AU2014100064A4 - An improved tow bar preventing rotation of the tow ball - Google Patents

Abstract

A tow bar including a draw bar adapted to be attached to a vehicle. The tow bar includes a tongue extending from the draw bar and having an aperture to be engaged by a threaded shaft of a tow ball. The tow ball and tongue having engaging surfaces so that when the tow ball is mounted on the tongue it is prevented from rotating. Typically this is two opposite flat surface on the flange that engage equivalent protrusions on the tongue. Alternatively the tongue may have an indent to be engaged by the tow ball, the indent and the tow ball so shaped to prevent the tow ball from rotating when mounted on the tow bar. $4 14 Fiur7

Description

1 An improved tow bar preventing rotation of the tow ball FIELD OF THE INVENTION [0001] The present invention relates to a tow bar and, in particular, to a tow bar adapted to be engaged by a tow ball the tow bar and the tow ball configured to prevent rotation of the tow ball when it is mounted to the tow bar. BACKGROUND [0002] There exist today many tow bars that aim to facilitate the attachment of a trailer to a vehicle. The tow bars include a draw bar that is attached to a vehicle and a tongue to which is attached a tow ball, the tow ball engaged by a trailer coupling. [0003] However in order to attach, remove or adjust the tightness of the ball onto the tow bar to which it is attached one needs to use a wrench on the nut on the underside of the bar. That at times may be physically challenging when trying to access the underside of the tow bar and requires the user to support the wrench in position whilst trying to rotate it. A further problem is that when a tow ball is used and adjusted on painted tow bars, the adjustment often leads to scratching of the paint. [0004] In order to overcome this problem tow balls have been developed that include a flange having two opposite flat surfaces that can be engaged by a wrench so as to prevent rotational movement of the two ball when the nut on the underside is being screwed or unscrewed. This requires the user to not only stop the tow ball from rotating but also to engage the nut requiring two tools to be used at the same time. [0005] It is therefore the object of this invention to overcome at least some of the above-mentioned problems or provide the public with a useful alternative. SUMMARY OF THE INVENTION 2 [0006] Therefore, in one form of the invention there is proposed a tow bar including: a draw bar adapted to be attached to a vehicle; a tongue extending from said draw bar and having an aperture to be engaged by a threaded shaft of a tow ball; the tow ball and tongue having engaging surfaces so that when the tow ball is mounted on the tongue it is prevented from rotating. [0007] In preference the tow ball includes a flange having an outer flat surface adapted to be engaged by a protrusion extending from said tongue. [0008] In preference the tongue includes an indent having a shape with at least one flat surface adapted to be engaged by a tow ball having a correspondingly shaped flat surface on the flange. [0009] In preference the tongue includes two opposite protrusions adapted to engage the tow ball flange flat surface. DRAWING LABELS [0010] The drawings include items labeled as follows: 10 tow bar 12 draw bar 14 aperture 16 tongue 18 hole 20 tow ball 22 threaded member 24 flange 26 flat surface 28 protrusion BRIEF DESCRIPTION OF THE DRAWINGS [0011] Figure 1 illustrates a tow bar according to an embodiment of the present invention; 3 [0012] Figure 2 is the tow bar of Figure 1 before a tow ball is mounted thereto; [0013] Figure 3 is the tow bar having a mounted tow ball; and [0014] Figure 4 is an alternate embodiment of the tow bar. DESCRIPTION OF THE PREFERRED EMBODIMENT [0015] The following detailed description of a preferred embodiment of the invention refers to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. As used herein, any usage of terms that suggest an absolute orientation (e.g. "top", "bottom", "front", "back", "horizontal", etc.) are for illustrative convenience and refer to the orientation shown in a particular figure. However, such terms are not to be construed in a limiting sense as it is contemplated that various components may in practice be utilized in orientations that are the same as, or different than those, described or shown. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration. In particular the present invention relates to a ceiling system which inherently includes long elements with relatively small features. Such elements have been shown shortened to aid clarity. [0016] In the drawings a tow bar 10 includes a draw bar 12 adapted to be attached to a vehicle as is well known in the art and wherein a pin or the like passing through aperture 14 locks the draw bar to the vehicle. [0017] Attached to the draw bar is a tongue 16 including a hole 18 adapted to be engaged by tow ball 20. The tow ball 20 includes a threaded member or shaft 22 that passes through the tongue and a washer and nut (not shown) are used to firmly attach the tow ball to the tongue to be then able to be engaged by a trailer coupling. [0018] The tow ball includes a flange 24 that sits on top of the tongue. Typically the flange is of a circular configuration but in some instance the flange may include a non-circular outer surface such as opposite flat surfaces 26. These typically allow the user to, by using a wrench or other suitable tool, 4 prevent rotation of the tow ball whilst a nut is being screwed onto the threaded shaft. [0019] In order to obviate the need for a wrench the present invention teaches that the tongue includes at least one upstanding protrusion 28 that is adapted to engage the flat surface 26 of the tow ball. The reader will instantly appreciate that this acts as a tool to prevent rotation of the tow ball and means that when it is being screwed onto the tongue the user only needs to worry about screwing a nut onto the tow ball. [0020] Illustrated in the Figures are two opposite protrusions extending upward from the tongue and having flat inner surfaces. It is of course to be understood that the number of protrusions may be varied together with their location on the tongue and the skilled addressee may make numerous designs that achieve the same result. [0021] Although not shown, instead of protrusions the tongue may include an indent to house the tow ball and have an internal wall at least some of which is non-circular and correspondingly shaped to the tow ball to prevent rotational movement of it. [0022] It is also to be understood that whilst the tongue may be lower than the draw bar, in some instance it may be higher as illustrated in Figure 4. [0023] It is to be understood that the shape of the tow ball flange is not intended to be limited to the embodiment shown. For example, in an alternate embodiment which is not shown, the flange ridge cut into it instead of the two parallel flattened edges 16. In another alternate embodiment, the flange could have multiple sets of parallel flattened edges, forming for example a square, a hexagon, or an octagon. [0024] In so far as the dimensions of the device are concerned, this is dependent on the regulations for tow ball dimensions in the region it is being sold. In Australia it is envisaged that the ball 26 is 50mm in diameter to conform to Australian standard 4177.2 and the thread 18 is 20mm in diameter and 65mm in length, for maximum strength and reliability. The flange 14 would be approximately 55mm in diameter at the rounded edges, and approximately 43mm at the parallel flattened edges 16.

5 [0025] Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognised that departures may be made from within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. [0026] In any claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further features in various embodiments of the invention.

Claims (4)

1. A tow bar including: a draw bar adapted to be attached to a vehicle; a tongue extending from said draw bar and having an aperture to be engaged by a threaded shaft of a tow ball; the tow ball and tongue having engaging surfaces so that when the tow ball is mounted on the tongue it is prevented from rotating.

2. A tow bar as in claim 1 wherein the tow ball includes a flange having an outer flat surface adapted to be engaged by a protrusion extending from said tongue.

3. A tow bar as in claim 1 wherein the tongue includes an indent having a shape with at least one flat surface adapted to be engaged by the tow ball having a correspondingly shaped flat surface on the flange.

4. A tow bar as in claim 1 wherein the tongue includes two opposite protrusions adapted to engage the tow ball flange flat surface.