Improvements in the Cutting Knives of Mowing and Reaping Machines.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Cutting Knives of Mowing and Reaping
Machines.
I. EDWARD PRATT, of the Albert Iron Works, Uxbridge, in the County of
Middlesex, Engineer, do hereby declare the nature of this invention to be as
follows:-
In mowing and reaping machines, triangular steel knives are used fixed upon a
rapidly reciprocating knife-bar, and the most simple and effective method of fixing
the knives upon the bar, is by bending round the heel or back of the blade so as
to form a more or less rectangular socket which fits upon a knife-bar of corre-
sponding section, a sufficient number of such knives being fitted in succession upon
the bar and being tightened up against each other by a nut or other adjustable
fastening at the end of the bar.
I have found, however, that if the ends of the sockets of the knife blades, which
fit against each other, are not perfectly parallel and true so that they touch each
other as far as possible over the whole of their surfaces,-when they are tightened
up their pressure against each other, being irregular, bends and distorts the bar
upon which they are fitted, and therefore renders the action of the blades
imperfect.
My present invention consists more especially in a novel method of constructing
the ends of the sockets upon the blades, by which such distortion is rendered
impossible.
For this purpose, I make two of the opposite parallel edges of the ends of the
socket slightly round instead of straight, so that they project slightly beyond the
other two sides of the socket end, and so therefore that they can only touch each
other at the centre of their length.
By this means, however tightly the several sockets are screwed up against each
other upon the knife-bar, there is no tendency whatever to bend or distort the
latter.
If, however, the touching points upon the two opposite parallel sides of the
socket, did not project exactly to the same distance, those upon one of the sides of
two adjoining sockets would touch each other somewhat sooner than those upon
the opposite parallel sides, and there would be a tendency to bend the bar in a
direction at right angles to that which the method of construction described is
intended to prevent.
As, however, the sockets fit freely and easily upon the bar, it can be at once
seen whether the one last fitted upon the bar properly comes in contact upon
both opposite edges with the one last arranged, and if not it is easy to reduce
the one most projecting until both sides exactly meet those of the adjoining
socket. The blades having been all so fitted and adjusted are then screwed tightly
together, and are perfectly rigid without the knife-bar being in any way bent or
distorted.
In order that the socket upon the blade may be very strong and easily made,
I make it by bending the back of the blade as follows. I first bend down the back
at right angles, at a sufficient distance from the edge. I then bend the edge
outward at right angles, or parallel with the blade, and then up for a sufficient

page_text: distance, and finally bend it again forward until its extreme edge rests upon the
blade just above the point where it is first bent down. In this way a more or less
rectangular socket is formed to fit the knife-bar, no rivet or fastening being
required, the socket and blade being very rigid and durable, and the cutting edge
of the blade being at the required height in relation to the socket.
Dated this 20th day of May 1896.
EDWARDS & Co.,
65 and 66, Chancery Lane, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Cutting Knives of Mowing and Reaping
Machines.
I, EDWARD PRATT, of the Albert Iron Works, Uxbridge, in the County of
Middlesex, Engineer, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement, and accompanying drawing, that is to say :-
In mowing and reaping machines, triangular steel knives are used fixed upon a
rapidly reciprocating knife-bar, and it is very important that the knives should be
firmly and securely fixed but be capable of removal and replacement when
necessary, and the most simple and effective method of fixing the knives upon the
bar has been found to be by bending round the heel or back part of the piece of sheet
metal which forms the blade so as to form a more or less rectangular socket which
fits upon a knife-bar of corresponding section, a sufficient number of the sockets
upon such knives being fitted in succession upon the bar and being tightened up
against each other in their places by a nut or other adjustable fastening at the end
of the bar.
I have found, however, that if the ends of the sockets formed upon the knife
blades, which fit and are tightened up against each other as described, are
not perfectly parallel and true so that they touch each other as much as possible
over the whole of their surfaces, their pressure against each other when they
are tightened up being irregular, bends and distorts the comparatively light bar
upon which they are fitted, and therefore renders the action of the blades
imperfect.
My present invention consists more especially in a novel method of constructing
the ends of the sockets upon the blades, by which such distortion is rendered
impossible.
The accompanying drawing is in illustration of my invention,
Figure 1 being a plan, and Figure 2 a side view, of my improved knife
blade.
and
Figure 3 shows two of the blades in place against each other upon the knife-bar
Figure 4 shows a somewhat modified shape of the end of the socket.
a is the knife blade, b the socket upon the blade, and c the knife-bar upon which
the sockets fit.
In order to attain the desired purpose, I make two of the opposite parallel
edges d, d, of the ends of the socket slightly round or convex, as shown in
Figures 1 and 3, instead of straight, so that they project slightly beyond the other
two sides of the socket end, and so therefore that they can only touch each other at
the centre of their length, when the sockets are arranged end to end against each
other, as shown in Figure 3.
By this means, however tightly the several sockets 6 are screwed up against

page_text: each other upon the knife bar c, there is no tendency whatever to bend or distort
the latter.
If, however, the convex touching points upon the two opposite parallel sides d, d,
of the socket, did not project exactly to the same distance, those upon one of the
sides of two adjoining sockets would touch each other somewhat sooner than those
upon the opposite parallel sides, and there would be a tendency to bend the bar c
in a direction at right angles to that which the method of construction described is
intended to prevent.
As, however, the sockets b fit freely and easily upon the bar c, it can be at once
seen whether the one last fitted upon the bar properly comes in contact upon both
opposite convex edges with the socket previously arranged in place, and if not it is
easy to reduce the edge most projecting until both sides d; d, exactly meet those of
the adjoining socket. The blades having been all so fitted and adjusted are then
screwed tightly together, and are perfectly rigid without the knife-bar c being in
any way bent or distorted. The socket may have one of its ends only, made with
convex edges to two of its opposite sides as described, all the edges of the other
end being made straight.
Instead of making two opposite edges of the socket 6 convex as described, they
may be made straight but having at one end of the socket a very slight projection,
or tooth, as shown at 1, Figure 4. The point of this projection can be readily filed
down so that the two opposite ones touch the plain end of the adjoining socket
simultaneously.
In order that the socket 6 upon the blade a may be very strong and easily made,
I make it by bending the back of the blade as follows, as illustrated in Figures 1
and 2. I first bend down the back at right angles at f, at a sufficient distance
from its edge. I then bend it outward at right angles at g, or parallel with
the blade a, and then up for a sufficient distance at 7, and finally bend it again
forward at i until its extreme edge k rests upon the blade just above the point
where it is first bent down. In this way a more or less rectangular socket is
formed to fit the knife-bar c, no rivet or fastening being required, the socket and
blade being very rigid and durable, and the cutting edge of the blade being at
the required height in relation to the socket, when at work in the mowing or
reaping machine.
I do not confine myself to the precise shape and proportions of the different
parts, which may be varied more or less as may be found desirable; but
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:-
1. In cutting knives for mowing and reaping machines, having sockets fitting
upon a knife-bar, the method of making the ends of two opposite sides of the socket
convex or projecting slightly at the centre, substantially as and for the purpose
described and illustrated.
2. The method of making a socket upon the cutting knife blade, by first bending
down the back, then bending it outward, then bending it up, and finally bending
it forward so that its edge rests upon the blade at the point where it is first turned
down, substantially as described and illustrated in Figures 1 and 2.
Dated this 22nd dom
1005
EDWARDS & Co.,
65 and 66, Chancery Lane, London, Agents for the Applicant.