AN IMPROVED LOCOMOTIVE ENGINE
Year: 1846

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
BEWICK LONGRIDGE, of the Bedlington Iron Works, near Morpeth, in the
County of Northumberland, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Thirteenth day-of
January, in the ninth year of Her reign, did, for Herself, Her heirs -and
successors, give and grant unto me, the said Robert Bewick Longridge, Her
especial license that I, the said Robert Bewick Longridge, my exors,
admors, and assigns, or such others as I, the said Robert Bewick Longridge,
my exors, adiñors, and assigns, should at any time agree with, and no others,
from time to time and at all times during the term of years therein expressed,
should and lawfully might make, use, exercise, and vend, within England,
Wales, and the Town of Berwick-upon-Tweed, and also within all Her
Majesty's Colonies and Plantations abroad, my Invention of "AN IMPROVED
LOCOMOTIVE ENGINE;" in which said Letters Patent there is contained a proviso
obliging me, the said Robert Bewick Longridge, by an instrument in writing
under my hand and seal, particularly to describe and ascertain the nature of
my said Invention, and in what manner the same is to be performed, and to
cause the same to be inrolled in Her Majesty's 'High Court of Chancery
within six calendar months next and immediately after the date of the said

page_text: recited Letters Patent, as in and by the same, reference being thereunto
had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Robert Bewick Longridge, do hereby declare that the nature of my said
Invention consists in a new system of working gear, by means of eccentrics,
rods, and levers, or some of them, by the aid of which the slide valves are
made to cut off the steam from admission into the cylinders of the engine at
various points corresponding to various positions of the pistons in the said
cylinders, thereby varying the degree of expansion at which the steam is
worked to such extent as may be necessary. And in further compliance with
the said proviso, I, the said Robert Bewick Longridge, do hereby describo tho
manner in which my said Invention is to be performed, by the following
statement thereof, reference being had to the Shect of Drawings annexed, and
to the figures and letters marked thereon.
And first, I would observe, that in most systems of variable expansion, as
applied to locomotive engines, the point of cutting off the admission of the
steam cannot be varied without at the same time varying the action of the
eduction or egress of the steam from the cylinders in a manner prejudicial.to
the economic working of the engines; in my said Invention, such prejudicial
variation of the eduction does not take place, whatever may be the extent of the
variation in the admission. The method by which I propose to accomplish
this, is by the application of slide valves worked by eccentrics, rods, levers,
links, &c., in the manner herein-after described; that is to say, to each cylinder
there are two eccentrics which work the slide valves belonging to the same; one
of these eccentrics A is fixed upon the main shaft B, B, of the engine, and
the other eccentric C is also placed upon but is moveable, in a circular
direction round the axis of the same main shaft. This circular motion is
given to the eccentric by means of a groove cut within that part called the
extension of the sheave in same spiral direction as the strengthening rib D, D,
assumes on the outside of the extension of the sheave of the eccentric C.
In this groove works a driver E, which can be moved longitudinally along
the aforesaid main shaft of the engine, but it is prevented from any circular
motion relative to the same by being retained by guides or a groove in the
main shaft, as shewn at E, E, Drawing No. 2. The result of this longitudinal
motion of the driver E is to give the afore-mentioned circular motion to the
eccentric, and its amount is sufficient to turn the eccentric through such an
angle as will place it at the same angle behind the crank as it was previously
before it, or of course at any other intermediate position. The tow extreme

page_text: positions for a lead of 30° are shewn by the lines a and b, in Drawing No. 1,
which is a side elevation of my said Invention. By this means the engine is
reversed or the lead of the eccentric varied at will. The aforesaid drivers for
the eccentrics for both cylinders are moved longitudinally and simultaneously
by means of a sheave box or frame F (also placed upon the axle), to which
they are attached, and the levers G, G, and weigh bar H connected therewith,
and the reversing handle or lever I placed in a convenient situation for the
engine driver. Furthermore there is for each cylinder a second eccentric A
fixed as aforesaid upon the main shaft B, B, at a certain angle relative to the
crank. These fixed eccentrics work the expansion slides K, K, of the engine.
The slide valves are of the description shewn in the Drawing. The top ones
are the expansion slides, one of these is shewn at K, K, and it moves upon
the top of the lower slide L, L, and is moved by the fixed eccentric A by the
intervention of the rods M, M, the levers N, and N, the weigh bar O, and
the link P attached at one end to the side spindle Q. The other end of this
link P can be raised or lowered by means of the levers R and R', the weigh
bar S worked by the side rod T and the lever T, at the command of the
engine driver, so that the distance of the end of P from the centre of the
lever N, N', may be varied at will, and consequently the travel or stroke of
the expansion slide may be thus varied at will. The rod M of the eccentric A
may be attached directly to the lever N', or may move it by the intervention
of a weigh bar, as is shewn in the Drawing No. 2, which is a plan of the
gear and part section of the cylinder slide valves and steam chest. The bottom
slide L has two steam passages or ports U, U, through it, and one eduction
port as an ordinary slide valve, and is worked by the moveable eccentric, C,
either from the rod or by the intervention of the rod W, as shewn in the
Drawing, or by levers and weigh bars. By the combined action of the two
slides the admission of steam to the cylinders is cut off at various points of
the stroke of the piston, according as the distance of the end of the rod P
from the centre of the weigh bar O is varied, but the eduction being only
dependant upon the lower slide remains unvaried at every degree of expansion.
When the end of the rod P is brought into its nearest position to, the centre o
the top slide does not effect the admission of steam, and the engine in this
case works with the least degree of expansion, and, according as the aforesaid
distance is increased, the degree of expansion is increased. Though I recom-
mend the particular arrangement of details shewn in the Drawings hereto
annexed, yet I do not base my claim upon this exact arrangement; for
instance, the position of the slide valves may be horizontal or inclined at

page_text: an angle to the horizon, or the position of the various weigh bars and levers
may be varied, neither is my claim confined to engines with cylinders out-
side of the framing; but what I claim with respect to this part of my
Invention is the method of working the double slides, videlicet, each pair
by two eccentrics, one of which is fixed and the other moveable, in a direction
concentric to the main shaft, by means of a driver working in a spiral groove,
or upon a spiral thread cut in or upon the eccentric sheave, and which driver
may be moved longitudinally along the main shaft, thereby causing the 'rota-
tion of the said moveable eccentric sheave, the alteration of the lead of the
slide, or the reversal of the engine. And whereas in some cases the power
of varying the expansion may not be needed, I then propose to employ slide
valves of the ordinary construction, worked by the moveable eccentric C alone,
without the expansion eccentric A, or the top slide K, K, and in this case' my
Invention consists in and is confined to the method of reversing the eccentrics
by means of the spiral grooves and drivers above described.
And I moreover declare, that another part of my said improvement consists
in a certain apparatus lierein-after described, whereby the feed water, pre-
viously to its entrance into the boiler, is raised in temperature by means of the
heated gases after their escape from the tubes of the boiler. The said appa-
ratus consists of one or more vessels or casings, or tubes, or a combination of
the same, placed in the smoke-box or chimney of the engine, and exposed to
the heated gases after their exit from the boiler tubes. The fcel water is
made to pass through this apparatus, and is thereby heated, and then enters
the boiler. The form of apparatus which I propose generally to adopt is
represented in Figures 3 and 4, of which Figure 3 is an elevation, and
Figure 4 a transverse section through X, Y, in Figure 3. A, A, Figure 3, is
the pipe by which the water passes from the pump into the warming appa-
ratus; after circulating through the tubes C, C, C, &c. (Figure 4) it enters the
cases or boxes D, D, from whence it passes by the pipe B, B, (Figure 3) into
the boiler. The form of the apparatus may be varied in many ways, and
though I recommend that herein-before described, I claim, with respect to this
part of my Invention, a combination of pipes or vessels through which the
feed water is made to pass before entering the boiler, provided only that the
same be so placed as to be in contact with the heated gases escaping from the
tubes of the boiler of a locomotive engine. And such my Invention being, to
the best of my knowledge and belief, entirely new, and never before used in
that part of Her said Majesty's United Kingdom of Great Britain and Ireland,
called England, Her Dominion of Wales, or Town of Berwick-upon-Tweed,

page_text: I hereby declare this to be my Specification of the said Invention, whereby I
claim to maintain exclusive right and privilege to the same.
In witness whereof, I have hereunto set my hand and seal, the Tenth
day of February, in the year of our Lord One thousand eight hundred
and forty-six.
AND BE IT REMEMBERED, that on the Tenth day of February, in the
year of our Lord 1846, the aforesaid Robert Bewick Longridge came before
our said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form above
written. And also the Specification aforesaid was stamped according to the
tenor of the Statute made for that purpose.
Enrolled the Fifth day of March, in the year of our Lord One thousand
eight hundred and forty-siz