Note: Descriptions are shown in the official language in which they were submitted.
109~3757
BACKGROUND OF THE INVENTION
The present invention relates to a spring tine
harrow trailing arm or drag arm assembly for use, for
example, as an agricultural implement to prepare seedbeds.
It is usual in preparing soil for seeding to drag
over the land by means of a tractor or other vehicle, a set
of farm implements in tandem such as an assembly of disks
followed by an assembly of spring tine harrows. The purpose
of the harrow is to break up large clumps of soil and to
level the ground. Conventionally, spring tine harrows are
comprised of a series of spring loaded teeth or tines mounted
on a set of transverse parallel bars with the bars being
fixed relative to one another by suitably spaced cross-
members clamped or welded to the bars. The resultant
assembly of tines is attached by one or more drag arms to
a disk, plough, cultivator or other similar unit that operates
ahead of and in tandem with the harrow.
Many conventional harrows have either depended upon
the weight of the unit itself for downward pressure or have
used a coil-spring acting in compression between the drag
arm and the support mounting for the drag arm. Such
coil-spring units have been susceptible to damage because of
the inherent limitation in compression of the spring,
consequently limiting the maximum deflection of the harrow
upon encountering large objects. In addition, such coil-
spring units in encountering large obstacles experience
very large downward forces because of the approximately
linear increase in compression of the spring with deflection
of the drag arm, thereby rendering the aforesaid units more
susceptible to damage during such large deflections. Occasionally
tension springs have been ~sed, but because of desiqn deficiencies
have failed to permit enough deflection of the trailinq arm
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to accommodate relatively large surface obstacles or have
been subjected to substantial increases in spring tension
when accommodating such obstacles.
Moreover, some existing harrow units generally
offer no mechanism for stabilizing the drag arm against
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lateral movement of the harrow, nor do they provi~e adequate
non-slip clamping mechanism for attaching the rearward end
of the drag arm to the parallel bars that carry the spring
tine support arms. This undesirably permits rotation of the
assembly of spring tines relative to the drag arm during
operation.
A further problem with many known spring tine
harrow units is their complexity of-manufacture, requiring
several components of unusual shapes or a relatively large
number of components or components of unduly large size of
shape, adding unnecessarily to the cost of manufacture and
consequently complicating the overall design of the harrow.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide
a spring-tensioning mechanism for applying downward pressure
to a drag arm suitable for use with a spring tine harrow
and which allows the drag arm to pass over relatively high
obstructions without substantially increasing the downward
pressure on the drag arm over that which is exerted on the
drag arm during normal operation, and which further permits
the drag arm to undergo relatively large deflections without
experiencing a spring-imposed limit to its maximum upward
deflection.
It is a further object to provide a drag arm
mounting mechanism as aforesaid from which to pivotally
suspend the drag arm so that the latter is stabilized against
lateral movement.
It is a further object to provide a positive
non-slip means for clamping the drag arm to the frame
supporting the spring tines which also permits lateral
adjustment of the spring tines.
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The invention is directed to a trailing arm
mechanism, comprising:
a support frame;
A trailing arm extending rearwardly from and
pivotally mounted about a substantially transverse
horizontal axi-s on the support frame and pivotable
upwardly from a lower operating position to an upper
operating position;
a support frame spring anchoring means fixed
to the support frame at a position proximate to and at
an elevation lower than the pivotal axis of the trailing
arm on the support frame;
a trailing arm spring anchoring means fixed to
the trailing arm at a position on the direct underside
of the trailing arm remote from the pivotal axis
thereof; and
a tension coil spring normally under tension
located on the direct underside of the trailing arm and
connected between the support frame spring anchoring
means and the trailing arm spring anchoring means. The
spring extends generally parallel to the trailing arm
and is closely spaced therefrom. The spring is
extensible within its elastic limit from a minimum
extension corresponding to the lower operating position
of the trailing arm to an extended position reached when
the trailing arm pivots upwardly to clear any obstacle
lying underneath the arm, such spring extension
occurring in a straight line so that the spring does not
bend at any time during extension.
The support frame may comprise a pair of
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vertical parallel plates, one on each side of the
trailing arm and closely spaced therefrom and extending
from the pivotal axis in the direction of the trailing
arm to provide lateral support for the trailing arm.
The coil spring in minimum extension may have
a length of at least about half the length of the
trailing arm.
In the mechanism, the trailing arm spring
anchoring means may be spaced downwardly rearwardly from
the pivotal axis of the trailing arm.
The mechanism may additionally comprise stop
means fixed to the support frame forwardly of the arm
spring anchor means underneath the trailing arm and
engageable with the trailing arm for limiting the
downward pivotal movement thereof.
The invention is also directed to a spring
tine harrow for use as an agricultural implement to
prepare seedbeds, comprising:
a set of spring tines supported from a harrow
frame;
a mounting support;
a trailing arm extending rearwardly from and
pivotally mounted about a substantially transverse
horizontal axis on the mounting support and extending
generally rearwardly therefrom, and pivotable upwardly
from a lower operating positon to an upper operating
position thereby to permit the tines to clear
encountered ground surface obstacles; said trailing arm
having means for supporting said tines at the end
thereof remote from the pivotal mounting;
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a tension coil spring normally under tension
positioned directly underneath the trailing arm,
extending generally parallel to the trailing arm and
being closely spaced therefrom, pivotally connected
underneath the trailing arm between a first anchor means
on the mounting support and a second anchor means
located on the trailing arm in a position such that as
the trailing arm pivots through a vertical plane, the
longitudinal axis of extension of the spring pivots
about an axis generally below and offset in a rearwardly
direction from the pivotal axis of the trailing arm;
said spring being extensible within its elastic limit
from a minimum extension corresponding to the lower
operating position of the trailng arm to an extended
position reached when the trailing arm pivots upwardly
to clear any encountered surface obstacle; the spring
always extending in a straight line and not being bent
at any time during extension; and
means for limiting the downward deflection of
the trailing arm below a predetermined point;
said pivotal axis being substantially
horizontal.
In the spring tine harrow as defined, the
mounting support may be comprised of a pair of parallel
plates each mounted in a vertical plane and between
which is sandwiched the trailing arm supported by a
transverse pivotal connecting means extending between
the plates.
In the spring tine harrow as defined, the
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means for supporting the harrow frame on the trailing
arm may be comprised of a plurality of U-shaped clamps
surrounding a transverse bar of said frame and securing
a sheared channel element between the bar and a backing
plate fixed to the end of the trailing arm remote from
its pivotal axis with the interior portion of the
sheared channel element being directed towards and
biting into the bar, the bar being fixed to a plurality
of tine-supporting arms to which said tines are
attached.
SUMMARY OF THE DRAWINGS
Figure 1 is a side elevation view of a
preferred embodiment of a spring tine harrow (including
trailing arm) assembly in accordance with the present
invention.
Figure 2 is an exploded perspective view of
the components forming the assembly of Figure 1.
Figure 3 is a side elevation view of the
spring tine harrow assembly of Figure 1 shown being
pulled over a large obstacle, showing the drag arm and
drag arm tensioning spring deflected upwards so as to
portray the relative positioning of the deflection
limiting cam, drag arm tensioning spring and drag arm.
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Figure 4 is a side elevation view of the drag
arm mounting support assembly showing different positions
of the height positioning cam or adjustment block.
Figure 5 is a side elevation view of the spring
tine harrow assembly of Figure 1, showing the drag arm in
transport position mode.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT WITH
REFERENCE TO DRAWINGS ~~
The preferred embodiment to be described is a
spring tine harrow implement for breaking down clods of soil
and levelling the ground in preparation for seeding. However,
this description is not to be taken as limiting the trailing
arm assembly invention, as the invention would obviously
have application to other situations in which a mechanism
such as a disk or other device is attached to the end of a
drag arm from which it receives a steady down pressure but
is capable of deflecting upwards when encountering large
obstacles, and subsequently returning to its normal operating
position in response to the return force exerted by a spring
on the drag arm and in which a simple, convenient, positive
means of adjusting the maximum downward deflection of the
drag arm is desired.
Referring to Figures 1 and 2, a spring tine harrow
attachment (including drag arm assembly) includes a number
of spring tines 26, suspended from a number of lateral,
substantially horizontal, substantially parallel beam
elements 22, 23 and 24, held in place by a rigidly attached
frame assembly 21 comprising transverse bar or pipe 33
and parallel spaced side arms 35. Embracing the transverse
bar 33 are a number of U-clamps 19 which are bolted to a plate
2 which is welded to the rearmost end of a drag arm 1.
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Between the plate 2 and the transverse bar is a sheared
channel element 4 whose sheared edges 37 bite into bar 33
when the U-clamps 19 are tightened, thereby tightly gripping
bar 33. It will be noted that the frame 21 can be adjusted
transversely relative to drag arm 1 when U-clamps 19 are
loosened.
The drag arm 1 is pivotally mounted on a trans-
verse bushing 7, which is sandwiched between a balance plate
assembly consisting of two substantially parallel vertical
plates 3 and 3A, said bushing being supported by a bolt 8,
which passes through~the plates and bushing. The plates 3,
3A also extend in a rearwardly direction from the pivotal
axis of the drag arm, a short distance over which they are
closely spaced from (and thereby constrain the lateral
movement of) the vertical sides of the drag arm.
A bolt 15 which passes in a transverse direction
through the plates 2, 3 below the level of the pivotal axis
of the drag arm and offset from the latter in a rearwardly
direction provides a convenient means for anchoring one
end of a spring 20 normally under tension, the other end of
which is connected to any eye bolt 14 mounted on a bracket
11 welded to the underside of the drag arm.
A bolt 16, also passing in a transverse direction
through the balance plates 2, 3, passes through an adjusting
block or deflection limiting cam 6, on the axis whose dis-
tance to any one of the four abutment surfaces of the cam
engageable with drag arm 1 is different from that to any
other side. The adjusting block 6 itself is sandwiched
between the plates of the balance plate assembly and is
positioned below the drag arm offset in a direction rear-
wardly of the pivotal axis of the drag arm (but forwardly
of spring anchoring bolt 15).
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The forward ends 39, 41 of the balance plates 2
and 3 are flanged so as to provide a convenient mounting
surface in combination with a mating forwardly positioned
clamping plate 5. A transverse beam 43 of an implement
frame is sandwiched between plate 5 and flanges 39, 41 bolted
to plate 5 above and below the beam 43. (As an alternative
construction, plates 3,3A could be formed as an integral U-
shaped plate, with flanges 39 and 4i forming an integral
surface.)
Figure 3 illustrates the upward pivotal deflection
of the drag arm 1 and tensioning spring 20 when the harrow
has encountered an unusually large object such as rock 31,
during operating. Note that a relatively large upward
deflection of the drag arm 1 can be accommodated without any
limit imposed by the spring 20, which extends longitudinally
relatively little for a relatively large upward deflection
of drag arm 1.
The adjusting block 6 is shown on Figure 4(a) in
a position which provides for the maximum permitted downward
deflection of the drag arm 1. The cam 6 is shown on
Figures 4(b), (c) and (d) in positions which provide for
progressively higher limit levels of permitted downward deflec-
tion of the drag arm 1. (In other words, the lowermost per-
mitted position of drag arm 1 is lowest in Figure 4(a) and
is highest in Figure 4(d), for the cam mounting illustrated.)
The bolt 16 supporting cam 6 may also be mounted,
instead of through lower holes 45, 46 in plates 2 and 3 as
seen in Figures 1, 3 and 4, alternatively through upper holes
47, 48 in these plates. This alternative mounting, illustrated
in Figure 5, permits the drag arm 1, during transportation to
the field, to be carried in a position where the spring tines
do not engage the ground, or the upper holes 47, 48 may be
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used for shallow draft implements requiring a higher mounting
for cam 6. In field operation, the cam 6 is mounted in the
preferred mounting position and rotated to adjust the drag
arm level so as to allow the spring tines to engage the
surface of the ground and penetrate the earth to a desired
extent. The entire assembly is pulled forward, usually behind
another farm implement such as a disk. The spring tines 26
receive a downward pressure because~of the tension exerted by
spring 20 and also by reason of the weight of the assembly.
This downward force causes the tines 26 to engage and till the
soil. Although the spring tines 26 themselves deflect to
accommodate small surface rocks and other similar objects,
when encountering unusually large objects it is necessary
for the entire frame 21 to be able to deflect upwards. By
minimizing the additional down pressure exerted on the spring
tines during large deflections, their susceptibility to damage
is considerably reduced. Moreover, during such deflections
of the drag arm, the constraining action of the balance
plates on the drag arm prevents undesirable lateral motion ---
of the spring tine assembly. Finally, in addition to theaforesaid features, the present device enables the drag arm
to deflect up and down in a vertical plane without slippage
of the frame assembly with respect to the drag arm because
of the gripping action of the channel section which is
clamped between the adjusting frame assembly and the end
plate of the drag arm.
It can be seen that the components illustrated
in Figures 1 to 5 are relatively easy to manufacture and
assembly in comparison with many prior units, and constitute
a relatively compact and lightweight device.
Other obvious variations, modifications and
departures from the specific assembly described above will
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readily occur to those skilled in the art without departing
from the spirit of the invention. The scope of the inven-
tion is as set forth in the accompanying claims. In the
description and claims, words such as "downward", "rearward",
"underneath", etc. are to be taken in a relative rather than
an absolute sense, since obviously the preferred orientation
of the trailing arm assembly may vary, depending upon
application.
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