IMPROVEMENTS IN LAWN MOWING MACHINES
Year: 1873

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN LAWN MOWING MACHINES."-A Communication
from abroad by Everett Griscom Passmore, of Philadelphia, Penn-
sylvania. United States of America.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 12th February 1873.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN LAWN MOWING MACHINES," a communica-
tion to me from abroad by Everett Griscom Passmore, of Philadelphia,
Pennsylvania, United States of America, to be as follows :—
This Invention relates to improvements in lawn mowing machines, and
more especially to hand lawn mowers having a revolving cutting
apparatus driving by two driving wheels, and consists,―

page_text: First. In arranging the gearing so that any required speed can be
communicated to the cutters, the said gearing being conveniently pro-
tected by the driving wheels and side plates or frame of the machine.
Secondly. In arranging the gearing and studs or shafting on which it
turns, so that different sized cog wheels supplied with the machine may
be conveniently used or interchanged to give any required speed to the
cutters.
In order to make a perfectly smooth close cut, it is necessary that the
knives should make one clip every time the machine advances one inch
or less, but if they do this in long grass. (say 5 inches high), the grass is
cut so often that the resistance is so great as to render the machine
useless; and as in wet weather, and for other causes, it is frequently
extremely difficult to cut the lawn often enough to allow the practical
working of a high speed machine, it is very desirable to have a lawn
mower so arranged that it can be used effectively in grass 5 or 6 inches
high, and at the same time make perfect work in short grass.
According to one mode of carrying out this Invention, the framing is
composed of two castings or side plates keyed on to an eccentric girth
or tie bar placed eccentrically to such castings, so as not to interfere with
the revolution of the knife barrel, the said castings or side plates being
recessed to receive and protect the gearing. These side plates are each
fitted with two fixed but removeable studs, one of which carries the
driving wheel, having an ordinary toothed wheel cast thereon, whilst
the other stud carries a double gear, consisting of a spur wheel and
pinion in one. The pinion of the double gear derives its motion from
the spur wheel on the inner recessed face of the driving wheel, which
encloses the whole of the gearing. The larger wheel of the double gear
engages into the teeth of a spur pinion mounted loosely upon the end of
the shaft or axis of the knife barrel, such spur pinion being engaged
with the said shaft or axis only when revolving in one direction by
means of a spring catch and inclined slots or ratchet grooves made
inside the boss of the said pinion. The gearing is precisely the same on
both sides of the machine. In this machine the high speed is obtained
by using the larger double gear with 28 teeth) and the ratchet pinion
with 12 teeth, and the slow speed is obtained by substituting a double
gear wheel having 25 teeth gearing into a pinion on the barrel shaft
containing 15 teeth, but I do not limit myself to these proportions.

page_text: According to another arrangement of the gearing of a lawn mower the
double gear is mounted upon a central hollow boss or stud in each side
plate, the smaller wheel of the double gear engaging into a carrier spur
wheel, turning loosely upon a second stud fixed to each side plate. This
last-mentioned wheel derives its motion from an internal toothed wheel
cast inside each driving wheel, whilst the larger wheel of the double
gear engages with the teeth of a spur pinion mounted ratchet fashion,
as before described upon each end of the knife barrel shaft. In this
arrangement a double gear wheel with 22 teeth gearing, into a pinion on
the barrel shaft with 13 teeth, gives the high speed, the low speed being
obtained by substituting a double gear wheel of 20 teeth, and a pinion
of 15 teeth, but of course these proportions may be varied. The driving
wheels each carry a central fixed stud, which revolves in the interior
of the before-mentioned hollow boss or stud in the centre of the side
plates.
According to a third arrangement of the gearing suitable for small
machines, the ends of the knife barrel shaft pass through the centre of
each of the side plates, and carry (ratchet fashion, as before-described,)
a spur pinion, into which pinion there is geared a second pinion, which
works loosely on a stud fixed eccentrically in the inner side of the
recessed driving wheel, the said driving wheels revolving freely on the
ends of the barrel shaft as an axis. A circle of internal teeth is cast
inside the side plates, and into these teeth gears the pinion carried on
the stud of the driving wheel, so that as the driving wheels revolve
motion is imparted to the said loose pinions, and is transmitted thereby
to the pinions on the knife barrel shaft. If desired, the construction of
this last-mentioned machine may be varied by connecting the two driving
wheels by a shaft passing through the centre of the knife barrel and
gearing, as described at one or both ends.
These machines may have grass boxes attached thereto in the usual

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of February, in the year
of our Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Henry Johnson, Her special
license that I, the said John Henry Johnson, my executors, adminis-
trators, and assigns, or such others as I, the said John Henry Johnson,
my executors, administrators, or assigns, should at any time agree with
and no others, from time to time and at all times thereafter 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 Invention for
"IMPROVEMENTS IN LAWN MOWING MACHINES," a communication to me
from abroad by Everett Griscom Passmore, of Philadelphia, Penn-
sylvania, United States of America, upon the condition (amongst others)
that I, the said John Henry Johnson, my executors or adminis-
trators, by an instrument in writing under my hand and seal, 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 John Henry Johnson, 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, reference being had to the accom-
panying Drawings, and to the letters and figures marked thereon, that is
to say :-
The said Invention relates to improvements in lawn mowing machines,
and more especially to hand lawn mowers having a revolving cutting
apparatus driven by two driving wheels, and consists,―
First, in arranging the gearing so that any required speed can be com-
municated to the cutters, the said gearing being conveniently protected
by the driving wheels and side plates or frame of the machine.
Secondly, in arranging the gearing and studs or shafting on which it
turns so that different sized cog wheels supplied with the machine may
be conveniently used or interchanged to give any required speed to the
cutters.

page_text: In order to make a perfectly smooth close cut it is necessary that the
knives should make oue clip every time the machine advances one inch
or less, but if they do this in long grass (say five inches high) the
grass is
cut so often that the resistance is so great as to render the machine
uscless; and as in wet weather, and for other causes, it is frequently
extremely difficult to cut the lawn often enough to allow the practical
working of a high-speed machine, it is very desirable to have a lawn
mower so arranged that it can be used effectively in grass five or six inches
high, and at the same time make perfect work in short grass.
And in order that the said Invention may be fully understood I shall
now proceed more particularly to describe the same, and for that purpose
shall refer to the several Figures on the annexed Sheet of Drawings, the
same letters of reference indicating corresponding parts in all the
Figures.
Figure 1 of the Drawings represents a plan of one of the improved
lawn mowers; Figure 2 is a side elevation with one of the driving
wheels removed, to show the gearing; Figure 3 is a vertical section
taken through the centre of the machine; Figure 4 is a section through
one of the driving wheels, taken along the line 1-2, in Figure 2; and
Figure 5 is a side clevation of the gearing alone, for driving the knife
barrel.
According to this arrangement of machine the framing is composed
of two castings or side plates a, a, keyed on to an eccentric girth or tie
bar 6 placed eccentrically to such castings so as not to interfere with the
revolution of the knife barrel c, the said castings or side plates being
recessed as shown at d to receive and protect the gearing herein-after
referred to. These side plates are each fitted with two fixed but
removeable studs e and f, one of which e, carries the driving wheel g,
having an ordinary toothed wheel cast thereon, whilst the other stud f
carries a double gear consisting of a spur wheel i and pinion / in one.
The pinion of the double gear derives its motion from the spur wheel /.
on the inner recessed face of the driving wheel, which is made hollow so
as to enclose the whole of the gearing. The larger wheel of the doublo
gear engages into the teeth of a spur pinion 7 mounted loosely upon the
end of the shaft or axis m of the knife barrel c, such spur pinion being
engaged with the said shaft or axis only when revolving in one direction
by means of a spring catch n and inclined slots or ratchet grooves o
made inside the boss of the said pinion, as shown clearly in Figure 2.

page_text: The gearing is precisely the same on both sides of the machine. In this
machine the high speed is obtained by using the larger double gear i
with twenty-eight teeth and the ratchet pinion with twelve teeth, as
represented in Figures 2 and 5, and the slow speed is obtained by sub-
stituting a double gear wheel having twenty-five teeth in lieu of twenty-
eight, gearing into a pinion on the barrel shaft containing fifteen teeth
in lieu of twelve, but I do not limit myself to these proportions. This
extra gearing is intended to be supplied with each machine. p is the
ledger or lower fixed blade and q is the roller. The handle for pushing
the machine is secured to the side frames a, a, in any convenient or well-
known manner, but is not shown in the Drawings. In this machine it
will be seen that the double gears and pinions are fully protected by the
side plates, and that as the studs are loose they can be conveniently
repaired.
Another arrangement of the gearing of a lawn mower is represented
by Figures 6, 7, 8, and 9 of the Drawings. Figure 6 is a plan of one-
half of the modified machine; Figure 7 is a section taken through one
of the driving wheels along the line 3-4, in Figure 8, so as to show the
gearing inclosed therein. Figure 8 is a section of the same wheel taken
along the line 5-6, in Figure 7; and Figure 9 is a side elevation of the
gearing alone. I may here observe that in Figures 5 and 9 the change
wheels are shown in full lines with their teeth complete, whilst the
invariable wheels are represented by red pitch lines only. In this
arrangement of the gearing the double gear i, k, is mounted upon a
central hollow boss or stud e¹ in each side plate a, the smaller wheel / of
the double gear engaging into a carrier spur wheel ¹ turning loosely
upon a second stud k¹¹ fixed to each side plate. This last-mentioned
wheel derives its motion from an internal toothed wheel 7, cast inside
the rim of each driving wheel g, whilst the larger wheel i of the double
gear engages with the teeth of a spur pinion mounted ratchet fashion
as before described upon each end of the shaft m of the knife barrel c.
In this arrangement a double gear wheel i with twenty-two teeth,
gearing into a pinion 7 on the barrel shaft with thirteen teeth, as shewn
in Figure 9 gives the high speed, the low speed being obtained by
substituting a double gear wheel of twenty teeth for the wheel of
twenty-two teeth, and a pinion of fifteen teeth for the pinion of thirteen
teeth, but of course these proportions may be varied. The driving
wheels g each carry a central fixed stud e which revolves in the interior

page_text: of the before-mentioned hollow boss or stud e¹ in the centre of the side
plates a, a. The eccentric girth or tie bar is shown at b, the ledger
blade at p, and the roller at q. The actuating handle, which is not
shown in my Drawings, is attached as before described. In both these
machines, by simply taking off the driving wheels and changing the
double gears and ratchet pinions, any desired speed may be obtained in
the rotation of the knife barrels c. Figure 10 represents in side
elevation, with the driving wheel removed, a third arrangement of the
gearing suitable for small machines; say of ten inches cut, and Figure 11
is a plan of the machine with one side in section to show the arrange-.
ment of gearing. The ends of the knife barrel shaft m in this arrange-
ment pass through the centre of each of the side plates a, a, and
carry (ratchet fashion, as before described) a spur pinion into
which pinion there is geared a second pinion which works loosely
on a stud k¹¹, fixed eccentrically in the inner side of the recessed
driving wheel g, the said driving wheels revolving freely on the ends
of the barrel shaft as an axis. A circle of stationary internal teeth h
is cast inside the side plates a, and into these teeth gears the
pinion ¹ carried on the stud 4" of the driving wheel g, so that as the
driving wheels revolve motion is imparted to the said loose pinions /¹,
and is transmitted thereby to the pinions on each end of the knife
barrel shaft m. If desired the construction of this last-mentioned
machine may be varied by connecting the two driving wheels 9, g, by a
shaft passing through the centre of the knife barrel and gearing as
described at one or both ends, the knife barrel in that case revolving on
the driving wheel shaft; b is the girth or tie bar secured eccentrically to
the side plates a, a, as before described. In this machine the roller q
before-mentioned is dispensed with; r is the pushing or driving handle
connected by the wrought-iron bridles 8, 8, to the side plates a, a, which
arrangement is equally applicable to the other machines herein-before
described.
All these machines may have grass boxes attached thereto in the
usual manner.
In order that the advantage of two speeds on a lawn mower may be
thoroughly ascertained I have annexed two diagrams showing the
motions of the cutters of the improved lawn mower at the two speeds.
Figure 12 is a section of a cutting apparatus in five inch grass driven
by gearing that causes the knife barrel to make one revolution every

page_text: time the machine is pushed forward, say 3.60 inches, whilst Figure 13
shows the same thing with the knife barrel geared so as to make one
revolution to say 5.60 inches of advance. The same numbers and
letters refer to the same parts in each diagram.
The machine being adjusted so that the lower or ledger blade p shall
move forward on the line A, A, half an inch above the surface of the
ground B, B. The perpendicular lines represent the grass drawn for
convenience one-tenth of an inch apart. The centres a, a, Figures 12
and 13 having moved forward as the cylinder or knife barrel c revolved,
have caused the knives c, c, to move forward and downward on the
curved lines C, C, drawing the grass to the cutting edge of the ledger
blade or the points p, p, where it is severed by the ledger or lower blade.
If this grass were straightened up after being cut it would shew an
inclined cut as indicated by the dotted lines 1, 2, 3. The blades c¹, c¹,
move on the curved lines C¹, C₁, and come in contact with the ledger
blades at p¹, p¹, cutting the grass as shewn by the curved and inclined
dotted lines 1, p¹, 4, 5, 6. In like manner the blades c¹, c", moving on.
the curved lines C", C", sever the grass at 2" as shewn by the curved and
inclined dotted lines 4, p¹¹, 7, 8. By this it will be seen that a machine
with a speed shown in Figure 12, will cut all the grass three times, as
the grass between 3¹ and 4' is cut first at 3 by the knife c; at 4, 5, by the
knife c¹; and at 9, 10, by the knife c"; while that from 1 to 4¹ has been
cut by preceding blades, and that from 3¹ to 6¹ will be cut by following
blades. Thus it will be seen that the grass from 2 to 3¹ is cut more
than once; but in Figure 13 a smaller portion only, namely that
between 21 and 3¹ will be cut more than once. In short grass a machine
will work as shown in Figure 12; but when in addition to the 3 cuts
the top of the grass is bent over and crushed down as shewn at c¹, and is
of necessity cut in several pieces, the machine is clogged up; the
practical effect being that the slow speed will cut five inch grass, and
the fast speed will not. But the grass being drawn to and severed
at the points p, p, and p", will spring up and leave an uneven cut as
shown at D, D, in Figure 12, although the unevenness is so slight as not
to be noticeable, whilst in Figure 13, it will present a more decided ridged
or waved appearance as shown at D', D¹. The object is in fact to so
arrange the machine that either plan can be adopted.
I am aware that a changeable speed has been used in vibrating knife
mowers, but the obiect is entirely different. it being to save the loss of

page_text: power and wear of the machine caused by a rapid vibrating motion, and
not to avoid cutting the grass or grain more than once, as the length of
the vibrating blade or section is generally made in proportion to its
speed so as to avoid this, and the stubble will present the same appearance
no matter what the speed or length of section may be, as the irregularity
of the cut is governed by the distance between the guards or fingers and
not by the speed of the vibrating knife.
Having now described and particularly ascertained the nature of the
said Invention and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider
to be novel and original, & therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,―
First. The construction and use of lawn mowers so arranged as to
admit of the gearing being readily changed in order that the knife
barrel may be driven at two speeds substantially in the manner and for
the purpose herein-before described and illustrated by the Drawings
annexed.
Second. The arrangement of gearing for driving the knife barrel or
revolving cutters of lawn mowers, substantially in the manner and for
the purpose herein-before described.
Third. The construction and use of lawn mowers wherein the frame is
composed of two castings or side plates a, a, keyed on to an eccentric
girth b, such castings being recessed to receive the gear wheels i and k,
and having the studs e and ƒ for the double gears and driving wheels
attached and arranged substantially in the manner and for the purpose
herein-before described and illustrated by Figures 1 to 5 inclusive of the
Drawings annexed.
In witness whereof, I, the said John Henry Johnson, have to
this my Specification set my hand and seal, this Fourth day
of August One thousand eight hundred and seventy-three