Improvements in Direct Acting Pumping Engines.
Year: 1893

page_text: Date of Application, 29th July, 1893-Accepted, 2nd Sept., 1893
COMPLETE. SPECIFICATION.
Improvements in Direct Acting Pumping Engines.
WILLIAM MURDOCH 11 Bothwell Street, Glasgow, 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 the working of the valve on the steam cylinder so as to
admit steam to each end of the said cylinder alternately for the purpose of reversing
the motion of the piston and producing a reciprocating motion without using a fly-
wheel. The steam cylinder has a circular casing cast on it, which is bored to receive.
a piston valve for admitting steam to the cylinder. The boss of said piston valve is:
flat at the back, and on this flat part a small slide valve is operated in a direction at:
right angles to the motion of piston valve and parallel to the line of motion of main
piston rod from which it receives its motion through a lever and connecting link.
The object of this small slide valve is to admit steam through ports in the pistoni
valve to the ends of the piston valve casing, so as to move the piston valve in
alternate directions and admit the steam which is circulating freely about the body:
of the piston valve into the steam cylinder as before mentioned.
Fig. 1 on accompanying drawing shews a sectional elevation through the steam
cylinder and piston valve casing.
Fig. 2(shews, a sectional plan through the steam cylinder and piston valve
casing.
Fig. 3 shews the back of the piston valve with the small-steam- and exhaust
ports.
$1.
.
Fig.
shews the face of the small slide valve, with the steam ports in and the
exhaust pocket on same.
In order that the nature of this invention may be thoroughly understood the
following is a detailed explanation of accompanying drawing :-
Steam or fluid pressure is admitted at D at back of slide valve A and circulates
freely about body of piston valve B: when the valve A is moved down the port a¹
is opened and steam is admitted along it to the end of piston valve casing and acts
on circular portion of piston valve B, pushing it towards the other end of casing,
thus opening port to the steam, which, as stated, circulates freely about body of
piston valve B: port leads to top end of steam cylinder and the steam causes the
main piston to descend. When the piston moves down, the piston rod G carries
down the lever E which is attached to socket H on piston rod G by means of
link F the lever E is swung about a fixed pin K, so when E moves down, small
end e moves up, strikes the upper washer on valve spindle and carries spindle and
valve A up this opens port a² to the steam, which alters the direction of motion
of piston valve B and opens to the steam circulating about body of piston
valve B port leads to bottom end of steam cylinder and the steam reverses the
motion of the piston and causes it to ascend: in this manner a reciprocating action
is carried on.
The auxiliary valve A is so constructed with the steam ports p', p' and the
exhaust pocket o (see Fig. 4), that in moving downwards and opening the port a¹
to steam it also opens the port a² to the exhaust, and when piston valve B moves
along it cuts off steam from port a' and also cuts off the exhaust from port a², and
thus prevents itself from striking the end of casing towards which it is moving :
then when valve A is moved up and opens port a to steam it also opens port a
to exhaust, and as before piston valve B in moving along, cuts off the steam from
port a' and also cuts off the exhaust from port a', thus cushioning itself at the
other end.

page_text: Attached to the end of the spindle of valve A are washers between which the
ende of lever E works. The distance between the washers is adjusted to suit the
travel of end e and the shorter travel of valve A, so that when the end e is moved
up to its top position the valve A is left, and does not descend till the end e
strikes the lower washer and carries the spindle and valve A down again, the
pressure on the back of valve A being sufficient to keep it in a dead position.
The exhaust from the ends of the piston valve casing flows into the main exhaust
port C through the small exhaust port C in the piston valve B.
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 direct acting pumping engines, the combination of a steam cylinder with
main valve working in a casing at right angles to line of motion of piston, and an
auxiliary slide valve at back of main valve, working parallel to line of motion of
piston, substantially as and for the purpose herein before described.
.
2. The combination of a small slide valve at the back of a main piston valve, to
reverse the motion of said piston valve, substantially as and for the purpose herein-
before described.
3. The combination of a main piston valve with a small auxiliary slide valve so
arranged that the piston valve cuts off the steam giving it its motion, while opening
the ports of the main cylinder to steam, substantially as and for the purpose herein-
before described.
Dated this 27th day of July 1893
WILLIAM MURDOCH.