IMPROVEMENTS IN STEAM ENGINES AND PUMPS
Year: 1878

page_text: LETTERS PATENT to Frederick Philip Preston, John Theodoro Prestige, and
Edwin James Preston, trading as J. Stone and Co., at Deptford, Kent, S.E., and
Jonas Dalby, Engineer, of Myrtle Road, Ipswich, Suffolk, for the Invention of
"IMPROVEMENTS IN STEAM ENGINES AND PUMPS."
Scaled the 19th November 1878, and dated the 21st May 1878.
PROVISIONAL SPECIFICATION left by the said Frederick Philip Preston,
John Theodore Prestige, Edwin James Preston, and Jonas Dalby at the Office
of the Commissioners of Patents on the 21st May 1878.
FREDERICK PHILIP PRESTON, JOHN THEODORE PRESTIGE, and EDWIN JAMES
PRESTON, trading as J. Stone and Co., at Deptford, Kent, S.E., and JONAS DALBY,
"IMPROVEMENTS IN STEAM ENGINES
Engineer, of Myrtle Road, Ipswich, Suffolk.
AND PUMPS."
According to this Invention we distribute the steam or other impelling fluid to
each end of the main cylinder by means of a slide valve by preference of the
ordinary D shape, such slide valve being in connection with a piston or pistons
working in a suitable chamber or chambers.
The slide valve is shot in one direction or the other by means of live steam or
other impelling fluid from the main cylinder acting on the slide valve piston or
pistons, and so that the engine can be started at any part of the stroke, all as
herein-after described.
For the purpose of shooting the slide valve the main cylinder is provided with
an auxiliary port or ports near each end, and when the main piston has passed such
port communication is opened with the back of the slide valve piston at that end,
so as to impel it back and open the admission port for fresh steam for the back
stroke of the main piston.
The steam enclosed behind the main piston is by means of a minute passage or
notch in the inner side of the cylinder allowed to commingle with the fresh steam,
the two together forming the cushion.

page_text: The slide valve is formed with a recess or ports in the face part at each end for
the purpose of allowing the steam to pass to the back of either of the slide valve
pistons to complete the stroke of the slide valve; or a small piston valve opened by
the steam may cause the latter to communicate with the back of the slide valve
piston, the slide valve being formed with a notch for letting steam to the small valve
so as to open it.
In some cases for pumping engines we make the piston rod and the pump ram
continuous and of the same diameter, and we make the glands for the two stuffing
boxes to screw into one another by single or by left and right handed screws, the
outer gland or socket being formned with flats or otherwise for turning it, and the
inner gland being by a pin working in a groove prevented from turning, or vice
versa.
The width of packing in the two stuffing boxes may be approximately propor-
tioned inversely, according to the pressure of the steam and the water.
This engine may be worked by compressed air or other suitable agent as well as
by steam, and may be constructed either as a simple or compound engine.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by 2
the said Frederick Philip Preston, John Theodore Prestige, Edwin James
7 Preston, and Jonas Dalby in the Great Seal Patent Office on the 21st
November 1878.
FREDERICK PHILIP PRESTON, JOHN THEODORE PRESTIGE, and EDWIN JAMES
PRESTON, trading as J. Stone and Co., at Deptford, Kent, S.E., and JONAS DALBY, 2
Engineer, of Myrtle Road, Ipswich, Suffolk. "IMPROVEMENTS IN STEAM ENGINES
AND PUMPS."
'
According to this Invention we distribute the steam or other impelling fluid to.
each end of the main cylinder by means of a slide valve by preference of the
ordinary D shape, such slide valve being in connection with a piston or pistons 3
working in a suitable chamber or chambers.
The slide valve is shot in one direction or the other by means of live steam or
other impelling fluid from the main cylinder acting on the slide valve piston or
pistons, and so that the engine can be started at any part of the stroke, all as
herein-after described.
3

page_text: For the purpose of shooting the slide valve the main cylinder is provided with
an auxiliary port or ports near each end, and when the main piston has passed such
port communication is opened with the back of the slide valve piston at that end,
so as to impel it back and open the admission port for fresh steam for the back
stroke of the main piston.
The steam enclosed behind the main piston is by means of a minute passage or
notch in the inner side of the cylinder allowed to commingle with the fresh steam,
the two together forming the cushion.
The slide valve is formed with a recess or port in the face part at each end, for
the purpose of allowing the steam to pass to the back of either of the slide valve
pistons to complete the stroke of the slide valve.
Figure 1 is a vertical longitudinal section of a direct-acting pumping engine
constructed according to our Invention; Figure 2 is a vertical cross section ;
Figure 3, a plan of same; Figure 4 is a separate face view of the slide valve.
A is the steam cylinder, and B the piston of same; C is the slide valve, which is
hre she wn, of the ordinary shape; D and D¹ are pistons connected by a hollow
stem D, which in the middle is formed suitable for fitting in between two ribs on
the back of the slide valve C, the stem being formed with a shoulder d at cach
end of the slide valve C. The cylinder is formed with the ordinary steam ports a, a',
and with the auxiliary ports b, b¹ near each end, and terminating at tho slide valve
face; c, c', are minute notches at each ond of the cylinder, but for clearness sake
shown larger than they really should be. The slide valve C is formed with a
port d*, d, at each end, communicating respectively by a passage at each end
through the valve, as shewn in dotted lines in Figure 1 and in Figure 4; these
ports dx, d', in certain positions correspond with one of the aforesaid auxiliary
ports b or b', and with the continuation ports or passages 62, 63, terminating at each
end of the slide chest, at the back of the pistons D and D' respectively; e, e', are
supplementary ports or notches, leading from the middle of the steam chest F
through the pistons D, D¹, and in certain positions communicating with the ends of
the cylinder by means of the passages f.f; E is the steam admission pipe to the
middle of the steam chest F; g and glare valves seated at each end of the hollow
stem D of the slide valve pistons D, D', and connected by a rod g, or the stem D²
might be recessed down larger at each end, and the valves and g¹, seated close to
one another near the middle of the stem D²; h is a passage leading from the interior
of the stem D, first in a lateral direction, as shown in Figure 2, and then turning
down to the slide valve face, where it constantly communicates with the exhaust
port G, which is shewn at h¹, h', in Figure 3, widened at that side to suit; H is a
lever working in a recess at the back of the stem D³, and serving to move the slide
valve by hand at starting, boing fixed on a spindle I which is fitted with a
handle K. The cylinder cover L is in this case shewn cast in one with the pump
cover M.
The pistons D, D₁, and the slide valve C are operated from the main cylinder as
follows: Steam being admitted into the valve chest F and the slide valve being in
the position shewn in Figure 1, fresh steam is admitted behind the piston B by the
supplementary port e, f, and also from the main port a', by the minute passage or
recess c¹; when the piston B has travelled past the port a¹ full steam is admitted
by it; when the steain has propelled the piston B past the edge of the auxiliary
port b it, the steam, passes by the auxiliary port band the passage d*, in and
through the slide valve C, down to and along the passage 6³, rising into the space
behind the piston D, thereby closing the valve g (the other g² opening simul-
taneously), and shooting the pistons D, D¹, and slide valve C over to the opposite
position, whereby fresh steam is admitted to the front of the piston B for the
return stroke by the port a, commingling with the part of the exhaust steam
enclosed between the piston B and cylinder cover L, the two together forming the
cushion. The steam behind the piston D' escapes by the opened valve g¹ and
passage h from the interior of the stem into the exhaust G.

page_text: The required cushion between the pistons D, D¹, and the ends of the slide chest
F may be obtained by allowing a slight leakage past the said pistons; or according
to another arrangement, a small piston valve opened by the steam may cause the
latter to communicate with the back of the slide valve piston, the slide valve being
formed with a notch for letting steam to the small valve so as to open it. An
arrangement like this is illustrated by Figures 5, 6, 7, 8, and 9.
Figure 5 is a longitudinal section through the lines X, Y, Z, of Figure 7, which
is a vertical cross section; Figure 6 is a central longitudinal section; and Figure 9,
a plan.
Figure 8 is a separate face view of the slide valve. The cylinder is also here
formed with the ordinary steam ports a, a³, Figure 6, and with the auxiliary ports
b, 61; these latter communicate with chambers or passages fitted with small piston
valves m, m³, which by passages n, n³, may open communication with the back of
the slide valve piston D or D¹. The slide valve C being formed with a notch on
one side as shown at o in Figure 8, for admitting steam to the small valve m or
m', by the ports or passages p, p¹, so as to open it; q, q', are ports or passages
leading to the back of the small valves m, m', and serving to bring them back.
The pistons D, D¹, and slide valve C are operated from the main cylinder as
follows: Steam from the slide chest enters the cylinder by the port a¹; when it
has propelled the piston B past the port 6 it passes away by the opened valve m
(this valve being opened by the fresh steam entering at the other end of same by
the notch o and port p); the steam then passes through the port n to the back of
the piston D, forcing it back along with the slide valve C, which then admits steam
for the return stroke by the main port a. The steam in the ports p, p³, exhausts
by the notched out enlarged parts r, r', Figure 8, of the exhaust cavity in the
slide valve C; the same notches also serve to carry away the exhaust from the
ports q, q'.
Figure 10 is a longitudinal section on line X, Y, Z, Figure 11, which latter is a
vertical central cross section of a modified arrangement; Figure 12 is a plan of
same; Figure 13 is a separate face view of the slide valve.
The arrangement of parts is similar to the one last described, but in this case the
ports or passages p', p, are turned downwards into the cylinder itself instead of
upwards to the slide face. Steam being admitted for the return stroke of the piston
B and the latter having passed the edge of the port p¹, the valve m' is prevented
from opening by reason of the steam pressure from the slide chest on the larger
back face of the valve m¹, being larger than the steam pressure (from the interior
of the steam cylinder) on the smaller front face of same." But when the piston B
passes the edge of the port p the valve m will be opened by the cylinder steam
pressure, because the back of the valve m is open to the exhaust through the
port and recess 7. The slide valve C, Figure 13, is in this case made without a
notch in the side as shown.
We further improve the action of direct-acting engines by the addition of self-
acting appliance or governor, for throttling the steam admission in case the load on
the engine (say by the pump dropping its water on the suction side), should sud-
denly be partially, or largely, or wholly removed, or in case of any variations by
obstructions causing irregular working. This governor is when acting operated
from the main cylinder by means of auxiliary ports or passages in the main
cylinder in a manner similar to that of the slide valve impelling pistons.
Figure 14 is a longitudinal section on line X, X, Figure 15, which latter is a
vertical cross section through line Y, Y, Figure 14; these Figures represent a part
of the slide chest F which is formed with a circular chamber N, N¹, on one side;
the steam pipe E is connected to the middle of the chamber N, N', and the steam
from the latter supplies the slide chest F with steam by the passage E¹. The
chamber N, N¹, is bored out to receive three well and easy fitting pistons O, P, Q,
the two former being of the same diameter and the piston Q of a larger diameter.
The pistons are united by the rods or parts S, T, the latter of which works with

page_text: a good and oasy fit in the partition between the chambers for the pistons P and Q;
u is a passage from the part N, and u¹ a passage from the part N', both leading to
the end of the main cylinder as shown, or into the aforesaid auxiliary ports ỗ, b',
or 62, 63, Fig. 3, or into the main steam ports.
There is a small passage through the piston p, as shown in dotted lines. The
full area of the piston O and the ring area of the piston Q are equal. The action
of this governor is as follows:-
As long as the load is on the engine and the steam pressure required to over-
come it is acting so as to work the pump or other apparatus at a regular rate, the
pistons O, P, Q, will remain stationary, or nearly so, in the position shewn in the
Drawing, that is, with the steam admission port E' full open; but in case the resist-
ance or load diminishes the steam pressure in the cylinder would diminish in
proportion. If the piston B be moving in the direction of the arrow and the steam
impelling its drops in pressure because of a diminished load, the superior steam
pressure in the slide chest will force the pistons O, P, Q, back in the same direction,
and the piston P will thereby partially cover or close the steam admission port E
when the equilibrium has again been recovered, "the load having increased," the
piston will be thrown back into its former or normal position, opening the port,
E full by the steam pressure on the largo area of the piston O, or on the ring area
of the piston Q (according as to whether the main piston is moving forward or
back).
Figure 16 is a longitudinal section of a direct-acting pumping engine where the
piston rod R and the pump ram are continuous and of the same diameter. S is the
cylinder gland and T the pump gland; both are screwed inside as shewn, one right
handed and the other left handed, and the two are held in a corresponding screw
socket U; the gland is by the pin v fitting in a groove formed in the gland, pre-
vented from turning. When the gland S is to be tightened up, turn the socket U
to suit, holding at the same time the gland T, say by means of a tommy or spanner
fitting in a hole in T; if the gland T is to be tightened up turn the gland T
itself.
Figure 17 is a part section showing an arrangement where the gland S screws
into the gland T, and where the width of the packing in the two stuffing boxes
may be proportioned about inverseley, according to the pressure of the steam and
the water, and by turning the gland T (the gland S being prevented from turning
by means of the pin v and groove), both bands are tightened up or released.
Engines constructed according to this Invention may be worked by comprossed
air or other impelling fluid as well as by steam, and may be constructed either as
simple or compound engines.
And having thus described and ascertained the nature of this Invention wo
declare that we claim,-
Firstly. The application of auxiliary steam ports to the cylinder when in con-
nection with slide valve impelling piston appliances, and when arranged, sub-
stantially as set forth.
Secondly. The mode and means substantially as here set forth for forming tho
cushion at the ends of the stroke of the main piston by commingling fresh steam
with exhaust stearn.
Thirdly. The construction of slide valve impelling piston appliance operated
from the main cylinder, substantially as herein set forth.
Fourthly. The application of small piston valves operated from the main cylinder
and in connection with slide valve impelling piston appliances, substantially as sot
forth.
Fifthly. The construction of self-acting governor operated from the main cylinder,
substantially as set forth.
Sixthly. The construction and combination of the stuffing box glands of the
cylinder and the pump of a direct-acting pumping engine, substantially as set
forth.

page_text: Seventhly. The general arrangement of working parts of a direct-acting engine
as illustrated in the Drawings when operating, substantially as set forth.
In witness whereof, we, the said Frederick Philip Preston, John Theodore
Prestige, Edwin James Preston, and Jonas Dalby, have hereunto set our
hands and seals, this Eighteenth day of November, in the year of our Lord
One thousand eight hundred and seventy-eight.