IMPROVEMENTS IN MACHINERY FOR GETTING COAL AND MINERALS, PART OF WHICH INVENTION IS APPLICABLE ALSO
Year: 1868

page_text: LETTERS PATENT to Wordsworth Donisthorpe, of Trinity College,
Cambridge, for the Invention of "IMPROVEMENTS IN MACHINERY FOR
GETTING COAL AND MINERALS, PART OF WHICH INVENTION IS APPLICABLE ALSO
Sealed the 11th May 1869, and dated the 12th November 1868.
PROVISIONAL SPECIFICATION left by the said Wordsworth Donis-
thorpe at the Office of the Commissioners of Patents, with his
Petition, on the 12th November 1868.
I, WORDSWORTH DONISTHORPE, of Trinity College, Cambridge, do
hereby declare the nature of the said Invention for "IMPROVEMENTS
MACHINERY FOR GETTING COAL AND MINERALS, PART OF WHICH INVENTION IS APPLI-
CABLE ALSO TO STEAM HAMMERS AND OTHER SIMILAR RECIPROCATING MACHINERY,"
to be as follows:-
This Invention has for its object improvements in machinery for
getting coal and minerals, part of which Invention is applicable also
to steam hammers and other similar reciprocating machinery. In
[Price 8d.]

page_text: giving motion to the cutters or picks of coal cutting machines it
has been common to use a cylinder and piston working with compressed
air in such manner that the blow on the face of the coal or mineral
has been produced directly by the admission of the compressed air to
the cylinder. It is proposed also in the Specification of a Patent
granted to George Edmund Donisthorpe, and dated the 26th day of
March 1867, No. 886, to aid in giving the cutting stroke by means of
a vacuum cylinder or cylinders, in which vacuum is produced during
the outward or non-effective stroke. Now according to my Invention
1 arrange the apparatus in such manner that during the outward stroke
a vacuum is produced by the direct admission of the compressed air to
the air cylinder, and then the inward or cutting stroke is produced by
means of this vacuum aided by the expansion of the compressed air
from the inner end of the cylinder to the outer end or ends of the
same or of another cylinder or cylinders. In this way the waste of
power which results from allowing the compressed air to escape without
previous expansion is avoided.
A similar arrangement is applicable to steam hammers and other
apparatus worked by steam or other fluid under pressure where a
powerful action is required in one direction only; or, if desired, the
actions may be rendered equal in both directions by suitably adjusting
the several areas. A convenient arrangement for cutting coal and
minerals is to employ two concentric cylinders, the one (say the inner)
fixed, the other moveable. The piston rod of the inner cylinder is
attached to the outer cylinder, and the piston of the outer cylinder is
fixed upon the inner cylinder. When air under pressure is admitted
under the piston of the inner cylinder it causes a vacuum space to be
produced between the piston of the outer cylinder and the cylinder cover,
which vacuum produces the return of the parts as soon as the steam
is allowed to pass from the small cylinder into the large cylinder at the
end opposite to the vacuum where it acts in aid of the vacuum. The
air may also pass simultaneously to the other end of the small cylinder
to obtain a higher degree of expansion.
Also according to my Invention when using water under pressure
to work machinery for cutting coal or minerals and other machinery
where a rapid and effectual action is required in one direction only I
use the water to produce the outward or non-effective stroke, and in

page_text: doing so also to produce a vacuum in a vacuum cylinder, by which
vacuum the blow is struck upon the face of the coal or mineral, or the
required rapid and effective action is produced.
Another part of my Invention relates to the cutter bar. Heretofore it
has been usual to arrange the cutters in steps upon the cutter bar, but
all or nearly all the cutters have been placed in rear of the line of thrust
of the machine, consequently at each forward motion of the cutter bar
there has been a tendency to slew the machine; this I obviate by
placing the cutters on either side of the line of thrust so that they about
balance each other. Also heretofore the cutters have been arranged on
the cutter bar at distances apart exceeding one-half of the stroke of the
machine, consequently at the end of the return stroke the distance of
each cutter from the coal which it is to cut at the next stroke is equal
only to one of the steps of the work, or, what is the same thing, the
distance that one cutter is set behind the next. These steps in the
work will, however, be filled with small coal; so that when the machine
is moved forward preparatory to making the next cut this small coal
becomes compressed between the cutter bar and the uncut coal, and the
working of the machine is thus retarded.
According to my Invention I place the cutters on the bar so that the
distance between them is less than one-half of the stroke, and then at
the time when the machine is moved forward the cutters will each be
clear of the next step in which the small coal lies and will pass it
without any compression taking place. In forming the sockets on the
cutter bar to receive the cutters they have heretofore simply been
openings to receive the stem of the cutter, and the part of the cutter
projecting from the socket has been forged and spread laterally to form
the edge.
According to my Invention I shape the socket and I form lips upon
it which support the cutter immediately behind the edge, thus I am
enabled to use much lighter cutters than would be requisite if unsup-
ported to bear the strain. The lips also by coming against the uncut
coal prevent the cutters from drawing into the coal to a depth exceeding
the distance that the cutting edge projects from the socket.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Wordsworth Donisthorpe in the Great Seal Patent
Office on the 12th May 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WORDS-
WORTH DONISTHORPE, of Trinity College, Cambridge, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of November, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her, heirs and successors, give
and grant unto me, the said Wordsworth Donisthorpe, Her special
licence that I, the said Wordsworth Donisthorpe, my executors, adminis-
trators, and assigns, or such others as I, the said Wordsworth Donis-
thorpe, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-
after 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 Inven-
tion for "IMPROVEMENTS IN MACHINERY FOR GETTING OR CUTTING COAL AND
MINERALS, PART OF WHICH INVENTION 18 APPLICABLE ALSO TO STEAM HAMMERS
AND OTHER SIMILAR RECIPROCATING MACHINERY," upon the condition (amongst
others) that I, the said Wordsworth Donisthorpe, 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 Wordsworth Donisthorpe, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say:-
This Invention has for its object improvements in machinery for
getting or cutting coal and minerals, part of which Invention is
applicable also to steam hammers and other similar reciprocating
machinery. In giving motion to the cutters or picks of coal cutting
machines it has been common to use a cylinder and piston working
with compressed air in such manner that the blow on the face of the

page_text: coal or mineral has been produced directly or indirectly by the admission
of the compressed air to the cylinder. It is proposed also in the Speci-
fication of a Patent granted to G. E. Donisthorpe, and dated the 26th
day of March 1867, No. 886, to aid in giving the cutting stroke by,
means of a vacuum cylinder or cylinders in which a vacuum is produced
during the outward or non-effective stroke. Now according to my
Invention I arrange the apparatus in such manner that during the
outward stroke a vacuum is produced by the direct admission of the
compressed air to the air cylinder, and then the inward or cutting
stroke is produced by means of this vacuum aided by the expansion of
the compressed air from the inner end of the cylinder to the outer
end or ends of the same or of another cylinder or cylinders. In this
way the waste of power which results from allowing the compressed
air to escape without previous expansion is avoided.
A similar arrangement is applicable to steam hammers and other
apparatus worked by steam or other fluid under pressure where
powerful quick action of indefinite length of stroke is required in one
direction only; or, if desired, the actions may be rendered equal in both
directions by suitably adjusting the several areas. A convenient
arrangement for cutting coal and minerals is to employ two con-
centric cylinders, the one (say the outer) fixed, the other moveable.
The piston rods of the inner cylinder and the outer cylinder are
attached to the framework, and the piston of the outer cylinder is
fixed upon the inner cylinder. When air under pressure is admitted
under the piston of the inner cylinder it causes a vacuum space to be
produced between the piston of the outer cylinder and the cylinder
cover or end, which vacuum produces the return of the parts as soon as
the air is allowed to pass from the small cylinder into the large cylinder
at the end opposite to the vacuum where it acts in aid of the vacuum.
The air may also pass simultaneously to the other end of the small
cylinder to obtain a higher degree of expansion.
On Sheet 1 of the Drawings hereunto annexed is shewn a coal
cutting machine, the cutter of which has a reciprocating to-and-fro
motion imparted to it by an arrangement such as is above described.
The general arrangement of the cutting machine is similar to machines
described in the Specifications of Patents granted to G. E. Donisthorpe,
and which machines are now well known, so that it is unnecessary to
give here any general description of them.

page_text: The arrangement of engine for giving motion to the cutter bar is
shown separately on a large scale on Sheet 2.. a is the cutter bar
connected at its rear end to the rear end of the cylinder b; the front
end of this cylinder carries a piston c, which works within the larger
cylinder d; this latter cylinder is fixed to the framing of the machine
and is provided at its end with a stuffing box through which the
cylinder b can move to and fro; e is a hollow rod which passes through
the centre of both cylinders; this rod is fixed at one end to the end
of the cylinder d and at the other is fixed to the framing of the
machine; it passes through stuffing boxes in the centre of the piston c
and in the end cover at the opposite end of the cylinder b. Air under
pressure is supplied to the rear end of the hollow rode through the
pipe f; the admission of air from this pipe to the hollow rod is governed
by a piston valve g on the rod g'; when this valve is in the position
shown in the Drawing air passes from the pipe f into the hollow rod
and from there through the opening.h into the back end of the
cylinder b, so causing this cylinder to move backwards, thereby drawing
back the cutter bar and at the same time forming a vacuum in front
of the cylinder d; the air from the front end of the cylinder b
and rear end of cylinder d escaping through the opening k into
the hollow rod e, and so out through its open end m into the
atmosphere. The passage of air under pressure to the end m of the
rode from the opposite end of this rod is prevented by the piston
valve n carried by the same rod as the piston valve g. By shifting the
rod gendwise these can be brought into such a position that the
passage of compressed air from the pipe f to the hollow rod e is shut off,
whilst at the same time the communication between the opening k and
the outer atmosphere is closed; the piston c and cylinder b, together
with the cutter bar, are then propelled forward by the vacuum and by
the expanding of the compressed air from the rear end of the cylinder b
to the rear end of the cylinder d. The valve rod in the arrangement
shown is worked to and fro by a lever handle o.
Also according to my Invention when using water under pressure to
work machinery for cutting coal or minerals and in other machinery
where a rapid and effective action is required in one direction only I
use the water to produce the outward or non-effective stroke, and in
doing so also to produce a vacuum in a vacuum cylinder, by which
vacuum the blow is struck upon the face of the coal or mineral, or
the required rapid and effective action is produced. I prefer to

page_text: employ water at a high pressure and to admit it into a cylinder of
small diameter to cause it to draw back the piston of a larger cylinder
and produce a vacuum in such larger cylinder, and for this purpose I
employ an arrangement of engine such as has heretofore been used
when similarly employing air under pressure to form a vacuum;
provision should, however, be made to afford a very free escape for the
water on the forward stroke.
Another part of my Invention relates to the cutter bar. Heretofore
it has been usual to arrange the cutters in steps upon the cutter bar,
but all or nearly all the cutters have been placed in rear of the line of
thrust of the machine, consequently at each forward motion of the
cutter bar there has been a tendency to slew the machine; this I
obviate by placing the cutters on either side of the line of thrust so
that they about balance each other. Also heretofore the cutters have
been arranged on the cutter bar at distances apart exceeding one-half of
the stroke of the machine, consequently at the end of the return stroke
the distance of each cutter from the coal which it is to cut at the next
stroke is equal only to one' of the steps of the work, or, what is the same
thing, the distance that one cutter is set behind the next. These steps
in the work will, however, be filled with small coal, so that when the
machine is moved forward preparatory to making the next cut this
small coal becomes compressed between the cutter bar and cutters and
the uncut coal, and the working of the machine is thus retarded in its
forward movement.
According to my Invention I place the cutters on the bar so that the
distance between them is less than one-half of the stroke, and then at
the time when the machine is moved forward the cutters will each be
clear of the next steps in which the small coal, lies and will
pass it
without compression taking place. This improvement is also shown in
the Drawing, Figure 7. In forming the sockets on the cutter bar to
receive the cutters they have heretofore simply been openings to receive
the stem of the cutter, and the part of the cutter projecting from the
socket has been forged and spread laterally to form the edge.
According to my Invention I shape the socket and I form lips upon
it which support the cutter immediately behind the edge, thus I am
enabled to use much lighter cutters than would be requisite if
unsupported to bear the strain.

page_text: A cutter bar having each of these improvements applied to it is
shown at Figure 7 of the Drawing annexed. a is the cutter bar; b, the
cutters applied to it; c, the sockets to receive the cutters. The stem of
the cutters passes into a hole in these sockets, whilst a portion of the
stem next to the head of the cutter is made of the full width of the
cutter head, and this portion of the stem is received into a slot or groove
in the top of the socket which is thus formed into two lips which receive
between them a portion of the stem of the cutter; the outer lip also by
coming against the uncut coal prevents the cutters from drawing into
the coal to a depth exceeding the distance that the cutting edge projects
from the socket.
It is not necessary that each of these improvements should be used
conjointly, they might be applied separately to other cutter bars.
In witness whereof, I, the said Wordsworth Donisthorpe, have
hereunto set my hand and seal, this Eleventh day of May,
in the year of our Lord One thousand eight hundred and sixty-
nine.
WORDSWORTH DONISTHORPE. (L.S.)