IMPROVEMENTS IN STEAM ENGINES
Year: 1862

page_text: LETTERS PATENT to James Tennant Caird, of Greenock, in the County
of Renfrew, North Britain, Engineer, for the Invention of "IMPROVEMENTS
IN STEAM ENGINES."
Sealed the 5th May 1863, and dated the 28th November 1862.
PROVISIONAL SPECIFICATION left by the said James Tennant Caird
at the Office of the Commissioners of Patents, with his Petition, on
the 28th November 1862.
I, JAMES TENNANT CAIRD, of Greenock, in the County of Renfrew, North
Britain, Engineer, do hereby declare the nature of the said Invention of
"IMPROVEMENTS IN STEAM ENGINES," to be as follows, that is to say: - .
This Invention relates to the novel arrangement and construction of certain
mechanically operative details connected with the valvular apparatus or move-
ments of steam engines, more particularly those of the oscillating class.
The improvements may be carried out under various modifications, but
according to one arrangement, as adapted specially to oscillating engines, the
details are contrived as follows: -The working steam cylinder is formed or
fitted with separate and distinct valve faces; two, for example, for the main
working steam slide valves, and two for the expansion slide valves on the
steam belt. These valve faces, and consequently their corresponding valves,
are disposed two on each side of the main trunnion on which the cylinder
oscillates, that is, there is one main steam slide valve and an expansion valve
on each side. The expansion valve is placed nearest the trunnion, or, in other
words, it is between the trunnion and the main steam slide valve, and it is
worked by a double lever arm from the link herein-after described. This

page_text: arrangement of the valves forms a good balance, and it enables the expansion
to be carried out in a much more effective manner than can be accomplished
according to the usual plan. To a segmentally slotted bar or cross-head piece,
similar to that ordinarily employed for the communication of the eccentric's
motion to the main slide valves, without any derangement from the oscillatory
action of the cylinder, there is attached at the centre a cranked stud. This
stud is bolted in laterally, and is cranked upwards, terminating in a large eye.
This eye is bored out horizontally to embrace a traversing bush cylindrical in
external form, but recessed laterally on each side, or formed with top and bottom
shoulders to fit into the expansion lever link. This link is composed of two
plain bars or curved segmental pieces bolted together, with a space between
them for the traverse of the bush therein. It is from this stud as a centre
that the motion of the eccentric is conveyed to the valve. One end of the link
is jointed in the usual manner by a fixed stud to the lower end of the eccentric
rod from the main shaft, and the link thus receives the vibratory action
necessary for the operation of the valve. The opposite end of the link is
similarly jointed to the lower end of a pendant radius rod or bar, the upper
end of which is fitted with a ring to embrace a concentric collar or shoulder
on the main shaft, or fixed to a stud placed as near the centre of the shaft as
possible; thus this rod has no longitudinal traverse motion, and its lower end
forms the fixed supporting centre for the link to work upon. This lower end
is fitted with an adjusting screw, spindle, lever, and link movement or other
adjusting arrangement, so that it can be set in or out from the main vertical
centre line of the cylinder, and thus vary the effective throw of the link, and
consequently alter the expansive action of the valve. This system of valve
gear is applicable to all classes of steam engines and valvular apparatus, and
it is available as well for the main slide valves as for separate expansion valves.
The adjustable radius bar always keeps the centres correct, and forms a steady
fulcrum for the link action, whilst its adjustment is so simple that the engines
can be handled with much greater facility than heretofore.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Tennant Caird in the Great Seal Patent Office on
the 27th May 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
TENNANT CAIRD, of Greenock, in the County of Renfrew, North Britain, 3
Engineer, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-eighth day of November, in the year of our
Lord One thousand eight hundred and sixty-two, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said James Tennant Caird, Her special license that I, the said James
Tennant Caird, my executors, administrators, and assigns, or such others
as I, the said James Tennant Caird, my executors, administrators, or
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 James Tennant Caird, my executors or administrators,
by an instrument in writing under my hand and seal, or under the hand and
seal of one of them, 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 James Tennant Caird, 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, reference being had to the accompanying Drawings,
and to the letters and figures marked thereon, that is to say :-
My said Invention relates to the novel arrangement and construction of
certain mechanically operative details connected with the valvular apparatus
or movements of steam engines, more particularly those of the oscillating
class.
The improvements may be carried out under various modifications, but
according to one arrangement, as adapted specially to oscillating engines, the
details are contrived as follows:-The working steam cylinder is formed or
fitted with separate and distinct valve faces; two, for example, for the main
working steam slide valves, and two for the expansion slide valves on the
steam belt. These valve faces, and consequently their corresponding valves,
are disposed two on each side of the main trunnion on which the cylinder
oscillates, that is, there is one main steam slide valve and one expansion valve
on each side. The expansion valve is placed nearest the trunnion, or, in other
words, it is between the trunnion and the main steam slide valve, and it is
worked by a double lever arm from the link herein-after described This

page_text: arrangement of the valves forms a good balance, and it enables the expansion
to be carried out in a much more effective manner than can be accomplished
according to the usual plan. To a segmentally slotted bar or cross-head piece,
similar to that ordinarily employed for the communication of the eccentric's
motion to the main slide valves, without any derangement from the oscillatory
action of the cylinder, there is attached at the centre a cranked stud. This
stud is bolted in laterally, and is cranked upwards, terminating in a large eye.
This eye is bored out horizontally to embrace a traversing bush cylindrical in
external form, but recessed laterally on each side, or formed with top and
bottom shoulders to fit into the expansion lever link. This link is composed
of two plain bars or curved segmental pieces bolted together, with a space
between them for the traverse of the bush therein. It is from this stud as a
centre that the motion of the eccentric is conveyed to the valve. One end of
the link is jointed in the usual manner by a fixed stud to the lower end of the
eccentric rod from the main shaft, and the link thus receives the vibratory
action necessary for the operation of the valve. The opposite end of the link
is similarly jointed to the lower end of a pendant radius rod or bar, the upper
end of which is fitted with a ring to embrace a concentrice collar or shoulder
on the main shaft, or fixed to a stud placed as near the centre of the shaft as
possible; thus this rod has no longitudinal traverse motion, and its lower
end forms the fixed supporting centre for the link to work upon. This lower
end is fitted with an adjusting screw, spindle, lever, and link movement or
other adjusting arrangement, so that it can be set in or out from the main
vertical centre line of the cylinder, and thus vary the effective throw of the
link, and consequently alter the expansive action of the valve. This system of
valve gear is applicable to all classes of steam engines and valvular apparatus,
and it is available as well for the main slide valves as for separate expansion
valves. The adjustable radius bar always keeps the centres correct, and
forms a steady fulcrum for the link action, whilst its adjustment is so simple
that the engines can be handled with much greater facility than heretofore.
.
And in order that my said Invention of improvements in steam engines
may be properly understood, I shall now proceed to describe the several
Figures on the explanatory Sheet of Drawings which I have hereunto
appended for the purpose of showing certain modifications under which my
Invention may be judiciously carried out in practice, that is to say :-
Figure 1 on the accompanying Sheet of Drawings is a front elevation,
showing one half of a marine engine of the oscillating cylinder class, and
Figure 2 is a corresponding end view of the engine; Figure 3 is a transverse
section corresponding to Figure 2, and taken on the line 1, 2, Figure 2;

page_text: Figure 4 is also a transverse section, which is taken on the line 3, 4, Figure 2;
Figure 5 is a vertical section, taken through the centre of one of the expan-
sion valves on the line 5, 6, Figure 4.
Figure 6 represents a partial elevation of another mode of arranging the
mechanical details for operating the valvular apparatus of steam engines ;
Figure 7 is a partially sectional elevation, taken at right angles to Figure 6 ;
and Figure 8 is a transverse section, showing a portion of the details delineated
in Figure 7.
In the modification shown in Figures 1 to 5 of the accompanying Drawings
the principal parts of the engine are of the ordinary construction. The steam
cylinder A, the belt B, together with the induction and eduction passages C
and D through the trunnions are each arranged in the manner common to
engines of this class. On each side of the trunnion C, through which the
steam enters, there is arranged an expansion valve, which regulates the admis-
sion of the steam to the cylinder A. Each valve casing E has fitted within it
the valve face F, a vertical section of which is shown in Figure 5, which also
shows the position of the expansion valve G and its connected spindle H. To
this part is attached the rod I, the upper end of which passes through an eye
formed in the guide J, which projects out in a lateral direction from the face
of the cylinder A. The prolongations I of the spindles H are each formed
with a boss or lateral enlargement at the central part, in which a bush is fitted
to admit of its being connected by means of a bolt and nut to the end of a
bent lever K. These levers are each centred on a stud, the back plate of
which is screwed to a projecting part cast on the face of the cylinder A. The
inner arm of each of the levers K extends towards each other, and terminates
in a brass bush or block L, so as to traverse easily to and fro in the segmental
slot, which is formed in the bar or cross head M. The cross head M is formed
with a prolongation that extends in an upward direction, the extremity passing
through the eye of a guide N, which is bolted to the beam of the framing, the
lateral extremities of the cross head being bolted to guide brasses which partly
encircle the columns of the framing. To the centre of the cross head M is
fixed a cranked stud O, which is cranked in an upward direction, and termi-
nates in a large eye. In this eye is fitted the traversing bush P, which is
recessed in a lateral direction on the front and back, or formed with top and
bottom shoulders which embrace the expansion lever link Q, as shown in the
sectional view, Figure 1. This link is composed of two plain bars or curved
segmental pieces, which are bolted together at the extremities, leaving a space
between them for the traverse of the bush P. One end of the link Q is
jointed to the lower end of the eccentric rod R, the reciprocatory movement of

page_text: which is communicated to the expansion valves. The other end of the link Q
is jointed in a similar manner to the pendent rod S, the upper end of which is
bolted to a strap that encircles a ring on the main shaft T. In lieu of this
arrangement the rod may be fixed to a stud arranged as near the centre or
axial line of the main shaft as possible. A slot is formed in the lower part of
the rod S, in which is fitted a nut U, and through-this the horizontal screw V
works. This screw is supported in bearings, which project out from the
columns of the framing, and on one extremity is fitted the hand wheel W.
By turning the hand wheel W the screw V is put in motion, which causes the
.rod S.to move in a lateral direction either to the right or left, according to the
direction given to the hand wheel by the engineer. In this way the link Qis
caused to move in either direction, so that it can be set to or from the vertical
centre line of the cylinder A, and thus vary the throw of the link, and so alter
the expansive action of the valves to the extent that may be found
desirable.
. Another mode of. arranging the mechanical details connected with the
expansion valves is shown in Figures 6, 7, and 8 of the accompanying
Drawings. In this modification the lever K, with the cross head M, cranked
stud O, and link Qare similar to the corresponding parts shown in Figures 1
to 3. The lower ends of the eccentric rod R and the pendent rod S are bored
and fitted with brasses, which form the bearings for the link studs. The rod S
is jointed by a link to the horizontal rack X, which is actuated by a pinion Y
on the back of the hand wheel Z. This wheel is mounted on a stud a, which
is bolted to the column of the framing; the inner part of this stud is formed
with a shoulder to receive an eye, in which the stud of the antifriction roller b
is carried. This roller presses on the back of the rack X, so as to keep it in
gear with the pinion Y. The tubular boss of the hand wheel Z fits on to the
cylindrical part of the stud a beyond the eye carrying the roller b, and outside
this part the stud is screwed to receive the small hand wheel c, the boss of
which is screwed internally to correspond to the stud. The inner edge of the
boss of this wheel is bevelled off, and it enters a corresponding part formed in
the boss of the hand wheel Z. The valves are set to the required point of
expansion by means of the hand wheel Z, which moves the rack X to and fro,
and both are fixed in the position desired by screwing up the hand wheel c,
which wedges the boss of the wheel Z, and holds the parts securely. In this
way the expansive action of the valves may be regulated and adjusted with
the utmost ease and facility.
These arrangements of valve gearing may also be adapted for regulating
the admission of the steam by the main slide valves as well as the separate

page_text: expansion valves, and with very trifling modifications are equally applicable to
all classes of steam engines.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion, that what I consider novel and original,
and therefore claim as the Invention secured to me by the herein-before in
part recited Letters Patent, is,-
First, the application and use of expansion or cut-off valves arranged on the
steam belt, and by preference between the steam trunnions and ordinary slide
valves of oscillating steam engines, as herein-before described and shown in
the accompanying Drawings.
Second, the systems or modes of arranging and constructing the gearing for
actuating the expansion or the slide valves of oscillating steam engines for
regulating the extent of the motion of the same, so as to produce any required
amount of expansion of the steam, as herein-before described and shown
in the accompanying Drawings, or any mere modification of the said
arrangements.
In witness whereof, I, the said James Tennant Caird, have hereunto set
my hand and seal, this Twenty-third day of May, One thousand eight
hundred and sixty-three.
TAMES TENNANT CAIDD
JAMES TENNANT CAIRD. (..)
JAMES TENNANT CURD
GETTITO
TITYTITITARY
CAIRD. (..)