IMPROVEMENTS IN WORKING STEAM ENGINE VALVES
Year: 1854

page_text: LETTERS PATENT to Herman Dirs Mertens, of Margate, in the County
of Kent, Gentleman, for the Invention of "IMPROVEMENTS IN WORKING
STEAM ENGINE VALVES."-A Communication.
Sealed the 16th May 1854, and dated the 4th March 1854.
PROVISIONAL SPECIFICATION left by the said Herman Dirs Mertens
at the Office of the Commissioners of Patents, with his Petition, on the
4th March 1854.
...I, HERMAN DIRS MERTENS, of Margate, in the County of Kent, Gentleman,
do hereby declare the nature of the Invention for "IMPROVEMENTS IN WORKING
STEAM ENGINE VALVES" to be as follows:-
1
This Invention consists of a peculiar combination of apparatus for working
the slide valves, of steam engines, with a view so to arrange their working,
that they may be constant when the pistons are.at. their dead points, notwith-
standing variation in the length of stroke and lead of the valves, and, this,
whether the engines are working in one or other direction. For this purpose,
an eccentric on the crank axis gives motion by a connecting rod to a curved
slotted lever, and to a link, which is connected at one end to the reversing
lever, and at, the other to the connecting rod. The valve rod is connected by
a link or connecting rod to a lever, which moves on an axis carried by an arm
on the axis of the slotted lever ;; the other end of the lever. in connection with
.

page_text: the slide rod is in connection with the piston rod; or, in place thereof, an
excentric may give motion to the lever in connection with the valve rod; by
these arrangements the escape of steam will be rendered more continuous and
uniform.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Herman Dirs Mertens in the Great Seal Patent Office on
the 2nd September 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HERMAN
DIRS MERTENS, of Margate, in the County of Kent, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourth day of March; in the year of our Lord
One thousand eight hundred and fifty-four, in the seventeenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Thomas Dirs Mertens, Her special licence that I, the said Herman
Dirs Mertens, my executors, administrators, and assigns, or such others as
I, the said Herman Dirs Mertens, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for "IM-
PROVEMENTS IN WORKING STEAM ENGINE VALVES," communicated to me from
abroad, upon the condition (amongst others) that I, the said Herman
Dirs Mertens, by an instrument in writing under my hand and seal, should
particularly describe and ascertain the nature of the said Invention, and
in what manner the same was to be performed, and cause the same to be
filed in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Herman Dirs Mertens, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement thereof (that is to say) :-
:
This Invention consists of a peculiar combination of apparatus for working
the slide valves of steam engines, with a view so to arrange their working
that they may be constant when the pistons are at their dead points, notwith-
standing variation in the length of stroke and lead of the valves, and this,
- whether the engines are working in one or other direction. For this purpose,

page_text: an excentric on the crank axis gives motion by a connecting rod to a curved
slotted lever and to a link, which is connected at one end to the reversing
lever and at the other to the connecting rod. The valve rod is connected by
a link or connecting rod to a lever, which moves on an axis carried by an arm
on the axis of the slotted lever, the other end of the lever in connection with
the slide rod is in connection with the piston rod; or, in place thereof, an
excentric may give motion to the lever in connection with the valve rod;
by these arrangements the escape of steam will be rendered more continuous
and uniform.
Having thus stated the nature of the Invention, I will proceed to describe
the manner of performing the same.
Figure 1 shows a side view; Figure 2, a plan, and Figure 3, a transverse
section of apparatus constructed according to the Invention; Figure 4 shows
a section of the steam cylinder separately.
The Drawings show the Invention applied to a locomotive steam engine
with inside cylinders, the parts being in the position when the piston is at the
dead point. By this arrangement of apparatus applied to the slide valve of a
steam engine a regular or variable motion may be obtained, as desired, by
the application of a fixed excentric and a lever, so combined as to give to the
slide valve for the forward and backward motion a determined lead at the
dead point of the piston, which lead remains always the same, whatever may
be the stroke of the slide valve. The working of this apparatus is on the
principle, that at the dead point of the piston, the lead given to the slide valve
backwards and forwards remains always the same, whatever may be the stroke
of the slide valve. C is an excentric fixed on the crank shaft or axis A, which
gives motion to the lever H by means of the connecting rod D; the lever H
being fixed on the shaft or axis K, gives motion to the double slotted lever G.
The excentric C being at the top centre when the piston is at the dead point,
its centres fall perpendicularly on a line passing through the centre of the
driving axle A and the centre of the end of the lever H, where it is connected
to the excentric rod D; the excentric is then in the middle of its rotation,
and the lever H must also then be perpendicular to that line. The length of
the excentric rod D is equal to the distance between the centres of the excen
tric C, and the end of the lever H. The double slotted lever G, which serves
to reverse the motion, and also to vary the stroke of the slide valve, has

page_text: curve, the radius of which is equal to the length of the rod-L; and this lever G
is fixed on the shaft K, and its curve has for centre the point O of the end of
the lever L. In this position, the opposite end Z of the rod L can move up or
down, more or less, in the slotted lever G, above and below the shaft K, to
reverse the motion, without changing the position of the point O; and so as to,
give whilst the engine is working a longer or shorter stroke to the rod L, and
consequently to the slide valve by means of the lever I: : It is by means of the
levers S and Q fixed on the shaft P, P, which are put in motion by the long
rod T, that the end Z of the rod L can be raised or lowered in the slotted
lever G; the rods R, being connected to the lever Q receive motion-up (or
down, so as to obtain the forward and backward motion, and also the different.
positions in which it may be desirable to place the end Z of the rod L in the
slotted lever G, in order to vary the length of stroke of the slide valve. The
lever I, which gives the lead motion of the slide valve, has its fulcrum in the
centre O. Mis a lever fixed to the cross piece V; carried: by the piston rod,
gives to the end N of the lever I the alternate motion of the piston, and the
other end of the lever I gives motion to the slide valve rod Y. Thus, the
motion of the slide valve is obtained by the combined motion of the excentric
C and of the lever I, put in motion by the piston rod. In some cases, where
it would be. difficult to use the piston rod to put in motion the lever I; a
special or additional excentric must be used to produce the said motion.
The piston being at. the dead. point, the excentric pulley is always in the
middle of its rotation; this will allow the end Z of the connecting rod L to be
placed in the slot G, over and under the shaft K, to reverse the motion, and
at a distance lesser or greater from the centre of the shaft K, to vary the
stroke of the slide valve, without giving any motion to the lever I, and con-
sequently to the slide valve, and the two ends of lever I fixed, the one to
the piston rod and the other to the slide valve rod, are always at the end of
their motion to produce the lead of the slide valve, lesser or greater, according
to the proportions given to the arms of the lever I... The lever I, which
produces the lead of the slide valve, has a constant stroke; and on the contrary,
the motion produced by the excentric is variable, and produces the variation
of stroke of the slide valve, and also the forward and backward motion by the
double: slotted lever G. The two united motions give to the slide valve the
most advantageous, working for the expansion of steam at different degrees,
according to the stroke of the slide valve.
Having thus described the nature of the Invention, and the manner of
performing the same, I would have it understood that I do not confine myself

page_text: to the precise details herein described, so long as the peculiar character of the
Invention be retained; but what I claim is, the arrangement of apparatus for
working the slide valves of steam engines, as herein described.
In witness whereof, I, the said Herman Dirs Mertens, have hereunto
set my hand and seal, this Twenty-ninth day of August, in the year
of our Lord One thousand eight hundred and fifty-four.
HERMAN D. MERTENS. (L.S.)
Witness,
GEO. NASS SOLLY,
Clerk to Messrs. Brooke & Mertens,
Sol™, Margate.