Hitch ball the standard sphere usually used in hitches to tow trailers which is accepted by the hitch ball coupler.

Dry} bar the part that entails the hitch ball coupler (close fasten to the trailer) to the receiver (fixed on the car frame). The drawbar shows three parts easy to distinguish: a mount that is a structural bar or lever with a hitch ball fixed on one end side and a fastening device on the other side.

Fasteling device the end side of the drawbar that is accepted by the receiver (with complementary geometrical surfaces) and where it remains tightly locked.

Receiver a concave device with a complementary geometry to the drawbar fastening part which is welded on the car frame.

Hitch a set of pieces consisting on the drawbar (or two hemi-drawbars) and the receiver where it is inserted.

BackAoucd of'the iitveation<BR> Field of t/l e inventiozt This invention is related with hitches for trailers. Specifically, this invention is related to an original designed hitch ball drawbar and the according receiver that is easy attachable and removable with a simple rotational movement without using any tools, screws, spikes, or locking devices.

DescriptioBI oft/lepriorart The hitch design to tow trailers has been commercially consolidated around the world onto known and usual standard hitch balls. We are talking about a square section receiver which lodges a similar shape bar. These pieces are fastened together with one or more screws in a transversal direction (orthogonal) to the receiver-drawbar axis. These transversal screws can be replaced by one coaxial screw to the receiver-drawbar axis. This arrangement improves the access to the set for an easy to install operation, but this system increases the fragility of the set because the weak screw thread will support the load, instead of the body of the screw like in the previous arrangement.

In both cases the use of tools are required to remove the screw and disassemble the drawbar from the receiver.

Another design is a solid rounded section hook with a conic end which is adapted in a complementary shaped receiver. In a similar way a transversal screw locks both pieces. This screw could be replaced by an eccentric spike welded to a lever which is fastened with 1/4 rotation. In this particular case no tools are required.

Both reported designs need to place the receiver on the lower part of the back fender in order to manipulate screws, lever, spike and tools.

The patent literature speaks about several improvements to this solutions but essentially with the same approach to the problem. All the solutions reported maintain the hitch ball sphere's integrity. For general background material, the reader is directed to: U. S. Pat. 6113125, 3600004,3633939, 3655221,3703301, 3716255,3741587, 3756624, 3796444, 3797685,3811706, 3811706,3837675, 3840252,3843161, 3863956,3900212, 3972541, 3990722,4046398, 4088339,4103928, 4119328,4157189, 4168082,4192524, 4220350. 4227713,4240647, 4253679,4256323, 4272098,4361939, 4365820,4398743, 4402523. 4420169,4426097, 4438944,4443025, 4560184,4606549, 4613149,4626154, 4664403. 4699395, 4714264, 4721323,4738464, 4792151,4811967, 4921266,4940096, 4944354. 4950010,4955631, 4968053, 4991864, 5016898,5058915, 5085451,5110024, 5110149, 5161815,5167423, 5259223,5328198, 5332248,5344173, 5378007,5387002, 5435585, 5435586,5472222, 5501481,5503421, 5509682,5516137, 5531560,5575491, 5609350. 5620198, 0093795 Problem to be solved The evolution of the automobile industry replacing the old strong chassis frame with the modern fake chassis makes the hitch installment more difficult to achieve.

The inexistence of a strong frame where to fix the hitch extends the dimension and complexity of the hitch structure itself. This over dimensioned structure of the hitch could contradict the original passive safety design of the car.

On the other hand, this proposal implies an overload on the rear part of the car. The overload of this structure is placed on the most rear part of the car, operating over the rear springs.

In addition, towed vehicles, which are usually manufactured in fiberglass, wood or steel/aluminum foil, make contrast with the over dimensioned steel structure of the hitch. When bicycles or skies or other light sport articles are needed to be loaded outside the car trunk, taking advantage of the hitch possibilities, this over dimensioned structure becomes more evident.

The modern design of the car back fenders shows high and wrapping shapes. In hitch installations, these aesthetic characteristics compel to round-up the rear fender in order to leave the receiver free to fasten the mentioned screw.

This solution causes two main troubles: first, it produces a torque or momentum over the fixed points of the fender that are usually solved by a further over dimension of the hitch structure; and second, the need to allocate the receiver under the rear fender causes another additional problem because it modifies the original rear attack angle designed to pass bumps. Furthermore, the standing legislation prohibits to keep the hitch drawbar on, when you are not making use of it. The difficulty to install and remove the hitch drawbar, taking off screws and using tools, make that many hitch users break the law by leaving it on.

Sunncary of the iiznerition Observing all of the details reported before, we propose a new design for a simple and light hitch (drawbar receiver and fastening arrangement between them), which minimizes moving parts, easy to adapt to the rear fender fixing points of the fake chassis where it will be installed. It is also another object of this invention to generate a creative and innovative mechanism to facilitate the installing and removing operations without tools.

This simplified operation facilitates the removal and induces to obey the regulations when the hitch is not being used.

Brief description of tlte dramings Fig. 1 a shows a front left isometric view of a possible hitch described in this invention ("sigma shape'). showing the receiver, the two hemi-drawbars in fastened position, and the hitch ball in a ready to use shape. Fig. I b and Fig. 1 c show top and left view respectively.

Fig. 2a. Fig. 2b and Fig. 2c show a top view of some different fastening devices possibilities.

Fig. 3a shows a front left isometric view of another possible hitch described in this invention ("hook shape"), showing the receiver, the two hemi-drawbars in unhitching position. Fig. 3b and Fig. 3c show top and left view of the same example respectively.

Detailed description of tize invention The present invention comprises two pieces: drawbar and receiver.

The drawbar is constituted by two approximate symmetrical mirror image (chiral) halves characterized by showing one approx. half fastening device on one side and one approx. half hitch ball on the other end side. The fastening device and the hitch ball become integrated through the attaching operation that locks the drawbar to the receiver and reconstitutes the hitch ball sphere. See Fig. 1, Fig. 2 and Fig. 3. This invention is the unique that does not keep the hitch ball sphere's integrity. Thus, the drawbar acquires its final three dimensional shape through the rotational coupling movement from the part/s of this device. This movement can be very diverse but it is usually a symmetrical rotational action (simultaneously or successively) in opposite (or orthogonal) sense. Another way would be to install the first half drawbar and then lock it by inserting the other half drawbar in a rotational movement too. This second piece locks the first one and itself to the receiver and they integrate the sphere that reconstitutes the hitch ball.

According to this invention the hitch ball mount and the fastening device can acquire different shapes and we can only show some of them as examples : Three examples of fastening device are shown in a top view on Fig. 2. (Fig. 2a symmetrical arc fastening device, Fig. 2b right fastening device which is tangential to the left fastening device; Fig. 2c left square fastening device and right rounded fastening device). The mounts are bended in Sigma shape in order to guarantee the coaxiality of the ball center and the receivers's point of strength application. This coaxial arrangement avoids needless torques over the hitch. In order to avoid relative displacements between each half ball and allowing a working behavior as a solid part. we make an engagement in the ball core.

Other example is shown in the Fig. 3 (Fig. 3a, Fig. 3b and Fig. 3c) where a drawbar like a hook is formed by assembling two symmetrical halves. It has an approx. triangular section in transversal cut view. Right hemi-drawbar is engaged by rotational movement through the fastening device- ball axis and then, successively, left hemi-drawbar is engaged by pivoting on an orthogonal plane. In this case the hitch ball could be constituted by one sphere lessened in a complementary spherical sector in one half drawbar and a spherical sector to the other half drawbar.

The body of the receiver is constituted by a piece with the complementary shape of the mentioned fastening device. In both cases the receiver is allocated behind the fender and tightly fixed to the fake chassis using the same fixation points of the fender. The windows or hole/s of the receiver must be accessible from the rear part of the vehicle in order to introduce the fastening device of the drawbar.

The option to access directly to the receiver through the rear fender allows to profit the original design of the fender fixation points, without any avoidable round-up.

This possibility improves the simplicity and the consequent lightening of the hitch structure. It is important to remember that another object of this invention is to avoid keeping the drawbar attached to the receiver when no trailers are towed. It is easy to understand that the present invention can only remain installed, and tightly fixed on the receiver, if the trailer's hitch ball coupler blocks the detaching movement. In this way, the hitch ball coupler acts as locking device.

These characteristics allow our invention to accomplish the original proposal inducing users to remove the drawbar after its use, according to the regulations.

Operative advantages : According to the present invention we only have three pieces: two moving parts (hemi-drawbars) and one stationary part (receiver).

The drawbar is attached through a simple movement. No tools are needed to execute this movement.

The present invention profits the hitch ball coupler as a locking device to maintain both hemi- drawbars in their working position.

The absence of a locking device when the trailer is unhitched induces the hitch removal according of the regulations.

The simplicity of the fastening mechanism and the minimum frame requirements allow to achieve lighter pieces.

The absence of transversal screws, spikes or pins added to the accessibility from the rear part of the rear fender, passing through a hole or holes made in it, do not imply great aesthetical modifications.

The allocation of the receiver behind the rear fender avoids modification in the rear attack angle designed to pass bumps.

The possibility to adapt racks and load bicycles, skies or other light sport articles.

Technological advantages : All the pieces are made with standard materials, through common operations. The selected sinusoidal or parabolic shapes of the mount prevent or avoid angles that could conform structural critical points.

The coaxiality of the receiver-hitch ball in order to minimize needless torques or momentum over the receiver favorishes the fixation to the chassis and the mechanical behavior.

The section shapes and dimension specifications could be selected to support the typical mechanical solicitations on working actions, according to the fake chassis where it will be mounted.

No materials (metallic or non metallic) are specified in this description because it is possible to select them according to the working operations heaviness. Most of the family or sport uses in class C cars never tow more than 600-700kg according to the vehicle specifications. In these cases plastic hitches, like we claim in this invention, can fulfill all the mechanical requirements with similar safety specifications.

It should be understood that the present invention is not limited to the examples described in the foregoing and that many alternative modes of execution can be contemplated without thereby departing from the scope of the invention as defined in the following claims.