IMPROVEMENTS IN OPERATING VALVES AND SLIDE VALVES OF STEAM AND OTHER ENGINES, AND IN DOUBLE BEAT VALVES FOR SUCH ENGINES
Year: 1878

page_text: LETTERS PATENT to Herbert John Haddan, of the Firm of Herbert and
Company, Solicitors of Patents, of 67, Strand, in the City of Westminster,
Civil Engineer, for the Invention of "IMPROVEMENTS IN OPERATING VALVES
AND SLIDE VALVES OF STEAM AND OTHER ENGINES, AND IN DOUBLE BEAT
VALVES FOR SUCH ENGINES." A communication from abroad by Charles
Brown, of Winterthur, in the Republic of Switzerland.
Sealed the 14th February 1879, and dated the 17th December 1878.
COMPLETE SPECIFICATION filed by the said Herbert John Haddan at the
Office of the Commissioners of Patents on the 17th December 1878.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
"IMPROVE-
Patents, of 67, Strand, in the City of Westminster, Civil Engineer.
MENTS IN OPERATING VALVES AND SLIDE VALVES OF STEAM AND OTHER ENGINES,
AND IN DOUBLE BEAT VALVES FOR SUCH ENGINES." A communication from
abroad by Charles Brown, of Winterthur, in the Republic of Switzerland.
Said improvements relate to an improved combination of mechanism for operating
the valves or slides of steam engines without the use of eccentrics or link motions,
and whereby any desired amount of lead or variable cut-off and reversed action
may be obtained.
The variable cut-off or reversing motion may be regulated by hand in locomotives
or tramway engines by the usual means, or in the case of land engines it may be
attached to the governor, as will be hereafter described.
Further, to an improved mode of constructing double beat or "Cornish valves,"
enabling them to be worked noiselessly at higher speeds or greater number of
strokes than usual.
The nature of said Invention, and in what manner the same is to be carried out,
will be clearly understood and particularly ascertained by reference to the accom
panying five Sheets of Drawings.
Sheet I., Fig. 1 represents a longitudinal section through the upper half of a
steam cylinder, with the improved double beat or Cornish induction valves, showing
also the mechanism for transmitting the motion of the valve gear to the valves
Fig. 2, view in plan of the same.

page_text: Sheet II., Fig. 1a is an enlarged section through the said valve, showing the
attachment of the valve rod to the valve, and the steam dash pot for softening the
fall of the valve. Fig. 3 is a vertical section through the steam cylinder and valve
mechanism.
Sheet III., Fig. 5 is an end view of the new valve gear, showing the mode of
combining it with a governor; Fig. 4, an elevation of valve and transmitting gear,
with governor attachment shown in the position of maximum admission; Fig. 7
shows governor and valve gear in the position of minimum admission (or earliest
cut-off); Figure 6 is ground plan of the above.
Sheet IV. shows the application of the valve gear to a locomotive of the balancier
or working beam type, the valve motion being shown in mid-gear.
Sheet V., Fig. 1 is a skeleton diagram of valve gear as applied to a locomotive of
the ordinary type; Fig. 2, idem, as applied to a locomotive fitted with a working
beam.
The same letters refer to the same parts in all the Drawings.
The mode in which it is preferred to make the induction valves is shown in
Fig. 1, Sheet I., and in Fig. 1ª, Sheet II.
A represents a flat seated equilibrium or Cornish valve, and C a small cylinder
cast with, or otherwise attached to the valve A. The cylinder C works on a piston
B cast with, or otherwise attached to the valve seat A'; said piston serving as one
of the guides for the valve A. On the piston B, a small valve D is fitted in the
axis of the piston B, permitting the flow of steam from the steam chest into the
interior of the small cylinder C, through the small openings at the base of the
piston d, d, d. The small valve D is furnished with an escape hole bored in the
line of its axis. On the valve A being raised from its seat, the steam lifts the valve
D, and allows steam from the jacket to fill the space formed between the piston B,
and the closed end of the cylinder C, forming a steam dash pot. As soon as the
valve A with its cylinder commences the return or closing stroke, the valve D
closes, and the imprisoned steam, having no other means of escape than through the
small hole bored in its axis, the descending motion of the valve is sufficiently
retarded to secure a nearly noiseless closing. This improvement, viz., placing the
dash pot in the steam jacket, affords the advantage of working in a medium of
greater density than common atmosphere, and the dash pot can therefore be made
smaller than usual, and in one piece with the valve and the valve seat, it con-
sequently does its work more perfectly by not being influenced by any irregularities
in the joints or connections which is generally the case, when the dash pots are
situated outside the valve jacket. The valve rod or spindle F is attached to the
valve A by means of a special nut E made in balves, with two or more ring grooves
to receive the holding rings on the valve rod F.
The ring grooves are made sufficiently wide laterally so as to allow for any little
inaccuracies in the relative position of the axi of F and A, so as not to bind or
binder the free motion of the valve A.
The manner in which the valve rods F are made (Fig. 1, Sheet I.) to work steam-
tight consists in a long socket in the valve jacket cover, into which the valve rod
is accurately ground, the rod is furnished with a series of annular grooves which get
filled with condensed steam, and form a series of pistons or obstacles to the escape
of steam, a small quantity of loose cotton or other elastic fibre in the chamber f
kept in place, and lightly compressed by the nut f', allowing the rod F to work
perfectly steam-tight, and with a very small amount of friction.
The connection between the valve gear and the valve piston rods F, is effected by
employing a number of steel discs a, a, through holes in the centre of which the valve
rods pass, the discs being secured by two two nuts on the valve rod, with washers
between the discs, so as to keep them slightly apart; the pillars h', h¹, hold the
discs in the same manner as the valve rod, this mode of forming the connection
ensures a slight amount of elasticity, and prevents injury to the valves or their
rods.

page_text: The pillars h¹, h¹, are secured into the loose fitting sleeves h, grooved to receive
the fork g.
This fork carries two trunnions working in the forked levers G, G.
These levers are in connection with the cam-shaped lever K, forming the connecting
link with the valve gear by the rod M, for lifting the induction valves.
It will be seen that when the valve gear through the rod M imparts a rocking
motion to K on the pivot J, that the first moment of contact with the levers G, G,
takes place at the end furthest from their pivots G', G₁, and nearest to the pivot J,
thus imparting at first a slow motion to the valves; the higher the valve rises, the
more the lifting motion is accelerated, because the cam lever, by reason of its
peculiar form, comes successively in contact with the levers G, G, at points which
are always approaching their pivots G₁, G¹, and receding from its own pivot J. On
the return oscillation, the closing of the valves (since they are caused to follow the
receding motion of the cam lever), is secured by the cross spring G".
Sheet III., Figs. 4, 5, 6, and 7 show the new valve gear worked off the con-
necting rod S¹, and applied to a steam engine.
Sheet V., Fig. 1 and Fig. 2 are skeleton diagrams to show the mode of applica-
tion to locomotive engines. This valve gear is one of the class known as
"Hack worth" or "Walshart," but differing from both inasmuch as the motion is
derived entirely from a point situated between the cross head and crank pin end
of the connecting rod without the further complications of excentrics or cranks.
The motion is taken from a point S off the connecting rod S', see Figs. 4 and 6,
Sheet III. Now the point $ must describe an ellipse, and to procure a correct
valve motion the pendulum lever P is not attached directly to the point S but
through the medium of a link R¹, connected at one end with the connecting rod
at S and at the other end with the radius link R. The pendulum lever P is con-
nected with R¹ at some point Q, intermediate between S and T, and therefore
partakes of the motion of both; the effect of this is that Q describes an ellipse
flattened on the side towards the lever P, these proportions being so chosen that
the point N of the lever P vibrates to an equal extent on each side of U, U³, U¹¹,
at N; the upper end of the pendulum lever P is attached or guided by a system of
links and radius rods; the whole of this system is carried by a double-armed
lever U, U¹, U¹¹, which can at will be placed either as shown in Fig. 7 or Fig. 4,
Sheet III., or in any other position intermediate between these two.
By the above arrangement it will be seen that the point N describes a nearly
rectilineal path N, N', at about right angles or inclined with the centre line of the
connecting rod S', according to the position of the above-mentioned system and
double-armed lever. Working from the point M³ of the connecting rod M, con-
necting the above valve gear to the before-described mechanism for working the
induction valves; the path of the point M' is an ellipse and in the position of the
system shown in Fig. 7, the minor axis is equal to the lead required, and this is
the least amount of travel that can be given.
In the position shown in Fig. 4 the ellipse takes an inclined position, so that the
travel of the valve being compounded of the minor and major axi is greater than
in Fig. 7. The difference in extent between the two travels is the amount of the
opening of the valve for the admission of steam to the cylinder.
'
Now it is clear that by connecting the before-described arrangement of
mechanism to a governor in a suitable manner, that the position of said mechanism
and consequently the amount of admission can be changed from that shown in
Fig. 7, when the governor is in its highest position and the admission a minimum,
to that shown in Fig. 4, when the governor is shown in its lowest and the admission
a maximum, any intermediate position giving a greater or lesser admission.
It is to be observed that at the moment the crank passes the dead points the
point N of the pendulum lever always coincides with the axis U of the double-
armed lever U, U", in whatever angle the latter may be, consequently the lead is
constant for all degrees of cut-off. Now the end of M' of the connecting rod M
describes a curved path by reason of its turning round a pivot at M", and to

page_text: eliminate the error this would occasion, by causing an inequality in the amount
of admission to each side of the piston, the proportions of the links N, X, U¹¹,
and X, U¹, are so chosen as to compensate for the error. The above-described valvo
motion may also be applied direct to work the slide valves of stationary engines or
locomotives, as shown on Sheets IV. and V. In this case the mechanism con-
trolling the working of the upper end of the pendulum lever can be put into an
inclined position on either side of the middle position marked "stop" on Figs. 1
and 2, Sheet V., so as to impart a suitable motion to the slide valve for the forward
or backward movement of the engine reversing motion, these positions being
marked "forwards" and "backwards on the Drawings.
It is clear than any position intermediate between these two extremes will give
a greater or less amount of admission or expansion, as required, either for backward
or forward gear. This combined reversing, stopping, and expanding gear can be
operated by the usual reversing lever and notched sector and pawl, as shown on
Sheet IV, or in very large engines by the usual screw reversing gear.
In Fig. 1, Sheet V., the pendulum lever is shown as worked off the coupling rod,
in this case there being no correction for the curve described by the lower end of
the pendulum lever, see Fig. 4, Sheet III., the motion communicated to the valve
is therefore slightly incorrect, that is to say, the admission is not perfectly equal on
both sides of the piston; but in applying this valve gear to engines where the
motion of the piston is transmitted to the driving wheels by means of a working
beam (system Belpaire, Sheet IV. and Sheet V., Fig. 2), one end of the crank con-
necting rod is compelled to move in a circle by being attached to one arm of the
working beam; now the pendulum lever being attached to the connecting rod at
a suitable point intermediate between the crank pin and working beam, the error
due to the curve described by the lower end of said pendulum lever may be so far
eliminated that the distribution of steam in the cylinders is nearly mathematically
correct for any notch of the sector (see Sheet IV. and the following table of
distributions)-

page_text: Having thus described the nature of my said Invention, and the manner in
which the same is to be carried out, I wish it to be particularly understood that I
do not confine myself to the particular form of apparatus herein described, but
that any other equivalent means of obtaining the same end may be used; I claim
as new,
1. The valve gear for working the valves or the slide valves of stationary steam
engines, locomotives, or other engines with variable expansion, regulated either by
hand or by the governor, or to be used as a means of reversing, in the manner
and for the purpose herein set forth and illustrated in the accompanying Sheets of
Drawings.
2. The arrangement of mechanism or parallel motion for correcting the error
introduced by the radius rod connecting the valve gear with the valve or valves,
in the manner and for the purpose herein-before described, and illustrated in the
accompanying Sheets of Drawings.
3. The arrangement for correcting the error produced by the curved path of
the pendulum lever, as herein-before described, and illustrated in the accompanying
Sheets of Drawings.
4. The construction of dash pot, for easing or deadening the fall, of Cornish or
other valves, so as to form part of the same and of their seats and inside their steam
jackets, in the manner and for the purpose herein-before described, and illustrated
in the accompanying Sheets of Drawings.
5. The improved method of connecting the valve spindles with their valves,
Cornish, or other, and the improved method for making the pistons or rods work
steam-tight without the use of tightly packed stuffing boxes, in the manner and
for the purpose herein-before described, and illustrated in the accompanying Sheets.
of Drawings.
In witness whereof, I, the said Herbert John Haddan, have hereunto set my
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