Improvements in the Motor Apparatus of Direct-acting Steam Pumps.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in the Motor Apparatus of Direct-acting Steam
Pumps.
I, JOHN HORNSBY CARRUTHERS, of Polmadie Iron Works, Polmadie, in the
County of Renfrew, North Britain, 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, that is to say :-
My said invention has for its object by improved constructive details to obtain
increased efficiency and economy of fuel in direct-acting steam pumps.
Examples of apparatus as made with my improvements are shown upon three
accompanying sheets of explanatory drawings which are hereinafter referred to in
describing my invention.
Figure, 1, on Sheet, 1, of the drawings is a longitudinal section and Figure, 2,
on Sheet, 2, is a transverse section of one modification, Figure, 3, being also a
transverse section showing the valve casing as without the valve details.
A second modification is shown in transverse section in Figure, 4, Sheet, 2, and
in longitudinal section in Figure, 5, Sheet, 3, and a third modification is shown in
longitudinal section in Figuro, 6.
In these drawings the same reference numerals are used to mark the same or
like parts wherever they are repeated.
In all modifications of my apparatus it is constructed with two steam cylinders, 7, 8,
arranged tandem and worked on the "compound" system, the pistons 9, 10, being
fixed on one rod, or as I prefer on two rods, 11, 12, which are coupled together to
act as one rod serving to transmit motion in the ordinary way to the piston of the
pump (which is not shown). A single valve casing, 13, with a valve, 14, serves
both cylinders, 7, 8, being placed transversely to them and at one side of the middle
part between them. The main port face in the valve casing, 13, is made with five
ports, 15, 16, 17, 18, 19, the middle one, 17, being the exhaust port, whilst the two
end ports, 15, 19, communicate by passages with the ends of the smaller or high-
pressure cylinder, 7, and the other two 16, 18, with the ends of the larger or low-
pressure cylinder, 8. The main valve, 14, in addition to the ordinary exhaust
cavity, 20, has formed in it a passage, 21, through which steam that has operated
in the high-pressure cylinder, 7, passes to the low-pressure cylinder, 8. The
valve, 14, is moved by means of a bar, 22, which has fixed to its ends,
pistons, 23, 24, working in cylinders, 25, 26, formed in the ends of the valve
casing, 13, the pistons being acted upon so as to move the main valve, 14, at the
proper times by the action of steain on their outer sides such action being
controlled by a small valve or equivalent deriving its motions from the main
pistons, 9, 10. This small valve or equivalent may be arranged in a variety
of ways.
In the modification shown in Figures, 1, 2, and 3, a small slide valve, 27, is
arranged to move upon a port face at one side of the valve casing, 13, this port
face having in it a middle exhaust port, 28, with two pairs, 29, 30, of ports one on
each side thereof. The ports 29, 30, communicate by passages with the cylinders, 25, 26,
respectively, one passage of each pair going to the end of the cylinder, and the other
passage of each pair going to a point at a short distance from the end. The
exhaust cavity of the small valve, 27, opens only the inner port of either pair, and
the corresponding port in the cylinder is closed by the piston before it gets to the
end of the cylinder, thereby confining sufficient cushioning steam to prevent con-
cussion and noise. The small slide valve, 27, is moved by a rod, 31, acted on by a
short lever, 32, on a spindle, 33, having on it another small lever, 34. The
lever, 34, is acted on by tappet pins, 35, 36, which work through bushes in the

page_text: ends of the cylinders, 7, 8, and are moved by the main pistons, 9, 10, respectively
when each approaches the inner end of its cylinder. The spindle, 33, extends out
through a stuffing box, and can be turned by means of an external lever or
handle, if required for putting the small vælve, 27, into a position for starting the
pump.
In the modification shown in Figures, 4, and 5, a single tappet piece, 37, moved
by the main pistons, 9, 10, is made to serve also as the small valve. It works in a
tube in the side of which there are a middle port, 28, communicating with the
exhaust, and lateral ports, 29, 30, communicating (by single passages) with the
cylinders, 25, 26. The valve tappet piece, 37, has its middle part diminished in
diameter to form a space communicating between the exhaust port, 28, and one or
other of the ports, 29, 30. In this modification the motion of the small pistons, 23, 24,
is due to internal pressure operating against the exhaust accordingly as one or
other cylinder, 25, 26, is put in communication with the exhaust. There is provided
for moving the main valve, 14, if required for starting, a lever, 38, on a
spindle, 39, which extends out through a stuffing box and has a lever, 40, on its
outer end. This device for moving the main valve may be adopted in the. first
modification also.
The modification shown in Figure. 6, differs from the one last hereinbefore
described in being without the tappet piece, 37, there being instead thereof reduced
parts, 41, 42, of the main piston rod, 11, which reduced parts, at the proper times,
puts one or other of the passages, 29, 30, leading to the small cylinders, 25, 26, in
communication with an exhaust port, 28, in the tube through which the piston
rod, 11, works between the main cylinders.
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 a direct-acting steam pump the improved combination of parts constituting
the compound steam motor apparatus and valve mechanism substantially as herein-
before described with reference to Figures 1, 2, and 3, of the accompanying
drawings.
2-In a direct-acting steam pump the improved combination of parts constituting
the compound steam motor apparatus and valve mechanism substantially as herein-
before described with reference to Figures, 4, 5, and 6, of the accompanying
drawings.
Dated this Twenty-ninth day of September 1891.
EDMUND HUNT,
Applicant's Agent.