CERTAIN IMPROVEMENTS IN LOCOMOTIVE AND OTHER STEAM ENGINES
Year: 1842

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
WILSON, Manager of the Works of Messieurs Nasmyths, Gaskell, and Com-
pany, at Patricroft, near Manchester, in the County of Lancaster, Engineers,
send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent, under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-second day of December, One thousand eight hundred and
forty-two, and in the sixth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Robert Wilson, her especial licence,
full power, sole privilege and authority, that I, the said Robert Wilson, my
executors, administrators, and assigns, and such others as I, the said Robert
Wilson, my executors, administrators, 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 and Wales, and the Town of Berwick-upon-Tweed,
my Invention of "CERTAIN IMPROVEMENTS IN LOCOMOTIVE AND OTHER STEAM
ENGINES;" in which said Letters Patent is contained a proviso that I, the said
Robert Wilson, shall cause a particular description of the nature of my said
Invention, and in what manner the same is to be performed, to be enrolled
in Her Majesty's High Court of Chancery within six calendar months next
and immediately after the date of the said in part 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 Wilson, do hereby declare that the nature of the said Invention, and
the manner in which the same is to be performed, is particularly described and

page_text: ascertained in and by the Drawings hereto annexed, and the following expla-
nation thereof, that is to say:-
"
These improvements consist partly in certain methods or arrangements of
gearing and valves of steam engines for working steam expansively, and by
which means the amount of expansion can be varied at pleasure while the
engine is in full motion, whatever the rate of motion may be, and partly for
other improvements in engines, some of which improvements are applicable to
other similar purposes. I shall first proceed to describe my methods of working
steam expansively, and more particularly with reference to the locomotive steam
engine. The advantages gained by working steam expansively are so well known
and so universally admitted as to need no comment; but proper means of ap-
plying the principle of variable expansion while the engine is in full motion, so as
to adapt its power to varying resistance, has long been a desideratum; conse-
quently many attempts have been made to attain this object, and various methods
have been tried, but (with few exceptions) the steam has been "wiredrawn
(to use a well understood phrase), in consequence of the steam being cut off
before it entered the valve casing instead of at the ports of the cylinder,
whereby the steam between the cut-off valve and the cylinder expands along
with the steam in the cylinder, whence a smaller advantage is gained than
would have been had the "wiredrawing" principle been excluded; yet such has
been the advantageous effect in the economy of fuel, that the adoption of the
expansion principle to every steam engine is now felt as a great desideratum.
Hitherto the application of variable expansion has been almost exclusively
confined to large engines, by reason of the comparative slow motion of their
geering being alone favorable to the application of the apparatus which has
hitherto been contrived for working with steam, variably expanded at pleasure.
Now the kind of valves and geering which I employ, and which I am about to
describe as my said Invention for the purpose of working the engine with
expanded steam, are of such a peculiar nature and arrangement as to admit of
their application to reciprocating steam engines, whatsoever be the rapidity of
the motion of the said steam engines, whether such be employed for marine,
stationary, or locomotive purposes.
Having now described the nature of my said Invention, I proceed to show
in what manner the same may be performed. And in order that my improved
methods for effecting this object may be clearly understood and readily carried
into effect, I shall proceed to describe them by referring to the accompanying
Drawings.
In Sheet 1, Fig. 1 is a side elevation of a locomotive engine with outside
cylinders. The cylinder and valves are shewn in section. The cylinder (A) is

page_text: of the construction generally applied to such engines with long ports, a and a',
and an exit port E; a short D valve is used with these ports, as shewn
in Fig. 2 (which is a sectional view of the ordinary steam valves), allowing the
steam to enter the cylinder ports a, a, at each end of the valve.alternately;
but in my improved valves, exhibited attached to the engine in Fig. 1, the
steam has to pass through the openings or ports a, a', so that by applying
another valve, C, the steam may be cut off at these ports at any portion of the
stroke without changing the lead of either ingress or egress steam. Both the
steam valve D, and the cut-off valve C, are moved by the common crank or
excentric motion; but the motion of the valve C, being a little later than valve D,
allows the opening or ports a, a¹, in the steam valves to be each alternately
brought opposite the opening c in the cut-off valve C, when the ports d, d¹, are
alternately brought over the openings a, a', .in the steam cylinder. This takes
place at the commencement of each half of the piston B, when the crank is just
about to pass the centre, and the valve C continues to move a short time
in the same direction after the steam valve D has terminated its stroke, and
the motion being reversed, thus not only shuts up the ports d, d', entirely, but
keeps them shut till the stroke is finished, or in other words, till the steam
valve D has closed the openings a or a¹. The variation of expansion or cut-
off of the steam is effected by varying the length of traverse of the valve C,
when that traverse is about three times the width of the opening or ports
d, d. The valve C will be in the relative position to the valve D, as shewn
in Fig. 1, Sheet 1, and Figs. 3, 4, Sheet 2. When the piston has travelled
one half of the stroke, the motion of the steam valve D will have been re-
versed, but as the motion of the valve C is later than the motion of the valve
D, they will now be moving in oposite directions, and by the time the piston
B reaches the end of the stroke; the port d in the steam valve will have begun
to open upon the port a in the cylinder, and the opening c in the expansion
valve C will be over the opening or port d in the steam valve. Hence there
will be free ingress for the steam until the valve C covers the port d, as before,
which must occur when the piston has travelled half its stroke the other way.
But if the valve C be made to traverse about six times the width of the port d
or d', then the valve C will cover the ports d and d', when the piston has
travelled one eighteenth part of the stroke, and consequently only one
eighteenth of steam is admitted. If the valve C be made to remain at rest,
it will then be over the centre of the steam valve D. In this position, there-
fore, all expansion, as due to the action of the valve C will be removed, there
will be no effect produced by it, and the engine will work as it would without
it; therefore, if the length of stroke of the valve C can be varied at pleasure,

page_text: we shall have thereby the power of giving any required degree of expansion.
This I effect by peculiar arrangements in the gearing, for the cut-off valve C,
(which arrangements being colored pink in the accompanying Drawings)
will be easily traced. The valve rod e (Fig. 1) of the cut-off or expansion valve
is attached to the lever F by the link e', which lever F is again connected
with the rod G, and this rod G, being united at the other extremity with the
stud T, which slides in a T groove or other suitable guide within the curved
lever H, H, and this curved lever receiving a reciprocating motion through
being connected with the excentric rod M, which is moved by an excentric
on the crank shaft, the required reciprocating motion is thereby imparted to
the cut-off valve C. So far as I have at present described, I have shewn
how I obtain a fixed amount of expansion or cut-off; I now proceed to
explain how I propose to vary the extent of cut-off or expansion at
pleasure, while the engine is either in motion or at rest. If the stud
T is directly on the centre of motion n, it will receive no reciprocating
motion, and therefore communicate none to the rod G, and consequently the
valve C will have no motion; but if the stud T be moved away from the
centre n, it will then receive a reciprocating motion from the lever L, greater
or less in extent. According to the distance of the stud T from the centre there
will be vibration, and the vibrations will be in proportion to the distance of the
stud T from the centre n. There are several obvious modes of moving the stud T.
I shall describe that which is shewn in the Drawing, wherein the stud T is
shewn connected with the bell crank J, J¹, by means of the link I¹, which
bell crank J, J', is connected with the lever L by the connecting rod K, and
this lever L receiving motion from the screw and handle s, s, which can be
worked by the engine-man while the engine is in motion or at rest, we then see
how the stud T can be moved at any time without stopping the engine. The re-
ciprocating motion thus given will be communicated to the valve C, and the cut
off will be in proportion; and as the point of the lever L ismoved along the index
plate O, the index points out the amount of expansion, or, in other words, the
portion of the stroke where the steam is cut off. The curve of the lever H is
a portion of a circle, with a radius equal to the length of the rod G, so that to
whatever part of the lever H the stud T is moved, to give the desired cut off
or amount of expansion, the traverse of the valve C will be equal at both ends
of the valve D, whatever the length of that traverse may be. When, the
motion of the steam valve D is reversed, the motion of the expansion valve C
must of course be reversed also. This may be done in several ways. It is
done in Fig. 1 by moving the lever L to the other side of the centre of the
index plate, thereby moving the T stud above the centre n of the lever H, I,

page_text: and thus a reverse motion is effected, and then the index plate points out the
amount of the "cut-off" of the steam on the other side of its centre, as
explained before. This lever L must always follow the reversing lever r in
this case, and also in Fig. 3 (Sheet 2), where the motion to work the curved
lever is brought from the opposite piston motion, the cranks being at right
angles to each other, which gives exactly the same motion as the additional
excentric on the crank shaft at right angles to the crank, see Fig. 1, Sheet 1 ;
but this can only be done in the case of double engines or locomotive engines.
In Sheet 2, Fig. 3 shews the manner in which I move the expansion valve
of one cylinder by means of the motion of the piston of the other cylinder.
P is the cross head of one cylinder, giving motion to the cranked lever Q, Q,
which by means of the link R, transmits the motion to the lever S, whence it
is conveyed by a hollow rod or tube to the lever T, which is fastened on the
other end of the tube opposite the second cylinder, whence it is carried to the
curved lever H, H, by the rod M, and by moving the T stud, as in Fig. 1,
the amount of expansion can be varied at pleasure.
In Fig. 4 I have shewn an additional fork V V¹ to each of the excentric
rods for the purpose of giving the required reciprocating motion to the curved
lever H H. When one of the excentrics is engaged with the common steam
valve lever, the other is thus engaged with the expansion valve lever W,
which, being connected with the lever W¹, conveys the motion of the excen-
tric rod to the curved lever H, H, by means of the rod M, as the motion of the
expansion valve is reversed simultaneously with the reverse of the steam valve
by changing the excentrics in the ordinary manner. The curved lever H, H,
has only to be half the length of that shewn in Figs. 1 Sheet 1, and 3
Sheet 2. The only difference between Figs. 1, 3, 4, is in the method of
moving the curved lever H, H, the other parts being unaltered. Fig. 5 is a
substitute for the curved lever H, H, and being on the same principle as the
curved lever will produce the same effect. The lever x, x, if made to vibrate
on its centre n by any of the methods already described, the ends of the crank
lever will vibrate in a curve proportioned to the distance from the centre n,
and the end of the rod y, being connected to the long end of the crank lever x',
will also move with it in the same curve, and the other end y¹ will move in
another curve, proportioned to its distance from the centre of motion n; and
as this end y' of the rod is moved further from or nearer to the centre n, by
the same means as the T stud in the lever H, H, Fig. 1, 3, 4 and is con-
nected with the cut-off valve C by the rods G and e, the effects will be
exactly the same on the cut-off valve C as in the cases already described.
Fig. 6 and 7 exhibit other methods different from those described, but by

page_text: which nearly the same effects are produced. In all the methods previously
described the alteration in the cut-off is effected by altering the traverse of
the cut-off valve C, but in Fig. 6 and 7 the traverse is not altered, the posi-
tion of the ports in the back of the steam valve D being altered instead, so that
nearly the same effets are produced. The motion of the cut-off valve in Figs. 6
and 7 is taken from the motion of the piston. In Fig. 6 the motion of the
valve C is contrary to the motion of the piston, the centre of motion n being
between the connections P and G. The cut-off valve C is a solid plate without
any opening through it, see Fig. 8. This method is best suited to engines
that seldom require the full steam, as the cut-off is very slow when nearly the
full steam is required, but is very quick in the cut-off with a small quan-
tity of steam or near the beginning of the stroke. To alter the amount
of cut-off, the plates D, D', are moved by the right and left screw S.
This screw is carried with the valve D, by the snugs g, between the two
collars, and is turned either one way or the other by the socket k, which
is caused to revolve by the wheels W when necessary, which are worked in
any common way by the engine-man. The square end of the screw S¹ fits
in the socket k, and revolves with it, whereby the plates D and D¹ are moved
towards the centre of the steam valve D, or from it, according to whichever
motion is given to the socket k by the wheel W. The nearer they are moved
towards the centre the sooner the valve C will cover the port or opening
d, d, and the farther from the centre, the plate or valve C will be the
longer in covering the ports or openings d, d', which admit the steam to the
cylinders.
In Fig. 7 the valve is open in the centre, see also Fig. 10, which shews a
plan view of the valve C. The motion of the valve C being in the same
direction as the piston, it covers the openings in the plates d, d', as it returns
to the centre of the valve D. The plates D, D¹, are moved in the same way
as in Fig. 6, and the screws in both cases are used only for changing the cut-
off, and not for carrying any of the valves, as the plates lie firm on the back of
the steam valve D when it is working, and the traverse of the valve C is a
constant quantity.
}
Secondly, my improvements in locomotive and other steam engines consist in
certain incans of producing or giving friction to the rim of the wheels of loco-
motive engines, with a view to arrest their motion, and also in certain means
(herein-after to be likewise described) of preparing the wood blocks employed in
giving the said friction, so that the heat thereby produced, (namely, the heat pro-
duced by the friction or rubbing on the rim of the wheel or wheels), shall not have
the usual effect of charring or burning, or otherwise rubbing away the wood,

page_text: as is the case when wood which has not been subjected to my said process is
employed. In Sheet 1, Fig. 11 represents the manner in which I produce
and apply friction to the rim of the driving wheel of an engine. The means by
which I effect this are by having a segmental band, or curved piece of iron, or
other suitable material Q, Q, which is attached by one extremity to a pin Z, in
a suitable fixed part of the framework of the engine, while the other extremity
of the arc Q, Q, is attached to the end of a lever a³, ", which lever can be
made to be raised or depressed, or otherwise suitably moved, by steam being
admitted either above or under the piston in the small cylinder W. It will be
evident that if I admit the steam from the boiler to press on the under side
of the piston, it will cause it to draw up the end ¹ of the lever, and so by
depressing the end a", bring the surface of the wooden rubbing blocks w, w,
in contact with the surface of the rim of the wheel with a force proportioned
to the pressure on the piston, and that as increased by the proportions of the
two arms of the lever, namely, as is to r¹¹. The advantage of this mode of
giving friction to the rim of the wheel is that it is done without any other expen-
diture of manual force otherwise than that requisite to open the little stopcocks
which admit the steam to the piston of the small cylinder, while the pressure and
consequent friction produced on the wheel is, by reason of its being derived
from an elastic agent, (namely, the steam), more suited to keep up a constant
and forcible rubbing, and therefore serves to arrest the motion of the engine in
a more certain and speedy manner than that which is effected by the ordinary
means when the force is derived from the mere muscular effort of the engine-
man's hand or foot aided by his weight.
The other improvement which I hereby claim consists of a means of giving
a much greater durability to the brake blocks which rub on the wheel. This
improvement consists in saturating the wood previous to use with a solution of
muriate of magnesia, or other deliquescent salt, or such other salt as has the
known property of impeding the combustion of wood. I, however, prefer
muriate of magnesia, or other deliquescent salt, inasmuch as by reason of their
continuing constantly damp, it gives to the wood the property of resisting the
abrasion and firing, which dry or unsaturated wood would have. The wood in
question may for this purpose be saturated or charged with the salt solution by
any of the ordinary processes for effecting that object; simple steeping in solu-
tion for a few days will suffice, provided the wood is previously dried.
In witness whereof, I, the said Robert Wilson, have hereunto set my
hand and seal, the Twenty-first day of June, in the year of our Lord
One thousand eight hundred and forty-three.
ROBERT (L.s.) WILSON.

page_text: AND BE IT REMEMBERED, that on the Twenty-first day of June, in the
seventh year of the reign of Her Majesty Queen Victoria, the said Robert
Wilson came before our said Lady the Queen in Her Chancery, and acknow-
ledged the Instrument aforesaid, and all and every thing therein contained
and specified, in form above written. And also the Instrument aforesaid was
stamped according to the tenor of the Statute made in the fifty-fifth year of
the reign of His late Majesty King George the Third.
Inrolled the Twenty-second day of June, One thousand eight hundred
and forty-three.