U.S. patent application number 12/219538 was filed with the patent office on 2008-11-20 for weed and grass trimmer.
Invention is credited to Albert S. Grace.
Application Number | 20080282554 12/219538 |
Document ID | / |
Family ID | 26845752 |
Filed Date | 2008-11-20 |
United States Patent
Application |
20080282554 |
Kind Code |
A1 |
Grace; Albert S. |
November 20, 2008 |
Weed and grass trimmer
Abstract
A weed and grass trimmer has a cutting line which is fed as the
weed trimmer is in use. The weed trimmer's cutting head includes a
spool for cutting line, and a housing. The spool has flanges around
its circumference, which may engage a corresponding upper or lower
set of flanges in the housing. Actuation of a control located near
the handle operates either a cable or a solenoid, causing the spool
to reciprocate between the upper and lower flanges. The difference
in centrifugal force and angular velocity during this reciprocation
causes additional cutting line to be fed.
Inventors: |
Grace; Albert S.; (Lowell,
AR) |
Correspondence
Address: |
LITMAN LAW OFFICES, LTD.
P.O. BOX 15035, CRYSTAL CITY STATION
ARLINGTON
VA
22215-0035
US
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Family ID: |
26845752 |
Appl. No.: |
12/219538 |
Filed: |
July 23, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09564949 |
May 5, 2000 |
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12219538 |
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60148321 |
Aug 11, 1999 |
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Current U.S.
Class: |
30/276 |
Current CPC
Class: |
A01D 34/4163
20130101 |
Class at
Publication: |
30/276 |
International
Class: |
A01D 34/416 20060101
A01D034/416 |
Claims
1. A line feed mechanism for a weed and grass trimmer, the weed and
grass trimmer having a boom, a handle at one end of the boom, a
cutting head at the opposite end of the boom, a motor, and a drive
shaft connected between the motor and cutting head, said line feed
mechanism comprising: a spool holding at least one cutting line,
said spool having a top, a top plate, and sides, said top plate
having circumferential flanges; a housing covering said top and
sides of said spool, said housing having one upper set of flanges
and one lower set of flanges, each of said upper and lower set of
flanges corresponding to said spool's flanges, said housing having
at least one hole for receiving said cutting line, said housing
further having a top and a bottom; a spring fitting between said
housing and said spool; and means for causing said spool's flanges
to selectively engage said upper flanges and said lower flanges of
said housing.
2-3. (canceled)
4. The line feed mechanism according to claim 1, wherein said means
for causing said spool's flanges to selectively engage said upper
flanges and said lower flanges of said housing further include: an
internal shaft slidably disposed within said driveshaft, said
internal shaft comprising an upper portion and a lower portion,
said upper portion having a threaded top, an internally threaded
hexagonal portion mating with said housing, said internal thread
mating with an external thread on said driveshaft, and a hollow
portion, said lower portion being dimensioned and configured to fit
within said hollow portion, said hollow portion defining a slot,
said lower portion including a pin dimensioned and configured to
reciprocate within said slot, said internal shaft passing through
said housing and said spool, said lower portion further having an
internally threaded end; a cap having a threaded rod mating with
said internal threads of said internal shaft; a bearing secured to
said threaded top of said internal shaft; and a lever having a
horizontal portion and a vertical portion, said horizontal portion,
said bearing resting on top of said horizontal portion, said cable
attaching to said vertical portion.
5. The line feed mechanism according to claim 1, wherein said means
for causing said spool's flanges to selectively engage said upper
flanges and said lower flanges of said housing includes a
solenoid.
6-8. (canceled)
9. A line feeder for a weed and grass trimmer, comprising: a) a
spool for holding a cutting line, the spool having a circular top
plate with a plurality of top plate flanges projecting radially
from the circumference of the plate spaced apart at a predetermined
angle; b) a spool housing enclosing said spool, the spool housing
being dome-shaped and having an open bottom and at least one hole
defined therein for dispensing the cutting line; c) a plurality of
upper flanges disposed inside said spool housing, the upper flanges
being equal in number to the flanges projecting from said top plate
and spaced apart at the same predetermined angle as said top plate
flanges; d) a plurality of lower flanges disposed inside said spool
housing in a horizontal plane below said upper flanges, the upper
flanges being equal in number to the flanges projecting from said
top plate and spaced apart at the same predetermined angle as said
top plate flanges, said lower flanges being rotated by an angle of
about one-half the predetermined angle separating said upper
flanges so that each lower flange is positioned about midway
between two of said upper flanges; e) a bias spring positioned
between the top plate of said spool and said spool housing, the
spring normally biasing the top plate flanges of said spool into
abutting contact with the lower flanges in said spool housing; and
f) line feeder means for causing relative movement between the top
plate flanges and the lower and upper flanges of said spool housing
in order to dispense increments of cutting line from said spool,
said means being operable from a handle of a weed and grass trimmer
without bumping the trimmer on the ground.
10. (canceled)
11. The line feeder according to claim 9, wherein said line feeder
means moves said spool relative to said housing.
12. (canceled)
13. The line feeder according to claim 9, wherein said line feeder
means comprises: a) a normally open electrical switch attachable to
a handle of the weed and grass trimmer; b) a bearing attached to
said spool housing; c) a solenoid having a plunger abutting said
bearing, the solenoid being electrically connected to said switch;
d) wherein said spool is attachable to a driveshaft of the trimmer
so that the spool is rotatable with the driveshaft; e) wherein the
top plate flanges are in abutting contact with said lower flanges
when said electrical switch is in an open position; f) wherein said
electrical switch has a closed position in which the plunger of
said solenoid moves to an extended position, pushing said bearing
and said spool housing downward until the top plate flanges engage
said upper flanges in order to dispense a first increment of
cutting line; and g) said bias spring raises said spool housing
when said electrical switch is returned to the open position until
the top plate flanges engage said lower flanges in order to
dispense a second increment of cutting line.
14. The line feeder according to claim 9, wherein said line feeder
means comprises: a) a hand lever attachable to the handle of the
weed and grass trimmer; b) a cable having a first end attached to
said hand lever and having a second end; c) an internal shaft
slidably insertable in a hollow driveshaft and having an upper end
and a lower end; d) a bearing disposed about the upper end of said
internal shaft; e) a pivotally mounted bearing lever having a first
arm attached to the second end of said cable and a second arm in
abutting contact with said bearing; f) wherein said spool housing
is connectable to the hollow driveshaft in order to rotate with the
driveshaft; g) wherein said spool is attached to the lower end of
said internal shaft; and h) wherein the second arm of said lever
raises said bearing when said hand lever is pressed, whereby said
spool is raised until the top plate flanges engage the upper
flanges in said housing in order to dispense a first increment of
cutting line; and g) wherein said bias spring lowers said spool
until the top plate flanges engage said lower flanges when said
hand lever is released in order to dispense a second increment of
cutting line.
15. The line feeder according to claim 9, wherein said line feeder
means comprises: a) a normally open electrical switch attachable to
a handle of the weed and grass trimmer; b) an internal shaft
slidably insertable in a hollow driveshaft and having an upper end
and a lower end; c) a bearing disposed about the upper end of said
internal shaft; d) a pivotally mounted bearing lever having a first
arm and a second arm in abutting contact with said bearing; e) a
solenoid having a plunger attached to the first arm of said bearing
lever, the solenoid being electrically connected to said switch and
the plunger being normally extended; f) wherein said spool housing
is connectable to the hollow driveshaft in order to rotate with the
driveshaft; g) wherein said spool is attached to the lower end of
said internal shaft; and h) wherein the second arm of said lever
raises said bearing when said electrically switch is closed, the
plunger being retracted, whereby said spool is raised until the top
plate flanges engage the upper flanges in said housing in order to
dispense a first increment of cutting line; and g) wherein said
bias spring lowers said spool until the top plate flanges engage
said lower flanges when said electrical switch is returned to an
open position in order to dispense a second increment of cutting
line.
16. The line feeder according to claim 9, wherein said spool has a
unitary, one-piece construction.
17. The line feeder according to claim 9, wherein said spool
comprises: a) a circular top plate with a plurality of top plate
flanges projecting radially from the circumference of the plate
spaced apart at a predetermined angle; b) a replaceable bobbin for
holding at least one wound coil of cutting line; c) a circular
bottom plate, said bobbin being disposed between said top plate and
said bottom plate; and d) means for interlocking said top plate
with said bobbin so that said bobbin rotates with said top
plate.
18. The line feeder according to claim 17, wherein said bottom
plate is threadably attached to said top plate.
19. The line feeder according to claim 17, wherein: a) said top
plate further comprises a bolt extending from the plate for
attachment to a driveshaft, and a cylindrical barrel depending from
the plate, the barrel having a bottom face with a cylindrical
cavity defined therein, the cavity having an annular groove defined
therein; b) the bottom plate further comprises a knob depending
therefrom and a cylindrical button housing extending through the
knob and above a top face of the bottom plate, the button housing
having a plurality of holes defined therein; and wherein said line
feeder further comprises: c) a cylindrical button slidably disposed
in the button housing, the button having a head and having an
annular groove defined about its circumference; d) a bias spring
disposed between said button and the button housing, the spring
biasing the button head below said knob; and e) a plurality of
detent balls disposed between said button and said button housing,
said balls partially extending through said holes and lodging in
the annular groove defined in the cavity defined in the barrel of
said top plate to secure the bottom plate to the top plate when
said button is biased downward, and said balls partly retracting
into the annular groove defined in said button so that said balls
do not extend through said holes when said button is pushed against
said bias spring in order to permit said bottom plate and said top
plate to separate for removal of said bobbin.
20. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/148,321, filed Aug. 11, 1999.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to cutting line feeders for
weed and grass trimmers. More specifically, the invention is a
cutting line feeder wherein pulling an actuation lever while
operating the weed trimmer moves corresponding flanges on the spool
and spool housing into and out of alignment, so that the difference
in centrifugal force and angular velocity feeds additional cutting
line.
[0004] 2. Description of Related Art
[0005] Weed and grass trimmers having a cutting wire spinning in a
horizontal plane are commonly used to trim grass in locations where
a lawnmower cannot reach or would be inconvenient. The cutting
wires used with such weed trimmers are designed to minimize injury
in the event a spinning wire comes in contact with a person. Such
cutting wires frequently break and/or wear during use,
necessitating a means for feeding additional wire.
[0006] Several inventors have proposed various means for feeding
additional wire as the weed trimmer is in operation, thereby saving
time. A common proposal has been a cutting head having a spool and
housing which rotate incrementally with respect to each other when
the ground is struck with the cutting head. However, this solution
risks damaging the weed trimmer. No one within the knowledge of the
present inventor has proposed a feed mechanism actuated by a lever
near the handle of the weed trimmer, actuating either a cable or
solenoid mechanism for causing a difference in centrifugal force
and angular velocity between the spool and spool housing, thereby
feeding additional wire.
[0007] U.S. Pat. No. 4,118,864, issued to Charles B. Pittinger, Sr.
et al. on Oct. 10, 1978, describes an incremental feed means for a
weed trimmer. The trimmer includes a worm pinion mounted coaxially
on top of a hollow shaft, and a plurality of spools mounted on
horizontal axes, with the spools having gears engaging the worm
pinion. A friction bar is positioned so that it can engage the
upper portion of the worm pinion. The wire passes from the spools,
between the worm pinion and hollow shaft, and down the hollow
shaft, with the friction between the pinion and hollow shaft
securing the wire in place. Engaging the worm pinion with the
friction bar prevents it from turning with the rest of the
assembly, causing it to rise, releasing the wire, so that
centrifugal force pulls additional wire out. When the worm gear
reaches a height wherein the friction bar is adjacent to a reduced
diameter portion, the friction bar can no longer engage the work
gear, so it falls back into place and continues to rotate, stopping
the dispensing of wire.
[0008] U.S. Pat. No. 4,136,446, issued to Dwight E. Tripp on Jan.
30, 1979, describes a vegetation cutter having a mechanical line
feed. A button on the handle is depressed, pushing a brake plate
against a control ring, which is in turn pressed against a brake
plate. The control ring is thereby angularly displaced. The control
ring is linked to a ratchet engaging the spool. The ratchet moves
from a first position to a second position, allowing the spool to
rotate incrementally, dispensing a measured amount of additional
wire.
[0009] U.S. Pat. No. 4,211,004, issued to Donald M. Woods on Jul.
8, 1980, describes a weed cutter with a mechanical line feed. The
spool includes a gear having a Maltese cross configuration. The
actuator is a round member having a shoulder portion with two
opposing convex surfaces and two opposing concave surfaces. A pair
of opposing pins are outside the actuator. The convex portion
engages the Maltese cross to prevent movement of the spool.
Rotation of the actuator brings the concave portion adjacent to the
Maltese cross, allowing space for movement, while simultaneously
bringing a pin within a slot on the Maltese cross, rotating the
spool.
[0010] U.S. Pat. No. 4,265,019, issued to Lauren G. Kilmer on May
5, 1981, describes a vegetation trimmer having a filament which
twists and untwists as it moves within a horizontal plane, thereby
presenting changing cutting surfaces to the vegetation, resulting
in even wear.
[0011] U.S. Pat. No. 4,285,128, issued to John W. Schnell et al. on
Aug. 25, 1981, describes a spool feed mechanism for a grass
trimmer. The spool has a ratchet wheel on each end, with the teeth
offset from each other. A U-shaped member alternately engages and
disengages the ratchet wheels, allowing the centrifugal force of
the spinning end of the wire to pull additional measured increments
of wire from the spool.
[0012] U.S. Pat. No. 4,633,588, issued to Charles B. Pittinger,
Jr., on Jan. 6, 1987, describes a bump-feed filament vegetation
trimmer. Several methods of feeding the filament are described. In
some embodiments, a spool and housing spin together, with the
housing having a series of upper and lower internal flanges
corresponding to a series of flanges on the spool. In one
embodiment, bumping the spool on the ground drives the spool from
the lower to the upper flanges, with the friction slowing the
rotation of the spool, so that the spool and housing rotate with
respect to each other until the spool engages the upper flanges.
Removing the spool from contact with the ground allows a spring to
push the spool back towards the lower flanges, causing another
increment of rotation. Another embodiment includes a fork for
pushing the housing towards the spool, again causing the upper and
lower flanges to sequentially engage the spool, allowing an
increment of wire to be dispensed. In a third embodiment, the
driveshaft includes a plunger having a large diameter portion and
smaller diameter portion pushes a pair of balls against the spool,
so that the driveshaft thereby engages the spool. Upward pressure
on the plunger causes the reduced diameter portion to move adjacent
to the balls, thereby momentarily disengaging the spool and
driveshaft.
[0013] U.S. Pat. No. 5,109,607, issued to Robert G. Everts on May
5, 1992, describes an automatic line trimmer head. An indexer cam
on top of the spool includes a plurality of ramps along its outer
edge, and a plurality of voids on its top surface. The ramps engage
a plurality of followers on the inner surface of the housing. When
sufficient wire is in use, the centrifugal force of the wire drives
the indexer cam against the followers, causing it to move upwards
where the voids engage a plurality of stop blocks. When the
centrifugal force decreases due to wire breaking away, the indexer
cam and spool travel downward within the housing, disengaging the
indexer cam from the stop blocks, and allowing more wire to be
dispensed.
[0014] U.S. Pat. No. 5,566,455, issued to Leonard Hagstrom on Oct.
22, 1996, describes a rotary filament vegetation trimmer with an
air cooled filament. The head is shaped to form a centrifugal air
pump, which rapidly increases the volume available for the air to
provide refrigeration. The refrigerated air is directed towards
bends in the wire, where the wire is most likely to fail.
[0015] U.S. Pat. No. 5,659,960, issued to Robert G. Everts et al.
on Aug. 26, 1997, describes a line trimmer head having a ratchet to
prevent spool rotation in the wrong direction during winding of
wire around the spool.
[0016] U.S. Pat. No. 5,743,019, issued to Robert C. Berfield on
Apr. 28, 1998, describes a line feed for a rotary wire trimmer. The
line is wound around a large diameter spool, then a smaller
diameter spool, then extends outward to form a cutting surface.
When the end breaks off, centrifugal force causes additional wire
to extend outward until equilibrium is reached.
[0017] U.S. Pat. No. 5,768,786, issued to Steven F. Kane et al. on
Jun. 23, 1998, describes a brush cutting device having a handle
which, when released, causes a brake to stop the rotation of the
cutter and a cover to completely enclose the cutter.
[0018] German Pat. No. 2,832,649, published on Feb. 1, 1979,
describes a mowing device having a wire which is fed by centrifugal
force.
[0019] International Pat. App. No. WO 81/03106, published on Nov.
12, 1981, describes a vegetation cutter using an eccentric pivot to
extend cutting line by centrifugal force as the cutting line
shortens.
[0020] None of the above inventions and patents, taken either
singly or in combination, is seen to describe the instant invention
as claimed.
SUMMARY OF THE INVENTION
[0021] The invention is a weed and grass trimmer having a line
feeder actuated by a control adjacent to the handle, and which is
operated during use of the grass trimmer. Although there are
several different embodiments of the line feed mechanism, the basic
structure includes a weed trimmer head having a spool for cutting
line and a housing. The spool has a series of external flanges, and
the housing has upper and lower groups of internal flanges
corresponding to the external flanges of the spool. The upper
flanges are offset from the lower flanges so that each upper flange
is centered between two lower flanges. The spool is attached to the
weed trimmer's drive shaft, while the housing spins freely.
[0022] The spool typically engages the lower flanges of the
housing. When it is necessary to extend additional cutting line,
the housing and spool are brought together, either by raising the
spool or lowering the housing, so that the spool engages the upper
flanges of the housing. The result is a brief difference in
centrifugal force and angular velocity between the spool and the
housing, and the housing will rotate until the offset upper flanges
engage the spool's flanges, thereby dispensing a first small
increment of cutting line. The housing and spool are then allowed
to return to their normal positioning. As the spool moves from the
upper to the lower flanges of the housing, there is once again a
brief period of time wherein there is a difference between the
centrifugal force and angular velocity of the spool and housing.
The spool and housing once again rotate relative to each other
until the housing's lower flanges again engage the spool's flanges,
thereby dispensing a second increment of wire.
[0023] There are different methods of causing the spool and housing
to move relative to each other, depending on whether the weed
trimmer is a cable drive, curved boom gasoline powered type,
driveshaft driven, straight boom gasoline powered type, or
electrically powered. The basic apparatus for moving the housing
and spool relative to each other may be either a lever-actuated
cable, or a solenoid, either of which may be interchanged with the
other.
[0024] One preferred embodiment, which may be used with any type of
weed trimmer regardless of drive type or motor type, uses a fork to
push the housing down towards the spool when additional line must
be extended. The fork is operated by a cable extending along the
weed trimmer's boom, connecting at its upper end to a lever near
the handle. The lever is pivotally attached to the boom, and the
cable is attached to the lever near its upper end, so that
squeezing the lever towards the boom pushes the housing towards the
spool.
[0025] Alternatively, a weed trimmer having a straight boom and
drive shaft may utilize a line feed mechanism wherein the spool is
pulled upward towards the housing. Typically, the housing will be
rotatably connected to the driveshaft, with the spool rotating
freely. A shaft passing through the hollow driveshaft connects to
the bottom end of the spool, with the upper end of the shaft having
a bearing abutting a lever. A cable extends from the lever to a
hand lever adjacent to the handle, The hand lever is pivotally
mounted near its base, and the cable is attached to the hand lever
well away from the boom, so that squeezing the hand lever will pull
the cable. The cable in turn operates the lever, raising the shaft
and spool, causing the spool to sequentially engage the upper and
lower flanges within the housing. The spool thereby rotates with
respect to the housing, dispensing two small increments of cutting
line.
[0026] In either of the above embodiments, a solenoid may be used
instead of a cable to actuate the line feed mechanism. The
solenoid's reciprocating member takes the place of the fork,
becoming the plunger which pushes the housing towards the spool, or
which actuates the lever raising the spool towards the housing. A
normally open push button is located adjacent to the handle for
controlling electricity flow to the solenoid. Electrical power is
supplied either by the weed trimmer's electric motor, or by the
electrical system of the gasoline engine. Pushing the button allows
electricity to flow to the solenoid's electromagnet, drawing the
plunger into the magnet, pushing on either the housing or the lever
actuating the spool. Releasing the button cuts off the flow of
electricity, thereby allowing the spool and housing to return to
their normal position.
[0027] The weed trimmer may use an interchangeable, universal
bobbin to hold the cutting line, forming part of the spool.
Preferably, the permanent portion of the spool will include a plate
having circumferential flanges, and will engage the bobbin with
corresponding teeth, so that the bobbin and flange plate spin
together.
[0028] Also, parts that otherwise would be exposed to the elements
are covered by a brush shield and a dust and dirt shield or cover
so as to assure uninterrupted operation of the invention in the
dust and/or dirt and brush environment of use of the invention.
[0029] In use, the user merely uses the weed trimmer in the
conventional manner until additional cutting line must be
dispensed. The user may then dispense the required additional
cutting line without stopping the weed trimmer, or even stopping
the trimming operation. Merely squeezing the lever or pushing the
button pushes the housing towards the spool, or pulls the spool
towards the housing. The spool disengages from the housing's lower
flanges, rotates a small increment with respect to the housing,
dispensing a first small increment of cutting line, and engages the
upper flanges in the housing. Releasing the button or lever allows
the housing to raise, or the spool to lower, so that the spool
disengages from the housing's upper flanges, rotates a small
increment relative to the housing, thereby dispensing a second
small increment of cutting line, until engaging the lower flanges
of the housing.
[0030] Several embodiments of the line feed mechanism may be
installed on existing weed trimmers without substantial difficulty.
The cutting head of an existing weed trimmer can be replaced with
one having the appropriate spool and housing. The fork or solenoid
to push the housing towards the spool may be attached to the
outside of the cutting head. The cable, electrical wiring, and
actuating handle or button may be attached to the outside of the
boom.
[0031] Accordingly, it is a principal object of the invention to
provide a cutting line feed mechanism for a weed trimmer which may
be operated from the weed trimmer's handle without stopping the
cutting operation.
[0032] It is another object of the invention to provide a cutting
line feed mechanism for a weed trimmer which may be added to
existing weed trimmers with minimal difficulty.
[0033] It is a further object of the invention to provide a cutting
line feed mechanism for a weed trimmer which avoids the necessity
of striking the ground with the weed trimmer to feed additional
line, thereby preventing damage to the weed trimmer.
[0034] It is still another object of the invention to provide a
cutting line feed mechanism for a weed trimmer with protective
cover or shield elements to protect parts from the dust and
debris-laden environment common to the area of use of the
invention.
[0035] It is an object of the invention to provide improved
elements and arrangements thereof in an apparatus for the purposes
described which is inexpensive, dependable and fully effective in
accomplishing its intended purposes.
[0036] These and other objects of the present invention will become
readily apparent upon further review of the following specification
and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is an environmental, perspective view of a weed and
grass trimmer using a line feeder according to the present
invention.
[0038] FIG. 2 is a perspective view of the trimming head of a weed
and grass trimmer using a line feeder according to the present
invention.
[0039] FIG. 3 is an exploded perspective view of the trimming head
of weed and grass trimmer using a line feeder according to the
present invention.
[0040] FIG. 3A is a side elevational view, partly in section,
showing the components illustrated in FIG. 3, in assembly, and also
with a skirted brush guard in place, shown in ghost line.
[0041] FIG. 3B is a perspective view of the rigid, biodegradable,
disposable refill bobbin cutting line spool of the invention.
[0042] FIG. 3C is an exploded section view of another embodiment of
the trimming head of a weed and grass trimmer according to the
present invention with the spool bottom plate retained by a detent
mechanism.
[0043] FIG. 3D is an exploded perspective view of another
embodiment of the trimming head of a weed and grass trimmer
according to the present invention with the spool bottom plate
retained by interlocking tabs.
[0044] FIG. 4 is a cross sectional view of the trimming head of a
weed and grass trimmer using a line feeder according to the present
invention, showing the spool housing in its upper position.
[0045] FIG. 5 is a cross sectional view of the trimming head of a
weed and grass trimmer using a line feeder according to the present
invention, showing the spool housing in its lower position.
[0046] FIG. 6 is an exploded perspective view of the trimming head
of a weed and grass trimmer using a line feeder according to the
present invention.
[0047] FIG. 7 is a cross sectional view of the trimming head of a
weed and grass trimmer using a line feeder according to the present
invention, showing the spool housing in its upper position.
[0048] FIG. 8 is a cross sectional view of the trimming head of a
weed and grass trimmer using a line feeder according to the present
invention, showing the spool housing in its lower position.
[0049] FIG. 9 is an environmental, perspective view of a weed and
grass trimmer using a line feeder according to the present
invention.
[0050] FIG. 10 is a perspective view of the trimming head of a weed
and grass trimmer using a line feeder according to the present
invention.
[0051] FIG. 11 is an exploded, partially cutaway, perspective view
of the trimming head of a weed and grass trimmer using a line
feeder according to the present invention.
[0052] FIG. 12 is a partially sectional side view of the trimming
head of a weed and grass trimmer using a line feeder according to
the present invention, with the spool in the lower position.
[0053] FIG. 12A is a fragmentary side view of FIG. 12, showing
components covered with a protective dust cover.
[0054] FIG. 13 is a partially sectional side view of the trimming
head of a weed and grass trimmer using a line feeder according to
the present invention, with the spool in the upper position.
[0055] FIG. 14 is a cross sectional side view of the trimming head
of a weed and grass trimmer using a line feeder according to the
present invention, with the housing in the upper position.
[0056] FIG. 15 is a cross sectional side view of the trimming head
of a weed and grass trimmer using a line feeder according to the
present invention, with the housing in the lower position.
[0057] FIG. 16 is an elevational view of a wheeled weed and grass
trimmer with a weed and grass trimmer line feeder according to the
present invention.
[0058] FIG. 17 is a front view of a wheeled weed and grass trimmer
configured as an edger and equipped with a weed and grass trimmer
line feeder according to the present invention.
[0059] FIG. 18 is a section view of a cutting head with a
mechanical line feed for a wheeled weed and grass trimmer according
to the present invention with the spool lowered.
[0060] FIG. 19 is a section view of a cutting head with a
mechanical line feed for a wheeled weed and grass trimmer according
to the present invention with the spool raised.
[0061] FIG. 20 is a section view of a cutting head with an
electrical line feed for a wheeled weed and grass trimmer according
to the present invention.
[0062] FIG. 21 is an exploded, detail view of a driveshaft assembly
for a cutting head of a wheeled gas powered weed and grass trimmer
according to the present invention.
[0063] Similar reference characters denote corresponding features
consistently throughout the attached drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0064] The present invention is a cutting line feed mechanism for a
weed and grass trimmer. Although the general construction and
operation of a weed trimmer is well known, it will be described
herein to the extent necessary for an understanding of the cutting
line feed mechanism of the present invention. Referring to FIGS. 1
and 9, the weed trimmer 10 includes a boom 12 having a handle 14 at
one end and a cutting head 16 at the other end. A motor 18 is also
included on the weed trimmer 10, and may be of the gasoline powered
or electrically powered type. A gasoline powered motor 18 will
typically be located on the boom 12 opposite the cutting head, and
will be connected to the cutting head's driveshaft 40 by either a
cable drive (not shown, and commonly used with curved boom weed
trimmers), or a second driveshaft 62 and gear system 64 (FIG. 11).
A guard 20 is located above the cutting head 16.
[0065] A preferred cutting head 16 is illustrated in FIGS. 2-5,
with a very similar cutting head 16 illustrated in FIGS. 2, and
6-8. Either cutting head described herein and illustrated in the
above named figures may be used with any gasoline or electric
powered weed cutter. The basic operation of both cutting heads 16
is described below. The cutting head 16 includes a spool 22 for
holding the cutting wire 24, and a housing 26 covering the top and
sides of the spool 22. The housing includes at least one, and
preferably two, holes 27 through which the cutting wire 24 passes.
The spool includes a plate 28 having outwardly extending flanges 30
around its circumference. The housing has one upper and one lower
set of flanges 32,34, respectively, with each set of flanges 32,34
corresponding to the flanges 30 of the spool. The lower flanges 34
are offset from the upper flanges 32, so that each lower flange 34
is centered between two upper flanges 32. The angular separation of
the lower flanges 34 is equal to the angular separation of the
upper flanges. The bottom plate 36 of the spool 22 includes a
threaded rod 38. A driveshaft 40 passes through the housing 26 and
spool 22, mating with the threaded rod 38. A spring 42 fits between
the spool 22 and housing 26, surrounding the driveshaft 40, biasing
the spool 22 and housing 26 apart so that the flanges 30 of the
spool 22 engage the lower flanges 34 of the housing 26. Also, the
internal female center tube element depending from plate 28 is
internally threaded so as to engage the matingly threaded, male
element upstanding on bottom plate 36, thus to hold the bobbin and
related parts in assembly as will be further explained below.
[0066] The cutting head 16 must include some means for causing the
spool's flanges 30 to selectively engage either the upper 32 or
lower 34 flanges of the housing 26. A bearing 44 extends above the
top of the housing 26, surrounding the driveshaft 40. The housing
is freely rotatable about the bearing 44 and driveshaft 40. It is
suggested that an adaptor 45 be utilized with the bearing, with
cylindrical portion 47 within the bearing 44, and hexagonal portion
49 within the top of the housing 26. A fork 46 is pivotally
attached to the boom 12, so that the fork's prongs 48 lie on either
side of driveshaft 40, abutting the bearing 44. The stem 50,
located opposite the fork's pivot 52, is connected at one end to a
cable 54. The opposite end of cable 54 is connected to hand lever
56, located adjacent to handle 14. Hand lever 56 is pivotally
mounted on the boom 12, with the pivot 58 in close proximity to the
boom 12 and the cable 54 connected farther from the boom 12. A
finger engaging portion 60 extends upward from the cable 54.
Squeezing the finger engaging portion 60 thereby pulls cable 54
upward, thereby pulling stem 50 upward and pushing prongs 48
downward on bearing 44. Housing 26 is thereby pushed towards spool
22, disengaging the spool's flanges 30 from the housing's lower
flanges 34, and causing the spool's flanges 30 to engage the
housing's upper flanges 32. During the interval in which the
spool's flanges 30 are transitioning from the lower flanges 34 to
the upper flanges 32, a first increment of cutting line 24 is fed
from the spool 22 due to rotation of the spool 22 by the driveshaft
40, the housing 26 being fixed by the prongs 48. Releasing the
finger engaging portion 60 allows the spring 42 to bias the housing
26 away from the spool 22, thereby allowing the spool's flanges 30
to engage the housing's lower flanges 34, the spool 22 feeding an
additional increment of cutting line 24 during the transition.
[0067] The cutting head 16 illustrated in FIGS. 3-5 has the
particular advantage of a spool 22 having a universal
interchangeable bobbin 66 for holding the cutting line 24. As best
seen in FIG. 3B, The bobbin 66 includes two series of teeth 68, one
of which is mated with a corresponding set of teeth 70 on the plate
28, so that the bobbin 66, plate 28, and bottom plate 36 which form
the spool 22 will rotate as a unit. Bobbin 66 is universal in that
it can be turned over and have the other series of teeth 68
matingly engage the teeth 70. Alternatively, the bobbin 66 may be
interlocked with the bottom plate 36 by a plurality of teeth (not
shown) on the bottom plate 36 which interlock with teeth 68 on the
bobbin 66. Further, although teeth 68 and 70 are shown in sawtooth
form in the drawings, the teeth 68 and 70 may be square,
rectangular, or any other form, provided that the teeth 68 and 70
interlock the bobbin 66 for rotation with the plate 28. Driveshaft
locking fork 74, pivotally connected to guard 20, engages the
hexagonal portion 75 of driveshaft 40 to prevent the driveshaft 40
from rotating while changing bobbins 66. Lock ring 72 is fastened
onto driveshaft 40 between the plate 28 and bobbin 66. When the
driveshaft locking fork 74 engages the driveshaft 40, the bottom
plate 36 may be unscrewed so that bobbin 66 can easily be removed
and replaced. Plate 28 and housing 26 are retained on driveshaft 40
by the lock ring 72.
[0068] With particular reference to FIG. 3A, it will be appreciated
that the upper left portion of the view indicates a brush guard in
ghost lines which may be latched in place, e.g., by a shaft adaptor
locking component. The brush guard protects all the lower
components and greatly aids in preventing tall grass, weeds and
other debris from winding about and jamming the head assembly, an
all too common problem with current grass trimmers.
[0069] With further specific reference to FIG. 3A, attention is
drawn to the lower part of the view and the following discussion.
The plate 36 has a center hole 35 with a square or hexagonal
configuration to match and mate with the corresponding square or
hexagonal configuration of the shank 35A of bolt 38. Thus, bolt 38
is free to move up and down in plate 36 but is rotatably slaved to
the plate so that both elements are rotated together. A ribbed knob
41 is provided on bolt 38. A spring 43 surrounds the unthreaded
shank 35A and is inserted in a shouldered hole 136 provided in
plate 36; the spring 43 biases the ribbed knob 41 and bolt 38 away
from the bottom of plate 36 so the spool 22 can be assembled. A
locking ring 72 attached to the upper portion of the unthreaded
shank 35A holds the bolt 38 in place. Thus, the bolt 38 can be
pressed in or upwardly, and turned in the tighten direction, to
attach the spool 22 to the drive shaft 40, to turn as a unit.
[0070] Similarly, the spool 22 in FIGS. 6-8 may be removed for
winding additional wire 24. After locking fork 74 is positioned
around the hexagonal portion 75 of driveshaft 40, threaded bolt 38
can be removed from driveshaft 40, allowing for the removal of
spool 22 and spring 42. The locking ring 72, fitting between the
spring 42 and housing 26 along driveshaft 40 prevents removal of
the housing 26 from the driveshaft 40, facilitating reassembly and
preventing unnecessary risk of losing parts. Once sufficient
additional wire 24 is wound around spool 22, the spring 42, spool
22, and bolt 38 are reinstalled on the driveshaft 40.
[0071] FIGS. 3C and 3D illustrate two additional methods for
attaching the spool 22 to the cutting head 16 which may have the
advantage of making it easier to detach the spool 22 in order to
replace the cutting line 24. FIG. 3C shows an embodiment in which
the bottom plate 36 is secured to the top plate 28 of the spool 22
by a detent mechanism. The body of the top plate 28 consists of a
circular plate 28a from which a cylindrical barrel 28b depends. The
top plate 28 has a threaded bolt 200 extending upward from the
plate 28, the head of the bolt 200 being molded into the body of
the plate 28. The bolt 200 is used to secure the top plate 28 to an
internally threaded aperture in the driveshaft 40, so that the top
plate 28 rotates with the driveshaft 40. The bottom face of the
barrel 28b has a cylindrical cavity 202 defined therein, the cavity
202 having an annular groove 204 disposed therein. The bobbin 66 is
inserted on the cylindrical barrel 28b.
[0072] The bottom plate 36 has a body composed of a flat circular
plate 36a of the same diameter as the top plate 28a, a knob 206
depending from the bottom face of the bottom plate 36a, and a
hollow, cylindrical button housing 36b extending through the center
of the knob and above the top face of the plate 36a. A spring 208
is attached to, and depends from, the top wall of the button
housing 36b. A cylindrical button 210 is slidably disposed in the
bottom housing 36b, the button 210 having a well 212 defined
therein for receiving spring 208 which biases button 210 downward
so that the head 210a of the button 210 protrudes through a hole in
the button housing 36b, the button 210 being retained in the
housing 36b by an annular shoulder 210b which abuts an annular
flange on the button housing 36b.
[0073] The button 210 has an annular groove 214 defined about its
circumference. At least two detent balls 216 are disposed between
the button 210 and button housing 36b, button housing 36b having at
least two holes 218 defined therein having a diameter slightly
smaller than the diameter of detent balls 216 so that detent balls
216 partially protrude through holes 218 when spring 208 biases
button 210 downward. Button housing 36b has an outside diameter
slightly smaller than the inside diameter of cavity 202. When
button 210 is pressed upward, spring 208 compresses and detent
balls 216 fall backward to partially lodge in groove 214, the outer
surface of the balls 216 being planar with the outer surface of
button housing 36b so that balls 210 are retained at the height of
holes 218. Button housing 36b may be inserted into cavity 202 so
that when button 210 is released, detent balls 216 protrude through
holes 218 and lodge in groove 204 to retain bottom plate 36 on top
plate 28, clamping bobbin 66 therebetween. Cutting line 24 may be
replaced by pressing button 210 upward and pulling knob 206 to
remove bottom plate 36. This construction has the advantage of
eliminating the need for locking fork 74. Cover 130, described
below, should be used with this embodiment to prevent accidental
triggering of button 210.
[0074] FIG. 3D shows an embodiment in which the bottom plate 36 of
the spool 22 is secured to the top plate 28 by a plurality of
interlocking tabs. In this embodiment, the top plate 28 again has a
flat, circular plate 28a with a cylindrical barrel 28b depending
therefrom. The barrel 28b is hollow and has a plurality of grooves
219, which may be, e.g., U-shaped, defined therein. The bottom
plate 36 has a body composed of a flat, circular plate 36a
substantially equal in diameter to the top plate 28a, a knob 206 on
the bottom face of the plate 36a, and a cylindrical post 220
arising from its upper face. The tabs 222 protrude from the wall of
the cylindrical post 220, and may be, e.g., dog-leg in shape. The
diameter of the post 220 is slightly smaller than the inside
diameter of the barrel 28b so that the post 220 may be inserted
into the barrel 28b, the tabs 222 sliding into a first section of
the grooves 219, then rotated through a second section of the
groove 219 until the descending leg of the tabs 222 slides down
into a third section of the groove 219 to lock the bottom plate 36
to the top plate 28 with the bobbin 66 clamped therebetween. A
spring (not shown) may be disposed in the hollow barrel 28b to bias
the bottom plate downward. In this embodiment, the cutting line 24
may be replaced by simply twisting the knob 206 to unlock the
bottom plate 36 from the spool 22. Advantageously, this embodiment
does not require use of the cover 130 to prevent accidental release
of the spool 22 from the cutting head 16.
[0075] Referring back to FIGS. 4-5, the optional cutting head cover
130 is illustrated. Cover 130 fits over the bottom portion of
housing 26, protecting the inside of housing 26 and the spool 22
from debris. Additionally, cover 130 allows cutting head 16 to be
rested on the ground during use. The cutting heads of conventional
weed trimmers must be continuously held above the ground, except
when bump feeding additional cutting wire. The cover 130 of the
present invention permits a user to momentarily rest the cutting
head 16 on the ground without interference with the cutting
operation. This advantage can be particularly helpful for
handicapped users or for users with unusually low strength.
[0076] It will be realized that in each of the embodiments shown in
FIGS. 2-8 the housing is rotatably disposed about the driveshaft 40
and/or bearing 44, rotating motion being imparted to the bearing
when the flanges 30 on the spool 22 engage either the upper 32 or
lower 34 flanges in the housing 26. In each embodiment the spool 22
is coupled to the driveshaft 40 so that the spool 22 rotates with
the driveshaft 40, cutting line being fed by pressing the housing
26 down on the spool 22. The differences in the embodiments arise
from whether the spool 22 has universal bobbin 66, from whether the
top plate 28 of the bottom plate 36 is attached to the driveshaft
40, and from the manner of removing the spool 22 to replace cutting
line 24.
[0077] FIGS. 14-15 illustrate a line feed mechanism very similar to
that of the above described FIGS. 2-8, with the difference being
the use of a solenoid 76 to actuate the line feed mechanism. For
purposes of illustration, the line feed mechanism is illustrated as
part of a weed trimmer 10 having an electric motor 18, although the
solenoid 76 is equally workable with any gasoline powered weed
trimmer 10, in exactly the same manner as described herein. The
cutting head 16 includes a spool 22 for holding the cutting wire
24, and a housing 26 covering the top and sides of the spool 22.
The housing includes at least one, and preferably two, holes 27
through which the cutting wire 24 passes. The spool includes a
plate 28 having outwardly extending flanges 30 around its
circumference. The housing has one upper and one lower set of
flanges 32,34, respectively, with each set of flanges 32,34
corresponding to the flanges 30 of the spool. The lower flanges 34
are offset from the upper flanges 32, so that each lower flange 34
is centered between two upper flanges 32. The bottom of the spool
22 includes a threaded bolt 37. A driveshaft 40 passes through the
housing 26 and spool 22, mating with the threaded bolt 37. A spring
42 fits between the spool 22 and housing 26, surrounding the
driveshaft 40, biasing the spool 22 and housing 26 apart so that
the flanges 30 of the spool 22 engage the lower flanges 34 of the
housing 26.
[0078] The cutting head 16 must include some means for causing the
spool's flanges 30 to selectively engage either the upper 32 or
lower 34 flanges of the housing 26. A bearing 44 fits on top of the
housing 26, surrounding the driveshaft 40, and preferably has a
bearing cap 78 directly on top of it. Solenoid 76 is located
directly above bearing cap 78 and also preferably surrounds the
driveshaft 40. Solenoid 76 includes an electromagnet 80,
surrounding a plunger 82. The plunger 82 has a ferrous portion 84
on top of a nonferrous portion 86, with the nonferrous portion 86
resting on top of the bearing cap 78. An electrical wire 88 extends
from the electromagnet 80 to the electric motor 18 (or to the
electrical system of a gasoline motor, which is not shown but would
be within the ability of one skilled in the art), thereby supplying
power to the electromagnet. A normally open button 90 is mounted on
the boom 12, in close proximity to the handle 14. As would be well
known to one skilled in the art, a complete electrical circuit will
be wired (not shown) between the motor 18 (power supply), the
button 90, and the electromagnet 80. Pushing the button 90 thereby
activates the electromagnet 80, pulling the ferrous portion 84
within the electromagnet 80, and pushing down on the nonferrous
portion 86, bearing cap 78, and bearing 44. Housing 26 is thereby
pushed towards spool 22, disengaging the spool's flanges 30 from
the housing's lower flanges 34, and causing the spool's flanges 30
to engage the housing's upper flanges 32. Releasing the button 90
deactivates the electromagnet 80, allowing the spring 42 to bias
the housing 26 away from the spool 22, thereby allowing the spool's
flanges 30 to engage the housing's lower flanges 34.
[0079] The electrically powered/solenoid actuated weed trimmer 10
of FIGS. 14-15 is illustrated having a spindle 22 without a
replaceable bobbin 66, but those skilled in the art, upon reading
the above description, will realize that a spindle having the
replaceable bobbin 66 could be easily used. Replacement of the wire
24 is accomplished in a manner similar to that described above.
First, the driveshaft 40 must be prevented from rotating to
facilitate removal of bolt 37. This is preferably accomplished by
using a pin 114 fitting within a hole 116 in the driveshaft 40. Pin
114 is normally biased outward by spring 120, and must be held
within the hole 116 during removal of the bolt 37. Next, spool 22
and spring 42 may be removed from driveshaft 40. Once sufficient
additional wire 24 is wound around spool 22, the spring 42, spool
22, and bolt 38 are reinstalled on the driveshaft 40.
[0080] An additional embodiment of a weed trimmer 10 using the line
feed mechanism of the present invention is illustrated in FIGS.
9-13. This line feed mechanism is particularly suited to gasoline
powered, straight boom, gear driven weed trimmers 10. The cutting
head 16 includes a spool 22 for holding the cutting wire 24, and a
housing 26 covering the top and sides of the spool 22. The housing
includes at least one, and preferably two, holes 27 through which
the cutting wire 24 passes. The spool includes a plate 28 having
outwardly extending flanges 30 around its circumference. The
housing has one upper and one lower set of flanges 32,34,
respectively, with each set of flanges 32,34 corresponding to the
flanges 30 of the spool. The lower flanges 34 are offset from the
upper flanges 32, so that each lower flange 34 is centered between
two upper flanges 32. The bottom of the spool 22 includes a cap 39
having a threaded rod 38. The cutting head 16 must include some
means for causing the spool's flanges 30 to selectively engage
either the upper 32 or lower 34 flanges of the housing 26.
Therefore, internal shaft 91 passes through the housing 26 and
spool 22, mating with the threaded rod 38 and with the driveshaft
40. The internal shaft 91 includes an upper portion 92 and a lower
portion 94. The bottom of upper portion 92 includes a hexagonal
section 96 for preventing rotation relative to the housing 26, and
a hollow portion 98 having a slot 100. The hexagonal section 96 is
internally threaded at its upper end, and is dimensioned and
configured to mate with the external threads 126 of driveshaft 40,
so that inner shaft 91 and driveshaft 40 rotate as a single unit.
The lower portion is dimensioned and configured to fit within the
hollow portion 98, with pin 102 sliding within the slot 100. The
lower portion 94 can therefore reciprocate vertically with respect
to the upper portion 92, but can not rotate with respect to the
upper portion 92. A spring 42 fits between the spool 22 and housing
26, surrounding the inner shaft 91, biasing the spool 22 and
housing 26 apart so that the flanges 30 of the spool 22 engage the
lower flanges 34 of the housing 26.
[0081] The driveshaft 40 extends upward through housing 104, and
has a bearing 106 at its upper end. Bearing 106 rests on top of the
horizontal portion 110 of a lever 108, secured in place by nut 122
engaging the threaded upper portion 124 of internal shaft 91. The
vertical portion 112 of the lever 108 is connected at one end to a
cable 54. The opposite end of cable 54 is connected to hand lever
56, located adjacent to handle 14. Hand lever 56 is pivotally
mounted on the boom 12, with the pivot 58 in close proximity to the
boom 12 and the cable 54 connected farther from the boom 12. A
finger engaging portion 60 extends upward from the cable 54. During
use, the spool 22 and housing 26 are located as illustrated in FIG.
12, with the spool's flanges 30 engaging the housing's lower
flanges 34. Squeezing the finger engaging portion 60 pulls cable 54
upward, thereby pulling shaft upper portion 92 upward. Spool 22 is
thereby pulled upward towards housing 26, disengaging the spool's
flanges 30 from the housing's lower flanges 34, and causing the
spool's flanges 30 to engage the housing's upper flanges 32 (FIG.
13). Releasing the finger engaging portion 60 allows the spring 42
to bias the spool 22 away from the housing 26, thereby allowing the
spool's flanges 30 to engage the housing's lower flanges 34.
[0082] The weed trimmer 10 of FIGS. 9-13 is illustrated having a
spool 22 without a replaceable bobbin 66, but those skilled in the
art will, upon reading the above description, recognize that a
replaceable bobbin 66, as described above, could easily be used. To
replace the wire 24, the end cap 39 is first unscrewed from the
inner shaft 91. Spool 22 may then be removed, and the wire 24
replaced. Spool 22 may then be reinstalled on inner shaft 91, and
end cap 39 reattached to inner shaft 91.
[0083] FIG. 12A illustrates another important protective structure
of the instant invention, namely, a dust cover for components,
e.g., 106, 110 and 112 illustrated in FIG. 12. The dust cover may
be secured firmly in place, as by screws through the top of the
cover (not shown) and a cooperative locking lip and flange at the
lower front edge of the dust cover (not shown).
[0084] FIGS. 16-21 show how the teachings of the present invention
may be applied to a wheeled weed and grass trimmer. FIG. 16 shows a
wheeled weed and grass trimmer 300 being operated with the cutting
head 302 aligned parallel to the ground, while FIG. 17 shows the
trimmer 300 with the cutting head 302 configured normal to the
ground for use as an edger. The trimmer 300 has an elongated
U-shaped handle 304, with a handle lever 306 connected to a cable
308 mounted on the handle 304. The model shown is powered by a
gasoline engine 310 which rotates a driveshaft by a belt 312 and
pulley 314 arrangement, as is known in the art. The assembly is
mounted on wheels 316 for ease in operation.
[0085] FIGS. 18 and 19 show a typical configuration for a
mechanically actuated cutting line feed mechanism. The end of cable
308 is secured to the vertical arm 320 of pivotally mounted lever
318. The horizontal arm 322 of the lever 318 is mounted below
bearing 324. As shown in FIG. 21, bearing 324 is an annular ring
mounted on cylindrical internal shaft 326 and secured by nut 328
attached to threaded upper end 330 of the shaft 326. Pulley 314 is
mounted on splines at the upper end of hollow driveshaft 340 and
secured by nut 332 attached to threads on the driveshaft 340 above
the splines. Internal shaft 326 is inserted into the hollow
driveshaft 340 and is slidable inside the driveshaft 340. Internal
shaft 326 has an annular flange 327 disposed about its exterior
circumference. The horizontal arm 322 of lever 318 may be forked,
or it may be broad and have an elongated hole defined therein so
that it may be disposed about internal shaft 326 above annular
flange 327. When cable 308 is pulled by depressing hand lever 306,
horizontal arm 322 pivots upward and bears upon the lower surface
of bearing 324, raising internal shaft 326, as shown in FIG.
19.
[0086] The hollow driveshaft 340 extends through trimmer housing
104. The lower end of hollow driveshaft 340 is engaged with spool
housing 26, e.g., by providing driveshaft 340 with a hexagonal
adapter 342 which mates with a hexagonal opening in housing 26 so
that housing 26 rotates with driveshaft 340. Spool 22 is mounted on
the lower end on internal shaft 326 and secured by knob 344. Bias
spring 42 normally biases spool 22 downward, so that flanges 30 on
top plate 28 engage lower flanges 34 of the spool housing 22, as
shown in FIG. 18, the rotational movement of the housing 26
imparting rotational movement to the spool 22 through engagement of
the flanges. When hand lever 306 is pressed, lever 318 raises
internal shaft 326, and consequently spool 22, until the flanges 30
engage upper flanges 32, as shown in FIG. 19, a first increment of
cutting line 24 being dispensed during the transition by
centrifugal force. When the hand lever 306 is released, bias spring
42 is relaxed, pulling internal shaft 326 down until flanges 30
engage lower flanges 34, dispensing a second increment of cutting
line during the transition.
[0087] FIG. 20 shows a cutting head 302 for a solenoid activated
cutting head for a wheeled weed and grass trimmer 300. In this
configuration, an electrical switch (not shown) is mounted on the
handle 304 and is connected by wiring 350 to solenoid 352. The
solenoid plunger 354 is attached to the vertical arm 320 of lever
318. The remainder of the configuration is identical to that
described with reference to FIGS. 18, 19, and 21. In use, the
solenoid plunger 354 is normally extended during cutting operation,
so that the flanges 30 of spool 22 engage the lower flanges 34 of
housing 26. When the electrical switch is activated, plunger 354 is
withdrawn into the solenoid coil 352, causing lever 318 to pivot
and raise internal shaft 326, raising the spool 22 so that flanges
30 engage upper flanges 32, dispensing a first increment of cutting
line 24 during the transition. When the switch is released, plunger
354 extends, bias spring 42 pushing spool 22 downward so that
flanges 30 engage lower flanges 34, dispensing a second increment
of cutting line 24 during the transition.
[0088] It is to be understood that, within any embodiments, the
gasoline motor 18 and electric motor 18 are totally
interchangeable. Additionally, within any embodiments, the cable 54
and hand lever 56 may interchanged with the solenoid 76. Further,
any embodiment may include a spool 22 with or without a replaceable
bobbin 66. Lastly, the cover 130 may be used with any cutting head
16.
[0089] It is to be understood that the present invention is not
limited to the embodiments described above, but encompasses any and
all embodiments within the scope of the following claims.
* * * * *