IMPROVEMENTS IN ENGINES
Year: 1873

page_text: LETTERS PATENT to Constantine De Negri, Engineer, of the Hornsey
Iron Works, Hornsey Road, Upper Holloway, London, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN
ENGINES."
PROVISIONAL SPECIFICATION left by the said Constantine De Negri
at the Office of the Commissioners of Patents, with his Petition,
on the 21st April 1873.
I, CONSTANTINE DE NEGRI, Engineer, of the Hornsey Iron Works,
Hornsey Road, Upper Holloway, London, in the County of Middlesex,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
ENGINES," to be as follows:-
One part of my Invention relates to the removal of pressure of steam
or other motor from the back of the slide valve or valves, and is effected
by placing a plate cast in one with a hollow cylinder on one side, and
faced on the opposite side so that the face shall cover the back of the
valve, which is also faced whilst the hollow cylindrical part comes

page_text: through a circular hole in the chest cover, the chest cover being fitted
with a gland which is made steam-tight by means of an india-rubber
ring or other suitable packing. The plate is then adjusted against the
back of the valve by set screws or other convenient means outside the
chest cover. When a back valve is used it is cast hollow and takes 5
steam through the two ends.
The other part of my Invention relates to an automatic variable
expansion gear applicable to a steam or any other expansively working
engine, so that when the governors fly out or fall, the steam or other
expansive body may be cut off at any earlier or later stage in the stroke 1
so as always to keep the engine at one regular pace (though the load
may vary considerably) without the use of a throttle valve.
To accomplish this according to my Invention I use only one
eccentric, eccentric rod, and valve rod; these, as usual, give action to
the principal valve. The back valve being entirely worked from the :
principal onc, in which the two steam ports are carried through, so that
in the two extreme positions of the back valve on the principal one,
when one induct port is open, the other is shut, the exhaust being
worked entirely by the principal valve.
Now to explain how the back valve is worked by the principal onc :-
About the centre of the back of the latter I rigidly fix a pin, leaving in
the former sufficient slot to allow of its relative play or stroke on the
principal valve; again, outside the back valve on the same pin or stud I
place a plate capable of turning freely, the centre of the pin forming the
centre of the said plate; now, at right angles to the stroke of the valves
and when the principal onc is at half stroke, in a line with the centre
of the said plate I form a straight slot, in which slot I fit a small block
with a pin hole in it, which hole receives a pin fixed to another block
capable of sliding up or down in a line also square with the stroke of
the valves in guides rigidly fixed at the back of the valve chest. This
last-named block and pin being made to shift in any usual manner up
or down entirely by the fall or rise of the governors. Again, in tho
before-named plate I cut out one or more curved slots, cach slot being
struck from the centre of the plate, but a portion of each slot being
struck with one radius, whose difference from the radius of the
remainder of the slot is equal to the stroke of the back valve on the
-principal one, whilst in the back of the back valve I rigidly fix a pin-

page_text: and roller to work in the or in each of the curved slots. Now supposing
the governors are down and the point where the radii of the curved slot
change is in such a position as to cut steam off at half stroke of the
piston of the engine, and motion being given to the front valve it is
clear that as the governors rise they will cause the plate to oscillate
further in both directions, and consequently in proportion to their rise
or fall will bring the point of the curved slot where its radii change to
act earlier or later upon the pin and roller in the back valve, causing it
to cut off steam from one port and open the other ready for the next
stroke.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Constantine De Negri in the Great Seal Patent
Office on the 21st October 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CONSTANTINE
DE NEGRI, of the Hornsey Iron Works, Hornsey Road, Upper Holloway,
London, in the County of Middlesex, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of April, in the
year of our Lord One thousand eight hundred and seventy-three, in
the thirty-sixth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Constantine De Negri,
Her special licence that I, the said Constantine De Negri, my executors,
administrators, and assigns, or such others as I, the said Constantine
De Negri, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom.
of Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN ENGINES," upon the condition (amongst
others), that I, the said Constantine De Negri, my executors, or
administrators, by an instrument in writing under my, or their, or one
of their hands and seals, should particularly describe and ascertain
the nature of tho said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months_next and immediately after the date
of the said Letters Patent.
A

page_text: NOW KNOW YE, that I, the said Constantine De Negri, do hereby
declare the nature of my said 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) :-
• One part of my Invention relates to the removal of pressure of steam
or other motor from the back of the slide valve or valves, and is effected
by placing a plate cast in one, with a hollow cylinder on one side, and
faced on the opposite side so that the face shall cover the back of the
valve, which is also faced, whilst the hollow cylindrical part comes
through a circular hole in the chest cover; the chest cover being fitted:
with a gland which is made steam-tight by means of an india-rubber
ring or other suitable packing. The plate is then adjusted against the
back of the valve by set screws or other convenient means outside the
chest cover.
When a back valve is used it is cast hollow, and takes
steam through the two ends.
The other part of my Invention relates to an automatically variable
expansion gear, applicable to a steam or any other expansively working
engine, so that when the governors fly out or fall the steam or other
expansive body may be cut off at any earlier or later stage in the stroke,
so as always to keep the engine at one regular pace though the load
may vary considerably without the use of a throttle valve.
To accomplish this according to my Invention I use only onc
eccentric, eccentric rod, and valve rod; these as usual give action to the
principal valve, the back valve being entirely worked from the principal
one, in which the two steam ports are carried through, so that in the
two extreme positions of the back valve on the principal one, when one
induct port is open the other is shut; the exhaust being worked entirely
by the principal valve.
Now to explain how the back valve is worked by the principal one :—
About the centre of the back of the latter I rigidly fix a pin, leaving in
the former sufficient slot to allow of its relative play or stroke on the
principal valve. Again, outside the back valve on the same pin or stud
I place a plate capable of turning freely, the centre of the pin forming
the centre of the said plate. Now at right angles to the stroke of the
valves and when the principal one is at half stroke in a line with the
centre of the said plate I form a straight slot, in which slot I fit a small

page_text: block with a pin hole in it, which hole receives a pin fixed to another
block, capable of sliding up or down in a line also square with the stroko
of the valves in guides rigidly fixed at the back of the valve chest.
This last-named block and pin being made to shift in any usual manner
up or down entirely by the fall or rise of the governors. Again, in the
before-named plate, I cut out one or more curved slots, each slot being
struck from the centre of the plate, but a portion of each slot being
struck with one radius, whose difference from the radius of the remainder
of the slot is equal to the stroke of the back valve on the principal one,
whilst in the back of the back valve I rigidly fix a pin and roller to
work in the or in each of the curved slots. Now supposing the governors
are down and the point where the radii of the curved slot change is in
such a position as to cut steam off at half stroke of the piston of the
engine, and motion being given to the front valve, it is clear that as the
governors rise they will cause the plate to oscillate further in both
directions, and consequently in proportion to their rise or fall will bring
the point of the curved slot where its radii change to act earlier or later
upon the pin and roller in the back valve, causing it to cut off steam
from one port and open the other ready for the next stroke.
A modification of my Invention is to substitute for the plate with one
or more curved slots a flat cylindrical piece with one, three, or any odd
number of recesses, cut or cast out of its circumference, the bottom of
such recesses being struck from the centre of the cylinder with a radius
as much less than the radius of the cylinder itself, as the required play
of the back valve on the front one; rollers being fixed in the back valve
so that the cylinder when revolving should work against and fit between
them at any point in its revolution. This cylinder is made to revolve, by
any ordinary gear or means, as many times to one revolution of the
engine as it has recesses on its periphery, the governors being so arranged
as to cause, when up, a lead to the revolutions of such cylinder.
Another modification of my Invention is to do away altogether with
the usual eccentric on the shaft of the engine, and to substitute a bevil
wheel to work into another bevil wheel on a small shaft running parallel
with the bore of the steam cylinder, the small shaft having at its other
end another bevil wheel gearing into another wheel on the end of a
small crank shaft, which crank shaft runs in two bearings, one on the
face of the steam chest and the other in the steam chest cover, the

page_text: J
cranked part extending between the two bearings, and its throw being
such as to give the required play of the principal valve. On one part
of such crank pin I put a small square block to work in a slot in the
front valve, the slot being at right angles to the play of the valve, the
crank giving it its ordinary reciprocating motion, whilst on the remaining
part of the crank pin I put a cylinder, similar to the one explained in
the last modification, and to work in the same way between two rollers
in the back valve, only that to this one is rigidly fixed a pinion standing
between the said cylinder and the chest cover and working either round
another fixed pinion or inside a fixed internal toothed wheel, the said
fixed pinion or internal toothed wheel being only moved by the action
of the governors. By this means it is clear that to every revolution of
the small crank the valves will travel together, the difference of their
travel being only that necessary for shutting or opening the back ports
by the back valve, and that as the governors rise or fall they will either
give a lead or retard the cut off.
In order that my Invention may be thoroughly understood, I proceed
to explain the annexed Sheets of Drawings, similar letters being
employed to denote similar parts.
Figures 1 and 2, Sheet 1, represent my arrangement for removing the
pressure of steam or other motor from the back of the slide valve, and
are respectively front view and sectional plan through the steam chest
of an engine, a being the valve; b, the valve rod; c, the plate cast in
one with the hollow cylinder d, which comes through a circular hole in
the chest cover e; f being a gland, made steam-tight by the india-
rubber ring g, and adjustable against the back of the valve by studs and
nuts h.
Figures 3 and 4 represent my arrangement for removing the pressure
of steam or other motor from the back of the valves when two arc
employed, i being the back valve. They also represent my automatically
variable expansion gear, & being a pin rigidly fixed to the back of the
principal valve a, and passing through the slot in the back valve to
form a centre for the plate 1; m is the small block with a hole m¹ to
receive a pin fixed on the other side of the slide n which is movable up
or down on the guides o. In the same Figures I show a simple method
for moving the block or slide n so that a lever fixed on the rocking
shaft P could be affected by the rise or fall of the governors; 9, 2,
:
are

page_text: Fourthly. The arrangement for working two valves with no eccentric
on the main shaft of the engine, and no eccentric rod or valve rod, as
shewn in Figures 7 and 8, Sheet 1.
Fifthly. The general arrangements herein-before described.
In witness whereof, I, the said Constantine De Negri, have here- 5
unto set my hand and seal, this Twenty-first day of October,
in the year of our Lord One thousand eight hundred and seventy-
three.