New or Improved Apparatus for Sharpening the Knives of Chaff Cutters and Harvesters.
Year: 1897

page_text: New or Improved Apparatus for Sharpening the Knives of Chaff
Cutters and Harvesters.
I, ROBERT MAYNARD, of Whittlesford Works, near Cambridge, Engineer, do hereby
declare the nature of this invention to be as follows :-
According to this invention a hinged lever furnished with a cutter, grinder, or
scraper is pivoted to a removable and adjustable cross bar or bearing mounted
either on the knife wheel or knife bar of the machine in any convenient position.
The hinged lever is centred so that the cutter, grinder or scraper works against
the cutting edge of the knife, thus sharpening the same.
The object of making the cross bar or other bearing whereto the hinged lever is
pivoted removable and adjustable, is to allow of such lever being shifted and centred
so as to sharpen each of the knives of the machine in succession, and for that purpose
suitable centres are provided into which the screws which hold the bearing in
position take.
A pressure bar may be fitted in any convenient position in order to automatically
control and regulate the pressure of the cutter, grinder, or scraper against the cutting
edge of the knife while sharpening the same.
A s Ten day on pin
ELT & Co.,
Registered Patent Agents,
43 Southampton Buildings, London, W.C., Agents for Applicant.
New or Improved Apparatus for Sharpening the Knives of Chaff
Cutters and Harvesters.
I, ROBERT MAYNARD, of Whittlesford Works, near Cambridge, Engineer, do
hereby declare the nature of this invention and in what manner the same is to be
performed, to he particularly described and ascertained in and by the following
statement:
The object of this invention is to provide improved means for mechanically
sharpening the knives of chaff cutters and harvesters whereby such operation is far
more expeditiously and perfectly performed than is possible by the present system of
sharpening by hand.
I attain such object by the mechanism illustrated in the accompanying drawings
wherein

page_text: Figure 1 is an elevation of the Kine wheel of a chan cutter snewing the application
of my invention thereto the scraper or sharpener being fitted with a handle as
presently described.
Figure 2 is a similar view shewing the scraper or sharpener fitted with a connecting
rod and arm in lieu of such handle.
Figure 3 shews a detail view in elevation of the hinged lever as presently
described.
Figure 4 shews the cutter bar of a harvester with my invention applied thereto,
and
Figure 5 shews a detail view in plan of the grooved bifurcated bracket k presently
described.
Similar letters of reference indicate corresponding parts throughout the several
views.
A hinged lever a, furnished with a scraper or sharpener b Fig. 3 is pivotted to a
removable and adjustable cross bar or bearing c, mounted either on the knife wheel
or knife bar of the machine in any convenient position. This hinged lever is so
centred that when operated by the attendant or otherwise, the scraper or sharpener
works against the cutting edge of the knife thus sharpening the same.
The object of making the cross bar or other bearing whereto the hinged lever is
pivotted, removable and adjustable, is to allow of such lever being shifted and
centred to sharpen each of the knives of the machine in succession as required, and
for this purpose suitable centres d, are provided into which the screws which hold
the cross bar or bearing in position take. An oblique hollow boss e, is formed on
the hinged lever in which boss a pin f is inserted that serves to carry the scraper or
sharpener b which is secured thereon by a linch-pin or bolt y Figure 3 or its
equivalent. The angle of the boss e is such, that when the scraper or sharpener is
mounted on the pin f, it is held in the requisite position to allow of its giving a
proper cutting edge to the knife. The pin f is mounted loose in the boss e and is
furnished with a handle / Figure 1, whereby its position can be varied to control
the action of the scraper or sharpener on the edge of the knife, so as to produce a
true bevel and consequently an even and perfect cutting edge thereon. Or, if
desired, in lieu of such handle h, its mechanical equivalent consisting of a connecting
rod, may be substituted, as shewn in Figure 2 of the drawings; one end of such
connecting rod being pivotted to the cross bar c eccentrically to the hinged lever,
while the other end is jointed by an arm to the pin that carries the scraper or
sharpener, thus automatically controlling the action of the latter on the cutting edge
of the knife as the hinged lever is operated.
In applying my invention to harvesters the cutter bar of the machine is taken out
and fitted in a grooved, bifurcated bracket wherein it is clamped or otherwise firmly
held in position, as shewn at Figure 4 of the drawings, wherein k is the bracket k¹ the
groove wherein the cutter bar is fitted by sliding the same therein. ² is a perforated
lug cast or otherwise forined on the stem of the bracket so that the cutter bar may be
fixed in position in such groove by a clamp and bolt or pin l' which takes into such
perforated lug. 1³, k, are the two bracket arms to which the hinged lever is pivotted
by a thumb screw or in any other convenient manner. Such arms are inade of
unequal length to allow of the scraper or sharpener, on the hinged lever travelling in
the proper plane to sharpen each series of edges of the cutters as such lever is
operated. When one series of edges has been sharpened the lever is removed from
the one bracket arm to the other so as to sharpen the reverse series of edges. If
desired a suitable scale may be marked on the stem of the bracket whereby the
position of the cutter bar may be accurately and readily varied and regulated, so as
to sharpen the edges of all the knives on the cutter bar seriatim.
It is to be observed that although the hinged lever together with the scraper or
sharpener has a to-and-fro motion when operated, it is only during the forward stroke
that the scraper or sharpener comes in contact with the edge of the knife to be
sharpened, thus taking a shaving off with each forward stroke, as at the end of such
forward stroke the operator slightly raises the lever so as to cause the scraper or

page_text: sharpener to clear the knife edge during the backward stroke.
When the apparatus
is fitted with a handle as hereinbefore described and shewn at Figure 1 of the
accompanying drawings, the operator by slightly canting such handle causes the
scraper or sharpener to bear evenly upon the knife thus producing a perfect cutting
edge. When a connecting rod and link are employed in lieu of such handle the
degree of torsion required in the scraper or sharpener is governed by the degree of
eccentricity of the connecting rod to the hinged lever, as the greater such eccentricity
the greater the torsion produced. In sharpening the knives of harvesters the cutter
bar is placed in the grooved, bifurcated bracket, and the hinged lever pivotted to the
latter in the manner already described. A slight pressure is then put upon such
hinged lever and it is turned round sufficiently to enable the scraper or sharpener to
come in contact with and sharpen the edge of the knife. When using the apparatus
for sharpening the knives of harvesters there is no occasion to cant the scraper or
sharpener either by hand or automatically as the knives of harvesters are very short
and straight.
When the scraper or sharpener is worn out it can be readily removed by taking out
the linch-pin or bolt and a fresh one substituted therefor. I make such scrapers or
sharpeners preferably of hard steel and drill them ready for immediate use, but stone
or any other suitable sharpening medium inay be employed.
I would here observe that the essential feature of my invention consists in
substituting a mechanical sharpening apparatus, made, arranged, and fitted,
substantially in the manner hereinbefore described and shewn, for the sharpening the
knives of chaff cutters and harvesters in lieu of the present system of hand sharpening,
thus effecting a considerable economy both in time and labour, and likewise
obtaining a truer bevel and a more perfect cutting edge than has hitherto been
possible.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that
what I claim is :-
1. The improved apparatus for sharpening the knives of chaff cutters consisting of
a hinged lever mounted on a cross bar or other suitable bearing and furnished with a
scraper or sharpener provided with a handle or its mechanical equivalent, such several
parts being respectively made, arranged, combined, and fitted, all substantially in the
manner herein before described and shewn,
2. The improved apparatus for sharpening the knives of harvesters consisting of a
hinged lever provided with a scraper or sharpener, and pivotted to a grooved,
bifurcated bracket, which may be furnished with a scale to facilitate the adjustment of
the cutter bar, all substantially as hereinbefore described and shewn.
Dated this 5th day of August 1891.
ELT & Co.,
Registered Patent Agents,
43, Southampton Buildings, London, W.C., Agents for Applicant.