Improvements in Slide-valves for Steam Engines.
Year: 1889

page_text: Date of Application, 22nd Oct., 1889-Accepted, 23rd Nov., 1289
COMPLETE SPECIFICATION.
Improvements in Slide-valves for Steam Engines.
A communication from abroad by HERMAN DIRK HAVERKAMP, of Deventer, in the
Kingdom of Holland, Engineer.
I, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street Manchester, both
in the County of Lancaster & 323 High Holborn in the County of Middlesex Civil
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 invention has for its object a steam-slide valve by means of which the "Port
clearances" of a steam engine (that is the port space occupied by steam which is
unavailable for work), are considerably reduced compared to those of steam engines
of the usual construction, and in this way a great economy in the use of steam
and loss condensation are effected, as the steam located in those port clearances has no
effect on the piston.
This advantage is obtained by using two slide valves, each of which has one face
for the steam supply located in close proximity to the cylinder, and one for the steam
exhaust port located somewhat further therefrom.
The faces for the steam supply ports aforesaid are located as near as possible to the
cylinder in order to render the passage for the steam very short and to reduce in this
way the port clearance to the utmost.
Referring to the accompanying drawing:-
Figure 1 represents a horizontal section of a part of the cylinder and of the valve
chest in which the piston and slide valve are supposed to be travelling in the directions
of their respective arrows.
Figure 2 represents a horizontal section of one of the valves of the same arrange-
ment on an enlarged scale, but this valve has no lap and is adapted to be applied to
steam engines working without expansion.
The cylinder A with piston B is of the usual type. The faces a a of the steam
supply ports are located just above the ends of the cylinder A and as near to the
cylinder as the thickness of the material will allow, so reducing the length of these
ports CC to about to 1 inch.
The faces bb for the exhaust ports are located somewhat further from the cylinder
than the faces a a aforesaid, just about sufficient space being left between them and
the adjacent wall of the cylinder to leave room for the exhaust ports D D.
The slide valves E E which may be united by one rod (not shown in the
drawing) slide on these faces a a and b b and as the stroke or travel of the valves
necessary to open and shut the respective ports is independent of the dimensions of
the faces, it is possible to make these as large as is necessary for a good working
and adjusting of the valves.
The form or shape of the valves is preferably such as to leave at F a con-
siderable space between the ports free to admit steam under the valves; the pressure
of the valves on their faces is consequently greatly reduced and a very good
equilibrium obtained; hence economy in the use of oil, etcetera.
The valve chest is considerably longer than those of the usual type and even
extends somewhat beyond the ends of the cylinder, its cover or lid may be cast
hollow in order to allow the steam to circulate through it, so reducing condensation
in the cylinder A.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :-
A side valve for steam engines in which the face or faces adapted to control the
admission of steam are placed in a different plane from those adapted to control the
exhaust, substantially as and for the purpose
described.
Dated this 21st day of October 1889.
WM. P. THOMPSON & Co.,
Agents for the Applicant.