IMPROVEMENTS IN COMPOUND PUMPING ENGINES
Year: 1876

page_text: LETTERS PATENT to Henry Davey, of Leeds, in the County of York, Engineer,
for the Invention of "IMPROVEMENTS IN COMPOUND PUMPING ENGINES.
PROVISIONAL SPECIFICATION left by the said Henry Davey at the Office of
the Commissioners of Patents on the 11th July 1876.
HENRY DAVEY, of Leeds, in the County of York, Engineer. "IMPROVEMENTS
IN COMPOUND PUMPING ENGINES."
My Invention relates to an improved construction and arrangement of steam
pumping engines of the compound type, that is to say, having a high-pressure
cylinder from which the steam after performing work therein passes to a low-pres-
sure cylinder and performs further work by expansion. I place the two cylinders
side by side, and I connect the piston of each to one arm of a bell-crank lever. I
connect the other arms of the two bell-crank levers to one another by a connecting
rod, so that the two pistons always move in opposite directions. I am thus enabled
to pass the steam directly from the one cylinder to the other at the same ends of
the cylinders, whereby I avoid long passages for the steam and simplify the valves,
and I also obtain a diminution of strain on the foundations and consequent economy
in their construction. The ports of the cylinders may be governed either by slides
or by double beat or equilibrium valves. When the cylinders are double acting
two slides are employed, one at each end, or six valves, three at each end, governing
respectively the supply to the high-pressure cylinder, the exhaust therefrom which
supplies the low-pressure cylinder, and the discharge from the latter.
For working the slides or valves I prefer to employ differential gear of the kind
described in the Specifications of Patents granted to me on the 1st February 1871,
No. 277, and the 4th June 1874, No. 1943.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Henry Davey in the Great Seal Patent Office on the 28th November 1876.
HENRY DAVEY, of Leeds, in the County of York, Engineer. "IMPROVEMENTS IN
COMPOUND PUMPING ENGINES."
My Invention relates to an improved construction and arrangement of steam
pumping engines of the compound type, that is to say, having a high-pressure cylinder

page_text: from which the steam after performing work therein passes to a low-pressure
cylinder and performs further work by expansion. I place the two cylinders side
by side and I connect the piston of each to one arm of a bell-crank lever. I connect
the other arms of the two bell-crank levers to one another by a connecting rod, so
that the two pistons always move in opposite directions. I am thus enabled to
pass the steam directly from the one cylinder to the other at the same ends of the
cylinders, whereby avoid long passages for the steam and simplify the valves,
and I also obtain a diminution of strain on the foundations, and consequent economy
in their construction. The ports to the cylinders may be governed either by slides
or by double beat or equilibrium valves. When the cylinders are double acting,
two slides are employed, one at each end, or six valves, three at each end, governing
respectively the supply to the high-pressure cylinder, the exhaust therefrom which
supplies the low pressure cylinder, and the discharge from the latter.
For working the slides or valves I prefer to employ differential gear of the kind
described in the Specifications of Patents granted to me on the 1st February 1871,
No. 277, and the 4th June 1874, No. 1943.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 of the accompanying Drawings represents an elevation of a compound
pumping engine constructed according to my Invention, the cylinders thereof
having their ports governed by slide valves, such as are shewn in Fig. 2, which
is a longitudinal section to an enlarged scale through the slides of the engine; Fig. 3
represents an elevation of a compound pumping engine of similar construction, in
which the cylinder ports are governed by equilibrium or double beat valves; Fig. 4
is a sectional plan through the two cylinders and valve box, and Fig. 5 is a vertical
section through the valve boxes and steam passages, the two latter Figures being
drawn to an enlarged scale.
Referring to Figs. 1 and 2, A is the high-pressure cylinder, and B the low-
pressure cylinder, C, C, are the upper and lower sides enclosed in jackets and
coupled to one rod c, which is preferably worked, as I will hereafter explain
by differential gear of the kind already Patented by me. The piston rod A¹
of the high-pressure cylinder is connected to the horizontal arm D of a bell-
crank lever, and the piston rod B₁ of the low-pressure cylinder is in like manner
connected to the horizontal arm E of another bell-crank lever mounted opposite
to the former, and the vertical arms D₁ and E¹ of the two bell-crank levers
are connected to one another by a connecting link F. From this arrangement it
follows that the pistons of A and B always move in opposite directions when the
one descends the other ascends, and hence the steam which has caused the descent
of the piston of A is led directly by the port a from the cylinder A through the
cavity of the slide C and the port 6 into the cylinder B to cause the descent of the
piston therein; and in like manner the steam which has caused the ascent of the
piston of A is led at once by the port a through the cavity of the slide and the
port in the cylinder B to cause the ascent of the piston therein. The steam
after operating in the cylinder B passes from the ports band b¹into the eduction
passage G, whence it may be led to the discharge pipe or to a condenser.
The con-
denser and air pump may be arranged as shewn by the dotted lines H, the air
pump being worked from an arm E on the shaft of the bell-crank lever E, E¹. As
in working the strain of the one cylinder is downwards, while that of the other is
upwards, the foundation on which the cylinder rests may be comparatively light
and simple in its construction, there being little or no excess of strain on it in
either direction. The engine constructed as above described may be applied to
work a pair of pumps P directly, as shewn in Fig. 1. By loading the plungers of
these pumps beyond their greatest water load the strain ou the links by which
they are connected to the bell-crank levers is always in the direction of tension,
and hence there is no shock at the reversal of motion, even when the joints and
bearing are slack. Moreover, by this arrangement as the load on the one plunger
always balances that on the other there is not at the end of the stroke that want of

page_text: equilibrium which is found detrimental in pumping engines of ordinary construction
especially when the water in the pump fails to follow closely the plunger in its
ascent.
I will now explain the nature and operation of the differential valve gear,
shewn in Fig. 1, for working the slides C, C, but it is to be understood that I make
no general claim to the use of valve gear of this kind except in combination with
engines such as I now describe. I is a small or subsidiary steam cylinder having
its ports governed by a slide i, which is worked by a rod ¹, and lever 2, and rod ³
from an arm on the shaft of the bell-crank lever E, E. K is a cataract cylinder
or cylinder charged with water or other liquid, and fitted with a piston connected
to the piston rod k of the cylinder I. There is a passage from one end of the
cylinder K to the other, which can be regulated in its area by a valve ³, so
that the flow of liquid from the one end of the cylinder K can be retarded
as desired, and the piston of K can thus be made to check or control the
movement of the piston of I. The piston rod k is linked to one end of a lever L,
the other end of which is worked by a rod l, lever 12, and rod 13 from an arm *
on the shaft of the bell-crank lever D, D¹. The middle of the lever L is linked to
the slide rod c, which is thus made to receive a differential motion, partly from the
arm acting on one end of the lever L, and partly from the piston rod acting
on the other end of the lever L, the stroke of the piston rod k being timed by the
movement of the slide i, worked from , and more or less checked by the piston
in K according to the adjustment of the valve k¹. Thus as the piston of A descends
the rod ascending tends to raise the slide rod c; but at the same time the piston
of B ascends, causing the slide rod i¹ to descend, admitting steam above the piston
of I which causes the rod to descend tending to lower the slide rod c, consequently
the movement of the slides C and C, so as to cut off and to admit the steam supply
at the upper and lower ends of the cylinders A and B respectively is that which
is due to the difference of the motions of land k, and by the adjustment of the
valve the latter motion can be checked as desired so as to effect a retardation
of the alternations of the engine, or to produce a pause between successive strokes
such as is found to be advantageous in working pumps.
Referring now to Figs. 3, 4, and 5, it will be seen that the construction and
operation of the engine are substantially the same as in the engine shewn in Fig. 1,
equilibrium or double beat valves being substituted for the slides. Retaining like
reference letters to indicate like parts to those already described.
I will now explain the modifications in respect of the valves and their gear. a is
the steam supply with passages to the inlet valves a, a, of the high-pressure
cylinder A; as, a; are the eduction valves from that cylinder commanding passages
for the supply of the low-pressure cylinder B; and b¹, b, are eduction valves from
the cylinder B commanding passages to the exhaust pipe b leading to the discharge
or condenser. These valves are worked in the usual way from arms on a rocking
shaft M, an arm on which is connected by a rod m to the middle of the lever L, so
as to receive a differential movement as already described, one end of the lever L
being worked by the rods 1, lever 1, and rod 18, from the stud on the shaft of
the bell-crank lever D, D', and the other end from the piston rod k, worked by the
piston of the steam cylinder I, and controlled by the piston of the cataract cylinder K.
The slide of the cylinder I is worked by a lever and rod from the lever L.
According to the arrangement of compound engine, shewn in Fig. 3, the bell-
crank levers D, D', and E, E, have additional horizontal arms D2 and E respectively,
either of which may be applied to work a pump as D,or to carry a counter weight at E*.
Having thus described the nature of my Invention, and in what manner the
saine is to be performed, I claim―
First. The construction of a compound pumping engine having the high and low
pressure cylinders placed side be side with steam ports leading directly from the
one to the other, their pistons being respectively connected to arms of bell-crank
levers, which are connected together so that the two pistons move in opposite
directions, substantially in the manner and for the purposes herein set forth.

page_text: Second. The use in combination with an engine of the kind referred to in the
preceding claim of differential gear for working the slides or valves of its cylinders,
substantially as herein described.
In witness whereof, I, the said Henry Davey, have hereunto set my hand and
in the year of our Lord One thousand
seal, this
day of
eight hundred and seventy-six
HENRY DAVEY. (L.S.)