IM- PROVEMENTS IN STEAM ENGINES
Year: 1874

page_text: LETTERS PATENT to William Henry Northcott, of 8, Union Court,
London, in the County of Middlesex, for the Invention of "IM-
PROVEMENTS IN STEAM ENGINES."
Scaled the 4th September 1874 and dated the 17th March 1874.
PROVISIONAL SPECIFICATION left by the said William Henry
Northcott at the Office of the Commissioners of Patents, with
his Petition, on the 17th March 1874.
I, WILLIAM HENRY NORTHCOTT, of 8, Union Court, London, in the
County of Middlesex, do hereby declare the nature of the said. In;
vention for "IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
In the construction of my improved steam engine,-
(1). I place the metal joining the cylinder to the crank shaft bearings
in as direct a line as possible, so that the strains resulting from the
pressure of steam upon the piston are withstood by a minimum weight
of metal. I cast the valve chest, cylinder, framing, and main bearings
all in a piece; and I affix to the framing at each end two flat lugs or

page_text: fect by which the entire engine may be fastened down upon a light
foundation of the ordinary construction, or upon two cast-iron standards
in the manner of a lathe bed. I place the crank pin between two discs,
so weighted as to counterbalance the momentum of the reciprocating
weights of the engine; and I enlarge these discs in diameter, and make
them of a heavy section, so that they may act in the manner of a fly
wheel. I make the crank pin hollow, and fill the hollow with tallow
with the intent that should the crank pin heat from the absence of the
usual lubricant the tallow may melt, and flow into the crank pin
bearings through holes drilled from the exterior of the crank pin to the
interior.
2. I prevent the nuts of the bearings and other parts of the engine
becoming loose by screwing a small screw through them into a hole
underneath, a ring of holes being drilled in the metal at the seat of the
nut, so that one of them may come opposite the screw notwithstanding
that the nut is moved round. This mode of locking nuts is also
applicable to any other class of machinery when from vibration or
other cause the nuts are liable to unscrew.
3. I make the valves of the class known as 68
'piston valves," and to
obtain an easy 'cut-off' I interpose a circular gridiron valve between the
two pistons of the main valve. This expansion valve is actuated by a
separate excentric. The rate of expansion is varied by varying the
travel of the valve, and the travel of the valve is either controlled by
hand or through the means of the governor.
4. I use a governor with light weights running at a fast speed, and I
make the weights as discs instead of as balls, and so that the central
holes upon which the discs are turned may serve also to attach tho
governor arms. The arms are in some cases made as springs acting in
opposition to centrifugal tendency.
5. I make the feed water heater or condenser in the form of a vertical ;
cylinder, at the upper end of which are placed a vertical perforated pipe
and a horizontal perforated diaphragm for the admission of the cold
water and the exhaust steam. At the lower end of the pipe is attached
a hemispherical shell, convex side uppermost. This contracts the area
of the vessel, and causes the water and steam to pass together through a 3
narrow annulus. The passage is contracted also further down into a

page_text: funnel-shaped throat, through which again the water and steam have to
pass together. Suitable orifices are provided for the exit of the uncon-
densed and uncondensible vapours.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Henry Northcott in the Great Seal
Patent Office on the 12th September 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HENRY NORTHCOTT, of 8, Union Court, London, in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventeenth day of March, in the
year of our Lord One thousand eight hundred and seventy-four, in
the thirty-seventh year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said William Henry Northcott,
Her special licence that I, the said William Henry Northcott, my
executors, administrators, and assigns, or such others as I, the said
William Henry Northcott, 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 STEAM ENGINES," upon the
condition (amongst others) that I, the said William Henry Northcott,
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 the 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.
NOW KNOW YE, that I, the said William Henry Northcott, 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:—

page_text: In the construction of my improved steam engines,-
1. I place the metal joining the cylinder to the crank shaft bearings
in as direct a line as possible, so that the strains resulting from the
pressure of steam upon the piston are withstood by a minimum weight
of metal. I cast the valve chiest, cylinder, fraining, and main bearings
all in a piece; and I affix to the framing at each end two flat lugs or
feet by which the entire engine may be fastened down upon a light
foundation of the ordinary construction, or upon two cast-iron standards
in the manner of a lathe bed. I place the crank pin between two discs,
so weighted as to counterbalance the reciprocating weights of the
engine; and I enlarge these discs in diameter, and make them of a
heavy section, so that they may act in the manner of a fly wheel. I
make the crank pin hollow, and fill the hole with tallow with. the intent
that should the crank pin heat from the absence of the usual lubricant
'the tallow may melt and flow into the crank pin bearings through holes
drilled from the exterior of the crank pin to the interior.
2. I prevent the nuts of the bearings and other parts of the engine
becoming loose by screwing a small screw through them into a hole
underneath, a ring of holes being drilled in the metal at the seat of the
nut, so that one of them may come under the screw notwithstanding
that the nut is moved round upon its bolt. This mode of locking nuts
is also applicable to any other class of machinery when from vibration
or other cause the nuts are liable to unscrew.
3. I make the valves of the class known as piston valves, and to
obtain an early cut-off I interpose a circular gridiron valve of novel con-
struction and arrangement between the two pistons of the main valve.
This expansion valve is actuated by a separate excentric or by a cam,
The rate of expansion is varied by varying the travel of the valve, and
the travel of the valve is either controlled by hand or through the means
of the governor.
4. I use a governor with light weights running at a fast speed, and I
make the weights as discs instead of as balls, and so that the central
holes upon which the discs are turned may serve also to attach the
governor arms. The arms are in some cases made as springs acting in
opposition to centrifugal tendency.
5. I make the feed water heater or condenser in the form of a vertical
cylinder, at the upper end of which is placed a vertical-perforated pipe
;

page_text: and a horizontal perforated diaphragm for the admission of the cold:
water and the exhaust steam respectively, or vice versa. At the lower.
end of the pipe is attached a hemispherical shell, convex side uppermost.
This shell contracts the area of the vessel, and causes the water. and
steam to pass together through a narrow annulus. The passage is con-
tracted also further down into a funnel-shaped throat, through which
again the water and steam have to pass together. Suitable orifices are
provided for the exit of the uncondensed and uncondensible vapours.
For the more effectual explanation of my improvements I give here-
with two Sheets of Drawings.
By referring to Sheet. 1 it will be seen that the main framing of the
engine is formed as two flat girders A, A, laid edgeways. These girders
may be cast of a box section wlien the engines are large. The valve
chest, cylinder, framing, and main bearings are all cast in a piece; and
at each end of the framing two lugs B, B, are formed by which the
engine is fastened down upon its supports.
In Fig. 1 is given a section of the crank and fly discs. C is the crank
pin made hollow, and D, D, are the fly discs.
Figs. 4 and 5 shew my method of preventing the unscrewing of nuts
by vibration.
Fig. 6, Sceet 2, shows the valve arrangement. The main valve A, A,
is an ordinary piston valve. Between the two pistons of this valve is
the expansion valve B free to move independently' of the main valve.
upon the spindle G joining the two main valve pistons. The steam is
admitted into the space D, and it follows the direction of the arrows
through the gridiron ports into the cylinder when one of the steam
ports is uncovered by the main valve. The degree of expansion is
determined by the travel of the expansion valve, according to a well-
known rule. The valve casing in this Figure is shown as made with a
liner or tube through which the ports are cut. But the casing may be
cast entire.
Fig. 7 is a modification of my expansion valve. The same letters
refer to the same parts, and the modification is clearly seen by the
Drawing.
Fig. S shows one form of the mechanism used for actuating the
expansion valve. A' is a spindle placed over the centre of the valve,

page_text: and projecting through a stuffing box. A lever B' keyed upon A' comes
down inside the valve box, and engages with the middle part of the
expansion valve through the means of a jaw. Another lever C' is keyed
upon A' on the outside of the valve box. The lever C¹ is caused to
oscillate by being connected to an excentric or crank pin on the engine
shaft through the connecting rod D¹. If the rate of expansion is to be
invariable then the expansion valve has an invariable travel, and the rod D¹
is fixedly connected to the lever C¹. But if the rate of expansion is to vary
the centre of the connections must be shifted along the lever C¹, so that
it may vibrato through a greater or lesser arc. As shown in the Figure
the expansion valve is under the control of the governor. The link E¹
leads to the governor, and F¹ is a balance weight.
Fig. 9 is a section of the feed water heater. As the function of each
part is marked upon the Drawing no further explanation is necessary.
A is the narrow annulus; and B, the contracted throat already
referred to.
In witness whereof, I, the said William Henry Northcott, have
hereunto set my hand and scal, this Twelfth day of September,
in the year of our Lord 1874.
WILLIAM HENRY NORTHCOTT.
(L.S.)