IMPROVEMENTS IN VALVE APPARATUS FOR STEAM PUMPS
Year: 1885

page_text: EDWARD HOLT Radcliffe near Manchester in the County of Lancaster Engineer
do hereby declare the nature of my invention for IMPROVEMENTS IN VALVE
APPARATUS FOR STEAM PUMPS to be as follows:-
This Invention has for its object improvements in and relating to valve apparatus
for steam pumps, and consists in an ordinary D slide valve having a bracket or
prolongation on its back working against a three ported valve face of the steam
cylinder. The bracket cast on the back of the valve fits in between two collars of
a valve spindle having a piston at each end known as valve moving pistons,
working steam tightly in cylinderical casings. These casings are freely open to the
steam chest on their inner side nearest to the valve but have no openings beyond
the pistons except the steam passages to be hereafter described.
These cylinderical casings are firmly fixed on the valve face of the steam cylinder,
the casting joining them usually form the steam chest, on the top of each cylin-
derical casing is formed a three ported valve face, the two inside ports on each
facing are for the admission and emission of steam to and from the valve moving
pistons, and the outside ones for admitting steam to the ends of the steam cylinder,
for the purpose of cushioning the main piston, and preventing it from coming in
contact with the heads of the steam cylinder, against each of these faces works a
small slide valve which are coupled together in any suitable manner, and aré
moved to and fro by a spindle, actuated by a lever or levers which receive their
motion from the piston; by a spindle working through the heads of the steam
cylinder or from a tappet on the piston rod, the valve moving pistons are fitted
with semi packing rings held to the sides of the cylinders either by springs or
steam pressure, in each of these cylinders is cut a small groove to admit steam
from the steam chest to the ends of the valve moving pistons, for the purpose of
cushioning them and terminating the stroke of the main valve.

page_text: '
I EDWARD HOLT of 15 Water Lane Street Radcliffe near Manchester in the
County of Lancaster, do hereby declare the nature of my 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 has for its object improvements in and relating to the valve
apparatus of steam pumps and consists in an ordinary D. slide valve working
against an ordinary three ported valve face on the steam cylinder. A bracket or
projection cast on the back of the valve fits in between two collars of a valve
spindle having a piston at each end (of the class known as valve moving pistons
and hereinafter termed the slide-valve piston) working steam-tight in cylindrical
casings. These casings are freely open to the steam chest on their inner sides
nearest the valve but have no openings beyond the pistons except the steain
passages hereinafter described.
These cylindrical casings are firmly affixed on the valve casing of the steam
cylinder the casting, joining them constituting the steam chest. On the top of each
cylindrical casing is formed a three-ported valve face. The two inside ports on
each facing are for the admission and emission of steam to and from the slide valve
pistons whilst the outside ports are for admitting steam to the ends of the main
steam cylinder for the purpose of cushioning the main piston and so preventing it
coming into contact with the heads or ends of the steam cylinder. Upon each of
these faces works a small slide-valve which are coupled together in any suitable
manner and which are moved to and fro by a spindle actuated by a lever or levers
receiving motion from the piston by a spindle working through the heads of the
steam cylinder or from a tappet on the piston rod. The slide-valve pistons are
fitted with semi-packing rings held to the sides of their respective cylinders either
by springs or steam pressure and in each of these cylinders is cut a small groove to
admit steam from the steam chest to the ends of the slide-valve pistons for the
purpose of cushioning them and terminating the stroke of the main valve.
On the accompanying drawing Fig. 1. is a longitudinal section of a Steam Pump
Cylinder and valve chest constructed in accordance with my improvements.
Fig. 2. is a plan of the same cylinder with the valve-chest cover removed and the
auxiliary valve shewn in section. Fig. 3. is a cross section of Fig. 1. on line A.-B.
and Fig. 4. is a cross section of the same on line C-D. In all the views a is the
steam cylinder, b, the main steam piston, c. c the main steam ports, d the main
slide valve; e. e. are the cylindrical casings or cylinders arranged inside the valve
chest and in which the slide-valve pistons f. f. work, these pistons being coupled
together by the webs e¹ e¹ which embrace the projection or bracket d¹ on the back
of the main valve d. and thus cause the two to travel together. g. g. are the semi-
packing rings fitted into corresponding recesses in the slide valve pistons and
h. h. are longitudinal grooves cut in the same cylinders for admitting steam to the
ends of the slide valve pistons. i. i. are boles formed in the slide-valve pistons for
admitting steam into the grooves h. h. and thus of cushioning the slide-valve
pistons. k. and k¹ are the auxiliary valves coupled together or forming one casting
as illustrated and mounted upon the valve facing forming the three-port valve
1. Z. being the ports for admitting steam to the ends of the steam cylinder through
the pipes or passages m. m. in order to cushion the main piston and to start it back
on the return stroke. o. o. are the ports leading into the cylinders of the slide-

page_text: valve pistons and p and p¹ are the exhaust ports of the same cylinders and which
lead into the main exhaust q through the pipes or passages r and r¹.
The action of my improved valve apparatus may be thus described. In the
drawing it will be observed that the main piston b has just closed the main port c
and that the auxiliary valves k. and k¹ are at half stroke. Now when the piston b.
moves a little further upon its back stroke the auxiliary valves k. will commence
to give steam to the end of the steam cylinder d through the port l. and passage m.
and also to give steam to the left-hand slide-valve pistons f. through the port o.
At the same instant steam will be exhausted from the right-hand slide-valve piston
cylinder through the port p¹ and passage r. and thus owing to the preponderance
of pressure upon the left-hand slide valve pistons, both pistons will move from left
to right carrying the main slide-valve d with them but steam will not enter the
main cylinder a through the port c until the main piston b has returned far enough
back to re-open the main port c and which return operation will be effected by the
steam which the auxiliary valve is admitting to the left-hand end of the main
cylinder through the port Z. and passage m. The same action will be repeated at
the other end of the steam cylinder and thus I am not only enabled to cushion the
main piston at each end of its stroke and to prevent the knocking out of the
cylinder covers but also to re-start the piston on its return stroke. It will also be
apparent that this improved form of slide valve pistons permits the pressure of
steam to keep them up to the top of the cylinders and thus prevent any escape
of steam through the ports o. o into the exhaust q. and this owing to the reduced
area presented to the steam pressure on the bottom half of the said pistons by
reason of the same being cut away to receive the semi-packing rings g. g. These
same rings also serve to prevent any steam passing through the grooves h. h. until
the proper instant viz-when the slide valve pistons close the ports o. o as shewn
more clearly by the position of the left-hand piston in Fig. 1.
"
I do not confine myself to the position of the ports l. l. as for instance they may
be arranged as shewn in Fig. 5. In large engines working under heavy loads
I place regulating valves in the passages m. m. to regulate the flow of steam to the
ends of the steam cylinder. Instead of pipes as illustrated, passages may be formed.
in the castings to admit steam to the ends of the steam cylinder but I prefer to
form them as shewn in Fig. 2..
Having thus particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I wish it to be distinctly
understood that I make no claim to actuate the slide valve of a steam pump by a
pair of pistons working in cylinder open on one side to the steam chest, as I am
aware that the same has been in use for some years, but what I do claim is :-
1st In the construction of steam pump valve apparatus the means of cushioning
the main piston and re-starting the same, substantially as hereinbefore described
and illustrated on the accompanying drawing.
2nd The application to each of the "slide valve piston cylinders" of a three-port
valve one port communicating with the main cylinder substantially as and for the
purposes herein before described and illustrated on the accompanying drawing.
3rd The means of cushioning the slide-valve pistons and keeping the same steam-
tight substantially as herein before described and illustrated on the accompanying
drawing.
'