U.S. patent application number 12/186788 was filed with the patent office on 2009-02-12 for tow hitch.
Invention is credited to Thomas A. Gries.
Application Number | 20090039619 12/186788 |
Document ID | / |
Family ID | 40339651 |
Filed Date | 2009-02-12 |
United States Patent
Application |
20090039619 |
Kind Code |
A1 |
Gries; Thomas A. |
February 12, 2009 |
TOW HITCH
Abstract
A tow hitch comprises an elongated tubular shank of rectangular
cross-section having four side walls; and at least one tow ball
mounted to an adjacent side wall of the shank with a mounting shank
extending from a base of the tow ball through a first hole in the
adjacent side wall and a second hole in a side wall opposite the
adjacent side wall.
Inventors: |
Gries; Thomas A.; (Solon,
OH) |
Correspondence
Address: |
RENNER OTTO BOISSELLE & SKLAR, LLP
1621 EUCLID AVENUE, NINETEENTH FLOOR
CLEVELAND
OH
44115
US
|
Family ID: |
40339651 |
Appl. No.: |
12/186788 |
Filed: |
August 6, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60954217 |
Aug 6, 2007 |
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Current U.S.
Class: |
280/511 |
Current CPC
Class: |
B60D 1/06 20130101; B60D
1/583 20130101; B60D 1/52 20130101; B60D 1/065 20130101; B60D 1/07
20130101; B60D 1/02 20130101 |
Class at
Publication: |
280/511 |
International
Class: |
B60D 1/06 20060101
B60D001/06 |
Claims
1. A tow hitch comprising an elongated tubular mount of rectangular
cross-section, the mount having four side walls; and at least one
tow ball mounted to an adjacent side wall of the mount, the tow
ball having a mounting shank extending from a base of the tow ball
through a first hole in the adjacent side wall and a second hole in
a side wall opposite the adjacent side wall.
2. A tow hitch as set forth in claim 1, wherein the first and
second holes receive the ball shank with a close fit.
3. A tow hitch as set forth in claim 1, wherein the tow ball is
secured in place by welding of the ball base and/or distal end of
the ball shank to the respective side wall of the tubular
mount.
4. A tow hitch as set forth in claim 1, wherein the tow ball is
secured in place by a nut threaded onto a threaded distal end of
the ball shank.
5. A tow hitch as set forth in claim 1, wherein the tubular mount
is formed unitary with a shank configured at an end opposite the
ball for receipt in a tow hitch receiver.
6. A tow hitch as set forth in claim 1, comprising a spacer
interposed between the adjacent side wall and the side wall
opposite the adjacent side wall.
7. A tow hitch as set forth in claim 6, wherein the spacer has a
length corresponding to the distance between opposed inner surfaces
of the adjacent side wall and the side wall opposite the adjacent
side wall.
8. A tow hitch as set forth in claim 6, wherein the spacer is
tubular and surrounds an intermediate portion of the ball shank.
Description
[0001] The present invention relates generally to devices and
methods for towing a trailer behind a vehicle, and more
particularly to tow hitches.
BACKGROUND OF THE INVENTION
[0002] Tow hitches are commonly used for towing one vehicle behind
another. Such an assembly generally comprises a tow ball that is
secured to the rear of a towing vehicle and a coupler or receiver
for the tow ball that is attached to the trailer or vehicle to be
towed.
[0003] Multi-ball tow hitches are disclosed in U.S. Pat. Nos.
3,922,006, 4,280,713, 4,248,450 and 5,839,744, and in U.S. Design
Patent No. 356,764. These tow hitches employ a four-sided tubular
ball mount and multiple tow balls of different sizes that are
welded to a side wall of the ball mount or attached by a threaded
shank and nut.
[0004] Another tow hitch is disclosed in U.S. Pat. No. 7,044,494.
In this hitch, different size balls are welded to respective side
surfaces of a four-sided solid shank. The solid shank was
considered necessary to satisfying higher capacity requirements,
such as a ball/pintle capacity of at least 10,000 pounds in the tow
hitch shown in the '494 patent. The solid shank contributed a
substantial part of the overall weight of the tow hitch.
SUMMARY OF THE INVENTION
[0005] The inventor of the present invention recognized that
significant weight reduction could be achieved by using a hollow
tubular ball mount, but tests proved that known designs could not
satisfy higher capacity requirements, such as a ball and/or pintle
capacity of at least 10,000 pounds. The side wall of the tubular
mount to which the pintle ball was attached was found to crumple
when subjected to the higher loads. While the thickness of the side
wall could be increased, this would lead to increased weight and
thus suffer from the same problem arising from use of the solid
shank.
[0006] The present inventor discovered that higher capacity could
be obtained with a tubular ball mount if the pintle or largest ball
of the tow hitch was provided with a mounting shank that extended
through a hole in the immediately adjacent side wall of the tubular
ball mount and also through a hole in the opposite side wall of the
tubular ball mount. Preferably the holes receive the shank with a
close fit. The ball may be secured in place by welding of the ball
base and/or distal end of the shank to the respective side wall of
the tubular mount. The tubular mount preferably is formed by one
end of a single piece tubular shank sized to fit within a receiver
tube on the towing vehicle.
[0007] Accordingly, the present invention provides a tow hitch
comprising an elongated tubular mount of rectangular cross-section,
the mount having four side walls; and at least one tow ball mounted
to an adjacent side wall of the mount, the tow ball having a
mounting shank extending from a base of the tow ball through a
first hole in the adjacent side wall and a second hole in a side
wall opposite the adjacent side wall.
[0008] In a preferred embodiment, the first and second holes
receive the ball shank with a close fit.
[0009] The tow ball may be secured in place by welding of the ball
base and/or distal end of the ball shank to the respective side
wall of the tubular mount, or by a nut threaded onto a threaded
distal end of the ball shank.
[0010] The tubular mount may be formed unitary with a shank
configured at an end opposite the ball for receipt in a tow hitch
receiver.
[0011] The tow hitch may include a spacer interposed between the
adjacent side wall and the side wall opposite the adjacent side
wall. The spacer preferably has a length corresponding to the
distance between opposed inner surfaces of the adjacent side wall
and the side wall opposite the adjacent side wall. The spacer
preferably is tubular and surrounds an intermediate portion of the
ball shank.
[0012] The foregoing and other features of the invention are
hereinafter described with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In the annexed drawings,
[0014] FIG. 1 is an exploded perspective view of a prior art tow
hitch employing a solid shank;
[0015] FIG. 2 is a side elevational view of a hitch assembly
including the tow hitch of FIG. 1 and a receiver, partly broken
away in section;
[0016] FIG. 3 is a plan view of the hitch assembly of FIG. 2,
partly broken away in section;
[0017] FIG. 4 is a side elevational view similar to FIG. 2, but
showing a locking jaw in an open position;
[0018] FIG. 5 is a perspective view of an exemplary tow hitch
employing a hollow tubular shank in accordance with the
invention;
[0019] FIG. 6 is a side elevational view of the tow hitch of FIG.
5;
[0020] FIG. 7 is an end view of the tow hitch of FIG. 5;
[0021] FIG. 8 is an end view similar to FIG. 7, with the tow hitch
provided with an optional tubular spacer and with the end of the
shank having a chamfer to facilitate welding; and
[0022] FIG. 9 is an end view similar to FIG. 8, but showing an
alternative means for attaching the larger ball to the tubular
mount.
DETAILED DESCRIPTION
[0023] Referring now to the drawings, FIG. 1 shows the tow hitch of
U.S. Pat. No. 7,044,494, which is hereby incorporated herein by
reference. The tow hitch 10 includes an elongated shank 12 having a
first end 14 and a second end 16. The shank 12 has a rectangular
cross-section and has a first side surface 12a, a second side
surface 12b, a third side surface 12c, and a fourth side surface
12d.
[0024] The first end 14 of shank 12 is dimensioned to be received
within a receiving mount (receiver) 22, best seen in FIG. 2, that
may be attached to a towing vehicle (not shown). The receiver 22,
as shown, typically is a tubular structure having an opening 24 of
rectangular cross-section extending therethrough. The receiver 22
is formed as part of a towing vehicle, or is secured to a towing
vehicle in a conventionally known fashion.
[0025] The first end 14 of the shank 12 is dimensioned to be
slidably received within opening 24 in receiving mount 22, as
illustrated in FIG. 2. A first bore 32 extends laterally through
the shank 12. The first bore 32 extends from the first side surface
12a to the third side surface 12c. A second bore 34 extends through
the shank 12. The second bore 34 is offset from first bore 32 along
the length of shank 12. The second bore 34 extends from the second
side surface 12b to the fourth side surface 12d. The bores 32 and
34 are positioned through shank 12 to be alignable with openings in
the receiver 22 depending upon the orientation of shank 12. A
locking pin may be inserted through the aligned openings to secure
the shank in the receiver.
[0026] Referring now to second end 16 of shank 12, a plurality of
tow balls are joined to the shank 12. The tow balls 52a, 52b and
52c are sized differently to allow the tow hitch 10 to mate with
differently sized couplers. Preferably, first tow ball 52a is
coupled to the first side face 12a, the second tow ball 52b is
coupled to the second side face 12b, and the third tow ball 52c is
coupled to the third side face 12c on shank 12. Each tow ball 52a,
52b, 52c includes a spherical portion and a base portion. Each tow
ball 52a, 52b, 52c is fixedly secured to the shank 12 preferably by
welding.
[0027] A locking jaw 72 is pivotally mounted to shank 12. The jaw
72 is dimensioned to engage a tow ball, and to form a
ring-retaining space between the shank 12 and the jaw 72. In this
respect, the jaw 72 is generally "L" shaped and has a generally
planar body portion 74 and two spaced-apart leg portions 76 that
extend to one side of the body portion 74. In the embodiment shown,
each leg portion 76 is essentially a mirror image of the other.
Each leg portion 76 has a mounting hole 78 formed therethrough. The
mounting opening in one leg portion 76 is axially aligned with the
mounting hole in the other leg portion 76. Each leg portion 76 also
includes a first locking hole 82 and a second locking hole 84. The
first and second locking holes 82 and 84 on one leg portion 76 are
aligned respectively with first and second locking holes 82 and 84
on the other leg portion 76.
[0028] The jaw 72 has a free end 92 that is formed to have a
surface 94 to matingly engage one of tow balls 52, 52b, 52c. In the
embodiment shown, surface 94 is a spherical surface and is
dimensioned to matingly engage the spherical portion of tow ball
52b which typically will be the largest diameter ball.
[0029] The jaw 72 is dimensioned to be mounted to the shank 12 with
leg portions 76 straddling shank 12. The jaw 72 is mounted to shank
12 by means of a hex-head bolt 112 extending through mounting
openings 78 in leg portions 76, and through a mounting bore 122 in
the shank 12. The bore 122 extends from first side surface 12a to
third side surface 12c. A hex nut 114 maintains hex-head bolt 112
in place.
[0030] The locking jaw 72 is movable between a first, ball-engaging
position, seen in FIG. 2, and a second, opened position, seen in
FIG. 4.
[0031] A locking pin 132 is provided for the locking jaw 72. The
jaw 72 is locked in the first position by locking pin 132 extending
through first locking holes 82 in jaw 72. The locking pin 132 has a
first bent end 132a and a second end 132b with a hole 134
therethrough. The hole 134 in second end 132b of locking pin 132 is
dimensioned to receive a conventional cotter pin 136, as
illustrated in FIG. 2. In the position shown in FIG. 2, the locking
pin 132 prevents clockwise rotation of the jaw 72 by engaging the
side surface 12b of the shank 12. Engagement between the tow ball
52b and the surface 94 of the jaw 72 prevents counterclockwise
rotation of jaw 72.
[0032] In the second position shown in FIG. 4, the locking pin 132
extends through the second locking holes 84 in the jaw 72. Rotation
of jaw 72 in a counterclockwise direction about the axis of the
bolt 112 is prevented by the locking pin 132 engaging the side
surface 12d of the shank 12. Rotation of the jaw 72 in a clockwise
direction is prevented by contact of the body portion 74 with the
surface 12b of the shank 12.
[0033] The tow hitch 10 is capable of towing different trailer
vehicles that may require different tow balls or a towing vehicle
that is equipped with a towing ring or like arrangement. The tow
hitch 10 is used by inserting the shank 12 into the opening 24 of
receiving mount 22. If one of the tow balls 52a, 52b or 52c is to
be used, the shank 12 is oriented within the receiver 22 to
position the desired tow ball in a vertical position. If tow ball
52a or 52c is in use, the jaw 72 is preferably locked in the first
position engaging the tow ball 52b. If tow ball 52b is to be used
for coupling to a tow ball connector (shown in phantom and
designated 152 in FIG. 4), the jaw 72 is moved and locked into the
second, opened position by inserting the locking pin 132 through
the second locking holes 84 in the leg portions 76 such that the
locking pin 132 is disposed beneath the side surface 12d.
[0034] If a Lunette eye or ring coupler (shown in FIGS. 2 and 3 and
designated 162) is to be attached to the tow hitch 10, the jaw 72
is moved to a second position to allow the ring to be inserted over
the second tow ball 52b, as illustrated in FIG. 4. The jaw 72 is
then pivoted to where surface 94 abuts the spherical portion of the
tow ball 52b. The jaw 72 is locked in this position by inserting
the locking pin 132 through the first locking holes 82 of the leg
portions 76 and inserting a cotter pin 136 into hole 134 of the
locking pin 132 to thereby prevent removal of the locking pin 132.
In this configuration, the tow ball 52b acts as a pintle for the
ring or Lunette eye.
[0035] Turning now to FIGS. 5-7, an exemplary tow hitch according
to the present invention is designated generally by reference
numeral 160. In its illustrated simplistic form, the tow hitch 160
comprises a tubular shank 162 to which one or more balls are
secured. In the illustrated embodiment, three different size tow
balls 164a, 164b and 164c are secured to respective side walls
166a, 166b and 156c of the tubular shank. The shank, which
preferably is square in cross-section, has a further side wall 166d
opposite side wall 166b.
[0036] In the illustrated simplistic form, the shank at its end
opposite the balls is provided with lock pin holes 170a, 170b, 170c
and 170d in respective side walls 166a, 166b, 166c and 166d. The
holes 170a and 170c are aligned, as are the holes 170b and 170d. As
above described, such an arrangement of holes enable the hitch to
be secured in a receiver in one of several relatively rotated
positions respectively positioning the balls at the top of the tow
hitch. In FIGS. 5-7 the holes reside in the same transverse plane,
but respective pairs could be offset as shown above in FIGS. 1-4.
Accordingly, any one of the three balls can be selected for
use.
[0037] In addition, the tow hitch may be configured with a jaw and
other features of the tow hitch shown in FIGS. 1-4, as will be
appreciated by those skilled in the art. The jaw would usually be
used in relation to the largest diameter ball 170b for use with a
Lunette eye or ring coupler as above described.
[0038] A significant difference between the tow hitch of FIGS. 1-4
and FIGS. 5-7 is that the mount 176 for the balls is tubular, and
the ball 170b is secured to the mount in a unique manner. As shown
and preferred, the tubular mount 176 may be formed by the end of
the shank 162 which is preferably tubular along its entire length
for reducing the weight of the tow hitch 160.
[0039] The tow balls 164a and 164c may be fastened to the tubular
mount in a conventional manner, such as by welding the base 178a
and 178c of each ball to a respective side wall 166a and 166c of
the mount. The other tow ball 164b, however, is uniquely fastened
to the tubular mount by means of a ball shank 180 that extends
through a hole in the adjacent side wall engaged by the base 178b
of the tow ball and also through an aligned hole in the opposite
side wall 178d. Preferably the holes receive the ball shank with a
close fit. The tow ball 164b may be secured in place by welding of
the ball base 178b and/or distal end of the ball shank to the
respective side wall of the tubular mount. The ball shank 180 may
be unitary with the tow ball 164b, as by being formed from the same
forging or casting, or it may be assembled to the tow ball.
[0040] As seen in FIG. 8, the distal end of the ball shank 180 may
be provided with a chamfer 184 to facilitate welding. In addition,
an intermediate portion of the ball shank 180 may be surrounded by
a tubular spacer 186 positioned between the side walls through
which the shank extends. The spacer preferably has an axial length
corresponding to the spacing between the inner surfaces of the side
wall to provide a close fit that serves to further rigidify the
tubular mount and provide further resistance to collapse of the
tubular mount under high loads.
[0041] Alternatively or additionally, the ball shank 180, as shown
in FIG. 9, may have a threaded portion 188 extending beyond the
opposite side wall and a nut 190 threaded thereon and tightened
against the opposite side wall to hold the tow ball to the tubular
mount. Again, the ball shank 180 may be surrounded by a tubular
spacer 186 positioned between the side walls through which the
shank extends. The spacer preferably has an axial length
corresponding to the spacing between the inner surfaces of the side
wall to provide a close fit that serves to further rigidify the
tubular mount and provide further resistance to collapse of the
tubular mount under high loads. The spacer also resists crushing of
the tubular mount if a high torque is applied to the nut 190. To
prevent loosening of the nut 190, a lock nut 192 may be threaded on
the threaded end of the shank.
[0042] The foregoing manner of mounting the tow ball 164b has been
found to allow for greater loads to be applied to the tow ball
164b, particularly when used as a pintle.
[0043] Although the invention has been shown and described with
respect to a certain preferred embodiment or embodiments, it is
obvious that equivalent alterations and modifications will occur to
others skilled in the art upon the reading and understanding of
this specification and the annexed drawings. In particular regard
to the various functions performed by the above described elements
(components, assemblies, devices, compositions, etc.), the terms
(including a reference to a "means") used to describe such elements
are intended to correspond, unless otherwise indicated, to any
element which performs the specified function of the described
element (i.e., that is functionally equivalent), even though not
structurally equivalent to the disclosed structure which performs
the function in the herein illustrated exemplary embodiment or
embodiments of the invention. In addition, while a particular
feature of the invention may have been described above with respect
to only one or more of several illustrated embodiments, such
feature may be combined with one or more other features of the
other embodiments, as may be desired and advantageous for any given
or particular application.
* * * * *