Note: Descriptions are shown in the official language in which they were submitted.
78S
QUICK ATTACHABLE AND DETACHABLE MOWER BLADE ASSEMBLY
Back~round of_the Invention
! When mowing grass on large acreages, such as golf
courses, parks, large estates and commercial areas, it
sometimes requires almost continuous mowing. Mower blades,
under such conditions, continuously need to be sharpened. It
is desirable that the blades be r~moved from the mowers for
such sharpening and that consequently, a simplified means of
detaching and attaching the mower blade to its drive shaft is
desirable.
one of the factors that makes a simplified structure for
such a purpose difficult to design is a safety factor. Since
a blade rotates at a relatively high speed, it is necessary
that the means of attaching the blade be completely reliable
in order to prevent accidents or damage to property. Also,
the nature of a lawn mower is such that stones and other
foreign matter are often contacted by the mower blade which
tends to scour or damage connectin~ elements holding the blade
on the shaft. Often, such damage to the connecting elements
will create a hardship in removing that blade for sharpening
purposes.
There have been many attempts to install a quick
attachable and detachable blade system on lawn mowers. Most
of these rely upon removing and replacing only the outer
cut~ing blade portion of the mower blades. One of the
problems with such a system is that the blade attachments tend
to break off at their connection. The high rate of rotation
of the motor itself causes these blade portions to be thrown,
and should they find their way out from under the mower
housing, they can do considerable damage and injury to people
and property.
Another method of providing a quick attachable and
detachable mower blade assembly is by use of a unique
arrangement of blade holder and blade developed and designed
by Mr. James L. Rittenhouse and shown and described in his
U.S. Pat. No. 4,586,257, which issued May 6, 1986. In this
assembly, he provides a downwardly opening, U-shaped in cross-
i.~''34785
section blade holderO A blade is slidably received in the
opening of the U-shaped holder. Upon the blade reaching a
desired location with respect to the holder, an opening in the
blade is positioned to receive a downwardly biased locking pin
that holds the blade against further sliding action. Mr.
Rittenhouse has provided notches in the leg portions of the U-
shaped holder and notches in the opposite edges of the blade
so that when properly aligned, the blade may be placed in the
holder from beneath and then slid to its proper cutting
position where ~he locking pin automatically inserts itself.
Some of the problems relating to Mr. Rittenhouse's design
is that the notches in the edges of the blades and holder
create stress areas that may cause premature ~ailure of them.
Should a stick, small stubble or other objects strike the pin
and depress it momentarily while mowing, the blade could
become unlocked and free to move radially, which could create
a dangerous condition. Also, the only thing restricting the
sliding movement of the blade relative to the holder is the
single locking pin. Rupture of this pin would create a
condition in which the blade was free to move or slide with
respect to the holder. This could create a condition in which
the mower blade could cause considerable damage to the mower
deck or housing and could create a hazard to property and
people working around the area of the mower.
Summary of_t e Invention
~ith the above in mind, it is the primary purpose of the
present invention to provide a mower blade assembly in which
the blade may be easily attached and detached without, in most
instances, the use of tools.
More specifically, it is the purpose of the present
invention to provide a combination of a blade holding member
and a blade member mounted on the lower end of a mower drive
shaft so as to rotate with the shaft. The blade holder member
has a pair of studs depending from its under surface
downwardly through suitable openings in the blade. The studs
have enlarged heads. A portion of each opening is large
enough to permit a head to pass through and a portion of each
7~5
openin~ is reduced to a narrow width which is substantially
I the diameter of the shank portion of the studs. One of the
! narrow portions is positioned and directed in the blade so
that it will prevent relative radial moYement between the
holder and the blade and the other of the narrow openings is
positioned so as to prevent relative angular movement between
the holder and the blade. The ends of the narrow portions are
rounded so that the shanks of the studs will rest along the
rounded semi-circular edge of that end. A locking pin is
provided in the main shaft and is biased downwardl~ to be
received in an opening of the blade when the blade is properly
positioned with respect to the ho:Lder. The locking pin serves
the purpose of preventing any sli~ling movement between the
blade and blade holder. However, should, for some reason, the
locking pin be compressed while the blades are rotating, the
relationship between the shanks and the direction of the
narrow portions of the slots will resist axial and radial
movement of the blade relative to its holder so as to prevent
a hazardous condition. However, when the locking pin is
compressed, the blade may be easily and manually moved to a
location in which the enlarged portions of the openings are in
position to pass the heads of the studs for removal of the
blade.
It is a further purpose of the invention to proYide lugs
or tabs on the holder that engage the trailing edges of the
blade and cooperate with and are so positioned with respect to
the studs that extend through the blade that the blade cannot
be mounted on the holder in other than the correct manner,
i.e., the blade cannot be mounted upside down, with the
cutting sdge not being the leading edge with respect to the
direction of rotation, or without the locking pin being seated
in its locked position.
Brief Description of the Drawings
Fig. 1 is a top view of a lawn mower utilizing the blade
mounting structure of the present invention.
Fig. 2 is a planned view of a lawn mower blade used in
the blade assembiy of the present invention with portions of
the blade holder shown in dotted line.
Fig. 3 is a side view of the blade shown in Fig. 2.
! Fig. 4 is a side view of the assembled mower blade
assembly as taken substantially along the line 4-4 of Fig. 1.
For purposes o~ clarity in showing internal mechanisms and
structure, part of the view is shown in section.
Fig. 5 is a plan view taken alon~ the line 5-5 of Fig. 4
of the blade holder used in the assembly of the present
invention.
Fig. 6 is an enlarged sectional view taken along line 6-6
of Fig. 5.
Description of the Invention
Referring now to Fig. 1, there is shown a multiple
spindle rotary mower 10 having a blade housing or deck 12 that
has a top 14 and a depending skirt portion 16. The entire
deck covers and supports three mower blades 18. The blades
are carried on vertical shafts 20 having at their upper ends
drive pulleys, which are driven through a belt drive indicated
in its entirety by the reference numeral 2~. The specifics of
the belt drive are unimportant with respect to the present
invention and other than to indicate that the shafts 20 and
their respective pulleys 22 are driven by the belt drive, no
further description thereof is believed necessary. The entire
belt drive 24 is carried under a drive shield 26.
The mower 10 is of the underslung type, i.e., it is
mounted on the underside of a tractor be~ween its front and
rear wheelsO Provision for gauging the height of cut of the
grass is provided through a front gauge roller 30 and a pair
of rear gauge wheels 32, 34 which are connected to the rear
ends of a pair of rearwardly convergin~ structural members 36,
38, the forward ends of which are carried by the roller 30.
Conventional means for adjusting the entire deck 12 with
respect to the roller 30 and gauge wheels 32, 34, while not
shown, are provided for the mower.
Referring now to Fig. 4, each blade 18 is provided with
its main drive shaft 20 which has keyed at 40 thereto a drive
pulley 22. The upper end of the sha~t 20 is threaded as at 42
J~
~ Z~135
and has mounted thereon a conventional nut 44. The shaft 20
is carried in a journal structure 46 that is fixed to the
I underside of the mower deck 14 and depends downwardly
therefrom. The journal ~6 carries a pair of shaft bearings
48, 50, and upper and lower seals 52, 54. The lower end of
the shaft 20 is provided with a frustoconical shaped end 56
that projects downwardly from the journal housing 46. The
lower end portion of the shaft 20 also has a axially extending
opening 58 which slidably receives a locking pin 60 projecting
downwardly from the frustoconical end 56. The opening 58 has
a pair of vertical slots 62 in its walls on diametrically
opposite sides thereof. A pin guide 64 projects from opposite
sides of the locking pin 60 and has its opposite ends resting
in the slots 62. Thus, the locking pin 60 may move vertically
the length of the slots 62. Above the locking pin 60 and in
the upper end of the opening 58 is a compression spring 66
which biases or forces the pin 60 downwardly to its position
as shown in Fig. 5. However, it should be understood that the
pin 60 may be forced up into the opening 58 and to a point
where it does not depend from the frustoconical end portion 56
of the shaft.
The blade assembly forming the basis of the present
invention is composed of the blade member 18 of the type shown
in Figs. 2 and 3 and a blade holder member 70 of a type shown
in Fig. 4. The blade 18 has a central opening 74 that, as
will later become apparent, serves a purpose of recei~ing the
lower end of the locking pin 60. At opposite ends and at
opposite edges, there is provided a pair of cutting edges
indicated at 75.
The blade holder member 70 is an elongated, flat plate
member having a central frustoconical shaped opening that
conforms to the frustoconical shaped end portion 56 of the
main drive shaft 20. The holder member 70 is placed on the
frustoconical end portion 56 and the nut 44 is turned to draw
the end portion 56 in close and tight contact with the
frustoconical surface 76 forming ~he frustoconical opening in
the member. This tight fit results in the shaft 20, the blade
.
member 18 and the blade holder member 70 rotating as a unit.
The holder member 70 is provided with a pair of stud-receiving
! threaded openings 78, 80. The stud opening 78 on the left of
the center opening 76, as viewed in Fig. ~, is offset a
smaller distance from the axis of the opening 76 than the
opposite opening 80 is offset to the right of opening 76. The
purpose of this will later become apparent. The holder member
70 has a flat, lower surface 72 that, when assembled with the
blade member 18, is alongside a flat upper surface 82 of the
blade member 18, both surfaces being flat and adjoining one
another permits the blade member 18, unless otherwise
restricted, to slide relative to t:he holder member 70. It
should be understood, however, that due to confinement within
the skirt portion 16 of the mower deck 12 or due to
interference with other blades or mower structure, each blade
member is permitted only a small or limited amount of sliding
action.
Threadedly received in the openings 78 and 80 are a pair
of headed stud elements 86, 88. The headed stud elements 86,
88 are in the form of a common bolt having enlarged head
portions 90, 92 spaced from the surface 72 substantially the
thickness of the blade member 18. The shanks of the bolts 86,
88 are threaded and are, as is conventional, considerably
smaller than the heads 90, 92. The threaded connection
between the bolts 86, 88 and their respective threaded
openings are self-locking thereby retaining the spacing
between head portions 90, 32 and surface 72 at the desired
distance. The studs 86, 88 depend from the surface 72 and
extend through openings indicated in their entireties at 94,
96 offset to opposite sides of the center portion of the blade
18. The opening 94 has an enlarged portion 98 that permits
passage of the head of its respective stud 86. The opening 94
also includes a narrow portion 100 extending from the enlarged
opening 98 to an end offset radially outwardly from the
opening 98. The narrow portion 100 of the opening 94 is
substantially the same size as the diameter of ~he shank
portion of the stud ~6. Thus, unless restricted, the stud may
, ,~'
4~85
.,
penetrate through the enlarged opening portion 98 and the
blade may then be slid until the shank portion of the stud is
moved outwardly into the narrow portion so that the blade is
held by the head 90 of the stud.
Referring to the right side of the blade member 18, the
opening 96 is provided with an enlarged por~ion 102 that
permits passage of the head 92 of the stud 88. The opening 98
also has a narrow portion 104 leading from the enlarged
portion 102. The portion 104 is L-shaped, terminating at an
end 106. The narrow portion 104 of the opening is also
substantially the diameter of the stud 88. When the shank of
the stud 88 is positioned in the end 106, the stud 88 will
prevent relative axial movement between the blade and the
blade holder. Again, the stud 88 may pass through the
enlarged portion 102 of the opening 96 and the blade may then
be slid along the narrow portion 104 of the opening 96 until
it rests in the end 106. The position of the studs with
respect to openings 94, 96 and when the blade is attached for
mowing are best shown in phantom in Fig. 2.
Referring now to the operation of mounting and
dismounting the blade from the blade holder, the blade is
positioned wherein the heads 90, 92 of the respective studs
86, 88 are moved through the enlarged portions 98, 102 of the
openings 94, 96. The blade 18 i5 then shifted or slid along
the undersurface 72 of the holder until the shank portions of
the respective studs 86, ~8 rests respectively in the end of
the narrow portion 100 of the left-hand opening and in the end
portion 106 of the narrow portion 104. At this time, the
opening 74 will come in registry with the locking pin 60 which
~ 30 permits it to drop or spring into the opening 74 and to
prevent any further sliding of the blade. In order to remove
the blade, it is necessary to compress or raise the locking
pin 60 until the blade 18 can be slid in a reverse direction
for removal.
It should also be understood that the studs may be
threadably adjusted to compensate for different thicknesses of
blade. However, in most instances, the blades will be of the
', ~
~47~s
same thickness and adjustment of the studs will not be
necessary.
! Referring to Fig. 2, it will be noted that the quantity
of material removed to form openings 96 is different. To
balance the blades properly, the openings 9~, 96 are radial
offset radially different a~ounts with respect to opening 74.
Studs 86 and 88 are also located in radially offset positions
with respect to opening 74. By positioning the studs and
openings in this manner, the rotating spindle assembly retains
lo a balance to make it more efficiently operated.
Also, the locations and direc:tions of the narrow portions
of the openings 94, 96 serve a unique purpose. When the studs
are positioned in the ends of the narrow portions, as shown in
Fig. 2, the edges of the narrow portion 100 will rest against
the shank of stud 86 thereby preventing relative angular
movement between the blade and blade holder. Likewise, on the
opposite side of opening 7~, the shank of stud 88 will contact
the end 106 of the narrow portion 104. Note that the edge
forming the end 106 is on the same side of the stud 88 as the
cutting edge 75 on that end of the blade. Thus, if the blade
strikes a foreiqn object while rotating, the two studs 86, 88
will resist angular separation between the blade and blade
holder. This substantially removes all load on the pin 60.
Also important, should a stick, stubble or other foreign
object temporarily compress the pin 60 while the mower is in
operation, the studs 86, 88 will resist shifting of the blade
both axially and radially with respect to the holder, thereby
preventing a hazardous condition of an unlocked blade and
holder. Also, the transverse disposition of the end portion
of the narrow portion 104 with respect to the longitudinal
dimension of the blade prevents radial shifting of the blade
with respect to the holder, thus removing a radial load on pin
60.
Referring now to Figs. 2, 5 and 6, the holder 70 has
fixed to its opposite edges a pair of lugs 110, 112 that
depend downwardly from the edges of the holder and are
disposed alongside the trailing edges of the blade 18,
~2~917~3S
trailing edges, for purposes of this description, being the
edges that are opposite of the cutting edges 76. The lug
¦ element 112 is L-shaped and has a inwardly projecting leg
portion 114 that underlies the trailing edge portion of the
blade 18. Referring to Fig. 2, it will be noted that the
distance between the trailing edge of the blade 18 and the
center of the enlarged portion 102 of opening 96 is less than
the transverse distance between the center of stud 88 and the
leading or forward edge 116 of the leg portion 114. This
lo becomes important for the reason that the blade can be
positioned so that the openings 102, 98 may receive the heads
of studs 86, 88 without interference between the blade and the
L-shaped lug 112. Should the blade as shown in Fig. 2 be
reversed, there would be interference with the leg portion 114
and the edge of the blade 18. Thus, the blade cannot be
reversed or turned over without creating interference with the
leg 114.
The lugs 110, 112 also serve other purposes. For
example, should the blade cutting edges 76 contact an embedded
object which would tend to turn or twist a blade about its
longitudinal axis, the leg portion 114 will rasist such
action. Also, the lugs 110, 112 which engage the trailing
edges of the blade 18 would tend to aid in driving the blade
along with the studs 86, 88. This, of course, gives added
strength to the entire blade assembly.
