Improvements in Cutter-bars for Lawn-mowers.
Year: 1895

page_text: Date of Application, 21st Nov., 1895
Compléte Specification Left, 20th Aug., 1896-Accepted, 17th Oct., 1896
PROVISIONAL SPECIFICATION.
Improvements in Cutter-bars for Lawn-mowers.
1, WILLIAM C. ALLEN, of Cambridge, in the County of Washington, and State
of New York, United States of America, Shirt Business, do hereby declare the
nature of this invention to be as follows:-
"
My improvement relates to that part of a lawn-mower termed the "fixed or
"stationary" cutter, against which the grass being cut is pressed by the rotary
cutters and the forward motion of the machine.
My invention consists in a flat steel cutter-bar serrated on its front edge by
alternate teeth and notches extending obliquely backward from the upper to the
lower surface of such edge, such bar having a longitudinal groove in its flat
upper surface extending from end to end along the bases of said teeth to avoid
friction of the revolving cutters on the bar behind the teeth, and each tooth is
preferably recessed in its upper surface for a similar purpose. Each tooth also has
its upper surface beveled forwardly and downwardly substantially parallel with
the curved path of the rotary cutters.
11
My improved cutter-bar is to be distinguished from those heretofore known formed
by turning up obliquely and corrugating by dies the edge of a thin steel strip.
The cutter-bar is a flat steel bar extending from end to end of the head of the
mower and is to be bolted firmly in position to coact with the blades of the
revolving cutter, which rotate in close proximity to it or slightly touching it.
I also employ teeth at the front edge of the cutter-bar, formed by milling out
obliquely the intervening metal, so as to leave a succession of teeth having sharp
cutting-edges where the oblique serrations intersect the flat upper surface of the steel
bar. Each tooth also has its upper surface beveled downwardly and forwardly, so
that when in position its said surface will lie close to and substantially parallel with
the arc of rotation of the edges of the rotary cutters, thus securing accurate
coaction between the said rotary cutters and the cutting-edges of the teeth.
I also employ a longitudinal groove, formed in the upper surface of the bar
and extending from end to end thereof behind and adjacent to the series of teeth,
to reduce friction of the rotary blades or foreign matter upon the bar behind the
teeth and to facilitate grinding the stationary cutter by the removal of a portion
of the metal from the bar adjoining the surface to be ground. Each tooth is
slightly recessed in its upper surface adjacent to said groove, for the same purpose.
In operation the blades of grass are forced by the forward motion of the machine
and the action of the rotary cutters between the teeth of the fixed cutter-bar,
where they are held from lateral displacement while being severed by said rotary
cutters in conjunction with the sharpened edges of said teeth.
The advantage of the beveled edge on my cutter-bar consists in the fact that it
admits of the bar being set far enough forward to cause the teeth to properly engage
the blades of grass near their roots and hold them on the proper cutting-line
until sheared off, while at the same time it is not necessary to set the bar so far
forward as to increase friction of the bar on the turf, and consequently increase
the power required, to run the machine. The ordinary plain bar, or a toothed bar
which is not beveled, must be set so far forward to secure proper action of the
cutting-edges that friction on the turf is greatly increased. If it is sought to avoid
such undue friction in the case of a toothed bar not beveled, the bar has to be
set so far back and also so tilted up to secure the proper shearing action of the
edges that the teeth will not engage the blades of grass properly, if at all. The

page_text: absence of such bevel is one of the numerous causes which have rendered serrated
cutter-bars heretofore constructed inefficient and useless. My bar is set so as to be
about horizontal from front to rear line when in working position, and the upper longi-
tudinal line of the beveled edge intersects the arc of rotation of the rotary cutters
at an angle of about twenty degrees backward from a perpendicular let fall from
the axis of rotation of said cutters. This location and adjustment of a cutter-bar
constructed as herein described secures thorough and absolutely reliable action of
the cutting-edges with close shearing of the lawn and at the same time a
lightness and ease of running never before attained in machines of this class.
Dated this 8th day of November 1895.
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in Cutter-bars for Lawn-mowers.
I, WILLIAM C. ALLEN, late of Cambridge, in the County of Washington and
State of New York, and now residing at Hoosick Falls, N.Y., United States of
America, Shirt Business, 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 :-
"
My improvement relates to that part of a lawn-mower termed the "fixed" or
stationary" cutter, against which the grass being cut is pressed by the rotary
cutters and the forward motion of the machine.
My invention consists in a flat steel cutter-bar serrated on its front edge by
alternate teeth and notches extending obliquely backward from the upper to the
lower surface of such edge, such bar having a longitudinal groove in its flat upper
surface extending from end to end along the bases of said teeth to avoid friction
of the revolving cutters on the bar behind the teeth, and each tooth is preferably
recessed in its upper surface for a similar purpose. Each tooth also has its upper
surface beveled forwardly and downwardly substantially parallel with the curved
path of the rotary cutters."
My improved cutter-bar is to be distinguished from those heretofore known
formed by turning up obliquely and corrugating by dies the edge of a thin steel
strip.
In the drawings, Fig. 1 is a perspective view of one of my improved cutter-bars,
and Fig. 2 is a transverse section thereof, the curve shown denoting the arc of
rotation of the rotary blades.
The cutter-bar A is a flat steel har extending from end to end of the head of
the mower and is to be bolted firmly in position to co-act with the blades of the
revolving cutter, which rotate in close proximity to it or slightly touching it.
BB are the teeth at the front edge of the cutter-bar, formed by milling out obliquely
the intervening metal, so as to leave a succession of teeth having sharp cutting-
edges where the oblique serrations intersect the flat upper surface of the steel bar A.
Each tooth also has its upper surface beveled downwardly and forwardly, as shown
at b, so that when in position its said surface will lie close to and substantially
parallel with the arc of rotation of the edges of the rotary cutters, thus securing
accurate co-action between the said rotary cutters and the cutting-edges of the
teeth. Crepresents a longitudinal groove, formed in the upper surface of the bar A
and extending from end to end thereof behind and adjacent to the series of teeth,
to reduce friction of the rotary blades or foreign matter upon the bar behind the
teeth and to facilitate grinding the stationary cutter by the removal of a portion
of the metal from the bar adjoining the surface to be ground. Each tooth is shown
slightly recessed in its upper surface adjacent to said groove, as at D, for the
same purpose.

page_text: In operation the blades of grass are forced by the forward motion of the machine
and the action of the rotary cutters between the teeth of the fixed cutter-bar,
where they are held from lateral displacement while being severed by said rotary
cutters in conjunction with the sharpened edges of said teeth.
The advantage of the beveled edge on my cutter-bar consists in the fact that it
admits of the bar being set far enough forward to cause the teeth to properly engage
the blades of grass near their roots and hold them on the proper cutting-line until
sheared off, while at the same time it is not necessary to set the bar so far forward
as to increase friction of the bar on the turf, and consequently increase the power
required to run the machine. The ordinary plain bar, or a toothed har which is
not beveled, must be set so far forward to secure proper action of the cutting-edges,
that friction on the turf is greatly increased. If it is sought to avoid such undue
friction in the case of a toothed bar not beveled, the bar has to be set so far back and
also so tilted up to secure the proper shearing action of the edges that the teeth will
not engage the blades of grass properly, if at all. The absence of such bevel is one
of the numerous causes which have rendered serrated cutter-bars heretofore constructed
inefficient and useless.
My bar is set so as to be about horizontal from front to rear line when in working
position, and the upper longitudinal line of the beveled edge intersects the arc of
rotation of the rotary cutters at an angle of about twenty degrees backward from
a perpendicular let fall from the axis of rotation of said cutters.
This location and adjustment of a cutter-bar constructed as herein described secures
thorough and absolutely reliable action of the cutting-edges with close shearing of the
lawn and at the same time a lightness and ease of running never before attained in
machines of this class.
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. A stationary cutter-bar for lawn-mowers consisting of a flat steel bar serrated on
its front edge by alternate teeth and notches extending obliquely backward from the
upper to the lower surface of such edge, and formed with a longitudinal groove or
recess in its upper surface adjacent to the bases of said teeth, substantially as
set forth.
2. A stationary cutter-bar for lawn-mowers, consisting of a flat steel bar serrated
on its front edge by alternate teeth and notches extending obliquely backward from
the upper to the lower surface of such edge, the upper surfaces of such teeth
being beveled outwardly and downwardly parallel with the arc of rotation of the
rotary cutters, substantially as set forth.
3. A stationary cutter-bar for lawn-mowers, consisting of a flat steel bar serrated
on its front edge by alternate teeth and notches extending obliquely backward from
the upper to the lower surface of such edge, the upper faces of such teeth being
beveled outwardly and downwardly parallel with the path of rotation of the rotary
cutters, and the upper surface of said bar having a longitudinal groove or recess
formed therein adjacent to the bases of said teeth, substantially as set forth.
4. A stationary cutter-bar for lawn-mowers, consisting of a flat steel bar serrated
on its front edge by alternate teeth and notches extending obliquely backward from
the upper to the lower surface of such edge, the upper faces of such teeth being
beveled outwardly and downwardly parallel with the path of rotation of the rotary
cutters, the upper surface of said bar containing a longitudinal groove adjacent to the
bases of said teeth, and the upper faces of said teeth having recesses or excavations
formed therein adjacent to an opening into said groove, substantially as set forth.
Dated this 20th day of August 1896.
HUGHES, SON & Co.,
38, Chancery Lane, London, W.C., Agents for the Applicant