Improvements in Slide Valves and Appliances connected therewith.
Year: 1899

page_text: Date of Application, 9th Oct., 1899-Accepted, 17th Feb., 1900
COMPLETE SPECIFICATION.
Improvements in Slide Valves and Appliances connected therewith.
I, DETLEV CARSTEN FRIEDRICH WULFF, of Brook Strasse, 13, Bremen, Ger-
many, Mechanical Engineer, do hereby declare the nature of my said invention
and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement:-
My invention relates to improvements in the construction and arrangement of
slide valve motion and appliance specially intended for single cylinder pumps
which work without fly wheels and carry full pressure of steam the whole length
of the piston stroke, and which are provided with independent cut off and
although the slide valve motion is of the single valve type, the cut off may be
obtained at any length of stroke without any compression.
In carrying out my invention with slide valves of pumps working at full
pressure of steam, the slide valve is attached to a small piston of which the top
end area is about twice that of the bottom end. This piston, hereinafter named
multiplex-piston, is fitted into a suitable cylinder on top of the valve chest, and
receives its motion from a small equilibrium disc valve, by which the steam
is led to and exhausted from the larger part of it.
The smaller part of the multiplex-piston is under constant pressure of steam
from the valve chest. The reversing of the slide valve only takes place at the
end of each stroke thus leaving the ports full open at all positions of the piston,
the thrust of the slide valve and muliplex-piston caused by the sudden motion
of reversing is neutralized by throttling the steam between the multiplex and a
suitably arranged buffer piston, or by an adjusting screw fitted through the
spindle of the disc valve.
On account of the full open ports at the commencement of the stroke, the
piston would start suddenly, thus producing a disturbing effect on the lift of the
pump valves. This fault is however removed by a special form of the cylinder
ports, which are partly covered by the piston at the end of its stroke and opened
gradually at the beginning.
The nature of my invention will be better understood on reference to the
accompanying sheet of drawings, in which,
Fig. 1 shows a sectional elevation of a cylinder with valve chest, and with a
piston valve attached at the top end to the multiplex-piston and fitted with
arrangement for independent cut off.
Fig. 2 represents a side view of the top part of a single cylinder steam pump
to a reduced scale.
Fig. 3 is a front section of a valve chest showing the disc valve with ports, the
multiplex and buffer piston and piston valve.
Fig. 4 shows the front view of the small disc valve and part of the chest.
Fig. 5 is a slide valve with part of arrangement for independent cut off.
The same letters refer to similar parts throughout the several views.
Referring to Fig. 1, A, denotes the chest for the buffer piston, B that of the
multiplex-piston: C the steam piston: D the cylinder: and E the valve chest.
Price 8d1

page_text: The multiplex-piston is composed of a¹ and c, the space between these parts
is marked by b. The proportion of the area of a¹ to c, is two to one; f, and f¹,
is the piston valve which is attached to the multiplex-piston by the spindle c
The covers of the piston valve project. into the body of the piston valve and
produce or form the thrust faces g, and g¹, against which the nuts h, and h¹,
of the rod r, is acting. The latter is provided with right and left handed
threads; also the nuts h, and h¹. The steam inlet is denoted by i, the steam
spaces at the top and bottom of the piston valve by i, and 2, and the ports of
the valve chest by e, and e¹, but those of the cylinder by d, and d. The exhaust
takes place at p. The position of the piston C, is shown at the commencement
of the stroke, it covers almost the port, d, and the piston valve f, f¹, is at
this position full open. d, is the front view of the main steam ports d, and d¹.
In the side view Fig. 2, L, denotes the steam chest of the disc valve; the
latter receives its motion by the lever a, and the rod w, which is attached to the
lever, connected to the piston rod C³, by a bracket C³, and a small lever or
levers. The slide rod r, by which the independent cut off is obtained is con-
nected to the short arm of the lever v, by links and a small cross head w¹. By
turning this rod, which is carried out by the hand wheel, t, the distance of the
nuts h, and h¹, (Fig. 1) is adjusted. The travel of is constant.
In Fig. 3 which represents a valve gear for full steam at the whole length of
the stroke, n, is a cylindric space of A, into which the buffer piston, a, is fitted
as shown in the down position. This space is connected to the top part of the
multiplex-piston chest through the small port m²; the steam in this space is
throttled by the adjusting screw, m, acting thus as a cushion of the piston valve
with the parts connected when it is on the upstroke. The same purpose is
attained for the downstroke of the valve by the port o¹, fitted with the adjusting
screw, o, which connects the space b, between the multiplex-piston with the
exhaust pl. Instead of a buffer piston an adjusting screw P, may be fitted
through the spindle G, of the disc valve by which the exhaust steam led through
the port s, is throttled.
The casing of the disc valve F, is marked L. The pin or spindle G, of F, is
made steam tight by a stuffing gland. The disc valve F, is provided with a
Ushaped channel s¹, which only serves for the exhaust steam coming from the
top part of the multiplex valve a¹, leading the same through s, s', and z¹, into p.
The valve chest L, is always filled with fresh steam entering the hole
connects ¹, with this space.
y, which
Fig. 4. A front elevation of the disc valve and chest showing the steam port y
on the left and also a portion of the small channels, by which the steam is led
to the upper part of the multiplex-piston, when the disc valve is in the position
as shown in this fig., the exhaust port z, is covered by the overlapping part F.
The equilibrium is adjusted by the ratio between the area of the section of G,
and the faces of F.
In Fig. 5 N, is a common slide valve with a bracket, on the back of which
the end surfaces are denoted with g, and g. The valve obtains at the end of
each stroke its motion by the rod c', attached to the multiplex-piston as described
in Figs. 1 and 3. The nuts h, and h¹, fitted to the rod r, by right and left handed
threads are moved on the back of the valve between guide bars.
The effect of my invention applied to pumps working with full steam at the
whole length of stroke, is as follows:
Referring to the multiplex-piston of which the smaller section (see Fig. 3)
is under steam pressure from ¹, is continually forced upwards. If however
steam is led through s, to the larger part a¹, the surplus of the steam pressure
will force the piston with valve attached downwards and to obtain an alternative
motion of the valve it only is required to lead steam to and from the top part of
the multiplex-piston, which is carried out by the disc valve F, closing before
the end of the stroke. The position of this valve for the down stroke of the
steam piston is shown in Fig. 4 and in Fig. 3 it will be seen, that the steam

page_text: has admission through s to a¹. Both multiplex-piston and slide valve remain
in this position until the steam piston is near the end of the down stroke at
which moment the disc valve is reversed by the rod w attached to the lever v
which pulls the lever so far that the disc valve obtains a vertical position thus
producing a clear exhaust by combining a¹, with p through the ports s¹, s, and z¹.
As the reversing of the full open slide valve takes place only at the end of the
stroke it follows that the width of the steam port opening does not vary at any
position of the piston.
The sudden start of the piston at the commencement of the stroke effected by
the full opening of the slide valve is removed by the piston which covers the
cylinder port d leaving open but a small portion of it and while set in motion
gradually increases the area of the steam port thus producing the same effect as
a slide valve having a small lead. The lower edge of the multiplex-piston a',
forms a steam tight valve face with the top edge of the cylinder containing the
smaller portion c, of the multiplex-piston, while the slide valve remains on the
down motion.
This slide valve gear as described is converted into a variable expansion
gear in a very simple manner based on the property of the slide valve, which
is kept in its position by steam and as the latter may be forced back from either
end of the multiplex-piston into ¹, it only requires an opposite mechanical force
by which the slide valve is pushed over the steam inlet before the piston has
reached the end of its stroke. This is carried out as shown in Figs. 1 to 3
while the piston is on the down stroke the rod in Fig. 2 on being attached by
links to the short arm of the lever v, is moving in the opposite direction. If
now the nuts h, and h, Fig. 1 are adjusted by the hand wheel Fig. 2 in such
a manner that at the commencement of the stroke the top nut h, is brought into
contact with, of the piston valve: then the steam port will be closed at a
certain part of the stroke, which of course depends upon the travel of the rod r,
and the length of the inside lap of the slide valve. Taking an instance in which
the cut off of the slide valve shall take place at ½ of the stroke the travel of the
rod requires to be fully three times the opening of the steam port, and if no
compression shall take place the width of the exhaust port must be the same as
the travel of r. Assuming the nuts h, and h¹, of this gear are set at such a
distance that a contact with g, or g¹, will be permitted at the commencement
of the stroke the cut off of the valve will take place at 3 of the stroke. If the
distance of the nuts is increased to such an extent that the pushing of the valve
by the nuts begins after 3 of the length of the stroke, a cut off at % of the
stroke is attained. If however the distance is still increased so that the nuts
commence pushing the slide valve after a distance of 3 of the piston stroke
the valve is closed by the expansion gear at the end of the stroke and no expan-
sion will take place. That part of the travel of the valve which is still left and
required to open the part to the opposite piston stroke is performed by the multi-
plex-piston.
From this it is evident that practically all degrees of expansion can be arrived
at and also that any degree of expansion may be adjusted at wish while the pump
is working. In some cases the rod r, has the great advantage of preventing the
valves from sticking on their faces no matter whether the gear works with ex-
pansion or not.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is
1. An improved slide valve gear intended for full pressure steam cylinders of
which the slide valve is reversed at the end of each piston stroke by a multiplex-
piston receiving steam at the large part which is exhausted from there by means
of an equilibrium disc valve as described from which the shocks caused by
the sudden reversing motion of the slide valve are removed by throttling the steam

page_text: in the space between the multiplex-piston, and a buffer piston or an adjusting
screw through the disc valve spindle and of which the cylinder ports are specially
formed and covered by the piston at the commencement of the stroke, obtaining
by this arrangement the same effect as with a slide valve having but a small lead.
2. The improved valve motion in Claim 1, converted into a slide valve motion with
independent cut off by introducing a rod fitted with nuts and attachment as
described or similar means by which the slide valve is pushed over the steam ports
at any position of the piston thus cutting off the steam.
Dated this 19th day of September 1900
R. HEBER RADFORD,
Agent for the Applicant.