Note: Descriptions are shown in the official language in which they were submitted.
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~ his is a divisional of copending Canadian Patent application serial
No. 322,262 filed February 26 1979 in the name of K ~ S Industries, Inc.
This invention relates in general to flexible line trimmers for cutting
vegetation and in particular to one that has a mechanism for feeding line out
whilc still rotating.
One type of weed and grass trimmer in use utilizes a monofilament nylon
line for cutting vegetation. The line is wound on a spool that is rotated by a
rotary drive. A free traveling end extends outward from the spool a few inches
cutting yegetation in its path.
One disadvantage of the trimmer is that the line wears fairly rapidly.
To extend the line back to its proper length, most devices have a feeding mechan-
ism that requires the operator to stop the motor. The operator then turns the
trimmer over, manipulates a release, then grasps the free end of the line and
pulls more out. This is a time consuming operation and a nuisance.
One proposal to provide for line feeding while still rotating is shown
in United States Patent 3,928,911. It requires, however, a hollow shaft, grip-
ping members and a linkage extending up the handle. It is desirable to have less
complexity.
Another disadvantage with filament trimmers is that at times the line
2Q will break off inside the housing, requiring the operator to rethread the line
out through the housing aperture. Most housings are connected to the shaft by a
threaded nut that bears against the bottom of the housing or the spool. It is
desirable to ma~e the housing more quickly releasable.
It is accordingly a general object of this invention to provide an im-
proved line feeding means for a fle~ible line vegetation trimmer.
It is a further object of this invention to provide a flexible line
trimmer with improved means for attaching the housing to the shaft that allows
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quick access for rethreading.
In accordance with these objects, a f;lament trimmer is provided that
has a mechanism that feeds line out while rotating when the tril~mer is bumped
against the ground. A spool for the line .is located in a housing. A button is
mounted below the bottom of the housing and is axially movable with respect to it.
An actuator mechanism is connected between the button and the spool for allowing
the housing to rotate a selected amount with respect to the spool when the button
is depressed. The actuator mechanism will release only a selected amount of line
for each button depression, regardless of the length of time that the button is
depressed. The housing is connected to the motor drive shaft by a cap. The cap
and housing have overlapping walls, with lugs and slots for retaining them to-
gether. The housing may be qulckly released for access to the spools by rotating
the lugs rom the slots.
According to a irst broad aspect of the present invention, there is
provided an apparatus for cutting vegetation with a rotating nonmetallic flexible
li.ne comprising: a rotary drive means for rotating a ree end of the line and
having a depending drive shaft; a cap secured to the drive shaft for rotation
therewith, the cap having a cylindrical sidewall; a housing having a cylindrical
sidewall and an open top for overlapping engagement with the cap; a plurality of
2Q lugs attached to and extending radially from one of the sidewalls, the other of
the sidewalls having a plurality of mating slots for receiving lugs for releas-
a~ly coupling the housing to the cap, each slot having an entrance extending from
the edge of the sidewall to a locking portion extending circumferentially from
the entrance a selected distance in the direction of rotation; an actuator button
located at the bottom o the housing and axially mo~eable wit~ res~ect to the
housing between a lower and an upper position; bias means cooperating with the
button for urging it into the lo~er position, a spool adapted to be wound with
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the line and carried :in the housing; and actuator means, connected b0tween the
spool and the button, for allowing the housing to rotate with respect to the
spool ~hen the button is forced from the lower position for feeding additional
line out~ard and for connecting the spool to the housing for rotation therewith
when tlle button is In the lower position.
According to a second broad aspect of the present invention, there
is provided an apparatus for cutting vegetation with a rotating nonmetallic flex-
ible line comprising: a rotary drive means for rotating a free end of the line
and having a depending drive shaft; a cap member secured to the drive shaft for
la rotation therewith; a housing member having a cylindrical sidewall and an open
top; retention means for securing the housing member to the cap member, the re-
tention means including a plurality of lugs attached to one of the members, the
other mem~er having a plurality of slots extending circumferentially a selected
distance, each lug positioned for insertion into one oE the slots~ each lug and
slot having means for allowing the lug to enter the slot, for allowing the cap
and housing members to be rotated with respect to each other until the lug
reaches the c~rcumferential end of the slot, and for retaining the housing member
to the cap member, but allowing a limited amount of axial movement between the
cap member and the housing member, while the lug is at the circumferential end of
2Q the slot; a spool adapted to be wound with the line and carried in the housing;
actua~or means, moveable 6etween a first position and a second position by bump-
lng the apparatus on the ground, connected between the spool and the housing mem-
aer, for causing the spool and the housing member to rotate in unison in the first
position and for allowing the spool and housing member to rotate with respect to
each other a selected amount to feed out additional line when moving from the
first position to the second position and from the second position back to the
first position; and bias means for urging the actuator means into the first
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position, and for urglng the hous;ng member away from the cap member; the re-
tention means and actuator means allowing the housing member to move a limited
amount toward the cap member each time the apparatus is bumped on ~he ground, to
reduce sonic welding.
The present invention together with that of copending Canadian patent
application serial No. 322,262 will now be descri'Ded in greater de~ail with re
ference to the accompanying drawings in which:
Figure 1 is a partial side elevational view o a ilament trimmer con-
structed in accordance with this invention with portions of the device in section;
Figure 2 is a perspective view of the housing and inner components of
the filament trimmer of Figure 1, with ~he cap shown detached, and portions in
section; and
Pigure 3 is a partially sectioned view of the actuator mechanism
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of the fil~lent trimmer of Figllre 1.
Description of the Preferred Embodiment
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Referring to Figure 1, a portion of a fla.~ible line trimmer is
sholm, includingS the electrical motor housing 11~ which encloses an elec-
trical motor (not shown). A handle 13 allows the operator to carry and
use the device while standing. A drive shaft 15 depends from the motor and
is screwed into a cap 17 for rotating it.
Referring also to Figure 2, cap 17 is cylindrical ~ith an outer
sidewall e~tending downward. An inner sidewall 21 is concentric with the
outer sidewall 19 and is spaced inward on the bottom side of cap 17. Another
inner sidewall 23 is concentric with sidewalls 19 and 21 and is spaced
inward from them. Cap 17 has an a.~ial bore with threads 25 for connection
to drive shaft 15. A coil spring 27 fits withill the bore and bears against
a shoulder at the base of the threads 25. Four equally spaced lugs 29 are
molded between inner sidewall 21 and outer sidewall 190 Lugs 29 are
radially oriented. A plurality of fins 31 are foI~ed in a radial pattern
; on the top of cap 17 for cooling the motor.
A housing 33 is releasably connected to cap 17. Housing 33 has
a cylindrical sidewall 35~ a closed base or bottom 37 and an open top.
Four slots 39 are formed on the upper edge of sidewall 35 for mating with
lugs 29. Each slot is generally L~shaped with an entrance portion 41 e~-
tendinO downward from the upper edge parallel with drive shaft 15, and a
locking portion 43 extending at a rlgllt angle to the entrance 417 l~ith a
~er~cical notch or portion 44 at the cnd of portion 43. Locking portion 43
e~tends in the direction of rotation so that the rotational force urges
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lugs ~9 against the encl of the lockin~ portion ~3. The t~idth of slo-t 39
is adapted to closely receive a lug 29g and the distance between cap outer
sidewa]l 19 and inner sidewall 21 is selected to closely receive housing
sidewall 35.
An aperture or metal eyelet e~tends throuOh housing sidewall 35
A square aperture 47 is located in the center of the housing bottom 37.
Housing sidewall 35 overhangs the housing bottom 37 a short distanceg
providin~ a recess 49.
A circular actuator button 51 is adapted to be received within
recess 49. It is connected to a threaded shaft 53 that e~tends upward
through square aperture 47. Shaft 53 fits within a square aperture in a
mandrel 55. The portion of shaft 53 within mandrel 55 and aperture 47 is
sq~lare. The top of shaft 53 above mandrel 55 is cylindrical c~nd bears
against spring 27 to bias the button 51 downward.
A cartridge or spool 57 having nylon filament line 59 wound ar-
ound it is carried in the housing 33 by a hub 61. ~Hub 61 is concentric
with the housing 33 and has a flange 63 at its base that is in sliding
contact with a small rib o2 formed concentrically on tl~ housing botto~ 37.
Spool 57 is closely received over the hub 61 and carried by flange 63.
A pair of keys 65 are formed on hub 61 and are received within mating slots
66 in the spool 57 to prevent rotation of the spool with respect to the hub.
The upper rim of spool 57 has cutout portions 68 to allow access to the end
of the line and to the eyelet 47, without removing the spool.
An actuator means for allowing the housing to rotate with respect
to the spool when the button is depressed is enclosed withirl hub 610 It
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includes an outcr gcar h<lvin~ uppcr and lower rin~s 67~ 69 rigidly connected
to shaft 53. Lo~er ring 69 is molded integrally with mandrel 55. Upper ring
67 slides over mandrel 55. A roll pin locks the upper ring 57 to the man-
drel 55~ and locl;s the mandrel ~5 to shaft 53 for aYial movement therewith.
Rings 67, 69 are spaced apart on shaft 53 and have teeth 71, 73 that face
each otherO Each tooth lies on a radial line, has a flat top~ vertical sides
and radually increases in width from the center outward. Teeth 71, 73 have
spaces between them equal to the width of three teeth. Each tooth 71 lies
in the same vertical plane with a tooth 730
An inner gear 75 is an intelrrally molded segment of the hub 61
side~Yall, and is spaced between the upper and lower rings 67, 69. It has
a center aperture (not shown) for slidingly receivinO mandrel 55 and is
independent of movement with respect to the upper and lower rings. Inner
gear 75 has upper and lower teeth 77, 79 oE substantially the same dimension
as teeth 71, 73. Teeth 77, 79 lie on radial lines and have spaces between
them equal to the width of three teeth. Teeth 77, 79 are staggered or
offset from each other, with an upper tooth 77 formed in the center of a
space betwcen two lower teeth 79.
The diameter of inner gear 75 is slightly larger than the upper
and lo~er rings 67, 69 to allow the rings to rotate within hub 610 The
vertical space between the upper and lower ring teeth 71, 73 is substan-
tially equal to the inner gear thickness, less the height of one of the
inner gear tceth. As shown in Figures 1 and 2~ when the upper surface 81
of the inner gear is in contact with the upper ring teeth 71, the tops
of the inner gear lowcr teeth 79 will be spaced slightly above the tops of
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the lower ring tecth 73. Correspondingly, as sho~m in Figure 3, when the
inner gear lower surface 83 is in contact with the lower ring teeth ~3, the
tops of the inner gear upper teeth 77 will be slightly below the tops of the
upper rin~ teeth 71. Consequently~ the inner and outer gear3 are free to
incrementally rotate with respect to each other until either the upper set
o~ teeth are in engagement with each other or the lower set of teeth are in
engagement with each other. There is no intermediate position that allows
the inner and outer gears to rotate completely free witll respect to each
other.
In operation, the free end of the line is threaded through eyelet
45 for a distance that may be appro~imately three to six inches. The elec-
tric or gasoline motor rotates the housing, swinging line 59 in a path to
cut vegetation. Figures 1 and 3 show the device when the actuating mechanism
and button 51 are in the lot~er position, being urged into that position by
spring 27. In the preferred embodiment, the rotation is clockwise as viewed
from the top, indicated by arrow 81. Spool 57 is prevented from movement
with respect to housing 33 when the button 51 is in the lo~1er position by
shaft 53, locked to square aperture 47, and by upper ring teeth 71~ which
bear against the inner gear upper teeth 77. The inner gear, being molded
20 to hub 61, drives the spool 57 through hub keys 65. Thus~ in normal rotat-
ion, the upper set o~ teeth of the inner and outer gears will be engaged~
with the upper ring teeth 71 serving as a latching member and the inner
gear upper teeth 77 serving as drive teeth.
When the line wears so as to require more swinging length, the
button is depressed by bumping it against the ground momcntarily. This
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placcs thc actuator in thc upper pOSitiOII. Shaft 53 moves upward with re-
spect to hOUS~lg 33 until the lol~er ring teeth 73 contact the inner gear
lower surface 83. At this point, which is shown in Figure 3~ the upper ring
teeth 71 will be disengaged from the inner gear upper teeth 77. This mom-
entarily disengages the hub and spool from rotation with the housing. The
hub and spool will slip with respect to the housing as indicated by arrow
83 ~Figure 2) since they are no longer driven until the lower ring tee~h 73
come into engagelnent with the inner gear lower teeth 79. Engagement of the
lower set of teeth stops the rotation of the housing with respect to the
spool momentarily. However spring 27, which urges the bu~ton back into the
lower position~ will quickly disengage the lower set of teeth from each
other. The hub and spool will slip again with respect to the housing ~mtil
the upper rin~ teeth 71 again contact the i~ler gear upper teeth 77.
This two-step feedout occurs very quickly because of the high
rotational speed, which may be seven thousand to nine thousand rotations per
minute. It feeds out a measured amo-mt of lil1e proportional to the width of
four teeth regardless of how long the button is depressed or how long it
takes spring 27 to urge the button back into the lower position. The lower
sets of tecth are thus only momentarily engaged to serve as incremental means
for allowing a selected amount of ~ine to be fed out.
The upper edge of hub 61 is flush with the upper rim of spool 57.
When the actuator mechanism is in the lower position, as sho~m in Figure 1~
a clearance of about .0~0 inch e.Yists between the upper edge of hub 61, and
the lower surface 85 of inner sidewall 23. This clearance~ and the length
of notches 44 ~I slots 39 allow thc housing 33 to move a.Yially upward ~Yith
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respect to cap 17 ~1he11 the button 51 is depressed. This a~ial movement,
repeated each time line is advanced, prevents sonic welding of the housing
to the cap due to vibration. A clearance of appro.~imately .030 inch e~ists
bet~een the outer ed,e of spool 57 and the inside ~all of inner sidewall 21.
Should the line break off inside housing 33, it must be rethreaded
through eyelet 45c The motor is stopped and the trimmer turned over to
e~pose housing 33. Housing 33 is depressed and rotated clockwise a short
distance, then p1~led away from cap 17, disengaging slots 39 from lugs 29,
The free end of the line is located and threaded through eyelet 45, access
being provided by the cutout portion 68. If desired~ the spool can be
removed entirely from the hub 61 by pulling upward.
It should be apparent that an invention having si~nificant improv-
emen~s has been providedO The filament trimmer has an actuator for feedin,
out additional line that operates simply by bumping the trimmer against
the gro~md, Incremental means prevents too much line from feeding out,
which can cause overheatinv of the motor. Access to the spool for rethread-
ing is quickly provided by the lugs and slot locking arrangement.
While the invention h~ been sholm in only one of ltS forms, it
should be apparent to those skilled in the art that it is nat so limited
20 but is susceptible to various changcs and modifications without departinv
from the spirit thereof. -
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