanism, to effect the objects of this invention in respect of
varying angular lead and exhaust or cushioning conditions, I will refer for
brevity to the valve whose principle duty according to this invention is to
regulate the steam as the admission valve, and to the valve whose principal duty,
according to this invention is to regulate the exhaust or cushioning as the exhaust
or cushioning valve.
I will particularly describe Figure 8, for example, in connection with Figure 6^,
Figure 8 is an elevation and Figure 84 a side view. The rocking shaft C supports
an ordinary reversing link (at or about the centre of the latter) and obtains a
rocking movement from it. This movement is transmitted through the shaft
to E. The ordinary valve movement is transmitted, by the block, to the lower
end of the lever of the rocking shaft D through which the movement is trans-
mitted to the upper end F. The rocking arm E. B. A, receives one movement
from its rocking pivot E, and another movement from an arm connected by
suitable attachment to the rocking arm F.
Thus, according to the Specification of my application for Letters Patent 24470
of 1895, the rocking arm EBA, has movements equivalent to those of the always
forward portion of a reversing link, and B has always more angular lead and less
travel than bas A. The pin B may operate the admission valve and the pin A
may operate the exhaust or cushioning valve. The single controlling lever L
controls both of the pins A & B, so that the pin B will always have an earlier
cut off movement than has the pin A. B and A may therefore operate the
valves Z and A. B. respectively, in Figure 6.
The valves in Figure 64 may also be controlled by one lever (say in a reversing
engine) when operated by other mechanism than that shewn in Figure 8 for
example, when the valve A B, is operated by a rocking shaft directly (trans-
mitting the ordinary valve movement as in the case of a locomotive) and when
the movement for Z2 is obtained from a lever rocked from the cross-head and

page_text: fulcrummed in the above mentioned rocking shaft arm, the lever effecting earlier
cut off movements in the valve Z2, than the valve A B has. The same effect may
be obtained from radial and other gears; for instance in "Joy's gear," the move-
ment for the valve A, B, in Figure 64 may be obtained from a pin, situated in the
usual way in the lever of "Joy's gear," whereas a second pin, situated further
from the fulcrum, may operate the valve Z2, in Figure 64 and both of these
valves may be controlled by the one lever angling the slot as usual.
In Figure 9, the valve A is the exhaust or cushioning valve. B is the steam
admission valve and B' is an auxiliary steam admission valve operating on the
back of the anchor plate C. The valve B also controls the exhaust, effecting an
early opening to exhaust when desired, but it will always close the exhaust
before the valve A will close it. If the steam lap of the valve B be so increased
that the said valve B will not open to steam at all, then this valve may be used
with the gear shewn in Figure 2. One block will be attached to the valve A and
the other block will be attached to the valve B B'. As now it is the first of the
two valve slides A or B', to cut off steam that will control the admission of steam,
so this valve (modified as described) Figure 9, may be combined with the gear in
Figure 2, to operate equally well for forward or reverse working and is a very
suitable combination for a locomotive. From the foregoing it will be seen that in
the modified form of Figure 9, the valve A, and the valve B, B' may each be
alternately steam admission or exhaust valves respectively and according as the
engine is running forward or reverse.
In Figure 10 the main or exhaust or cushioning valve, attached to the block A,
is controlled, by governor or otherwise, in the same variable link as is the
expansion or admission valve, attached to the other block B. This is a non-
reversing gear. The eccentric E, is attached to the link at C, and the eccentric F
is attached to the link, at D; D is the early cut off end and C is the late cut off
end of the link. The early cut off eccentric F is, set opposite to the crank and
half its travel is about equal to the lead, of the late cut off eccentric E, on either
side of the centre.
This gear may be used with the arrangement Figures 4, 9 and others. The
block B has always more lead and less travel than has the block A.
In the arrangement Figure 11 the varying lead and travel properties are
obtained for example, from the one block in the reversing link. There are two
pins in this block connected to two valve rods. The two valve rods are supported
by reason of the one block being supported by the rod C. This gear is suitable
for example, for a locomotive and the movements for the valves may be transmitted
suitably by the rocking shafts. The pins A and B, are alternately, and as the
engine is reversed to and fro, applicable for an admission valve, and an exhaust or
cushioning valve respectively and they may operate, for example, with the valves
shewn in Figure 2 & Figure 9. There may be three pins in the one block, or
three blocks in the one link and for example, the two outside ones may be admission
valves alternately.
If for example, this reversing gear, Figure 11, operates, with an ordinary
expansion valve system such as that shewn in Figure 16 (or with other forms as
herein described) then it will only operate the expansion valve B with the
particular advantage according to this invention, say, in forward position as shewn.
C in Figure 16 is an anchor plate. Thus B, Figure 11, will operate the expansion
or admission valve B, Figure 16, with more lead and less travel than A Figure 11,
which operates the main valve A Figure 16. When reversed however the
expansion valve will be simply ineffective in its operation, as thus reversed, the
expansion valve will always only shut off steam after the main valve has shut off
the steam supply, and the main valve will control the entire distribution of steam
like any ordinary and simple valve. Such a valve arrangement will therefore be
very economical and effective for running in one direction, whereas when reversed
it will work simply as an ordinary simple valve.

page_text: If, say, a locomotive cannot be turned round, then before a long run in the
reverse direction, the valve attachments could be changed over by hand.
In the arrangement Figure 12 the varying lead and travel properties are
obtained, for example, under the following conditions.
The eccentrics A and B are combined and slotted, as shewn, so as to be shifted
together on the crank shaft in the direction of the line 1. 2. The eccentric A,
operates the main valve rod A', and the eccentric B operates the rider-link R, by
the rod B¹. A is shewn, for example, as set with 30° of advance as at A" and B
with 60° of advance as at B¹¹.
When reversed on the crank shaft the eccentrics A and B bear the same angular
relationship to each other and to the crank as before the engine was reversed and
:80 on.
In the arrangement Figure 13 the eccentrics operate as they do in Figure 12,
except that they are controlled by a shaft governor, or equivalent mechanism, and
that they are only shifted, on the crank shaft, sufficiently to vary expansion and
. not to reverse the engine.
A operates the admission valve or expansion valve rods A¹ A' through the
rocking shaft R, and B operates the exhaust or cushioning valve (or main valve)
rod B with variable movement as hereinbefore exemplified.
The eccentrics and rods are shown, for example, as set, at such angles that the
angular advance of B, is only varied from 15° to 45°, whereas the angular advance
of A is varied from 30° to 90° in varying expansion."
In the arrangement Figure 14 the varying lead and travel properties are
obtained, for example, under the following conditions.
A is a shaft governor eccentric and it operates, with the variable movement, the
exhaust or cushioning valve rod B' while the movement for the admission valve
rod A¹, is obtained at such an angle that A' operates always with more lead than
does Bí.
This effect is produced by attaching A¹ to a point in the eccentric strap different
from that of B₁. The rods A' A' operate through the medium of the rocking
shaft R.
In the arrangement, Figure 15 the varying lead and travel properties are
obtained, for example, under the following conditions.
A is the shaft governor eccentric.
B is an eccentric set opposite to the crank and its half travel is about equal to
the lead of A on either side of the centre. The eccentric A. is shewn as operating
the admission valve directly, and it is attached to the link A' B' at A¹. The
eccentric B is attached to this link at B
In varying both the admission and exhaust or cushioning valves, A' has always
more lead and less travel than has B¹.
Figure 16 has already been referred to, in describing Figure 11, and is an
ordinary expansion valve system capable of operation with mechanism such for
example as that shewn in Figure 11.
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. Valves, for reversing or non-reversing engines, which valves are so constructed
and operated as herein before explained that the exhaust or cushioning conditions
can be controlled or regulated independently of, or separately from, the regulation
of variable expansion.
2. Linkage or equivalent mechanism, for reversing or non-reversing engines,
arranged or constructed in such manner that the properties of varied lead and
travel, developed from them, are employed to effect the control or regulation of
the exhaust or cushioning conditions, independently of, or separately from, the
regulation of variable expansion as hereinbefore explained.

page_text: 3. The combination with one link of either two or more pins or of two or more
blocks or of a combination of a pin or pins and a block or blocks (or equivalent
devices for other than simple linkage gears) for reversing or non-reversing engines,
each of which is connected to or with a separate valve slide, so as to control or
regulate exhaust or cushioning conditions, independently of or separately from, the
regulation of variable expansion, as hereinbefore explained.
4. In reversing or non-reversing engines the combination of valves and linkages
or equivalent mechanism substantially as hereinbefore explained so as to control or-
regulate the exhaust or cushioning conditions independently of, or separately from,.
the regulation of variable expansion.
Dated this 16th day of April 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.