Improvements in and relating to Slide Valves of Steam and other Engines.
Year: 1891

page_text: ate of Application, 21st July, 1891-Accepted, 5th Sept., 1891
COMPLETE SPECIFICATION.
Improvements in and relating to Slide Valves of Steam and other
Engines.
I, NESTOR FOUQUEMBERG of Wasmes in the Kingdom of Belgium, 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 slide valves for controlling the inlet and outlet of steam
or other fluid to engines and the improvements consist principally in the use
or construction of a double passage slide valve or double valve acting upon the
ordinary sliding surface or table of the cylinder the said table having simple
ports only.
I am aware that a double passage slide valve has been used in connexion with a
double port table with the intention and effect of enabling the length of stroke of
the valve to be reduced, but the double passage valve is according to this invention
considered to be composed of two simple-port slide valves of which the one controls
the movement of the machine in one direction, the other in the contrary direction
when reversed.
In the accompanying drawings, Figs. 1 and 2 show the two valves which would
result from the separation of the combined valve. These two simple valves have
their different axes X and Y which letters may be used hereinafter to denote the
valves. The reversing of the engine is obtained by bringing the valves alternately
into function. For this purpose it is necessary either to displace the axis of the
cylinder table to coincide with the one axis X or the other Y according to the
direction of movement, or else to move the axes of the valves so that the one or
other of them coincides with the axis of the cylinder table. Both these arrange-
ments are shown hereinafter and claimed as part of this invention. The first
arrangement is shown in Figs. 3 to 8 the slide E is moved by a bar of fixed length,
its axis of oscillation remains undisturbed. A false table D is interposed between
the cylinder table and the slide this false table being movable so that its axis
may be brought into coincidence with that of the one or other simple slide valve X
or Y according to the direction of movement. The false table D has three ports
corresponding respectively with those in the cylinder table; the latter are however
sufficiently wide to enable the false table to move from one limit to the other without
closing the communications. Figures 3, 5 and 7 show the three principal positions of the
false table D under three different models of combined slide valve E. Fig. 3 shows
the position for forward travel, the slide E governs the admission at the extreme
left band and at the port d', the exhaust by the port e and interior band c. Fig. 5
is the position for reversed movement, admission governed by ports d and d¹ (interior
bands), and the exhaust by ports e e' (exterior to the bands). Fig. 7 indicates a
midway position in which the engine is stopped the ports fare here either both
closed or when open the one always in communication with the inlet port the other
with the exhaust so that the engine cannot move. In the examples above described
the slide E governed by the excentric or equivalent gear controls the distribution
of motive fluid while the table D moved by hand controls the direction of move-
ment of the machine, but it is obvious that the functions of these two parts E and D
may be exchanged one for the other. In this case the valve or slide E must occupy
the same relative positions with regard to the table D to assure 1st the forward
movement, 2nd the rearward movement 3rd the stopping of the machine. This
property of interchange renders this system easily applicable to different types of
machines. The above described system is well adapted for use in connexion with
mechanism intended to stop or reverse the machine automatically, even from a
distance, after completion for instance of a certain number of revolutions. Thus it

page_text: is necessary only to connect the slide D or E as the case may be which controls
the reversing, with a suitable gear operated by the machine so as to move this
slide to shut off the admission after the determined number of revolutions is
completed.
Figs. 9 and 10 show mechanism on this principle. In addition to the usual fixed
sector shown here as adapted only to prevent the hand lever from being moved
beyond its proper limits, the shaft of the lever carries a sector A movable thereon
and having two notches in which engages a pawl on said lever. To the sector A
is fastened a rod B carrying at suitable places two rings or dogs preferably adjust-
ably fixed thereon (not shown). A running block or the like, tappet etc. moved by
the machine strikes the dog or dogs and thus shifts the rod B in the one or other
direction moving the slide to its centre or otherwise so as to stop or reverse the
machine. This running block may for instance be in the form of a screw,
such as
is employed in a striking train of a clockwork, of a reduced period connected to the
main shaft of the machine.
With the second of the two arrangements hereinbefore referred to, the axis of
oscillation of the slide E may be displaced by suitable means. The false table D
is not required, the slide E moves direct upon the cylinder table. The mechanisms
for displacing the axis of the slide E may be divided into two classes. 1st those
modifying the length of the connecting bar of the slide, 2nd those leaving this bar
of unaltered length. The first of these is especially suitable for machines in which
the excentric rod or crank rod is in a straight line with the slide rod. An example
is shown in Fig. 12. The slide rod terminates in a squared end for engagement
with a hand crank at one end, and in a threaded portion engaging with a nut at the
end of the excentric rod at the other end. The squared end passes through a
similar hole in a sleeve journalled in a suitable bearing and carrying the hand crank.
The slide rod can thus move back and forth within the sleeve, while by revolving
the latter the threaded end may be screwed into or unscrewed in the nut connected
to the excentric rod so as to adjust the position of the axis of oscillation of the slide
in conformity with the desired one of the three positions equivalent to 1st forward
movement, 2nd backward movement 3rd rest.
Figs. 11. 14. 15 and 16 show an arrangement by which the axis of oscillation of
the slide may be adjusted without alteration of the length of the excentric or the
slide rod. The excentric rod is connected to one end of a rocking beam to the other
end of which is connected the slide rod. The two arms of the beam may be of
unequal length so that any crank or excentric may be used for driving the slide
rod. The beam may be fulcrumed on a crank elbow or excentric upon a shaft
journalled in suitable bearings and governed by the hand lever L. By moving this
hand lever and shaft according to the diagram Fig. 16 the fulcrum may be made
to occupy any of the three positions s. s respectively for forward movement
backward movement and rest. Figs. 11 to 13 show the three positions of the slide.
Fig. 11 shows the forward movement. The active part of the valve is that shown
in Fig 1. admission to the left of the valve and through the port d', exhaust
through the port e and the interior band c. Fig. 12 shows the backward movement
in which the part of the valve shown in Fig. 2 is brought into action, admission by
the ports dd, exhaust by the ports e e. Fig. 13 illustrates the machine in position
of rest in which the inlet passages in the cylinder are both covered, or the one
may be continually in communication with an inlet port, the other with an
exhaust port.
This system in common with all systems of distribution in which the reversing
is effected by inversion requires the excentric to be keyed in a normal position that
is to say without lead to the valve either in admission or exhaust.
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 ;-
1). In steam and fluid distributing slide valves a valve constructed with a double

page_text: system of ports or passages in combination with a cylinder table having a single
system of ports or passages, the valve and the table being displaceable the one with
regard to the other as and for the purpose or purposes herein described.
2). The combination with a slide valve having a double system of ports or
passages, a fixed cylinder table having a single system of ports or passages, and a
false table movable between the cylinder table and the valve and having also a single
system of ports or passages-the false table and the valve being respectively and
interchangeably movable as hercin described.
3). The combination with the herein described double valve and single table of
the mechanism for adjusting the position of the valve for forward movement, back-
ward movement and rest, herein described and illustrated.
Dated this 21st dov of July 1891
HERBERT & Co.,
18, Buckingham Street, Strand, London, W.C., Agents to Applicant.