Carrying device mountable on a tow-ball

This is a device where one component is a member which, without recourse to any tools, can be attached to or removed from a tow-ball that is anchored to or integral with a tow-bar. The member is rigidly located and unable to move in any plane or about any axis when it is engaged with the tow-ball and the remainder of the device. The member has an integral platform that can be used to support and or tow any desired object e.g. bicycles on a rack attached to the platform.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable.

Not Applicable.

BACKGROUND OF THE INVENTION

The field of endeavor generally relates to means of mounting a carrier rack on a vehicle and particularly concerns mounting on a tow-ball that is securely attached to or integral with a tow-bar.A variety of mechanisms have been adopted to fulfill the objective of providing a rigidly located member on a tow-bar that has the tow-ball attached. The previously adopted mechanisms fall into one of two categories:1) Category 1. The tow-ball is only used to bolt the member or the base-plate for a member to the tow-bar. In the case of it being a base-plate the member is then rigidly linked to the base-plate by a variety of methods that would be obvious to anyone skilled in the art. With this category the stability of the member is not dependent on any direct engagement between the member and the head of the tow-ball.2) Category 2. The head of the tow-ball is critical to establishing a rigidly located member. Thus far this approach has involved surrounding the head of the tow-ball to a varying degree and using friction to grip the head of the tow-ball. Various means have been described to establish a sufficient compression force to create adequate friction between the member and the tow-ball head to avoid the member slipping from its desired position when subjected to a displacing force. In many instances generating the gripping (compression) force requires a specific tool. U.S. Pat. No. 5,228,607 and New Zealand Patent number 226926 are relevant to the concept of using friction between a tow-ball head and a member to retain the member in a desired position.

Both of the above categories of attachment suffer from the possibility of the member moving substantially, relative to the tow-bar, if the securing-nut on the stem of the tow-ball is not sufficiently tight. In both categories the member can separate completely from the tow-bar if the securing-nut on the stem of the tow-ball comes completely off. An object separating from a tow-bar represents a significant hazard to other road users.

Category 1 mechanisms that are bolted directly to the tow-bar also suffer from the disadvantage of having to unbolt then re-attach the tow-ball each time the device is to be removed or attached.

Category 1 mechanisms that use a base-plate have the advantage of convenience of removal or attachment of the remainder of the member without having to unbolt the tow-ball. Previously disclosed base-plate designs however present certain shortcomings that relate to their type of configuration. There have been two broad types of configuration adopted:

a) a vertical component that extends upwards in close proximity to the tow-ball wherein the vertical component obstructs a ball-coupling articulating with the tow-ball. The obstruction occurs because there is generally insufficient space to locate such a vertical component between the tow-ball and the rear of the vehicle where it would not hinder the articulation of a ball-coupling.

b) a horizontal component that extends for quite a distance to one or both sides of the tow-bar so that vertical elements arising from it cause minimal interference with the range of articulation available to a ball-coupling linked to the tow-ball that secures the base-plate. These bulky horizontal plates represent an impediment to standing behind the vehicle to access the boot (trunk). Such sideways extensions from the tow-bar are also unsightly and a potential hazard to pedestrians.

Category 2 devices invite the risk of the member slipping on the tow-ball if the friction between the tow-ball and the device is inadequate. The friction may be inadequate because the compression force exerted on the tow-ball is inadequate at the outset or declines during use. Friction between the tow-ball and the member is also lowered if the tow-ball is lubricated, as is often the case following use of the tow-ball for towing.

BRIEF SUMMARY OF THE INVENTION

The primary object of this invention is to provide a new and improved device for mounting a readily removable member, which is capable of securely supporting a desired object(s), on a tow-bar that has either an integral or a fitted tow-ball. The improvements are directed at improved safety and overcoming the above listed shortcomings of earlier devices.

A rigidly located member extending from a tow-bar can be put to numerous uses. For example someone skilled in the art could use such an extension to support a rack for carrying bicycles. Additional devices attached to the rigidly located member can be made integral to the member or can be articulated with the member.

The specific aims are that the device provides a means of attaching a member to a tow-bar in a manner that:a) Allows, without recourse to any tools, the member to be readily attached to or to be removed from the remainder of the device which is permanently attached to the tow-bar.b) Precludes significant movement, relative to the tow-bar, of the attached member.c) Requires contact between the member and the tow-ball for its stability and rattle free performance.d) Maintains the desired position of the attached member without frictional engagement between the member and the tow-ball which is integral to or mounted on the tow-bar.e) Leaves the tow-ball accessible for normal articulation with a ball-coupling when the member is not attached to the permanently attached component of the device.f) The permanently attached component of the device does not impede access to the boot (trunk) of the vehicle.g) The permanently attached component of the device does not constitute a hazard to pedestrians beyond that posed by a tow-bar with no attachments.h) Is secure and amenable to locking to discourage theft.i) Is suitable for low cost manufacture.j) Is reliable under demanding conditions over extended periods of time.k) Avoids significant movement of the member relative to the tow-bar if the securing-nut on the stem of the tow-ball is loose.l) Precludes the tow-ball and the device separating from the tow-bar if the securing-nut on the stem of the tow-ball comes completely off.

DETAILED DESCRIPTION OF THE INVENTION

InFIG. 1the tow-bar1has a hole2. The part of the tow-bar1that joins to the back of the associated vehicle (not depicted) is drawn as ragged to distinguish it from the free end which is furthest from the back of the vehicle and has a rounded outline.

In the following description the term “front” applies to being nearer to the vehicle and the term “rear” applies to being further away from the vehicle to which the tow-bar1is attached.

The tow ball3has a seating flange4and a stem5. The tow-ball3is secured with a spring washer6and securing-nut7that fit the stem5after it has passed through the hole8in the anchoring-plate9and the hole2in the tow-bar1.

The bottom face of the anchoring-plate9is flat to engage the flat upper face of the tow-bar1. The rear of the anchoring-plate9is shaped to lie within the outline of the rear of the tow-bar1. The top face of the anchoring-plate9is flat.

Some tow-bars1are angled upwards forward of the tow-ball3(referFIG. 2). The dimensions of anchoring-plate9are therefore set to ensure that when holes8and2align the front edge of anchoring-plate9does not extend forward of the place, if any, where the tow-bar1starts to bend upward. If this requirement is not met the flat anchoring-plate9is distorted when the securing-nut7is tightened and the flange4acts to bend the anchoring-plate9into a contour that matches the angled section of the tow-bar1.

The anchoring-plate9has lugs10and11that extend down and fit snuggly alongside opposite sides of the tow-bar1. The lugs10and11have holes12and13respectively. The diameter of the hitching-pin14is matched to the diameter of the holes12and13. The lugs10and11are long enough to ensure that a hitching-pin14passing between the holes12and13will clear the underside of the tow-bar1.

The shape of the lugs10and11is such that they do not interfere with a spanner tightening the securing-nut7on the stem5after it has passed through the hole8and the hole2. In addition the holes12and13are positioned in a manner that allows the hitching-pin14to pass between them without fouling the securing-nut7or the stem5.

Rotation of the anchoring-plate9, about the axis of the stem5, is limited by the lugs10and11embracing the sides of the tow-bar1. The inability of the anchoring-plate9to rotate on the axis of the stem5is retained even if the securing-nut7is not tight enough to generate sufficient friction between the anchoring-plate9and the tow-bar1to prevent one turning on the other.

The foot-plate15has downward extending lugs16and17that have holes18and19respectively. The diameter of the holes18and19are matched to the diameter of the holes12and13and are positioned so that the hitching-pin14can pass through holes19,13,12and18when the underside of the foot-plate15is uniformly separated from the topside of the anchoring-plate9by a distance of 0.5 to 1 millimeter.

The 0.5 to 1 mm tolerance between the foot-plate15and the anchoring-plate9allows subtle tilting of the foot-plate15about the axis of the hitching-pin14. The relevance of this tolerance and possible tilting relates to fitting the device to tow-balls1which have dimensions which vary slightly from that nominated by the manufacturer. See below for further details.

The lugs16and17fit snuggly alongside the lugs10and11when the foot-plate15is linked to the anchoring-plate9by passing the hitching-pin14through the aligned holes19,13,12and18.

The foot-plate15has a hole20that is centered over the hole8in anchoring-plate9when the holes19,13,12and18are aligned. Hole20is sufficiently large to ensure that the foot-plate15can pass over the tow-ball3and the flange4. The hole20is also large enough to ensure that its edge cannot contact the flange4after the hitching-pin14has located in the holes19,13,12and18.

Tow-balls generally have dimensions that are specified by a government authority. Some governments have safety design rules for tow-balls which mandate that the flange4has a larger diameter than the head of the tow-ball3. The government mandated dimensions generally have a manufacturing tolerance which is typically about 1 mm. The hole20is therefore made large enough to satisfy the size criteria listed in the immediately preceding paragraph, for the largest tow-ball dimension likely to be encountered for the nominated tow-ball size being used.

Permanently attached to the upper surface of the foot-plate15is a tube21. The walls of the tube21are located outside the perimeter of the hole20. InFIG. 1tube21has a square cross-section but a circular or other cross-section is satisfactory provided the walls do not encroach on the hole20.

The top of the tube21has a platform22permanently attached to it. The platform22thus caps the top of the tube21. Any desired attachment26can be rigidly linked to or articulated with the platform22by means that would be obvious to those skilled in the art.Tube21is set to a length that ensures, that even if the locking-nut7is not attached, the tow-ball3can only pass up the tube21to a point where the stem5still protrudes sufficiently through the hole8to engage the hole2while the foot-plate15remains attached to the anchoring-plate9by the hitching-pin14being located across the holes19,13,12and18.

After passing through holes19,13,12and18the hitching-pin14is secured in position with a retaining-pin23through a hole24in its end. The hitching-pin14can have a further suitably located hole25that accepts a padlock to deter removal of the hitching-pin14and theft of any of the illustrated components of the device. Specific hitching-pin locks, which have been described by others, can also be deployed to deter theft.

The lugs10and11on anchoring-plate9are made short enough to preclude the stem5from disengaging with the hole2whenever the hitching-pin14is engaged, below the tow-bar1, with the holes19,13,12and18. This arrangement ensures that it is impossible for the assembled device to separate from the tow-bar1even if the securing-nut7is absent. This arrangement also means that when the hitching-pin14is locked in position it is not possible to steal the device by undoing the securing-nut7.

The rear of the tube21has a threaded hole27that accepts a setting-screw28that in turn carries a locking-nut29. The setting-screw28is critical to controlling rotation of the foot-plate15about the axis of the hitching-pin14. Controlling this rotation stabilizes the position of the tube21relative to the tow-bar1. The setting-screw28is also critical to avoiding rattles between the foot-plate15and the anchoring-plate9and also rattles between the tube21and the tow-ball3.

The integrity of the connection between the anchoring-plate9and the foot-plate15is assured whenever the hitching-pin14is permanently engaged in the holes19,13,12and18. The setting-screw28is only necessary to avoid undue rotation of the foot-plate15around the axis of the hitching-pin14. The setting-screw28is tightened just up to the point where no rotation of the foot-plate15, about the hitching-pin14, is possible. Over tightening setting-screw28results in a constant compression force on the tow-ball3and this makes it impractical to readily insert and remove the hitching-pin14through the holes19,13,12and18.

The setting-screw28is made only finger tight to eliminate rattles and is then locked in position with the locking-nut29. The setting-screw28may need readjustment at a later time if significant wear or distortion of the engaged components occurs with prolonged use.

The setting-screw28does not perform the same function as the “T” locks (parts17) disclosed in New Zealand Patent number 226926. Those “T” locks generate constant compression forces against a tow-ball and thereby friction between the tow-ball and the “T” locks as well as friction between the tow-ball and the cylinder supporting the “T” locks. The stability of the device disclosed in the current application is not dependent upon friction between the tow-ball3and the setting-screw28.

In addition the properly adjusted setting-screw28does not need to be tightened or loosened every time the tube21is engaged with or removed from the tow-ball3. This is totally different to the mechanism disclosed in New Zealand Patent number 226926 where the “T” locks have to be released and tightened each time that mechanism is attached to or removed from a tow-ball.

When the tow-ball3has known dimensions, which do not vary between batches, there is no need for a setting screw28if the internal dimensions of the tube21, at the level of the head of the tow-ball3, is matched to the diameter of the equator of the head of the tow-ball3

Referring now toFIG. 2, this is a side view of the device fitted to a tow-bar1that has an angulated segment between the tow-ball3and the vehicle (not illustrated). The various components are numbered as forFIG. 1. The part of the tow-ball3and the setting-screw28that are inside the tube21are depicted with broken lines.

FIG. 2clarifies how, with the hitching-pin14in place, the device cannot release from the tow-bar1, even if the securing-nut7is absent.FIG. 2also demonstrates how the setting-screw28can avoid rattles by tilting the tube21, about the axis of the hitching-pin14, and thereby simultaneously taking up any slack between the rear of the tow-ball3and the neighboring face of the inside of the tube21as well as between the underside of the foot-plate15and the topside of the anchoring-plate9. Point A indicates the location where the underside of the tilted foot-plate15contacts the topside of the anchoring-plate9.

It should be appreciated that modifications and alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention. For example, any alternative means, such as welding, of securely attaching anchoring-plate9to the tow-bar1may be adapted. Alternative means of attaching anchoring-plate9to the tow-bar1would be essential if the tow-ball3was manufactured as an integral part of the tow-bar1.