Improvements in Valve Gear for Prime Movers.
Year: 1897

page_text: Date of Application, 28th May, 1897-Accepted, 3rd July, 1897
QUAFLMIE SIMULTICATION.
Improvements in Valve Gear for Prime Movers.
I JAMES APPLETON of 23 Carlton Street, Eccles New Road, Salford, in the
County of Lancaster, 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 and accompanying drawings:-
My said invention relates to improvements in valve gear for operating the valves
of prime movers, and is intended to greatly simplify the method of operating the
valves. Although I onslder my invention to be particularly applicable to steam
pumps, and have described my improved valve gear in conjunction with a doublé
acting and duplex pump, I do not limit myself to this application alone, as the
same is applicable to prime movers generally in which valves of the type herein.
after described are employed.
And in order that my said invention may be completely understood I will now
describe the same with reference to the annexed two sheets of drawings.
ON SHEET
1.
Fig. 1 shows a longitudinal sectional view of the steam cylinder of a pump
fitted with my improved valve gear.
Fig. 2 is a cross section of the same.
ON SHEET 2.
Fig. 3 shows my invention applied to a duplex pump.
The cylinder A in Figs. 1 and 2 is formed with the usual steam ports a.a¹ and
exhaust port b. The steam and exhaust ports are governed by the valve c which is
disposed between and operated by the pistons de. The pistons de work fluid tight
within the steam chest B. A screw el (see Fig. 2) projecting into a groove cut in
the slide valve e prevents the valve from turning round.
This piston valve is of the ordinary construction and in itself forms no part of
my invention, which consists only in the simplified method of operating the valve.
To effect this I provide the covers A¹ A2 of the steam cylinder A with short
cylinders. securely screwed to the covers. Within the cylinders f g are two
chambers marked f f in the sectional view of the cylinder f.
Steam is admitted to the steam chest B by the pipe h.
Pipes h¹² conduct steam from the interior of the steam chest to one of the
chambers of the cylinders f g.
This is shown at f¹ in the sectional view of the cylinder f and a corresponding
chamber is formed within the cylinder Communication between the chambers
ff is governed by means of a valve i mounted on a valve spindle i¹ which passes
through a packed gland and is provided at the outer end with a handle. A
spring is provided, the tendency of which is to maintain the valve i upon its seat.
The chamber communicates by means of a pipe k to the back of the piston d,
whilst a similar pipe is provided to communicate between the corresponding
chamber in the cylinder g and the back of the piston e. The cylinder g is shown
in outside view but it will be understood that the interior arrangement is exactly
similar to the cylinder f. The valve spindle. i is screwed or otherwise secured
to a tappet m projecting within the cylinder A and which is capable of sliding in

page_text: a bearing formed within the cylinder f. If preferred the tappet m may be formed
in one with the valve spindle ¹. A similar tappet n is also secured to the valve
spindle of the cylinder g.
The working of the valve gear is as follows,
."
As shown in the drawing the valve is on a dead centre and both steam ports are
closed. It is considered impossible that on the stopping of the pump the piston
valve should ever remain on a dead centre and in the ordinary working of the
pump the piston valve must of necessity be always at the end of its stroke as will
be seen from the following description. In case however when fitting or repairing
the pump, the valve should be left in the position indicated, means are provided to
readily operate the valve manually to effect the starting of the pump.
To do this it would only be necessary manually to operate the handle of one of the
valve spindles of the cylinders f or g. Suppose steam be admitted to the steam
chest B and the valve spindle ¹ be pulled forward by means of the handle 3. The
valve is thereby pulled off its seat allowing steam to enter the chamber f from
the chamber which is supplied with steam from the steam chest by the pipe has
already described.
The handle 3 is then released, the spring ; assisted by the steam pressure within
the chamber freturning the valve to its seat. The steam thus admitted to the
chamber passes along the pipe k to the back of the piston which is thus flashed.
to the end of the valve chest and thus opens the steam port a. to steam. Upon
reaching the end of its stroke the steam behind the piston d exhausts along the port d'
to the main exhaust port b. The port a being thus opened to steam the piston C
is traversed to the end of its stroke when it comes into contact with the tappet n
and automatically opens the valve on the valve, spindle within the cylinder g.
Steam is then admitted to the back of the piston e which is thus flashed forward
opening the port a¹ to steam and the port a to exhaust. The steam behind the
piston e is exhausted by the port e¹ into the main exhaust port b.
1.1
The springs within the cylinders' f g assisted by the pressure of steam behind the
valves return the valves to their scats immediately the tappets are released from
contact with the piston C.
The handles on the valve spindles are also utilized to grind the valves upon their
seats.
⋅
It will be seen therefore that each forward and backward stroke of the piston C
is utilized to operate the tappets m n and thus admit steam alternately to the
back of the pistons d e and thus effect the working of the piston valve. The
traverse of the piston valve is extremely rapid. providing for a quick opening of
the ports to steam and thus effectually preventing wire drawing. No matter
what may be the position of the piston C on the stopping of the pump, the piston
valve would be at the end of its stroke and one or other of the steam ports be left
open to steam, ready for the re-starting of the pump. The cushioning of the steam
behind the pistons de prevents their too abrupt contact with the ends of the steam
chest B.
Fig. 3 represents an end view of a duplex pump fitted with my improved. valve
gear. In this arrangement I have provided for the pistons of the cylinders DE
to move in unison. In order that the pistons will synchronise in. their stroke I
arrange that the piston of the cylinder D shall operate the valve of the cylinder E
and vice versa. This I effect by crossing the pipes admitting. steam behind: the
pistons of the valves. Referring to Fig. 3 of the drawings, suppose the piston of
the cylinder D has completed its stroke, the tappet will be operated to admit
steam from the steam pipe o along the crossed pipe o to the back of the piston of
the valve governing the steam to the cylinder E.
The valve of the cylinder E is thus operated by means of the piston of the
cylinder D.
**
The piston of the cylinder E similarly operates the valve of the cylinder D by
means of the pipe p and crossed pipe p³.

page_text: It will of course be understood that the other end of the pump is provided with
a similar arrangement of pipes.
If instead of making the pistons work in unison it is desired to work them
alternately, the pipes admitting steam to the piston valves, as well as being crossed
would also have to be carried from the front of one cylinder to the back of the
piston valve and vice versa.
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. The general arrangement construction and combination of parts comprising
the improved valve gear. for actuating the piston valves of prime movers
substantially as described and shown.
2. In valve gear for the indicated purpose, the cylinders f g secured to the steam
cylinder covers, formed with chambers in communication with the steam chest and
governed by a valve actuated by means of tappets so as to conduct steam at the
required times from the cylinders f g to the back of the pistons of the piston valve,
in the manner, for the purposes and substantially as described and illustrated in
Figs. 1 and 2 of the drawings.
3. As means for positively operating the piston valves of prime movers, the
employment of tappets disposed within the cylinder and operated by the piston, to
alternately admit steam behind the pistons of the piston valve so as to effect the
traverse of the same, in the manner, by the means and substantially as described
and shown.
4. The improved valve gear for duplex pumps, arranged and acting in the
manner and substantially as described and illustrated with reference to Fig. 3 of
the drawings.
.