Improvements in the Valve Mechanism of Steam Engines or other Expansible Fluid Pressure Engines.
Year: 1895

page_text: Date of Application, 20th Dec.. 1895
Complete Specification Left, 13th Jan., 1856-Accepted, 15th Feb., 186
PROVISIONAL SPECIFICATION.
Improvements in the Valve Mechanism of Steam Engines or other
Expansible Fluid Pressure Engines.
1 COURTENAY WILLIAM THOMPSON of 30 College Road Bromley in the
County of Kent Mining Engineer do hereby declare the nature of this invention
to be as follows:-
The object of this invention is to provide improved and simple valve mechanism
whereby reversal of the engine can be effected without altering the rate of
expansion and without requiring to reverse the expansion mechanism separately.
I will describe the nature of my invention with reference to the accompanying
diagrams. The diagrams are given merely to assist the explanation of the nature
of my invention and I wish it to be understood that I do not limit myself to the
particular arrangement of the devices shewn.
In Figure 1 a reversing link M M' is coupled at to and respectively to the
forward and reverse eccentrics T and O. In the example shewn this link is
suspended mid-way at sa from the point s' in connection with the reversing shaft Q.
The expansion valve mechanism may be operated directly from the bar s¹ s² with
of course a little evident modification as its movement is equivalent to that of an
expansion eccentric set as indicated at N but it is usual and preferable that the
expansion eccentric be set in a position 1st between that of N and T when the
engine is running in the direction of the arrow, and 2nd between that of N and O
when the engine is running in the reverse direction.
I obtain equivalent results from the link M M'; thus I obtain the equivalent
movement for the 1st case anywhere in the M half of the link M M', and for the
2nd case anywhere in the M half of the said link. When the reversing link M M'
is raised or lowered, the movement tradsmitted from the point s' is (in the example
shewn) twice that transmitted from the point R'; which latter operates the
block R in the auxiliary link M². The link M M is shewn in mid-gear (or
practically "shut off") but when such link is lowered to its lowest point, the block R
will only have fallen half the distance and will be at the upper end of its link
or equivalent to being mid-way in the M half of the link M M and will thus have
When the engine
a movement equivalent to an eccentric set between N and T.
is reversed by the link being raised to its highest point, the block R, is at the
lower end of its link, or equivalent to being mid-way in the M' half of the
link M M', and will thus have a movement equivalent to an eccentric set between
N and O.
Thus the expansion movement is reversed with that of the main valve, so that
the engine can be reversed without altering separately the conditions of the
expansion mechanism; and so variable expansion can be regulated, in forward or
reverse working, by hand or by governor in the link K¹K".
By regulating the position of the point R¹ relatively to the point 8' the move-
ment of the block R can be regulated to the equivalent to that of an eccentric set
at such varying angles, as desired, between N and T or between N and O in
forward, or reverse, working respectively.
The movement of the block R, is transmitted by connection at K to the lever
expansion link K, K" pivotted at D. The block J. effects the movement of the
cut off valve suitably by its attachment to a point situated on the far side of S,

page_text: which is the main valve attachment and variation in expansion is effected by
raising or lowering the block J, in the link KK"; K' being the earliest cut off
position and K being the latest cut off position with the intermediate points
between them.
An essential feature of the arrangement described is that the relative positions
of the blocks S, and R, are similar in both forward and reverse position of the gear
and the means for moving the parts to adjust their position to secure this result
may be varied without departing from the nature of my invention.
Any reversing mechanism may be manipulated according to my invention as for
example; in Figure 2 m is the reversing link and the fulcrum of the cross-head
lever His presumed to be in full forward position, whereas an auxiliary cross-
head lever fulcrum may be caused to take up equivalent positions, in reversing the
engine, to those shown in connection with Figure 1 so as to produce equivalent
results.
Dated this 20th day of December 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents
COMPLETE SPECIFICATION.
Improvements in the Valve Mechanism of Steam Engines or other
Expansible Fluid Pressure Engines.
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 object of this invention is to provide improved and simple valve mechanism
whereby reversal of the engine can be effected without altering the rate of
expansion and without requiring to reverse the expansion mechanism separately.
will describe the nature of my invention with reference to the accompanying
diagrams. The diagrams are given merely to assist the explanation of the nature
of my invention and I wish it to be understood that I do not limit myself to the
particular arrangement of the devices shewn.
In Figure 1 a reversing link M M' is coupled at w and a respectively to the
forward and reverse eccentrics T and O. In the example shewn this link is
suspended mid-way at s² from the point s¹ in connection with the reversing shaft Q.
The expansion valve mechanism may be operated directly from the bar ss with of
course a little evident modification as its movement is equivalent to that of an
expansion eccentric set as indicated at N, but it is usual and preferable that the
expansion eccentric be set in a position first between that of N and T when the
engine is running in the direction of the arrow, and second between that of N
I obtain equivalent
and O when the engine is running in the reverse direction.
results from the link M. M'; thus I obtain the equivalent movement for the first
case anywhere in the M half of the link. M M and for the second case anywhere
in the M half of the said link-these points then being selected in a reversing link
such as for example the link M M' in this manner for forward and reverse running
they may by any ordinary or suitable linkage gear be suitably connected to any
suitable expansion link which may be combined in any suitable or ordinary manner
either being swung on a pivot, or combined with a radius rod, or other ordinary or
suitable, mechanism in such manner that the reversal of the expansion movement
is effected with that of the main valve, thus:-
When the reversing link M M, is raised or lowered the movement transmitted
from the points is (in: the example, shewn) twice that transmitted from the
point R which latter operates the block R in the auxilliary link M². The

page_text: link M M is shewn in mid-gear (or practically "shut off") but when such link is
lowered to its lowest point, the block R will only have fallen half the distance and
will be at the upper end of its link or equivalent to being mid-way in the M half
of the link M M and will thus have a movement equivalent to an eccentric set
between N and T. When the engine is reversed by the link being raised to its
highest point the block R is at the lower end of its link, or equivalent to being
mid-way in the M' half of the link M, M', and will thus have a
equivalent to an eccentric set between N and O.
"
movement
Thus the expansion movement is reverssd with that of the main valve, so that
the engine can be reversed without altering separately the conditions of the
expansion mechanism; and so variable expansion can be regulated, in forward
or reverse working, by hand or by a governor in the link K¹ Ku
By regulating the position of the point R' relatively to the point s the movement
of the block R can be regulated to be equivalent to that of an eccentric set at
such varying angles, as desired between N and T or between N and O in forward,
or reverse working respectively.
The movement of the block R, is transmitted by connection at K to the lever
expansion link K' K" pivotted at D. The block J, effects the movement of the
cut off valve suitably by its attachment to a point situated on the far side of S
which is the main valve attachment and variation in expansion is effected by raising
or lowering the block J in the link K' K", K' being the earliest cut off position
and K being the latest cut off position with the intermediate points between them.
An essential feature of the arrangement described is that the relative positions of
the blocks S and R are simliar in both forward and reverse position of the gear
and the means for moving the parts to adjust their position to secure this result
may be varied without departing from the nature of my invention.
Any reversing mechanism may be manipulated according to my invention as for
example in Figure 2 m is the reversing link and the fulcrum k of the cross-head
lever H' is presumed to be in full forward position whereas an auxiliary cross-
head lever fulcrum may be caused to take up equivalent positions, in reversing
the engine, to those shown in connection with Figure 1 so as to produce equivalent
results.
By the foregoing examples of manners in which my invention may be carried
out in practice it will be readily seen that a variety of other and equivalent means
may also be employed for carrying my invention into effect.
Figure 3 is similar to Figure 1 except that the link M is differently supported.
In the arrangement Figure 4 the connection at St moves the block $ in the
link M by means of the attachment at S2 and the connection at R¹ moves the
link M M', M' on the block R. The movement of the block R being trans-
mitted by the rod R K and arm d to the shaft D having the link K' K" secured
thereto.
The arrangement Figure 5 differs from the arrangement Figure 4 only in that
the block R rocks the shaft D directly and Figure 5A shews an end view of the
links in Figure 1. X, shews the reversing rods attached to the bottom of the
link N.
Figure 6 is an arrangement similar to Figure 5, except that the valve movements
are shewn brought up on to the top of the cylinder.
Figure 7 is an arrangement similar to Figure 5 except that the block R transmits
its movement through the shaft D to the expansion link K' K₁ at the point K,
K' being the late cut off position in the link K' K", and K" being the early cut
off position. The link K' K" may be combined with a radius rod or other
ordinary mechanism as indicated at y.
Variable expansion is obtained by raising or lowering the link K¹K" on the
expansion block J which operates the expansion valve block B.
Further it will be understood from the foregoing that whatever lead is given to
the forward and reverse eccentrics the movement for the main valve will be always
taken further from the centre of a linkage arrangement connected thereto than

page_text: will be the movement for the expansion link; or if two separate links are operated
from two such eccentrics the two movements may be obtained from the two links
respectively and from points in the same having the before mentioned equivalent
relationship to each other and to the centres of the links; in fact the required
results as set forth may be effected by any equivalent means embodying the
features described and elucidated in this Specification.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
-claim is :-
•
1. A reversing linkage mechanism so fitted as to give forward and reverse
positions for the movement of the main valve and also forward and reverse
positions for the movement of an expansion link so that the movement of the
main valve and that of the expansion link can be reversed and controlled
independently of the control of variable expansion all substantially as herein-
before described.
2. The several arrangements of mechanism herein before, described and illus-
trated in the several figures of the accompanying drawings for operating in the
manner herein before described and claimed.
Dated 13th day of January 1896
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.