Improvements in Equilibrated Slide Valves with Variable Expansion for Steam Engines.
Year: 1890

page_text: Date of Application, 2nd July, 1890-Accepted, 2nd Aug.,
1890
COMPLETE SPECIFICATION.
Improvements in Equilibrated Slide Valves with Variable
Expansion for Steam Engines.
I. GUSTAVE DUVINAGE of Pase walk in the Kingdom of Prussia, and German
Empire, 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 :-
This Invention relates to equilibrated slide valves for steam engines and it has for its
object to secure greater simplicity in construction, and an almost perfect and easily
variable degree of equilibration.
The peculiarity of the slide valve constructed according to these Improvements
consists in its being formed of a hollow piston longitudinally slotted along its upper
side, in which a cylindrical expansion slide is arranged excentrically so as to enable
the distribution of the steam to the main valve to be varied as may be desired by
turning the expansion slide, which is provided with angular ends.
I will more particularly describe my said Invention with reference to the accom-
panying drawings in which
Figure 1 shews a cross section of a valve constructed according to these Im-
provements;
Figure 2 a longitudinal vertical section of the same; and
Figure 3 a plan of the expansion valve surface represented as being rolled off to
a plane surface, and of the main valve not unrolled:
The main slide A is constructed as a piston-like cylindrical body, bored excentrically
and provided with openings for the passage of the steam, and slides in the valve chest
which is bored out cylindrically.
It has formed in its upper side, opposite to the steam channels D F and the
exhaust port G, a longitudinal slot s, which gives the main slide a certain degree
of elasticity and serves to ensure its fitting closely in its seating within the valve
chest.
Through the slots, the steam, which enters the hollow part of the expansion slide B,
is caused to exert a certain pressure upon the main slide A and thus to force it
against the cylindrical bore of the steam chest, and causes it to fit closely therein and
prevents its being lifted, without at the same time causing any undue friction. The
amount of the steam pressure upon the surface of the slide may be regulated by the
width of the slot.
The sliding surface of the expansion valve is formed to a curvature corre-
sponding with the inner curvature of the main valve. The expansion slide is
arranged in an excentric position relatively to the axis of the main valve as shewn
in Figures 1 and 2, and it is constructed with angular ends U V as represented
in Figure 3 in a similar manner to the rider valve. According to the angular
position of this valve the steam will be cut off earlier or later.
The main valve and the expansion valve are moved independently of each other
by means of suitable rods.
By the hereinbefore described arrangement, the main valve is almost entirely
equilibrated without the necessity for the use of any complicated mechanism.
Moreover, short steam passages are secured within the main valve and the dimen-
sions of the slides themselves are considerably reduced.
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―
The construction combination and arrangement of a cylindrical main valve bored

page_text: exentrically, provided with a longitudinal slot, and fitting within a cylindrical valve
chest, and an expansion valve having a transverse curvature to fit the bore of
the main valve, and angular ends, substantially as and for the purpose hereinbefore
described and as illustrated by the accompanying drawings.
Dated this 1st day of July A.D. 1890.
WILLIAM E. HEYS,
Agent for the Applicant.