Improvements in the Construction of Cutter Bars for Mining Machinery, and the Manner of Using them.
Year: 1891

page_text: Date of Application, 8th Oct., 1891
Complete Specification Left, 7th July, 1892-Accepted, 13th Aug., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Cutter Bars for Mining
Machinery, and the Manner of Using them.
I, GEORGE WILLIAM ELLIOTT of 160 Shirebrook Road, Heeley, Sheffield,
Mining and Mechanical Engineer do hereby declare the nature of this invention
to be as follows :-
The object of this invention is to produce cutter-bars for mining machinery
which will withdraw effectually the debris formed in cutting the material so that
it shall not interfere with the free working of the cutter-bars in the slots cut by
them, also to reduce the cost of the cutters.
To effect this, I form the cutter-bar preferably of a wrought steel bar of a
section having a thick circular centre, and a thin web on two of its opposite sides,
so that when twisted the webs form a double spiral around the thick circular
centre.
Suitable cutters are attached to the outer edge of the spiral webs in such a
manner that they may readily be replaced.
One method of attaching these cutters is by drilling tapered holes through each
web, at right angles, or nearly so, to the axis of the bar, and near the edges of the
webs and at suitable distances apart, and so arranged that the holes on one web,
are opposite the spaces between the holes on the other, and when the bar revolves,
the holes, and the cutters in them on one web, travel in a path midway between
those on the other, so that each cutter on the bar has a distinct path to travel in.
The cutters, which are preferably made of chilled cast iron, are made with
tapered shanks to fit the tapered holes in the cutter-bar webs, and are held in
their places by means of this taper. The parts of the webs between the holes,
and cutters in them, are cut down towards the centre of the bar so as to be
well clear of the material to be cut.
Cutters are also fixed to the end of the bar to enable it bore into the material.
By this arrangement a cutter bar is formed with spiral webs which withdraw
the debris, and will cut sideways or will bore endways.
There may be one or more webs on the bar, and the thick centre may be other
than circular in section.
The thick centre part may be dispensed with and the twisted bar be of sufficient
thickness to be sufficiently rigid without it.
Instead of forming the bar of twisted wrought steel or iron, it may be made of
cast steel or other suitable metal cast in the spiral form.
The bar may be tapered or parallel. Instead of fixing the cutters directly in
the webs of the bar, holders for the cutters may be fixed to the webs so that they
may be easily replaced, or these holders may be fixed in the bar between the
webs.
The usual manner of using a cutter-bar for mining machinery is to cause it to
revolve rapidly and at the same time to move in a direction at right angles to its
axis so that it cuts a slot in the material as deep as it may be entered into it. This
mode of cutting causes a considerable side strain on the cutter-bar and the bearings
on the machine driving it on account of the large even surface of the material
acted upon at once.
To reduce these defects, I give the cutter-bar a reciprocating motion in the
direction of its length, and at the moment it is withdrawn furthest out of the slot,
advance it sideways against the material.
By making the cutter-bar tapered with its least diameter at its loose end, the

page_text: material is cut as the bar is advancing endways into the material, and the chief
strain on it is an end thrust instead of a side strain.
The form of bar which I prefer for this manner of using it is to divide its length
into distances not greater than the length of the reciprocating motion given to
it, and making the bar to cut different diameters in each division, decreasing in
diameter towards the loose end.
By this means the bar cuts the material into a series of projections as it advances
into it, the chief strain on it being in the direction of its length, also a smaller
surface of material is acted upon at once and in a form rendering it easier to break
out by the cutters than when cut in a direction at right angles to the length of the
cutter-bar.
G. W. ELLIOTT.
COMPLETE SPECIFICATION.
Improvements in the Construction of Cutter Bars for Mining
Machinery, and the Manner of Using them.
I, GEORGE WILLIAM ELLIOTT, of 160 Shirebrook Road, Heeley, Sheffield
Mining and Mechanical Engineer do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
The object and aim of this invention being to produce cutter bars for mining
machinery which will withdraw effectually the debris formed in cutting the material
operated upon in such a manner that it shall not interfere with the free working of
the cutter bars and cutters in the holes or slots made by them, and also reduce
the cost of cutters, it will be seen by refering to the accompanying sheet of
drawings that to effect this I form the cutter bar preferably of a wrought steel bar
Fig. 1, of a section having a thick circular centre A, and a thin web on the two
opposite sides B, and B', so that, when twisted the webs B and B', form a double
spiral around the thick circular centre A. Cutters of suitable shape, preferably
that shewn by Fig. 6, are attached to the outer edge of the spiral webs B and B',
in such a manner that they may be expeditiously and easily replaced. It will be
seen that one method of attaching or securing these cutters, is by drilling tapered
holes D, through the webs B, and B', at or about right angles to the axis of the
bar A. and near the edges of the webs B & B at approved distances apart, but
so arranged that the holes and cutters on web B¹ are placed opposite the spaces E,
between the cutters fixed on web B, so that when the bar revolves, the holes, and
cutters in them, in web B, travel in a path midway between the cutters attached to
web B', thus giving the cutters on each side of the bar a distinct and seperate
path to travel in. The cutters C, which are preferably made of chilled cast iron,
are provided with tapered shanks H, to fit into the tapered holes D, formed in
the cutter bar webs B and B', being held in their places by means of this taper.
The parts of the webs between the holes and cutters E, are cut down towards the
center of the bar A, thus enabling the webs to be well clear of the material
being operated upon.. Similar, C, cutters are also attached to the end of the bar
for the purpose of boring into the material.
By another method, instead of fixing or attaching the cutters C, directly. in
the webs B ard B', holders or carriers of suitable shape and size F, for the
cutters C, may be fixed in the thick circular centre A, between the webs B, and B',
Fig. 2, or, suitable holders may be fixed to the webs B, B', for the purpose of
carrying the cutters C, which holders can be easily replaced.
The bars may be tapered or parallel as desired.
The usual manner of using a cutter bar for mining purposes is to cause it to
revolve rapidly and at the same time to move in a direction at right angles to

page_text: its axis, by this means cutting a slot in the material being operated upon, as
deep as the bar may be entered into it. This mode of working throws con-
siderable strain on the cutter bar, and the bearings of the machinery actuating
it, on account of the large even surface of material acted upon at one and the
same time.
To reduce these ill effects I give the cutter bar a reciprocating motion in the
direction of its length, and at the moment it is withdrawn farthest out of the
slot I advance it sideways against the material. By making the cutter bar tapered
with its smaller or least diametre at its loose end J, the bar cuts the material
while advancing endways into it, thus giving chiefly an end thrust instead of a
side strain. The form of bar which I prefer for this manner of using it is
illustrated by Fig. 3, having its length divided into distances, not greater than
the length of the reciprocating movement given to it, arranged to cut different
diametres, each division decreasing in diametre towards its loose end J. By this
method the bar cuts the material into a series of steps or projections, as it
advances into it, thus throwing the principal part of the strain in the direction
of its length, in addition, a smaller surface of material is operated upon at once,
and in a form rendering it much easier to break out by the cutters C, than when
cut in a direction at right angles to the axis of the cutter bar.
Instead of forming the bar of twisted wrought steel or iron, the same can, if
desired, be made of cast steel or other suitable metal cast into the spiral form
required. The bar may be provided with one or more webs, as may be found
advantageous, and the thick centre A may be other than circular in section as
occasion may determine. In some instances I dispense with the thick centre
altogether, and make the twisted bar of sufficient strength and section to obtain the
required rigidity without it.
The same letters of reference apply to the different figures or illustrations shewn
on drawing.
Fig. 1 shews a tapered bar with thick centre having cutters in position on the
edges of the webs.
Fig. 2, shews a tapered bar with thick centre but having cutters carried in
holders fixed in circular centre of bar.
Fig. 3 shews a bar divided into equal divisions each of different diametres, with
the cutters fixed in the webs.
Figs. 4 and 5 are cross sections of Figs. 1 and 2.
Fig. 6 is a full size view of the chilled iron cutter with tapered shank for
attaching to cutter bar webs or holders.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is;
CLAIMS.
1st. A cutter bar having a thick centre and one or more thin webs radiating
from the said centre either tapered or parallel and made of wrought iron or steel,
twisted to the spiral form required, or made by casting the same.
2nd. A cutter bar of similar section to the before-mentioned one, but divided into
lengths, each of different diametres, substantially as shewn on drawing and described
herein.
3rd. A cutter bar having several cutters attached to it near the edges of the webs
by means of tapered holes and shanks, or by adjustable and loose holders or
brackets, as shewn and herein described Fig. 1.
4th. A cutter bar as herein described, having cutters carried in holders or
carriers attached to the thick central portion of bar Fig. 2.
5th. The use of mining machinery for driving the said cutter bars, having a
reciprocating motion for the purposes herein described.

page_text: 6th. Cutter bars with spiral webs, having fixed or adjustable cutters on the webs,
central portion, or in holders attached to any part, also bars being tapered, parallel
or divided into lengths.
7th. The combination of the said cutter bars, with chilled cast iron cutters as
herein described and shewn.
G. W. ELLIOTT.