Note: Descriptions are shown in the official language in which they were submitted.
8~31
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This invention relates to an improved hollow shaft filament
trimmer for use in safely cutting vegetation.
~ilament-type vegetation trimmers are well known in the art. ~ith
such apparatus, a length of stiff filament line is rapidly slung in a
circular arc to provide cutting means which are relatively safe to use in
comparison with bladed trimming mechanisms.
The bet~er models of said trimmers normally use a frame mounted
rotary drive means having a hollow output shaft. A length of filament line
; is fed through the hollow shaft to a rotating head mounted on said shaft
which engages the line and slings it in a plane radial to the shaft axis.
As the cuttirg line wears or breaks, additional line is fed through the
hollow shaft to the rotating head from a reserve supply of filament mounted
above the rotary drive means. ~s the centrifugal force of the moving line
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will pull the line from the reserve filament, the filament trimmers have a
filament lock interposed between the reserve supply and the hollow shaft
which may be released to allow additional line to descend through the
hollow shaft to the rotating head.
The hollow shaft feed filament trimmer disclosed in United States
Patent No. 3,9 ~ 911 is ;lliustrative of such a trimmer. In that patent,
the rotatir~ head mounted to the hollow shaft comprises an open-ended
bellmouth structure having one or more radial grooves for engagir~ and
swinging the filament in a plane perpendicular to the hollow shaft. A
pair of spring biased toothed jaws grip the filament line above the hollow
shaft, and a manual control mechanism is used to open the jaws during
operation for feed of additiona1 line to the bellmouth through the hollow
shaft.
The aforementioned device and similar type trimmers have certain
-; disadvantages incorporated therein which become apparent upon observation.
One problem lies in inititally getting the filament line to swing in the
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radial plane. Admittedly, once the filament is started swinging, centri-
fugal force might keep the line pressed in the radial groove of the open
bellmouth, however, there is nothing disclosed to initiate such an action.
In addition, the rotation of the head forces the filament to turn in the
bellmouth groove which tends to roll the Eilament from the groove. Further-
more, if the filament is swinging rapidly, the centrifugal force on the
line makes the addition of fresh filament a matter of guesswork and there
are no convenient means to retrieve excess filament once an error has been
made.
It is therefore an object of this invention to provide an improved
hollow shaft filament trimmer.
According to the present invention there is provided an improved
non-metallic filament weed-grass trimmer of the type in which a frame-
mounted drive means rotates a hollow output shaft having a conduit, a feed-
able length of filament, one end of which is non-rotatably fixed to said
frame or parts connected thereto, the other free end of which is threaded
through said conduit to a head affixed to said shaft and rotatable there-
with, the improvement comprising: said head having an arcuate enclosed
conduit extension for the continual passage of the said free end of said
filament therethrough, one end of said conduit extension substantially
aligned and in open communication with the conduit of the hollow output
shaft and the other end of said conduit extension projecting outward from
the hollow output shaft axis.
In a preferred embodiment of the invention, said means for pos-
itively feeding defined increments of f;lament fed to said head comprises:
an annular cup mounted to the end of the fixed drive means opposite the head
for holding a supply of filaments; a distributor rotatably mounted to the
center of the annular cup, and having a central opening therethrough in sub-
stantial alignment and in open communication with said one end of the hollow
output shaft, and further having at least one groove in the head of said
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distributor for receiving and guiding filament from the annular cup to the
distributor through said conduit in said hollow output shaft through said
conduit extension and thence outward of said head; and means for rotating
the distributor to allow positive feed of the defined increment of filament
passing from the annular cup to the distributor.
The means for rotating the distributor preferably comprises: a
circular rack affixed to the outer perimeter of the distriburor interposed
between the drive means and the annular cup; a rotatably-mounted pinion
gear engageable with the rack; and a handle for rotating the pinion gear.
In the accompanying drawings:
Figure 1 is an elevational view, partly in section, of one embodi-
ment of the invention;
Figure 2 is a top elevational view of one embodiment of the filament
reserve;
Figure 3 is a view taken-along line 3-3 of Figure l;
Figure 4 is an elevational view, partly in section, of the filament
reserve, taken along line 4-4 of Figure 2;
Figure 5 is an elevational view, partly in section, of a second
embodiment of the filament reserve;
Figure 6 is a view, partly in section, of the filament reserve taken
along line 6-6 of Figure 5; and
Figure 7 is a view taken along line 7-7 of Figure 5.
Referring now to Figure 1, reference character 10 generally ind-
~ icates an improved hollow shaft filament trimmer. An electric motor 12 i5
; mounted to frame 14 having a handle 16. Preferably, the trimmer 10 is
lightweight in design for easy manipulation by hand to ideally trim those
areas of vegetation which are inaccessible by conventional mowers or those
areas where the terrain is rough and the use of conventional
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mowers creates considerable hazard to the operator. The motor 12 has an
armature-driven output shaft 18 of sufficiently large inside diameter to
receive a length of stiff filament line 20 extendir,g therethrough.
A slinger head 22 is attached in any suitable manner to the
lower end of output shaft 18, as shown in Figure 1. An arcuate bore 24
extends through slinger head 22, the upper end 26 of said arcuate bore
terminating in substantial alignment and in open communication with the
hollow bore 28 provided by the shaft 18. The other end 30 of said arcuate
bore 24 terminates on the outer periphery of slinger head 22 projecting
generally in a radial direction from the hollow output shàft axis, The
filament 20 extends through the arcuate bore 24 and protrudes from the
slinger head for use as a cutting whip when in operation.
A filament reserve, referred to generally by reference character
32, is mounted above the motor 12 for holding a coiled supply of filament
line. In one embodiment of the filament reserve, shown in Figures 1-4, the
reserve comprises an annular supply cup 34 mounted to the top of electric
motor 12 by means of a skirt 36 extending from the outer cup wall. A
small aperture 3~ is bored through the outer cup wall to provide a means
for readily securing one end of the filament coil 20 placed within the
cup annulus. A substantially cylindrical distributor 40 havir~ central
axial opening 42 therethrough is rotatably mounted in the central opening
of ar,nular supply cup 34. The bottom of distributor 40~ as oriented in
Figure 1, has a shoulder 44, and the top 46 of said distributor projects
above the inner wall 48 of the annular cup 34. Distributor 40 is provided
with a circumferential groove 50 in the outer periphery of the top thereof
above inner cup wall 48 for receiving the cover cap 52. Cover cap 52 is
preferably constructed of a stiff, flexible material such as plastic and
is provided with a circularly shaped central aperture substantially equal
in diameter to the diameter of the distributor groove 50. A plurality of
~ 48~
slits 54 extend radially from the circular aperture of cap 52 as shown in
Figure 2 for ease in sliding the cap around the outer periphery of the
distributor 40. A hole 56 offset from the center of cap 52 is bored
through said cap in open communication with the annular supply cup. At
least one slot 58 is provided in the top 46 of distributor 40. Slot 58 is
preferably longitudinally slanted along a non-diametrical chord of the
distributor rather than radially directed, for reasons which will become
apparent later.
Shoulder ~4 of distributor 40 provides a circular rack along
the outer perimeter thereof for engaging a two-toothed pinion gear 60
mounted in skirt 3~ under the annular supply cup. A handle 62 is attached
to the pinion gear for manually rotating~the distributor.
In operation, one end of a coil of filament is passed through
aperture 38 and knotted. The bulk of the filament is then coiled in
arnular cup 34. The loose filament end is threaded through hole 56 of the
cover cap 52, passed through distributor slot 58, and down the central
distributor opening 42, where the filament enters the hollow feed shaft.
The filament is further threaded through the hollow shaft and the arcuate
- bore of slinger head 22~ Actuation of the electric motor slings the
` 20 filament protruding from the slinger head in a plane radial to the hollow
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shaft axis. As the cutting line wears or breaks, additional line can be
fed to the slinger head by rotation of the distributor in the opposite
direction of the filament winding. The length of filament protruding from
the slinger head can also be retracted by simply reversing the direction
of the distributor rotation. Distributor groo~e 58 and cover cap 52
prevent the line from being drawn through the trim~er by centrifugal force
urless the distributor is rotated and thus affords a positive line metering
. . . .
mechanism not presented in the prior art.
In a second embodiment of the filament reserve as shown in
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Figures 5 to 7, the filament reserve comprises an annular supply cup 70
mounted to the top of motor 12 by means of a skirt extension 72. A
distributor 74 having a central aperture 76 therethrough in open communi-
cation and in substantial alignment with the hollow bore 28 of output
shaft 18 is rotatably mounted in a center opening of ar~ular cup 70 and
the distributor head 77 thereof projects above the inner rim 78 of annular
cup 70. The bottom periphery 80 of the distributor provides a wheel gear
designed to mesh with a worm gear 82 mounted in any suitable manner to
the underside of cup 70 and having a handle 84 extending through cup
skirt 72. The distributor head 76 has at least one groove 86 leading from
the center aperture toward the inner rim of ar,nular cup 70, said groove
being preferably curved.
In operation, a coil of filament is wrapped around the ir~er
wall of the annular cup as in the previous embodiment, and the line is
inserted through the distributor aperture 76~ hollow shaft bore 28, and
slinger head 22~ Actuation of the electric mokor imparts a centrifugal
force to the filament line, drawing same tightly into the groove 86 of
the distributor head. As the cuttir~ line wears or breaks, additional
line is fed to the slinger head by rotation of the distributor.
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