U.S. patent application number 09/899864 was filed with the patent office on 2001-11-15 for revolving shackle.
This patent application is currently assigned to Metal Made Rite, L.L.C.. Invention is credited to Hildebrand, Curt C..
Application Number | 20010040359 09/899864 |
Document ID | / |
Family ID | 23384433 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040359 |
Kind Code |
A1 |
Hildebrand, Curt C. |
November 15, 2001 |
Revolving shackle
Abstract
An apparatus and method of articulating a vehicle is disclosed
using a rotatable shackle connected to the frame and the suspension
system of the vehicle. As one side of an axle is moved to a
different level from the other side, the shackle rotates, allowing
the vehicle to articulate and assisting the spring eye of a leaf
spring suspension system to remain substantially in its resting
position. Pivoting connections may be provided where the rotatable
shackle is connected to the frame, where the rotatable shackle is
connected to the suspension system, and within the rotatable
shackle itself. The rotatable shackle is self supporting and may
include a bushing to receive a portion of the rotatable
shackle.
Inventors: |
Hildebrand, Curt C.;
(Casper, WY) |
Correspondence
Address: |
Craig C. Groseth, Esq.
SHERIDAN ROSS P.C.
1560 Broadway, Suite 1200
Denver
CO
80202-5141
US
|
Assignee: |
Metal Made Rite, L.L.C.
|
Family ID: |
23384433 |
Appl. No.: |
09/899864 |
Filed: |
July 5, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09899864 |
Jul 5, 2001 |
|
|
|
09352264 |
Jul 13, 1999 |
|
|
|
Current U.S.
Class: |
280/686 ;
280/124.175 |
Current CPC
Class: |
B60G 11/12 20130101;
B60G 2200/30 20130101; B60G 2500/30 20130101; B60G 7/001 20130101;
B60G 2202/112 20130101; B60G 2204/121 20130101; B60G 11/10
20130101 |
Class at
Publication: |
280/686 ;
280/124.175 |
International
Class: |
B60G 007/00 |
Claims
I claim:
1. A shackle for a vehicle, comprising: a first section having a
distal end for connection to a vehicle and a proximal end; a second
section having a distal end and a proximal end; a third section
having a distal end for connection to a suspension system of the
vehicle and a proximal end; wherein said third section is rotatably
connected to said second section.
2. The shackle, as claimed in claim 1, wherein: said proximal end
of said first section is pivotally connected to said proximal end
of said second section.
3. The shackle, as claimed in claim 2, wherein: the axis of
rotation of said third section about said second section is
approximately perpendicular to the axis of pivot between said
second section and said first section.
4. The shackle, as claimed in claim 1, wherein: said distal end of
said first section is pivotally connected to said vehicle.
5. The shackle, as claimed in claim 1, wherein: said distal end of
said third section is pivotally connected to said suspension
system.
6. The shackle, as claimed in claim 1, wherein: said second section
comprises a base and a cylindrical neck; and said third section
comprises a cylindrical neck and a flange for connection to said
suspension system.
7. The shackle, as claimed in claim 1, wherein: said distal end of
said third section is substantially U-shaped.
8. The shackle, as claimed in claim 1, wherein: said suspension
system is a leaf spring suspension system.
9. The shackle, as claimed in claim 1, further comprising: a
bushing connected to said first section.
10. The shackle, as claimed in claim 9, wherein: at least a portion
of said second section rests against said bushing when the shackle
is in a closed position.
11. The shackle, as claimed in claim 10, wherein: said bushing is
shaped to receive at least a portion of said second section.
12. A revolving shackle for a leaf spring suspension assembly of a
vehicle, comprising: a first section comprising a first flange, a
second flange and a member connecting said first flange and said
second flange, said first section having a proximal end and a
distal end for connection to the frame of said vehicle; a second
section comprising a base and a cylindrical neck, said second
section having a proximal end and a distal end; a third section
comprising a cylindrical neck and a third flange for connection to
said leaf spring suspension assembly; a bushing connected to said
first section; wherein said proximal end of said first section is
pivotally connected to said proximal end of said second section;
and wherein said cylindrical neck of said second section is
rotatably connected to said cylindrical neck of said third
section.
13. The shackle, as claimed in claim 12, wherein: the axis of
rotation of said third section about said second section is
approximately perpendicular to the axis of pivot between said
second section and said first section.
14. The shackle, as claimed in claim 12, wherein: said distal end
of said first section is pivotally connected to said vehicle.
15. The shackle, as claimed in claim 12, wherein: said distal end
of said third section is pivotally connected to said suspension
system.
16. The shackle, as claimed in claim 12, wherein: at least a
portion of said second section rests against said bushing when the
shackle is in a closed position.
17. The shackle, as claimed in claim 16, wherein: said bushing is
shaped to receive at least a portion of said second section.
18. A method of articulating a vehicle, comprising: positioning
said vehicle with one side of at least one axle at a different
level than the other side of said at least one axle; and rotating a
shackle connected to at least a portion of the frame of said
vehicle and at least a portion of the suspension system of said
vehicle; whereby said vehicle articulates and said suspension
system remains in substantially the same position as before said
vehicle articulates.
19. The method of articulating a vehicle, as claimed in claim 18,
further comprising: pivoting at least a portion of said
shackle.
20. The method of articulating a vehicle, as claimed in claim 20,
further comprising: resting at least a portion of said shackle
against a bushing at least before said vehicle articulates.
Description
FIELD OF THE INVENTION
[0001] The invention generally relates to structures and methods
for increasing articulation in a vehicle, and more particularly, to
hinged shackles for connecting leaf spring suspension assemblies to
the frame of an off road vehicle.
BACKGROUND
[0002] Vehicles designed, built and marketed for off road use are
increasingly being driven in more severe off road applications,
while also being driven on paved highways and streets. One type of
more severe off road driving is "rock crawling," which is commonly
referred to as slowly driving a four wheel drive vehicle over,
through or between natural or even man made obstacles of a wide
variety of shapes, angles, heights, widths, depths, compositions,
etc. Such natural obstacles may include rocks, gulleys, ravines,
stream beds, inclines or drops, among other things. Rock crawling
refers not only to traversing the typically uneven rock surfaces,
but also a variety of natural and man made surface material,
including gravel, sand, dirt, concrete or metal barriers, and
vegetation including exposed roots and tree stumps.
[0003] Rock crawling, and other types of off road use, can place
severe demands on the suspension system of the vehicle. To maximize
traction and control, it is generally advantageous to maintain each
tire in full contact with the surface being driven, or at least as
many tires and as much of each tire as possible. Similarly, it is
also generally advantageous to keep the weight of the vehicle
evenly distributed over each of the tires, or at least as much as
possible. Because each axle of most non-military off road vehicles
extend to at least one wheel on each side, driving on an uneven
surface often means one wheel is significantly lower than the
other, resulting in one or more tires losing maximum contact, or
even being lifted off the surface. This is an even greater issue
when the front and rear axles are at different levels or even at
different angles. The relative ability of a vehicle to keep the
tires on the ground during such maneuvering is commonly referred to
as the articulation of the vehicle.
[0004] Off road vehicles commonly employ either a leaf spring or a
coil spring suspension system to suspend the vehicle over the
axles. Generally, in a leaf spring suspension system, a series of
elongated bands of metal, or leaves, of varying lengths are stacked
and banded together. One end of the assembly is bolted or otherwise
fixed to the bottom of the vehicle, typically towards the center of
the vehicle and away from the axle to be suspended. In a stock
configuration, the leaves are commonly positioned under the axle,
with a shallow U-shaped arc extending towards the outside of the
vehicle. The end of the leaves near the outside of the vehicle
typically terminates with a spring eye that allows a connection to
a movable bar or shackle or other device that in turn is connected
to the vehicle. One such leaf spring assembly is installed near
each wheel. When at rest or under compression, the conventional
leaf spring assembly typically presses the shackle up against the
vehicle frame.
[0005] During compression of the leaf spring, this type of
suspension allows the leaf spring to flatten and move toward the
direction of the shackle. When the leaf spring is required to
droop, or stretch as far as possible, it is restricted by the flex
of the leaf spring itself For this type of primarily vertical
suspension, the bolted inner end of the leaf spring and the plates
that make up the shackle limit the amount the leaf spring assembly
can move.
[0006] The conventional leaf spring assembly is limited in
articulation, e.g., when one side of the axle compresses and the
other side does not compress as much, does not compress at all, or
is required to droop. The axle is no longer level and the vehicle
tilts. Because the leaf spring at the inner end is bolted and at
the outer end has only limited vertical and forward movement, but
no lateral movement, the leaves themselves must twist or flex to
try to accommodate the changing lateral angle between the axle and
the vehicle. Reliance on the leaf spring twisting not only limits
articulation, but also can cause metal fatigue in the leaf spring
assembly and result in premature failure.
[0007] To increase articulation, several modifications to leaf
spring assemblies have been attempted, generally by allowing the
leaf spring to more readily drop away from the frame. For example,
in one configuration, the inner end of the leaf spring remains
bolted to the vehicle frame and the spring eye remains connected to
a shackle. However, the arm of the shackle is lengthened, which
provides more droop. Although this configuration provides enhanced
vertical suspension, it still relies on the leaf springs to twist
to provide articulation. Also, lengthening the arm of the shackle
generally reduces the lateral stability of the vehicle,
particularly at higher speeds.
[0008] In another design, known as a folded hinged shackle, the
shackle has a first arm with one end connected to the vehicle and
the other end pivotally connected to a second arm, that in turn is
connected to the spring eye of the leaf spring. When at rest or
under compression, the folded hinged shackle is pressed up against
the vehicle and the leaf springs primarily provide for compression.
When the leaf spring is required to droop, however, the folded
hinged shackle opens, providing increased droop. Again,
articulation is limited by the amount of twisting of the leaf
springs.
[0009] Another attempt to increase articulation is commonly
referred to as a "buggy spring" suspension. Again, the end of the
leaf spring towards the center of the vehicle is bolted to the
vehicle frame. The outer shackle is replaced essentially with a
second, shorter leaf spring assembly. The end of the shorter leaf
spring assembly towards the center of the vehicle is bolted to the
vehicle between the spring eye of the main leaf spring and the
axle. The end of the shorter leaf spring assembly near the outside
of the vehicle is connected to the spring eye of the main leaf
spring by a conventional shackle design. This buggy spring assembly
provides another level of vertical suspension and may provide more
droop. It also increases articulation, as both the main and the
shorter leaf springs will twist somewhat. However, articulation is
still limited by the amount of twisting of the leaf springs. As
with lengthening the shackle arm, replacing the shackle with a
second leaf spring assembly generally reduces the lateral stability
of the vehicle, particularly at higher speeds.
[0010] A more complicated assembly to try to increase articulation,
known as a "four link" suspension, is commonly installed to greatly
increase droop of the rear axle. This assembly again has the inner
end of the leaf spring bolted to the vehicle, but is inverted,
i.e., the leaf spring forms a concave shape opening downward. The
outer end of the leaf spring extends only just past the axle and is
not fixed to another component. Rather, it merely rests on top of
the axle. To protect the vehicle from the slapping of the leaf
springs, a small bumper is commonly inserted on the vehicle frame
between the two ends of the leaf spring. The relative vertical drop
is controlled by a four arm link system, with two arms for each
side of the axle. One arm is pivotally connected at the outer end
of the vehicle and extends to rest under the axle. A shorter arm is
pivotally connected toward the inside of the longer arm and extends
to suspend above the axle. The inverted leaf springs provide
compression and the arms can be set to provide little or no
pressure, resulting in very large amounts of droop if both sides of
the axle are required to droop. This four link assembly is commonly
used in faster off road races with big, fast jumps requiring large
droop of both rear wheels. The rear axle essentially is momentarily
free hanging, supporting little or no weight of the vehicle. In
part because one end of the leaf spring is unattached, articulation
is increased, although it is still limited by the amount of twist
of the leaf springs. Again, the four link system reduces the
lateral stability of the vehicle, particularly at the higher speeds
on the road.
[0011] A more simple approach to increase articulation is to simply
move the leaf springs of a conventional leaf spring assembly from
under the axle to over the axle. This is commonly referred to as a
"spring over" suspension or a "lift," as it literally lifts the
body of the vehicle several inches relative to the axle. Because
the leaf springs are above the axle, they are able to flatten more
during compression and may twist more to increase articulation.
However, the amount of articulation is still limited by the amount
of twist of the leaf springs. Also, the increased ability of the
leaf spring to twist and the raised center of gravity reduces the
lateral stability of the vehicle.
[0012] Another more complicated approach, known as a "3/4
elliptical" suspension, uses the spring over suspension, leaving
the leaf springs unattached to the axle. Instead, a long arm is
pivotally connected at the outer end of the vehicle and extends to
rest under the axle. A shorter arm connected to the longer arm
extends to suspend above the axle. As with the four link system,
the leaf springs provide compression and the arms can be adjusted
to provide little or no pressure, resulting in very large amounts
of droop if both sides of the axle are required to droop.
Articulation is increased, but still is limited by the twist or
flex of the leaf springs.
[0013] Many other attempts have been made to increase the
articulation of off road vehicles, particularly leaf spring
assemblies of four wheel drive vehicles and all terrain vehicles.
Nonetheless, a need exists for a new or modified leaf spring
assembly and method to increase articulation, while decreasing the
lateral twisting forces on the leaf springs. A further need exists
to provide such an assembly and method that is sufficiently stable
to allow the vehicle to be driven both off road and on road.
SUMMARY
[0014] The present invention is directed to a structure and method
for increasing articulation of a vehicle. In one embodiment of the
invention, a shackle comprises a first section having a proximal
end and a distal end for connection to a vehicle, a second section
having a proximal end connected to the proximal end of the first
section and a distal end, a third section having a proximal end
rotatably connected to the distal end of the second section and a
distal end for connection to a suspension assembly of the
vehicle.
[0015] A further embodiment of the invention is directed to a
shackle for suspension assemblies in vehicles comprising a first
section having a first leg, a second leg and a piece connecting the
first and second legs. The first and second legs each comprise a
distal end for connection to the frame of a vehicle and a proximal
end that is rotatably connected to the proximal end of a second
section. The second section further comprises a cylindrical distal
end that is rotatably connected to the cylindrical proximal end of
a third section. The third section also comprises a distal end for
connection to the suspension assembly of the vehicle.
[0016] Yet another embodiment of the invention comprises a method
for articulating a vehicle comprising rotating at least part of the
suspension in a direction substantially parallel to the axle of the
vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a side view of a rotating shackle in a closed
position.
[0018] FIG. 2 is a perspective view of the rotating shackle shown
in FIG. 1.
[0019] FIG. 3 is a front plan view of a bushing for the rotating
shackle shown in FIG. 1.
[0020] FIG. 4 is a side plan view of the bushing shown in FIG.
3.
[0021] FIG. 5 is a perspective view of the rotating shackle shown
in FIG. 1 showing rotation of the shackle while in a closed
position.
[0022] FIG. 6 is a perspective view of the rotating shackle shown
in FIG. 1 showing rotation of the shackle while in an open
position.
[0023] FIG. 7 is a perspective view of the rotating shackle shown
in FIG. 1 showing rotation of the shackle while in an open
position.
[0024] FIG. 8 is a side view of the rotating shackle shown in FIG.
1 in a closed position and connected to a vehicle and to a leaf
spring suspension assembly.
[0025] FIG. 9 is a side view of the rotating shackle shown in FIG.
1 in an open position and connected to a vehicle and to a leaf
spring suspension assembly.
[0026] FIG. 10 is a back view of a vehicle having rotating
shackles, in closed, non-rotating positions, connected to its frame
and to its leaf spring suspension assemblies.
[0027] FIG. 11 is a back view of a vehicle having rotating
shackles, one in an open, rotating position and the other in a
closed, rotating position, connected to its frame and to its leaf
spring suspension assemblies.
[0028] FIG. 12 is perspective view of an alternative embodiment of
a rotating shackle in a partially open position to show a
bushing.
DETAILED DESCRIPTION
[0029] One embodiment of the present invention is shown in FIGS.
1-5. A rotating shackle 10 comprises a first section 11, a second
section 30 and a third section 40, each of which have a distal end
and a proximal end, and a bushing 60. Generally, the first section
11 has a distal end for connection to the frame of a vehicle and a
proximal end for connection to the proximal end of the second
section 30. Both of these preferably are pivoting connections, as
set forth in more detail below. The third section 40 has a proximal
end rotatably connected to the distal end of the second section 30
and a distal end for connection, preferably a pivoting connection,
to a suspension assembly of the vehicle. The size, shape,
dimensions, materials, number and configuration of the sections and
other variations and details of the shackle 10 depend on, among
other things, the configuration of the suspension system and
vehicle on which it is to be used, as would be recognized by one of
ordinary skill in the art.
[0030] The embodiment shown in FIGS. 1-5 is specifically designed
for use with Jeep YJ and CJ models manufactured from about 1976 to
about 1996. Similar or alternative embodiments will work for
vehicles from many other manufacturers, including Toyota, Isuzu,
Suzuki and International Harvester. For example, FIG. 12 shows an
alternative embodiment of the invention for installation on a Jeep
XJ model manufactured since about 1984. Similar or alternative
embodiments also will work for other types of vehicles, such as all
terrain vehicles.
[0031] As shown in FIGS. 1-5, the first section 11 preferably
comprises a first leg 12 having a hole 20 at a distal end and a
hole 16 at a proximal end, a second leg 14 having a hole 22 at a
distal end and a hole (not shown) at a proximal end, and a plate 24
connecting the first leg 12 and the second 14. The second section
30 comprises a base 32, a neck 34 and preferably an over extension
stop 36. The third section 40 comprises a neck 42 and a U-shaped
member 44, which further comprises a base 46, a bolt 47, a first
flange 48 having a hole 52, a second flange 50 having a hole 54,
and a port 56.
[0032] The first section 11 comprises holes 20, 22 to allow the
shackle 10 to be connected to the vehicle, preferably by fastening
a bolt through each of holes 20, 22 and through the stock holes on
the bottom side of the vehicle located approximately above the
spring eye of the leaf spring assembly. Alternatively, first
section may be connected with other types of connector known in the
art. Most preferably, the first section 11 is allowed to pivot
about this connection with the vehicle.
[0033] The first leg 12 and the second leg 14 are preferably
fabricated from {fraction (5/16)} inch mild steel and are
preferably approximately the same dimensions. For example, the
preferred length of both legs 12 and 14 is about 4 inches to about
51/4 inches from the center of hole 16 to the center of hole 20,
depending on the vehicle. For the Jeep CJ, the legs 12 and 14 will
be about 4 inches in this dimension. The plate 24 is preferably
mild steel approximately 1/2 inch deep by 1 inch wide and welded to
the first leg 12 and to the second leg 14 about 1 inch below the
center of hole 16 and the corresponding hole (not shown) of the
second leg 14. The length of plate 24, and therefore the distance
between the first leg 12 and the second leg 14, must be sufficient
to accommodate the width of the leaf springs. Typically, the leaf
springs installed on recreational off road vehicles vary from about
2 inches to about 21/2 inches in width and the plate 24 preferably
is about 1/2 inch longer than the width of the leaf springs. In
Jeep YJ, the leaf springs are about 21/2 inches wide and the
preferred length of the plate 24 is about 3 inches.
[0034] If present, first section 11 may take any number of
alternative configurations, including a solid single piece, that
provide a connection, preferably pivoting, to the rotating portion
of the shackle 10 and another connection, preferably pivoting, to
the frame of the vehicle. Variations of materials, including other
metals, alloys, composites and polymers, as well as variations of
dimensions and configurations, would be recognized by one of
ordinary skill in the art.
[0035] The second section 30 comprises a base 32 to connect the
second section 30 to the first section 11. Although this connection
may fixed, preferably it is pivoting. Preferably, the base 32 spans
substantially the entire distance between the first leg 12 and the
second leg 14 and comprises an opening to insert a pin 58, bolt or
other fastener through the first leg 12, the base 32 and the second
leg 14 to provide a pivotal connection.
[0036] The second section 30 also preferably comprises a neck 34
extending from the base 32. Most preferably, second section 30 is
generally T-shaped, with base 32 and neck 34 being welded together.
Preferably, base 32 is a hollow cylinder formed of drive line or
D.O.M. tubing, with a 1 inch inside diameter and a 11/4 inch
outside diameter, and neck 34 has a 1 inch outside diameter and a
1/2 inch threaded hole approximately 21/8 inch deep. Variations of
materials, including other metals, alloys, composites and polymers,
as well as variations of dimensions and configurations, would be
recognized by one of ordinary skill in the art.
[0037] The third section 40 comprises a generally cylindrical neck
42 fixed, preferably by welding, to a U-shaped member 44. The neck
42 of the third section 40 has at least a slightly larger inside
diameter than the outside diameter of the neck 34 of the second
section 30, preferably about 0.003 inch to about 0.005 inch larger.
Most preferably, the neck 42 of the third section 40 is fabricated
of drive line or D.O.M. tubing having a 1 inch inside diameter and
a 1{fraction (5/16)} inch outside diameter. Port 56 may be added to
introduce grease or other lubricants to the interior surface of
neck 42. Variations of materials, including other metals, alloys,
composites and polymers, as well as variations of dimensions and
configurations, would be recognized by one of ordinary skill in the
art.
[0038] Referring particularly now to FIG. 5, the neck 34 of the
second section 30 is generally cylindrical and is fitted for at
least partial insertion into the generally cylindrical neck 42 of
the third section 40. Bolt 47 preferably rotatably connects the
U-shaped member 44 of the third section 40 to a threaded hole in
the neck 34 of the second section 30. Most preferably, bolt 47 is
about {fraction (1/2)} inch by 11/2 inch long. The connection
allows the third section 40 to rotate relative to the second
section 30.
[0039] The U-shaped member 44 comprises a first flange 48 having
hole 52 and a second flange 50 having hole 54 for connecting the
shackle 10 to the spring eye of the suspension system. Preferably,
a bolt or pin or similar fastener is used to allow the third
section 40 to pivot about this connection. The holes 52 and 54
preferably are sized and located for connection at or near the
stock, or standard manufactured, location of the leaf spring
assembly. The U-shaped member 44 may have an alternative size,
shape or configuration, even one that is not U-shaped, depending on
the suspension system that is to be connected, preferably by a
pivoting connection, to the shackle 10.
[0040] The distance between the first flange 48 and the second
flange 50 should be sufficient to accommodate the width of the leaf
spring, and preferably is about the same distance as that between
the first leg 12 and the second leg 14 of the first section 11. The
U-shaped member 44 is preferably fabricated by bending a single
piece of mild steel about 1/4 inch deep and about 13/4 inch wide to
form the base 46, the first flange 48 and the second flange 50.
[0041] As shown in FIGS. 1-5, shackle 10 further comprises a
bushing 60, sized to fit between the first leg 12 and the second
leg 14, as well as between the plate 24 and the neck 34 of the
second section 30 when the shackle 10 is in the closed position. To
accommodate the shape of the neck 34 and thereby support the second
section 30 when the shackle 10 is in a closed position, the bushing
60 preferably has a semi-circular cutout having about a 1 inch
diameter. The bushing 60 is fixed in place by bolts 62 and 64,
which extend through the bushing 60 and into the plate 24. Most
preferably, bushing 60 comprises a Delrin block having a 1/4 inch
hole, with a 3/8 inch countersink, for bolts 62 and 64, and also a
slight taper of about 25 degrees from the side view, on which the
neck 34 may rest. The bushing 60 may be fabricated from a variety
of materials, and preferably is fabricated of resilient and durable
polymers such as nylon, teflon, urethane, or Delrin. Most
preferably, bushing 60 is constructed of Delrin, a polymer mix of
nylon and teflon manufactured by U.S. Plastic of Lima, Ohio.
[0042] Now referring to FIG. 8, a revolving shackle 10 is shown
installed on a vehicle. The first section 11 is attached to frame
80, preferably by bolt 82 and washer 84. The third section 40 is
attached to spring eye 88 of the leaf spring assembly 86,
preferably by bolt 90 and washer 92. When the vehicle is at rest,
the shackle is in a "closed position," as shown in FIG. 8. The
first section 11 typically will extend back toward the axle. The
second section 30 and the third section 40 typically will extend
away from the axle, forming an acute angle with the first section
11. The weight of the vehicle presses the first section 11,
particularly the plate 24, and the bushing 60 onto the neck 34 of
the second section 30. In this way, the shackle 10 is
self-supporting, i.e., the shackle 10 contacts the frame of the
vehicle only where it connects with the first section 11 and
contacts the suspension system only where it connects with the
third section 40.
[0043] The shackle 10 could be installed such that there is little
or no pivoting movement at any of the connections 1) between the
first section 11 and the frame 80, 2) between the first section 11
and the second section 30 and 3) between the third section 40 and
the spring eye 88. If the leaf spring 86 were required to droop or
compress in a vertical direction only, the leaf springs would be
forced to provide the extension for the droop and the
upward/forward movement for the compression.
[0044] However, in actual operation, there is typically a
significant lateral component to such droop and compression, and
particularly so in rock crawling, when one side of the axle
compresses, and the other side does not compress as much, does not
compress at all, or is required to droop. Then the third section 40
of the shackle 10 rotates relative to the second section 30, which
allows the spring eye 88 of the leaf spring assembly 86 to remain
essentially in its resting position, approximately parallel to the
axle. From full compression, even with a negative arch, to fully
extended droop, the rotating shackle 10 allows the spring eye 88 to
remain essentially in its resting position.
[0045] Rotating the third section 40 of the shackle 10 results in
significantly greater articulation, as articulation is no longer
limited by the twist or flex of the spring leaves. Instead, the
rotating shackle 10 provides the articulation, minimizing the twist
or flex of the leaf spring assembly 86 and leaving the leaf spring
assembly 86 to provide the vertical movement of the suspension. By
maintaining the resting position of the spring eye 88, rotating the
shackle 10 also reduces metal fatigue, and thereby increases the
life, of the leaf spring assembly 86.
[0046] Preferably, the shackle 10 comprises a pivotal connection
between the first section 11 and the second section 30, and most
preferably also comprises pivotal connections between the first
section 11 and the frame 80, as well as between the third section
40 and the spring eye 88. As shown in FIG. 9, when the leaf spring
assembly 86 is required to droop, the shackle 10 then is allowed to
"open." Rotating the shackle 10 on both the compression and droop
sides of the axle, coupled with opening the shackle 10, greatly
increases articulation of the vehicle.
[0047] Because the rotating shackle 10 is self-supporting, the leaf
spring assembly 86 is able to start compression earlier, resulting
in a softer action and a more comfortable ride. For example, as can
be seen from FIG. 8, on initial compression of the suspension, the
shackle 10 can close slightly, compressing the bushing 60 and
allowing the leaf spring 86 to start to move before the leaf spring
86 starts to straighten out. This results in a quicker spring
action and a better ride.
[0048] Referring now to FIGS. 10, shackles 10A, 10B are installed
on the frame 80 of vehicle 100 and to spring eyes 88A, 88B of leaf
spring assemblies 86A, 86B, respectively. Vehicle 100 is at rest on
level ground, with no compression, other than the weight of the
vehicle, and no droop on either side of axle 94. Base 32 of the
second section 30 is essentially parallel to spring eye 88, as well
as to the leaves of the leaf spring assembly 86 and the axle 94.
That is, there is little or no twist or flex of the leaf spring
assembly 86 in this position, which is the "resting" position of
spring eye 88.
[0049] Vehicle 100 is then subjected to being driven onto an uneven
surface, as shown in FIG. 11. Leaf spring assembly 86B compresses
to accommodate the higher terrain and shackle 10B rotates,
maintaining the spring eye 88B essentially in its resting position.
This minimizes the pressure on, and therefore the twist or flex of,
the leaves of the leaf spring assembly 86B.
[0050] At the same time, the lower terrain on the other side of the
axle 94 requires that the axle 94 droop from the vehicle frame 80.
Shackle 10A rotates and opens, allowing the axle 94 to droop. If
additional droop is required, the leaf spring assembly 86A extends
the droop further. Again, the rotation of the shackle 10A allows
the spring eye 88A to remain essentially in its resting position,
which minimizes the twist or flex on the leaf spring assembly 86A.
In contrast, in a conventional leaf spring assembly, the droop side
leaf spring will rotate laterally with the axle, thereby limiting
the amount of articulation by the twist or flex of the leaf
springs.
[0051] The rotation of the compression side shackle 10B is an
important element in the ability of the droop side shackle 10A to
fully open and to fully droop. On the compression side of the
vehicle 100 during articulation, the compression side shackle 10B
rotates and allows the compression side leaf spring 86B to stay
essentially parallel to the axle 94, which will bring the
compression side wheel into its wheel well. In turn, this allows
the suspension system to increase the angle between the vehicle
frame 80 and the axle 94, allowing the vehicle to droop further on
the droop side.
[0052] The rotating shackle 10 has improved lateral stability,
particularly for higher speed and on road use, over other designs
to increase articulation. During such driving conditions, the
shackle 10 is in a closed position, with the vehicle weight
supported by the shackle 10, including the bushing 60. The primary
lateral movement of the suspension system is in the bushings of the
frame 80 and spring eye 88.
[0053] The rotating shackle of the present invention may take other
forms in addition to those described herein. For example, the first
section 11 may be essentially omitted or combined with second
section 30 or third section 40, as long as at least a portion of
the shackle, or other structural piece, rotates to assist the
spring eye 88 in remaining substantially in a resting position or
substantially parallel to the rest of the leaf spring and the axle.
The size, shape, dimensions, materials, number and configuration of
the sections and other variations and details of the shackle 10
depend on, among other things, the configuration of the suspension
system and vehicle on which it is to be used, as would be
recognized by one of ordinary skill in the art.
[0054] The foregoing description of the present invention has been
presented for purposes of illustration and description. The
description is not intended to limit the invention to the forms
disclosed herein. Consequently, variations and modifications
commensurate with the above teachings, and the skill or knowledge
of the relevant art, are within the scope of the present invention.
The embodiments described herein are further intended to explain
the best mode known for practicing the invention and to enable
others skilled in the art to utilize the invention in such, or
other, embodiments and with various modifications required by the
particular applications or uses of the present invention. It is
intended that the appended claims be construed to include
embodiments to the extent permitted by the prior art.
* * * * *