 |
Description  |
|
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to sighting devices for use on a tractor to enable a
tractor driver to visually align the direction of movement of the tractor
with previously cut swaths or furrows in a field, and particularly to
sighting devices which are remotely adjustable by the driver while he is
seated in the driver's seat of the tractor.
2. Description of the Prior Art
A variety of sighting devices have been utilized for attachment to tractors
or farm implements towed by tractors to enable drivers seated in the
driver's seats of the tractors to visually align the tractors with
previously cut swaths or furrows dug into the ground by the towed farming
implements. The sighting devices must be adjusted so that the tractors are
oriented to pull the farming implements so that the farming implements cut
swaths or furrows which are adjacent to and perfectly aligned with
previously cut swaths or furrows when the sighting devices are in line
with points in straight lines between the eyes of the drivers and edges of
previously cut swaths or furrows. The state of the art for sighting
devices, especially those for use in conjunction with tractors and farm
implements, is believed to be accurately represented by U.S. Pat. Nos.
3,028,678; 2,827,704; 2,538,112; 2,559,761; 2,548,226; 3,932,028; and
4,034,480. None of the sighting devices disclosed in the above patents is
adjustable by a person seated in the driver's seat of a tractor.
Consequently, the sighting devices must be adjusted in a trial-and-error
manner wherein the tractor driver dismounts from the driver's seat,
adjusts the sighting device to an initial setting, remounts the tractor,
and drives the tractor for a distance to see if the swath or furrow being
cut by the towed farm implement is accurately aligned with the previously
cut swath or furrow. Since it is very important that the swath or furrow
cut by the towed implement be properly aligned with previously cut swaths
or furrows, the above mentioned trial-and-error adjustment method may
necessitate an unduly large number of trial settings before satisfactory
adjustment of any of the prior sighting devices is achieved.
Accordingly, it is an object of the invention to provide a sighting device
for use in conjunction with tractors towing agricultural implements, which
sighting device avoids the necessity of the driver dismounting from the
driver's seat in order to adjust the sighting device.
It is another object of the invention to provide a sighting device which
avoids the necessity of a second person adjusting the sighting device in
accordance with instructions from a driver seated in the driver's seat of
the tractor.
Some of the previous sighting devices are attached to the farm implement
being towed, rather than to the tractor. This approach to providing
sighting devices requires a separate sighting device for each farm
implement. Since the sighting devices are quite expensive, this approach
is undesirable.
Accordingly, another object of the invention is to provide an adjustable
sighting device which avoids the necessity of trial-and-error sighting
methods which require dismounting of the tractor driver or assistance of a
second person, which sighting devices are attached to a tractor rather
than to a farm implement.
Another object of the invention is to provide a sighting device for
attachment to a tractor, which sighting device is conveniently and
continuously adjustable by a person seated in the driver's seat of the
tractor.
Another object of the invention is to provide a low-cost sighting device
which is adjustable from the driver's seat of the tractor.
Another object of the invention is to provide a sighting device in
conjunction with tractors towing farm implements, which sighting device
overcomes the shortcomings of the sighting devices of the prior art.
Another object of the invention is to provide a sighting device which is
easily adjustable from the seat of a tractor and which maintains a correct
sighting despite obrupt jolting of the tractor as it moves over irregular
ground.
SUMMARY OF THE INVENTION
Briefly described, and in accordance with one embodiment thereof, the
invention provides a remotely adjustable sighting device for attachment to
an engine hood of a tractor to enable a driver seated in the driver's seat
of the tractor to visually align the direction of travel of the tractor so
that a towed farm implement cuts a swath or furrow in proper alignment
with previously cut swaths or furrows. In the described embodiment of the
invention, the sighting device includes two opposed telescoping extension
arms for extending outwardly through variable distances from a point of
the tractor on which the sighting apparatus is attached to the hood of the
tractor. Each telescoping extension arm includes a fixed outer tube and an
inner tube slidably disposed within the outer tube. A nut block is
attached to one end of the inner tube. A drive screw extends through the
nut block, and is turned by means of a drive mechanism remotely controlled
by the driver as he is seated in the seat of the tractor. Pivot arms, each
serving as a sighting blade, are pivotally attached to the outer ends of
the respective inner tubes. Each pivot arm is controlled by means of an
assembly including a drive screw connected by means of a clevis to a lower
end of a pivot arm, a nut block through which the drive screw extends, the
nut block being attached in fixed relationship to the inner tube on which
the pivot arm is attached, and a flexible drive cable driven by the drive
mechanism. The drive mechanism includes a DC motor, a pair of
electromagnetic clutches coupled, respectively, by means of pulleys and
drive belts to first and second rotating shafts. The first rotating shaft
is connected to the drive screws passing through the nut block attached to
the inner tubes, the second rotating shaft being attached to the flexible
cables. A tractor battery is controllably coupled to cause the DC motor to
operate in either the forward or reverse direction in response to each of
a first momentary switch and a second momentary switch actuated by the
seated driver. The battery is also controllably coupled to one or the
other of the electromagnetic clutches in response to the actuation of the
first and second momentary switches, respectively. A first and second
electromagnetic breaking devices are coupled to first and second ones of
the electromagnetic clutches, respectively, for preventing undesired
rotation of the first and second shafts, and are energized in response to
the first and second momentary switches, respectively, to disengage the
electromagnetic breaking devices when the first and second electromagnetic
clutches are respectively engaged. In use, the driver deploys the
momentary switches, while seated in the driver's seat, to extend the
extension arms and to pivot the pivot arms so that the driver sees the
pivot arms aligned along and parallel to the previously cut furrows. In
one embodiment of the invention, two bevel gear assemblies coupled by
means of two flexible cables to first and second hand cranks located
immediately adjacent to the driver's seat are utilized to rotate the first
and second shafts. The driver thus turns the first and second cranks to
adjust the extension arms and the pivot arms, respectively, while he is
seated in the driver's seat. In one embodiment of the invention, the
telescoping extension arms each comprise a rack gear which is moved
inwardly and outwardly from a housing by means of a pinion gear mounted
within the housing. The pinion gear is attached to one of the flexible
cables and is rotated by means of one of the cranks. The housing is
pivotally attached to the front of the tractor. A damping means is
attached to the housing, so that when the tractor undergoes tilting or
jolting as it moves over irregular ground, the housing pivots to maintain
its orientation despite the jolting of the tractor. Damping means are
provided to dampened oscillatory pivoting of the housing relative to the
tractor. In one embodiment of the invention, a heavy pendulum weight is
connected to and suspended beneath the housing to maintain the housing the
telescoping arms level. Friction surfaces contact the surface of the
pendulum weight to effect damping of movement of the pendulum weight as
the housing pivots.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of a tractor towing an implement, the sighting device
of the invention being mounted on the hood of the tractor and adjusted to
enable the tractor driver to align the tractor with a previously cut swath
or furrow.
FIG. 2 is an enlarged view of detail 2 of FIG. 1.
FIG. 3 is a partial schematic diagram of a drive system utilized in
conjunction with the sighting device shown in FIG. 1.
FIG. 4 is an enlarged view of a control panel shown in FIG. 2.
FIG. 5 is a partial sectional side view of the sighting device shown in
FIG. 1.
FIG. 6 is a partial side view useful in describing the operation of the
pivot arm of the sighting device shown in FIG. 5.
FIG. 7 is a section view taken along section line 7--7 of FIG. 5.
FIG. 8 is a partial section view taken along section line 8--8 of FIG. 5.
FIG. 9 is a partial sectional top view of the sighting device of FIG. 5.
FIG. 10 is a partial side view useful in explaining the operation of the
sighting device of FIG. 5.
FIG. 11 is another partial side view useful in illustrating the operation
of the sighting device of FIG. 1.
FIG. 12 is a perspective view of part of an alternate manual drive system
replacing the motor and pulley system shown in FIGS. 3, 4, 5, and 9.
FIG. 13 is a partial isometric view illustrating another embodiment of the
invention.
FIG. 14 is a partial section view taken along section line 14--14 of FIG.
13.
FIG. 15 is a partial section view taken along section line 15--15 of FIG.
13.
FIG. 16 is a partial cutaway section view taken along section line 16--16
of FIG. 14.
FIG. 17 is a section view taken along section line 17--17 of FIG. 15.
FIG. 18 is a section view of a detailed implementation of a clutch assembly
of the alignment rods of FIG. 1.
FIG. 19 is an enlarged sectional view of detail 19 of FIG. 18.
FIG. 20 is an end view of another embodiment of the invention.
FIG. 21 is a partial sectional view taken along section line 21--21 of FIG.
20.
FIG. 22 is a partial section view taken along section line 22--22 of FIG.
20.
FIG. 23 is a partial section view taken along section line 23--23 of FIG.
20.
FIG. 24 is a perspective view from the driver's seat of the tractor of FIG.
1.
FIG. 25 is a top view illustrating the line of sight of a driver seated in
the tractor of FIG. 25.
FIG. 26 is an isometric drawing of another embodiment of the invention.
FIG. 27 is an isometric drawing of an alternate means of implementing a
portion of the embodiment of FIG. 26.
FIG. 28 is a sighting device shown in FIG. 24.
DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, sighting apparatus 1, which includes two opposed
horizontal extension arms 1A and 1B, each extending outwardly from a
center housing 49, are mounted on hood 3A of tractor 3. Tractor 3 pulls a
farming implement 5 in a forward direction. Farming implement 5 cuts a
swath or group of furrows 7A as it is pulled forward through the field.
The purpose of sighting device 1 is to enable the driver of tractor 3 to
keep tractor 3 oriented so that its direction of travel is parallel to the
edge of previously plowed furrows 7, so that farming implement 5 cuts
furrows 7A precisely parallel to furrows 7.
In order to accomplish this, the tractor driver 3 adjusts the outward
extension of horizontal extension arm 1B until the outer edge 19A of pivot
arm 17A (see FIG. 6, subsequently described) is aligned with the tractor
driver's eye along the edge of furrows 7.
The structure and operation of sighting device 1 can be best understood by
referring to FIGS. 5 and 9. Referring first to FIG. 5 (which is a partial
sectional side view of sighting device 1 taken from the tractor driver's
side of the device when it is mounted on the hood 3A of tractor 3),
extension arms 1A and 1B extend horizontally outward from the sides of
housing 49. As subsequently explained, housing 49 contains an electric
motor, several clutches, pulleys, and belts and is attached rigidly to
hood 3A of tractor 3.
In FIGS. 5 and 9, each of the reference numerals designating parts of left
extension arm 1A includes the letter "A", while reference numerals
including a "B" are used to designate corresponding parts of right
extension arm 1B.
As indicated by FIG. 7, taken along section lines 7--7 of FIG. 5, a pair of
telescopic square tubes 37A and 39A are included in extension arm 1A.
Outer tube 37A is rigidly attached to the left vertical side of housing
49. Inner tube 39A extends into the open end of outer tube 37A through a
closely fitting guide cap 45A. Guide cap 45A maintains square tube 39A in
proper parallel relationship to outer tube 37A, and also prevents dirt and
dust from entering into tube 37A.
A nut block 43A is attached to the right end of inner tube 39A and slides
along the inner surfaces of outer tube 37A. Driver screw 41A extends
through nut block 43A, and is attached to axel 51, which is mounted within
housing 49 by means of a pair of bearings 56A and 56B. But block 43A moves
to the right or left as screw shaft 41A turns clockwise or
counterclockwise, causing inner arm 39A to be extended or retracted.
Right extension arm 1B, which includes outer tube 37B, inner tube 39B, nut
block 43B and drive screw 41B is entirely similar in structure and
operation to left arm 1A, and therefore will not be described herein in
detail.
A pivot arm 17A, which is vertical in one plane, is pivotally attached by
means of pivot pin 23A to the left end of inner tube 39A. Pivot arm 17A is
utilized as a sighting blade, outer edge 19A of which is aligned along
previously cut swath 7 as seen by the seated driver along sighting line 9
(FIG. 1). Typically, pivot arm 17A will be adjusted to an angle which is
roughly 45 degrees with respect to extension arm 1A. The angle depends, of
course, on the height of the driver's eye above the ground, the width of
the farm implement being towed, the location of the mounting of sighting
apparatus on the hood of the tractor, and the amount of extension of
extension arm 1A.
The lower end 18A of pivot arm 17A is pivotally connected by means of pivot
pin 25A to clevis 27A. Clevis 27A is connected to drive screw 29A. Drive
screw 29A is connected by means of coupler 65A to a flexible drive cable
47A.
Drive screw 29A passes through nut block 31A, which is pivotally connected
to bracket 32A. Bracket 32A is rigidly attached to inner tube 39A.
As can be easily seen by referring to FIG. 6, as flexible cable 49A turns
drive screw 29A in the direction indicated by arrow 35A, drive screw 29A
moves in the direction indicated by arrow 33A along stationary nut block
31A. This causes clevis 27A to move to the left, causing pivot arm 17A to
pivot in the direction indicated by arrow 21A. As indicated by dotted line
17A' in FIG. 6, the position of pivot arm 17A can be varied to suit the
needs of the user.
A more detailed top view of the above pivot arm assembly is shown in FIG.
8, which is taken along section lines 8--8 of FIG. 5. Referring now to
FIG. 8, pivot arm 17 includes vertical portion 18A' and a horizontal
section 18A" which is perpendicular to section 18A'. The lower end section
20A' is perpendicular to section 18A", and extends into clevis 27A. Pivot
pin 25A extends into a hole in section 20A and holes in clevis 27A,
allowing pivot arm 17A to pivot about pivot pin 25A.
Drive screw 29A is attached by means of a coupler including end section
61A, bearing rod 64, and end section 62. End section 61A is rigidly
attached to the left end of drive screw 29A. Bearing rod 64 turns
rotatably in a hole in the end of clevis 27A, and is rigidly attached to
end section 62. Thus, as drive screw 29A moves right and left, clevis 27A
is forced to move right or left but is not caused to rotate with drive
screw 29A.
Nut block 31A, through which drive screw 29A extends, its threads being
mated to threads in nut block 31A, is pivotally mounted by means of pivot
pin 59A to rigid bracket 32A.
Flexible cable 49A is attached by means of coupler 65 to the right end of
drive screw 29A, so that cable 47A translates its rotary motion to drive
screw 29A.
A pivot arm 17B, not shown, is mounted on the extreme right end of right
extension arm 1B, and is controlled in an entirely similar manner.
Referring now to FIG. 9, which is a sectional top view of the structure
shown in FIG. 5, a reversible DC motor 67 is rigidly mounted in housing
49. DC motor 67 has a drive shaft which extends through both ends of DC
motor 67. The left end of the drive shaft of motor 67 is coupled to one
plate of an electromagnetic clutch 69, the other plate of which is
attached to a rotatable shaft 71. Similarly, the right end of the drive
shaft of DC motor 67 is rigidly attached to one plate of a second
electromagnetic clutch 77, the other plate of which is attached to
rotatable shaft 80.
Pulley 73 is rigidly attached to rotatable shaft 71. A larger pulley 63 is
rigidly attached to rotatable shaft 51, which, as previously explained, is
rigidly attached to the inner ends of drive screws 41A and 41B, to effect
extension and retraction of inner tubes 39A and 39B of extension arms 1A
and 1B, respectively.
Thus, it is seen that when electromagnetic clutch 69 and DC motor 67 are
both energized, belt 55 translates rotational motion from electromagnetic
clutch 69 and shaft 71 to shaft 51 and drive screws 41A and 41B.
An electromagnetic brake device 75 is also attached to rotatable shaft 71.
Electromagnetic brake device 75 is engaged to produce braking action on
shaft 71 when electromagnetic shaft 75 is not energized, thereby
preventing undesirable rotation of rotatable shaft 71. Whenever
electromagnetic clutch 69 is energized, electromagnetic brake device 75 is
also energized, whereby electromagnetic brake 75 becomes disengaged at the
same time that electromagnetic clutch 69 becomes engaged. Electromagnetic
brake device 83, which can be identical to electromagnetic brake device
75, is attached to rotatable shaft 80.
Referring now to FIGS. 2 and 4, it is seen that a control panel 11 is
mounted on dashboard 3B of tractor 3, which control panel is located very
close to the steering column 3C on which the steering wheel is mounted.
Control panel 11 is located sufficiently close to the tractor driver that
he can activate two momentary switches 13 and 15 without altering his
driving position, thereby enabling him to move extension arm 1B (or 1A)
and pivot arm 17A (or 17B) to adjust sighting device 1 so that outer edge
19A of pivot arm 17A appears parallel to and aligned along the edge of
previously cut swath 7 to the eye of the seated driver as he views pivot
arm 17A along line of sight 9. Thus, tractor 3 pulls farming implement 5
so that furrows 7A are in perfect alignment with an in proper spaced
relation to furrows 7.
As indicated in FIG. 4, momentary switch 13 is normally in a centered or
neutral position. Momentary switch 13 can be pushed or deflected upward,
causing extension arms 1A and 1B to be extended outwardly. As soon as the
operator releases momentary switch 13, it returns to its center or neutral
position. When the operator deflects momentary switch 13 downward, it
causes DC motor 67 to turn in the opposite direction, causing threaded
screws 41A and 41B to retract extension arms 1A and 1B.
Referring agian to FIG. 9, it is seen that pulley 79 engages rotatable
shaft 80. Pulley 79 is coupled by means of drive belt 81 to pulley 82.
Pulley 82 is mounted on rotatable shaft 83, which is supported in housing
49 by means of bearings 85A and 85B. Flexible shafts 47A and 47B (which,
as previously explained, are coupled to the pivot arm assemblies 17A and
17B) are connected by means of collars 56A and 56B to the opposite ends of
rotatable shaft 89. When electromagnetic clutch 77 is energized, rotation
of the drive shaft of DC motor 67 is translated to rotatable shaft 80 and
flexible cables 47A and 47B, causing pivot arms 17A and 17B to be pivoted.
Thus, it is seen that lateral extension of extension arms 1A and 1B and the
position of pivot arms 17A and 17B can be independently controlled,
depending upon which of electromagnetic clutches 69 and 77 are engaged.
Referring back to FIG. 4, momentary switch 15 is deployed by the tractor
driver to pivot pivot arm 17A in precisely the same manner that momentary
switch 13 is deployed to extend or retract extension arms 1A and 1B, as
previously explained.
FIGS. 10 and 11 disclose how flexible cable 47A bends to accommodate
extension and retraction of inner arm 39A and pivoting of pivoting arm
17A. A bracket 89 is rigidly attached to a clamp bracket 87 some of which
is in turn attached by means of lower screw 88 to other tub 37A. A lower
clamp assembly 91 is removably attached to the sides of hood 3A of tractor
3.
Referring now to FIG. 3, a schematic diagram is shown illustrating the
electrical coupling between reversible DC motor 67, clutches 69 and 77,
and electromagnetic brakes 75 and 83' to momentary switches 13 and 15 of
FIGS. 3 and 4.
Referring now to FIG. 3, motor 67 has a positive terminal 103 and a
negative terminal 104, designated by M+ and M-, respectively.
Electromagnetic clutches 69 and 77 have energization terminals 103 and
105, designated, respectively by CL1 and CL2. Electromagnetic brakes 75
and 83' have brake pads 75A and 83A which are normally engaged. When a
positive voltage is applied to energization terminals 101 and 106,
designated BR1 and BR2, respectively, brake pads 75A and 83A are
disengaged from brake drums which are attached to rotatable shafts 71 and
80.
Motor 67 rotates in one direction when a positive DC voltage is applied
between the M+ and M- terminals. The direction of rotation is reversed if
the polarity applied voltage is reversed.
Electromagnetic clutches 69 and 77 have plates which are engaged when a
positive voltage is applied to energization terminals CL1 and CL2.
Momentary switch 13 can be implemented by means of a switch assembly 13',
which includes three ganged single pole double throw switches. The first
switch includes terminal 126, which is connected to the M+ motor terminal
and to wiper 30. Wiper 30 is spring biased to rest in a neutral position
between terminals 121 and 122, which are connected, respectively, to
negative battery terminal B- and positive battery terminal B+, also
designated by reference numerals 115 and 114, respectively.
The second switch includes terminal 127, which is connected to wiper 131
and M- motor terminal 104. Wiper 131 is also spring biased in a neutral
position between terminals 123 and 123', which are connected,
respectively, to B+ terminal 114 and B- terminal 113.
The third switch has a terminal 128 connected to wiper 132 and to B+
battery terminal 114. Wiper 132 is normally biased between terminals 124
and 125, both of which are connected to both CL1 clutch terminal 102 and
BR1 brake terminal 101.
If momentary switch 13 is deflected upward, wipers 130, 131, and 132
electrically contact terminals 121, 123, and 124, respectively. This
causes the CL1 and BR1 terminals to be energized, disengaging
electromagnetic brake 75 and engaging clutch 69. Electromagnetic clutch 79
remains disengaged, and electromagnetic brake 83' remains engaged. The M+
and M- motor terminals are connected to the negative and positive battery
terminals, respectively, causing the drive shaft of motor 67 to rotate in
one direction.
If the momentary switch is lowered instead of raised, the CL1 terminal 102
and BR1 terminal 101 are nevertheless energized, disengaging brake 75 and
engaging clutch 69, as before. However, the connection of the motor
terminals M+ and M- motor terminals to the positive and negative battery
terminals is now reversed, causing the direction of rotation of the drive
shaft of motor 67 to be reversed.
If momentary switch 15 is deflected upward or downward, electromagnetic
clutch 77 is energized, causing it to be engaged, and brake 83' is then
energized, causing it to be disengaged. Motor 67 is energized and caused
to rotate either clockwise or counterclockwise in the manner previously
described.
A wide variety of reversible DC motors are commercially readily available.
Similarly, electromagnetic clutches and electromagnetic brake assemblies
are readily available and can be selected readily by those skilled in the
art. A detailed description of these components of the invention is
therefore not set forth herein.
In an alternate embodiment of the invention, DC motor 67, the associated
electromagnetic clutches, electromagnetic brakes, pulleys, belts, the
switching circuitry of FIG. 3, and the control panel of FIG. 4 are
eliminated and replaced by a simple manual drive system including a pair
of flexible cables connected by means of first and second bevel gear
assemblies to rotating shafts 51 and 83, respectively. The first and
second flexible cables are connected to first and second cranks or control
knobs or handles, which are located near the seat of the tractor so that
the driver can easily turn the cranks while seated in the tractor to
extend or retract extension arms 1A and 1B and to adjust the inclination
of pivot arms 17A and 17B.
Referring now to FIGS. 5, 9 and 12, crank 150 is mounted in mounting plate
151 (attached to the tractor near the driver's seat) by means of bearing
152, which is seated in mounting plate 151. Crank 150 is connected to
flexible cable 146. Flexible cable 146 is extended along the hood of the
tractor and is coupled by means of coupler 145 to rotating shaft 144.
Shaft 144 is supported by bearing assembly 143 and is connected to bevel
gear 142. Bevel gear 142 matches with bevel gear 141, which is attached to
rotating shaft 51. Thus, when crank 150 is turned in the directions
indicated by arrow 171, extension arms 1A and 1B are extended or
retracted.
Similarly, crank 149 is mounted by means of bearing 153 and is connected
flexbile cable 148. Flexible cable 148 is connected by means of coupler
147 to shaft 140. Shaft 140 is supported by means of bearing assembly 139
and is connected to bevel gear 138. Bevel gear 138 meshes with bevel gear
137. Bevel gear 137 is attached to rotating shaft 83. Thus, when crank 149
is turned in the directions indicated by arrow 172, pivot arms 17A and 17B
are adjusted.
Another embodiment of the invention is shown in FIGS. 13-19. Where
applicable, the same reference numerals are utilized as previously to
identify similar or corresponding parts. Referring now to FIG. 13,
sighting apparatus 1 includes a housing 49 pivotally mounted by means of
pivot pin 137 on front end of tractor 3. Housing 49 includes a horizontal,
hollow member 49A out of which horizontal extension arms 1A and 1B
adjustably extend in a manner similar to that previously described. As
best seen in FIGS. 14 and 16, horizontal extension arm 1B forms a gear
rack having a plurality of gear teeth 140 that cooperate in conjunction
with a pinion gear 141. Pinion gear 141 is housed in a housing section
149A' that extends upwardly from the upper surface of horizontal member
49A. Pinion gear 141 is coaxially attached to a center member 141' of a
flexible cable 146B that extends rearward from housing 149A to a control
panel 180, shown in FIG. 24. The driver of tractor 3 can turn crank 180A
in order to cause pinion gear 141 to rotate either clockwise or
counterclockwise, thereby moving horizontal extension arm 1B outward or
inward relative to housing 49A. As best seen in FIGS. 14 and 16, a
plurality of ball bearings such as 49A' and 49A" ride in channels disposed
in the lower surface of horizontal extension arm 1B and in the inner
bottom surface of horizontal member 49A to effect lateral movement of
horizontal extension arm 1B relative to horizontal member 49A.
It should be noted that a frictional "keeper" 184 is disposed between the
upper portion of horizontal member 49A and the teeth 140 of horizontal
extension arm 1B, as shown in FIG. 14. Friction keeper 184 can have a
lower surface composed of any highly durable plastic material, such as
Teflon, or the like. A plurality of compression springs such as 185
maintain a downward pressure of keeper plate 184 on teeth 140. Suitable
adjustment means (not shown) are provided for adjusting the downward
pressure on keeper plate 184. The purpose of keeper plate 184 is to
provide a predetermined amount of resistance to lateral movement of
horizontal extension arm 1B with reference to horizontal member 49A, so
that as the tractor shifts and jolts as it moves over irregular ground,
the amount of extension of horizontal extension arm 1B does not vary.
The structure and operation of horizontal extension arm 1A are essentially
similar to that of horizontal extension 1B, and therefore will not be
repeated.
In FIG. 13, a heavy weight 147 is suspended by means of cables 149 attached
in symmetrical manner to the eyelets disposed on the opposite ends of
horizontal member 49A. A retaining bracket 148 has a pair of taut cables
148A and 148B suspended therebetween on either side of the opposed major
faces of pendalum weight 147. The tension of cables 148A and 148B has
adjusted to produce a selected amount of frictional damping of the
swinging lateral movement of pendalum weight 147. Thus, when tractor
undergoes a sharp jolt or an abrupt tipping, horizontal member 49A remains
relatively horizontal. The frictional damping provided on pendulum weight
147 dampens any oscillatory modulations of horizontal member 49A and the
sighting rod 17A and 17B attached thereto, thereby enabling the driver of
tractor 3 to keep sighting rod 17A and 17B more precisely aligned with the
edge of the previously cut swath.
A pair of sighting rods 17A and 17B are pivotally mounted on the outer ends
of horizontal extension arms 1A and 1B, respectively. Sighting rod 17A is
rotated by means of a center member of flexible cable 146B. Cable 146B
extends to a control crank 180B on control panel 180, as shown in FIG. 24.
Similarly, sighting rod 17B is rotated by means of the center member of
flexible cable 146A, which extends to control crank 180C on control panel
180. Thus, the driver of tractor 3 can, while seated in the driver's seat,
adjust the orientation of sighting rods 17A and 17B and the extension of
horizontal extension arms 1A and 1B.
According to the present invention, a friction clutch arrangement prevents
sighting rods 17A and 17B from wobbling or oscillating due to the
springiness of the center members of flexible cables 146A and 146B. To
avoid such wobbling or oscillation, a friction brake arrangement is
provided. One such friction brake arrangement is shown in FIG. 15, wherein
bracket member 145 has two vertical portions 145A and 145B. A chuck for
receiving and engaging the end of cable 146A is disposed in bracket member
145A. A stationary brake plate 145C is attached to the opposite vertical
bracket member 145B. A Teflon disc 145D is disposed between stationary
brake plate 145C and a rotatable brake plate 145E. Rotatable brake plate
145E is attached to axle member 142', which is rigidly attached to the end
of the center member 142 of cable 146A. As cable center member 142
rotates, axle member 142' rotates. Rotatable brake plate 145E is rigidly
attached to axle member 142' and therefore, rotates with it. Stationary
brake plate 145C is rigidly attached to bracket 145, and therefore remains
stationary. The pressure applied by brake plate 145C and 145E is adjusted
to produce the desired frictional resistance to undesired wobbling or
oscillation of sighting element 17B. It should be noted that the structure
shown in FIG. 15 is presented mainly to schematically illustrate the
application of the frictional concept. A practical implementation of this
concept is shown in FIGS. 18 and 19. Referring now to FIGS. 18 and 19,
wherein the end of center cable 142 of cable 146A extends through opening
147 of bracket 145 to engage the end of axle member 142'. Two friction
brake plates 145E and 145E' are rigidly attached to axle member 142'.
Sighting rod 17B is rigidly attached to rotatable brake plate 145E. Two
stationary brake plates 145C and 145C' are rigidly attached to bracket
145. An annular flange 145D extends outwardly from brake plate 145E',
forming a recess within which a flexible rubber O-ring 150 is disposed
| | |
