IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES
Year: 1872

page_text: LETTERS PATENT to Alexander Baumann, of Heilbronn, in the
Kingdom of Wurtemburg, in the Empire of Germany, for the
Invention of "IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES."
Sealed the 20th May 1873, and dated the 23rd November 1872.

page_text: Letters Patent for the same, and have made solemn Declaration that I am
the true and first Inventor thereof.
NOW KNOW YE, that I, the said Alexander Baumann, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention, and 5
in what manner the same is to be performed, in and by the following
statement, reference being had to the annexed Drawings and to
the figures and letters marked thereon, that is to say :-
My said Invention consists in the employment of certain arrangements
whereby the action of steam engines which are used for moving direct 10
acting steam pumps and similar contrivances is greatly improved.
In order that the Invention may be clearly understood, I will at once
proceed to refer to the annexed Drawings.
Figure 1 represents a vertical longitudinal section through the centre
of the engine; Figure 2 is a vertical transverse section through the 1
and Figure 3 is a horizontal section through the steam chest along
the line p, q, in Figures 1 and 2. The same letters indicate similar
parts in the several Figures.
same;
The steam enters the engine at M, as shewn in Figure 2, and fills the
space
K;
the steam leaves the engine at N; the space L is always in 2
communication with the exhaust. E is the steam chest; A, the steam
cylinder; B, the steam piston; C, the piston rod; and D, the stuffing
box. The distribution of steam is effected by two differential slides or
piston valves shewn at F and G, which are of the same shape and
symmetrically situated; they are so shaped that cach of them may 2
either give steam or exhaust to the end of the cylinder near which the
same is situated. The entire surfaces of the rear ends r and s of the
slides F and G are exposed to the steam or to the exhaust, but their
front ends and u are not so exposed. On the covers e and f of the
cylinder in which the slides F and G move are formed two cylindrical 3
picces k and i on which the piston valves F and G slide, so that for the
slide F the steam from Q acts only upon the reduced surface t, and for
the slide G the steam entering at X acts only upon the reduced surface
; the steam acts upon the surfaces t and u continuously. Two
passages T and U lead from the larger surfaces r and 8 of the slides Fa

page_text: and G into the steam cylinder A. The passage U is shewn in Figure 1;
but the passage T being symmetrically situated is only visible in
Figure 3 in dotted lines, and in Figure 2. The slide which, when the
parts are in the position shewn in the Drawing, gives steam to the
cylinder A, is the slide F, which has through the passage T its larger
surface in the exhaust, given at the other end of the cylinder A by the
slide G through the exhaust port R. The slide G has its larger surface
s through the passage U in the steam. The slides F and G are
prevented from turning round in their cylinders by small set screws n
and o, which work in slots as shewn in Figure 3.
The steam piston B having steam from Q and exhaust at R, moves
from Q to R, thereby passing over and closing the passage T, so that the
small steam supply at 6 formed in the end of the cylinder in which the
slide F moves (as shewn in Figures 2 and 3) is no longer exhausted
through the passage T, and therefore shifts the slide F in the direction
from to t, its inner surface being in communication with the exhaust
through the port m. When shifted the slide F closes the steam port Q,
and opens the exhaust port S; the passage U being now in the exhaust,
the slide G will be shifted in the direction from n to s, always having
steam acting upon its smaller surface u, and the steam supply formed
at a, as shewn in Figures 2 and 3, being unable to keep up the steam
pressure which is exhausted through the passage U into the cylinder.
When shifted, the slide G will give steam at P, and close the exhaust
port R; the steam piston B will therefore now move from P to S until
similar movements to those previously described take place. As the
piston B has to close the passages Tand U leading into the cylinder,
it must be so constructed, by means of piston rings or otherwise, as will
be well understood, that no leakage from these passages T and U into the
steam cylinder can take place when the steam piston passes over and
closes them; this is effectually done by placing the piston rings (when
the same are employed) so that their slots are at the lower side of the
steam cylinder, as shewn in the annexed Drawings. The slides F and G
are prevented from striking the bottom (H) of the cylinder in which
they move, from the circumstance that the passages T and U, through
which exhaust is communicated to the surfaces and s are not quite at
the ends of the cylinders, so that the slides may pass over and close the
passages, and then the steam supplies a and b which are formed at the
r

page_text: ends of the cylinders will stop the slides in their course. The steam
supplies a and b as well as the passages T and U are regulated by set
screws c, d, V, W, as shewn in Figure 3, and the bottom H is fixed in
its place by a set screw I shewn in Figure 2.
In order to prevent the slides F and G from striking the covers e
and of the cylinder in which they move they are so formed that
although their front ends and u, as before mentioned, offer to the
steam a smaller surface than their rear ends and 8, the effect of the
inequality of surfaces ceases as soon as the slides F and G approach
the covers e and f. For this purpose the slide G having approached the
cover has its inner surface, which was through the port 7 in com-
munication with the exhaust at R, now in communication with the
steam at P; the steam pressure upon the larger surface s is therefore
without effect, and the slide is also kept in its position by steam
pressure from above at P, pressing it down against the cylinder A, the
exhaust of which takes place through the port R. In a similar manner
the slide F is when it shifts prevented from striking the cover e.
The circumstance that the steam presses the slide G, when in the
position shewn in the Drawings, against the cylinder A, and also that
the steam in the cylinder A entering through Q, presses the slide F
upwards against the exhaust L, must be borne in mind in designing and
constructing engines in accordance with my said Invention, and the
surfacts r, s, t, u, must be formed of sufficient size so that the steam
pressure acting upon them may overcome the friction occasioned by the
steam pressure in a direction at right angles to the axis of the slides.
The piston B, if it moves very fast, will pass over the exhaust ports R
and S, but it cannot come in contact with the cylinder covers, because
in its movement it compresses the steam between R and P or between S
and Q, and so forms a cushion.
Having thus declared and ascertained the nature of my said Invention,
and in what manner the same is to be performed, I would observe in
conclusion that I do not claim the several and distinct parts of the
mechanism, herein-before described, separate and apart from each other
as being of my Invention, but what I consider novel and original, and
therefore claim as constituting my said Invention is, the combination
and arrangement of parts and mechanism, substantially as and for the

page_text: purposes herein-before described and set forth, or any mere modifications
thereof.
In witness whereof, I, the said Alexander Baumann, have here-
unto set my hand and seal, this Twenty-first day of November,
in the year of our Lord One thousand eight hundred and seventy-
two.
Vitness,
R. S. MORDAUNT VAUGHAN,
54, Chancery Lane.
A. BAUMANN. (L.S.)