Year: 1887

page_text: I, HENRY DAVEY, of 3 Prince's Street, Westminster, 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 improved means of actuating the valves of Pumping
Engines, by which the admission of steam is regulated, the stroke of the engine is
automatically adjusted, and the cylinders are kept free from accumulation of water.
Fig. 1 shows my invention applied to a Compound Pumping Engine, whilst
Figs. 2, 3, and 4 show examples of the main part of the valve gearing in simpler
forms of application. The same letters of reference are used to denote corresponding
parts in the various figures. In Fig. 2, a is a steam cylinder of an engine; bits
slide valve, connected to a subsidiary steam piston c, regulated by means of a
cataract d. On the rod e, connecting together the valve 6 and the subsidiary and
cataract pistons, is fulcrumed a lever f, one end of which receives the motion of the
engine piston, whilst the other end gives motion to the expansion valve g. The said
valve g may be made to move on a plate on the back of the D slide valve, as in
Fig. 2, or on the valve itself, as in Fig. 3, or in a separate valve box, as in Fig. 4
and Fig. 1.
In Fig. 3, the lever f has a fixed fulcrum H, and the cut off valve g
receives the positive motion of the engine, while the main valve b receives the inde-
pendent motion of the subsidiary piston. In Fig. 2 and Fig. 4, the lever f is fulcrumed
on the rod e of the subsidiary piston from which the main valve b receives its motion,
whilst the cut-off valve g receives a differential motion due to the combined motions
of the main and subsidiary pistons. In all of the examples the exhaust valve has the
simple motion of the subsidiary piston, whilst the cut-off of steam is effected by the
combined motions of the main and subsidiary pistons.
Fig. 11 illustrates the subsidiary and cataract cylinders in greater detail than in
Fig. 2. The subsidiary piston c and the cataract piston d are connected together by
means of the rod e. Attached to the rod e, between the pistons c and d, is a cross-
head I; and on this cross-head is fulcrumed the lever f. On the lever f is an arm L,
in which works a tappet rod attached to the D slide valve M by means of the lever K,

page_text: The said lever K serves to give the slide valve M a motion opposite in direction to
that of the subsidiary piston c, the valve being moved by the stop L striking the
tappets. The cataract cylinder d is provided with a passage which allows the water
to pass from one side of the piston to the other, and this passage can be throttled, and
even completely closed, by screwing down the plug J. By thus throttling the passage
of the water from one side of the piston to the other the speed of the subsidiary
piston can be regulated.
In Fig. 1, h is a cylinder fitted with a piston connected by the rod A. to a rocking
shaft B, for giving motion to the valves of the engine. The cylinder h is fitted with
an ordinary D slide valve, connected by any convenient device to the engine, so that
towards the end of the stroke of the engine the said D slide valve is reversed, so as to
reverse the motion of the piston. When it is desired to cause the engine to pause at
the end of the stroke, the D slide valve of the cylinder h is not actuated directly.by
the engine, but is reversed by means of the piston of a second cylinder, h', constructed
precisely like that of h, and having a D slide valve connected by any suitable device
to the engine. In my patent No. 1943 I described the pistons-of-these cylinders
actuated by steam and controlled by a water cataract. In this case I dispense with
the cataract cylinders by working the subsidiary cylinders themselves by water
pressure, which may be obtained either direct from the water main of the pumping
engine or from any other convenient source. I regulate the speed of the main and
pausing subsidiary cylinders h h by micans of simple stop valves in the supply
pipes. The cylinder C forms a trip gear fully described in my patent specification
No. 37858º
In Fig. 1, A' is the high pressure cylinder and B' the low pressure cylinder of a
compound steam pumping engine. 99 g are the steam valves, and bbb the exhaust
valves. C¹is a bell crank lever working on the rocking shaft B, and receives its
motion from the subsidiary cylinder h through the rod A. The bell crank lever C¹
is connected by a rod a' to a long lever D¹, fulcrumed at . The said lever D¹ is
connected to the exhaust valves bbb by means of the rods and the cross-
heads ; and thus the said exhaust valves are made to receive the motion of the
subsidiary piston h. The steam valves g g of the high pressure cylinder are actuated
by the upper arm of the bell crank lever F¹, fulcrumed on D'; and the lower arm of
the said bell crank lever, being connected by means of the rod f¹ to the lever W,
receives, through the rod 1, from the rocking shaft V, the motion of the engine piston
on a reduced scale. And since the lever D-to which the bell crank lever F¹ is
fulcrumed receives the motion of the subsidiary piston h, as hereinbefore described
the steam valves g g are actuated by the combined motion of the engine piston and
the subsidiary piston h. The steam valves of the low pressure cylinder B₁ of which
only one, g', is shewn-receive the same motion as those of the high pressure cylinder
but increased in degree by means of the lever H, fulcrumed at L', and receiving its
motion at from the bell crank lever F¹. I make the engine automatically adjust
its stroke, so that it preserves the same amount of clearance at each end of the
cylinder in the following way:-The shaft V, Fig. 1, is actuated by attaching the
lever T to any moving part of the engine which gives it the motion of the main piston
on a reduced scale. On the rod 1, which connects the lever W with the rocking
shaft V, 1 place a screw coupling D having a right and left handed thread, so that
by turning the coupling in one direction the rod is lengthened, and turning it in the
other direction the rod is shortened. An alteration in the length of the rod will alter
the relative positions of the steam valves and the main pistons. I make the screw
coupling to work through a sleeve on a feather. The said sleeve is made to turn in a
socket, attached to the bed plate of the gear, by means of a worm and worm wheel, as
shewn in Fig. 1.-On the shaft of the worm are fixed two ratchet wheels with ratchets
cut in opposite directions, Fig. 6 and 7. A lever, carrying two pawls i and k, is
connected by means of a rod R to a lever S on the rocking shaft v, Fig. 1. A
stationary guide plate q, Fig. 6, keeps the pawls i and k from falling into the ratchets
of the wheels until the engine has nearly completed its stroke; and the guide plate q
is so placed that if the engine make the sanie.length. of stroke on one side of the

page_text: :
centre as it does on the other the pawl i engages the same number of ratchets as the
pawl k, and as the pawls operate in opposite directions their motions neutralize each
other but if the engine, from any cause, make a longer stroke in one direction than
in the other, then one of the pawls will engage a larger number of ratchets than the
other, thereby lengthening or shortening the rod 1, and thus correcting the setting of
the valves.
As regards the equality of clearance in the cylinders, I make the engine auto-
matically keep the clearance space constant in the following way-On the screw
spindle y of the stop valve P, Figs. 8, 9 and 10, of the engine, I place two ratchet
wheels with teeth in opposite directions. On the same spindle, between the ratchet
wheels, is placed a weighted lever Z carrying on either side a pawl, each engaging in
one of the ratchet wheels. The pawls oporato in opposite directions, so that if the
pawl take the same number of ratchets as the pawl p then the two motions
neutralize each other. The pawls are prevented from engaging the ratchets at the
same time by means of fixed guide plates. A rod m (which is connected by suitable
levers to the cross-head of the engine, so as to receive the motion of the piston on a
reduced scale) works in a slot in the lever Z, and is provided with a tappet n above
the lever Z. When the rod m moves" downwards-that is in the direction of the
arrow it actuates the lever Z, by means of the said tappet n, and raises the
weight W. But when the rod m moves in the opposite direction to the arrow,
the action of gravity on the weight W₁ causes it to actuate the lever Z in the opposite
direction to that in which it was previously moved by the tappet n. The extent of
the motion produced by the weight W₁ is, however, fixed, because the motion of the
lever Z in this direction is ultimately arrested by the stop X, and thus the pawl p can
only engage a definite number of ratchets; while the number of ratchets engaged by
the pawl depends upon the length of stroke made by the engine piston. It will
thus be seen that at each stroke of the engine the pawl p being made to engage a
definite number of ratchets thereby causes the stop valve to open wider slowly, by
turning the screwed rod y in the fixed nut N. Should this opening of the stop valve
cause the engine to lengthen its stroke beyond the normal, then the pawl O will
engage a greater number of ratchets than the pawl p, which tends to close the stop
valve P. Thus the valve gear by its action is constantly slowly opening the stop
valve of the engine, whilst its tendency to increase the length of its stroke tends to
close the said valve. The result is that the engine is kept working at its full length
of stroke without the aid of the engine man.
I cause the engine cylinders to be drained of water in the following way :-I make
the rocking shaft V, Fig. 1, give motion to a bell crank lever u, in any convenient
way, and thereby actuate the slide valves and s, of which an enlarged section is
shewn in Fig. 5; the valve s for draining the high pressure cylinder, and the
valve for draining the low pressure cylinder. The valves are ordinary three-
ported D slide valves, the outer ports E E, Figs. 1 and 5, being connected by means
of pipes to the lowest parts of the ends of the cylinders; and the centre or exhaust
port G, in the case of the high pressure cylinder being connected to an ordinary
steam trap t, Fig. 1, and in the case of the low pressure cylinder to the condenser.
It will be seen that the said slide valves partake of the motion of the main valves, and
open to exhaust at the same time as the main valves. The water is thereby allowed
to gravitate away from the cylinders during the period of exhaust without causing
any waste of steam.
Having now described the nature of my invention and the manner in which it may
be carried out, I wish it to be understood that I do not confine myself to the exact
method shewn on the drawing, as it may be variously modified to suit different
circumstances; I claim,
1. Actuating the valves of Pumping engines in such a way that the exhaust valve
or valves receives a simple motion from a subsidiary piston, whilst the cut-off of
steam is effected by the combined motions of the main and subsidiary pistons,
substantially as described and illustrated.

page_text: 2. Working the subsidiary pistons by means of water pressure, substantially as
described and illustrated.
3. Causing the engine to automatically adjust the clearances at the end of the
stroke by means of a device, substantially as described and illustrated.
4. Causing the engine automatically to adjust its length of stroke by means of the
apparatus fixed on the stop valve spindle, substantially as described and illustrated.
5. Causing the engine to automatically drain the cylinder of water by means of
the apparatus, substantially as described and illustrated.
Dated this 6th day of June 1887.