IMPROVEMENTS IN STEAM ENGINES, APPLICABLE ESPECIALLY TO THE ENGINES OF TOWING VESSELS
Year: 1875

page_text: LETTERS PATENT to Frederick William Crohn, of 10, Hammers
Terrace, Greenwich, in the County of Kent, for the Invention of
** IMPROVEMENTS IN STEAM ENGINES, APPLICABLE ESPECIALLY TO THE ENGINES
OF TOWING VESSELS,”
Sealed the 18th February 1876, and dated the 3rd December 1875.
PROVISIONAL SPECIFICATION left by the said Frederick William
Crohn at the Office of the Commissioners of Patents, with his
Petition, on the 3rd December 1875.
I, FREDERICK WILLIAM CROHN, of 10, Hammers Terrace, Greenwich,
in the County of Kent, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN STEAM ENGINES, APPLICABLE ESPECIALLY TO THE
ENGINES OF TOWING VESSELS," to be as follows:-
"
This Invention has for its object improvements in steam engines
applicable especially to the engines of towing vessels. Engines of this
class are so constructed that they can be readily uncoupled in order to
drive either paddle wheel independently of the other. The valve gear
of such engines can be instantaneously thrown out, and the valves are

page_text: then worked by hand levers. Now I have, invented expansion gear
which is especially applicable to such engines. I mount a cut-off slide
on the back of the main slide, and I connect the cut-off slide with an
arm upon a rocking shaft having another arm from which a connecting
rod passes to a slotted link, and the end of the connecting rod can be
placed at any point in the length of the link. The link is jointed at
one end to the eccentric rod of an eccentric provided to control the
cut-off slide, and at the other end the link is jointed to a rod passing to
an arm on the rocking shaft which actuates the main slide valve. Thus
when the extremity of the connecting rod is at one end of the link the
cut-off slide is entirely controlled by its own eccentric, and when the
connecting rod is at the other end of the link the cut-off slide takes its
motion entirely from the rocking shaft of the main valve; the valve and
cut-off slide then move together as one whether the slide valve be
worked by its eccentric or by the hand lever, and the engines can then
be handled with as much facility as when no cut-off slide on the valve
is employed.
The amount of expansion is regulated by placing the connecting rod
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Frederick William Crohn in the Great Seal
Patent Office on the 2nd June 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERICK
WILLIAM CROHN, of 10, Hammers Terrace, Greenwich, in the County of
Kent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Third day of December, in the year
of our Lord One thousand eight hundred and seventy-five, in the thirty-
ninth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Frederick William Crohn, Her special
license that I, the said Frederick William Crohn, my executors, ad-
ministrators, and assigns, or such others as I, the said Frederick
William Crohn, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all

page_text: 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, APPLICABLE ESPECIALLY TO
THE ENGINES OF TOWING VESSELS," upon the condition (amongst others)
that I, the said Frederick William Crohn, my executors or adminis-
trators, 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 Frederick William Crohn, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascer-
tained in and by the following statement thereof, that is to say:—
This Invention has for its object improvements in steam engines,
applicable especially to the engines of towing vessels. Engines of this
class are so constructed that they can be readily uncoupled in order to
drive either paddle wheel independently of the other. The valve gear
of such engines can be instantaneously thrown out and the valves are
then worked by hand levers. Now I have invented expansion gear
which is especially applicable to such engines. I mount a cut-off slide
on the back of the main slide, and I connect the cut-off slide with an
arm upon a rocking shaft having another arm from which a connecting
rod passes to a slotted link, and the end of the connecting rod can be
placed at any point in the length of the link. The link is jointed at
one end to the eccentric rod of an eccentric provided to control the
cut-off slide, and at the other end the link is jointed to a rod passing to
an arm on the rocking shaft which actuates the main slide valve. Thus
when the extremity of the connecting rod is at one end of the link the
cut-off slide is entirely controlled by its own eccentric, and when the
connecting rod is at the other end of the link the cut-off slide takes its
motion entirely from the rocking shaft of the main valve; the valve and
cut-off slide then move together as one whether the slide valve be
worked by its eccentric or by the hand lever, and the engines can then
be handled with as much facility as when no cut-off slide on the valve is
emploved

page_text: The amount of expansion is regulated by placing the connecting rod
in intermediate positions.
In order that my said Invention may be most fully understood and
readily carried into effect, I will proceed to describe the Drawings here-
unto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is an elevation partly in section of a portion of one of a pair
of towing engines provided with valve gear arranged according to my
Invention.
Figures 2 and 3 show some of the parts separately. a is the cylinder
and 6 the main valve, its rod b¹ is connected with an arm c' on the
rocking shaft o which is actuated by an eccentric d on the main shaft,
the eccentric rod ai engaging with a pin upon another arm of on the
shaft o in the usual manner. e is a treddle by which the eccentric rod &¹
can be lifted and thrown out of gear; fis the expansion valve on the
back of the main slide, its rod f¹ is connected with an arm g¹ of another
rocking shaft ġ; g³ is a second arm on the same shaft to which is con-
nected a pair of rods h passing to the block which is able to traverse
along the link k when the rods h are raised or lowered by the hand
screw and gear 1. The link k is supported by the rocking arms m, and
its lower end is connected with the rod of the expansion eccentric n.
At its upper end also the link k is connected by a rod o with a third
arm on the shaft c, so that at this end the link moves in unison with
the main valve gear, and when the block i is raised to this end of the
link the expansion valve will not slide on the main valve whether this
valve be moved by the eccentric d or by the hand lever c* which is
fixed on the rocking shaft c.
.
Figure 4 shows an elevation and Figure 5 a portion of a plan of an
arrangement similar to the above, but in which the details are somewhat
modified. and g are rocking shafts, as before, for actuating the main
and expansion valves respectively. The shaft o has an arm c* to which
is jointed one end of the rod p, this rod is forked at its other end and
embraces the main shaft so that the shaft serves as a guide for it as it
moves to and fro. The rod o is jointed to the rod p at one end and at
the other end to the link k, one extremity of which it controls. n is
the expansion eccentric and its rod passes to the link k and controls it

page_text: at one end as before, the other end being controlled by connection with
the main valve gear, as explained. The block i which traverses along
the link is in this case directly connected with an arm of the rocking
shaft g. r is a lever handle which by rods ¹ serves to raise and lower
the link k.
Figure 6 is a plan partly in section; and Figure 7 is an elevation
showing a similar arrangement applied to a direct acting engine. The
main valve 6 is worked by an ordinary link motion, and a sliding bar 6*
is attached to the valve rod 6¹. To the bar b* is jointed the rod o con-
trolling one end of the expansion link k, the other end being as before
controlled by an eccentric n. The link k can be raised or lowered by
means of the suspending rods ¹ which are worked by a lever handle,
and so the block i to which the rod of the valve ƒ is attached can be
brought to any part of the link.
Figures 8 and 9 show an arrangement for equalizing the length of
the two rods which control the link k. The sliding bar b× is made to
terminate in an enlarged head, through which by a slotted passage the
main shaft passes. The head is made to a cylindrical form to receive a
strap similar to that of an eccentric in which the rod o is made to
terminate.
It is obvious that the construction and arrangement of the cut-off
slide may be varied without departing from my Invention.
What I claim is the means, substantially as described, for actuating
the expansion valves of steam engines, the expansion valve being con-
nected with a block controlled by a link which at one end takes motion
from the main valve gear, and at the other end receives a separate
motion, as herein set forth.
In witness whereof, I, the said Frederick William Crohn, have
hereunto set my hand and seal, this 19th day of May, in the
1700* of our Lord One thousand eight hundred and sevents