BACKGROUND OF THE INVENTION

The invention relates to an assembly of a tow hitch and a tow hitch adapter that can be placed thereon for attaching accessories to the tow hitch.

Such assemblies usually comprise a standard tow hitch having a tow ball at a tow bar, wherein accessories, such as for instance a bike rack, are attached with as little rotation as possible to the tow ball and/or the tow bar by means of a coupling. To that end the coupling has a part that engages about the tow ball in order to subsequently be secured to the tow ball using one or several screw pins. Due to the round shape of the tow ball the attachment offers insufficient stability. For that reason additional coupling members may be attached to the tow bar, such as horizontally or vertically positioned connecting bushes, with which by means of screw pins additional connections can be made between the tow hitch and the coupling. As the additional coupling members often are difficult to remove from the tow hitch, they usually are left as protrusions after use of the accessory, as a result of which they are unnecessarily in the way and constitute an injury hazard. Tow hitch adapters are known per se that can be clamped to the tow ball without leaving additional coupling members. Due to the round shape of the tow ball such adapters, however, offer an insufficiently stable connection.

It is an object of the invention to provide an assembly of a tow hitch and a tow hitch adapter that can be placed thereon for attaching accessories to the tow hitch wherein the fastening means at the tow hitch constitute a minor obstacle or minor injury hazard.

It is a further object of the invention to provide an assembly of a tow hitch and a tow hitch adapter that can be placed thereon for attaching accessories to the tow hitch with which in a simple way the freedom of movement between the tow hitch and the adapter is blocked in several, preferably all directions.

It is a further object of the invention to provide an assembly of a tow hitch and a tow hitch adapter that can be placed thereon for attaching accessories to the tow hitch with which the freedom of movement between the tow hitch and the adapter is stably blocked in all directions.

SUMMARY OF THE INVENTION

At least one of the above-mentioned objects, from a first aspect of the invention, is achieved with an assembly of a tow hitch and a tow hitch adapter that can be placed on a free end of the tow hitch for attaching an accessory to the tow hitch, wherein the tow hitch comprises a tow bar having a tow ball thereon, and wherein the tow hitch adapter comprises a holder having fastening means for at least partially engaging about the tow ball when placing the tow hitch adapter on the tow hitch, wherein the assembly comprises a holder with a locking body for from the tow hitch adapter engaging into at least one locking hole in the free end of the tow hitch.

Due to the internal position of the locking hole in the tow hitch, the tow hitch can be free from extra protruding parts for the attachment of accessories to the tow hitch.

Preferably the locking hole is situated in the tow ball. An advantage thereof is that the tow hitch adapter can be compact as a result as it already engages about the tow ball.

Placing the tow hitch adapter on the tow hitch is facilitated when the locking hole extends into the tow hitch in a placing direction of the tow hitch adapter. Preferably the locking body and the locking hole are positioned for placing the locking body in the locking hole during placing the tow hitch adapter on the tow hitch in the placing direction.

Rotation of the tow hitch adapter about a centre line of the locking hole and the locking body is counteracted when, in a cross-section transverse to their centre line, the locking hole and the locking body have an unround shape.

Such rotations are particularly counteracted when, in a cross-section transverse to their centre line, the locking hole and the locking body have a polygonal shape.

In a simple embodiment, in a cross-section transverse to their centre line, the locking hole and the locking body are square.

Pressure forces on the locking body can remain limited when the tow hitch adapter comprises a support surface which in engagement direction of the locking body is positioned receded from the insertion end of the locking body, wherein in engaged condition of the locking body in the locking hole, the support surface and the tow ball at least partially snugly abut. Due to the limited pressure forces it can be prevented that the locking body gets inadvertently stuck in the locking hole.

In engaged condition of the locking body in the locking hole, a circumferential wall of the locking body and a circumferential wall of the locking hole preferably mutually at least partially snugly abut, due to which play between the locking body and the locking hole is minimal or even entirely impossible.

Preferably the locking body tapers in engagement direction. In this way a press fit can be effected between the locking body and the locking hole when accommodating the tow ball so as to engage about it with the fastening means. Moreover the tapering shape compensates wear of the locking hole by in the long run having the locking body penetrate the locking hole deeper and deeper.

Alternatively or additionally the locking hole tapers from an outside of the tow hitch, preferably at the same angle as the tapering locking body.

If the locking hole is a blind hole, the quantity of material that has to be left out for the locking hole can remain limited, due to which the presence of the locking hole does not or hardly affects the strength of the tow hitch.

In addition, in engaged condition of the locking body in the locking hole, an end face of the locking body and a bottom surface of the locking hole can at least partially snugly abut, so that said bottom surface is able to transfer a part of the load of the accessory to the tow hitch. In an easy-to-manufacture embodiment, in engaged condition of the locking body in the locking hole, a centre line of the locking hole and the locking body is concentric to the centre of the tow ball.

Alternatively or additionally, in engaged condition of the locking body in the locking hole, a centre line of the locking hole and the locking body is eccentric to the centre of the tow ball. Due to the eccentric position rotations of the tow hitch adapter about the tow ball are counteracted.

The tow hitch adapter, when the locking body is already inserted into the locking hole, can to a limited degree be moved or swung with respect to the tow hitch when the locking body is within limits movably connected to the fastening means. Such a movement may for instance be used for operating the fastening means or folding up a bike rack.

In a separate action, separate from placing the tow hitch adapter, the locking body can be brought into the locking hole if the locking body and/or the holder of the locking body is detachable from the tow hitch adapter.

In a simple embodiment the locking body is fixedly connected to the holder for the locking body, so that when placing the tow hitch adapter onto the tow hitch it can move along with the holder.

The tow hitch can be accommodated in the tow hitch adapter in shape- closed condition when the fastening means are adapted for bringing the accommodated tow ball in confined condition.

The confined condition can be maintained during use of the accessory when the fastening means are adapted for keeping the accommodated tow ball in confined condition. Preferably the fastening means are also adapted for keeping the locking body in engaged condition with the locking hole.

Between the tow hitch adapter and the tow hitch a force-closed connection that may or may not be supplementary, can be effected when the fastening means are adapted for clamping the tow ball.

The attachment can be carried out surveyably in several steps, when the fastening means are adapted for becoming active after the locking body has been placed in the locking hole.

Such a surveyable attachment can easily be effected and surveyed from the outside if the fastening means are adapted for becoming active by swinging at least a part of the tow hitch adapter or accessory at the tow hitch adapter with respect to the tow hitch from a placement position, in which the tow hitch adapter is placed on the tow ball, to an operative position, in which the tow hitch is confined, preferably clamped.

In a first development the fastening means of the tow hitch adapter are adapted for engagement onto the tow ball in a direction substantially parallel to the placing direction of the tow hitch adapter.

Alternatively formulated the fastening means of the tow hitch adapter are adapted for engagement onto the tow ball in a direction substantially parallel to the engagement direction of the locking body.

Again alternatively formulated the fastening means of the tow hitch adapter are adapted for engagement on the tow ball substantially in vertical direction. Pressure forces on the locking hole and the locking body are then kept within limits when the fastening means comprise a first abutment surface for supporting the tow hitch adapter on a second abutment surface situated at the tow ball.

Transfer of pressure forces from the tow hitch adapter to the tow ball are improved when the second abutment surface has a convex shape provided by the round shape of the tow ball, wherein the first abutment surface has a concave shape corresponding to the convex shape of the second abutment surface for the first abutment surface snugly abutting the second abutment surface. Moreover the stability between the tow hitch and the tow hitch adapter is improved in this way.

The stability between the tow hitch and the tow hitch adapter is further improved when the tow ball at the side facing away from the tow bar comprises a third abutment surface that is flat and situated transverse to the placing direction, wherein the tow hitch adapter comprises a fourth abutment surface that is flat and situated transverse to the placing direction for the third abutment surface snugly abutting the fourth abutment surface.

In a due to symmetry easy-to-manufacture embodiment, the first and/or fourth abutment surface are situated concentrically around the locking body, wherein the locking body in the placing direction extends from the first and/or fourth abutment surface into a confining space defined by the fastening means. It is preferred here that there is some play between the said first and second and the third and fourth abutment surface when the first and/or fourth abutment surface are situated concentrically around the locking body and the locking body tapers for effecting the press fit in the locking hole. Between the tow hitch adapter and the tow ball a clamping multipoint connection onto the tow ball can be effected when the fastening means comprise a fifth abutment surface for substantially opposite the first and/or fourth abutment surface abutting a sixth abutment surface at the neck portion of the tow hitch that is situated around the tow bar at the tow ball, wherein the fifth abutment surface is movable with respect to the first and/or fourth abutment surface.

The stability of the clamping multipoint connection is improved when the fifth abutment surface as regards shape corresponds to the sixth abutment surface for the fifth abutment surface snugly abutting the sixth abutment surface.

Preferably the fastening means comprise at least one claw for engaging under the tow ball in placing direction, wherein the fifth abutment surface is provided at the at least one claw. An advantage thereof is that by the claw engaging under the tow ball, the fifth abutment surface after placing the tow hitch adapter is ready to be brought to the sixth abutment surface in order to be clamped against it.

Alternatively or additionally the fastening means may comprise at least two claws for engaging under the tow ball in placing direction, wherein the fifth abutment surface is provided at least at one of the two claws.

In order to prevent the claw from detaching from the tow ball, at least one claw can be forked for engaging onto the tow ball transverse to the placing direction past the middle of the tow bar.

Preferably the claw(s) is/are movable with respect to the holder and/or the first abutment surface and/or the fourth abutment surface by means of a locking mechanism. An advantage thereof is that the tow hitch adapter after placing on the tow hitch can be secured to the tow hitch by operating the locking mechanism.

When the tow hitch adapter comprises a lever mechanism for operating the locking mechanism, the clamping forces can be larger than the forces exerted on the lever mechanism during operating the locking mechanism by a user.

Preferably the tow hitch adapter comprises blocking means for the locking mechanism. An advantage thereof is that in this way the locked position of the tow hitch adapter on the tow hitch is secured.

In a second, further development the fastening means of the tow hitch adapter are adapted for engagement onto the tow ball in a direction substantially transverse to the placing direction of the tow hitch adapter, preferably on both sides of the tow ball.

Alternatively formulated the fastening means of the tow hitch adapter are adapted for engagement onto the tow ball in a direction substantially transverse to engagement direction of the locking body, preferably on both sides of the tow ball.

Again alternatively formulated, the fastening means of the tow hitch adapter are adapted for engagement onto the tow ball in substantially horizontal direction, preferably on both sides of the tow ball.

Preferably the tow hitch adapter comprises at least two clamping members for clamping the tow ball accommodated in the housing at several sides in the clamping direction transverse to the placing direction. The clamping members, and particularly its movable parts, can be shielded by the housing, as a result of which it can for instance be prevented that fingers get wedged between the clamping members. The clamping members can already effect a shape-closed connection when placing the tow hitch adapter on the tow ball if the clamping members comprise a recess for partial accommodation of the tow ball. Due to the recesses the clamping members are moreover correctly positioned with respect to the tow ball.

To that end the clamping members can be moved apart for mutually accommodating the tow ball when placing the tow hitch adapter on the tow hitch.

If at least one of the clamping members is pre-biassed in its clamping direction, the accommodation of the tow ball between the clamping members can be felt during placing the tow hitch adapter on the tow ball. In case the clamping members have recesses a snapping sound can moreover be heard which confirms the correct placement.

The shape-closed accommodation of the tow ball between the clamping members can be locked when the tow hitch adapter comprises stopping means for at least partially stopping a movement of the clamping member opposite its clamping direction.

Preferably the clamping members and/or stopping means are adapted for becoming active by swinging a part of the tow hitch adapter with respect to the locking body from a placement position, in which the tow hitch adapter is placed on the tow ball, to an operative position, in which the tow ball is confined in the tow hitch adapter, preferably clamped. Such an action can easily be overseen from the outside.

Alternatively or in combination, the clamping members and/or stopping means are adapted for at least partially and/or fully becoming active by swinging the accessory or a part thereof with respect to the locking body from a placement position, in which the tow hitch adapter is placed on the tow ball, and an operative position of the accessory. Likewise the clamping members and/or stopping means can be adapted for becoming active by operating an operation member, such as a lever, at the tow hitch adapter.

In a further development the fastening means comprise a slotted hole having a first passage opening for the tow ball, which transverse to the placing direction merges into a second, narrower passage opening for accommodation of a neck portion of the tow hitch. By moving the fastening means with respect to the accommodated tow ball, the tow hitch can be placed under the tow ball and/or against the neck portion under the tow ball for confining the tow ball in the tow hitch adapter. The slotted hole may serve as extra confining means, in addition to or in cooperation with the locking body.

Preferably the second passage opening is bounded by a wall section of the tow hitch adapter for fitting abutment against the neck portion of the tow hitch, as a result of which a play-free engagement onto the neck portion can be achieved.

The confinement can be effected by swinging the tow hitch adapter with respect to the tow hitch when the first and second passage opening are situated in a housing of the tow hitch adapter, wherein the neck portion of the first passage opening can be placed towards the second passage opening by swinging the housing with respect to the tow hitch adapter from a placement position, in which the tow hitch adapter is placed on the tow ball, and an operative position, in which the neck portion is accommodated in the second passage opening.

The first and second passage opening are able to cooperate particularly with the locking body at opposite sides when the tow hitch adapter comprises a housing having a straight cylindrical part, preferably a straight circle-cylindrical part, for accommodating the tow ball in a direction transverse to the centre line of the housing, wherein the slotted hole is formed by a casing of the housing, wherein the centres of the first and second passage opening are situated in the same plane transverse to the centre line of the cylindrical housing.

The locking body can be held in engaged condition whereas the confinement by the second opening in the housing still is yet to be completed, when the locking body is rotation-swingably connected to the housing and extends into the housing, wherein the centre line of the locking body in the placement position and the operative position, respectively, extends through the centre of the first and second passage opening, respectively, preferably while the distance between the locking body and the centres remains the same. Inserting the locking body and confinement by the second opening can therefore be carried out in separate steps.

The said step-wise coupling can be completed or locked when the tow hitch adapter comprises blocking means for blocking the swinging motion of the locking body in the position in which the centre line of the locking body extends through the centre of the first passage opening and/or in the position in which the centre line of the locking body extends through the centre of the second passage opening.

The invention furthermore provides, from a further aspect, an assembly of a tow hitch and a tow hitch adapter that can be placed on a free end of the tow hitch for attaching accessories to the tow hitch, wherein the tow hitch comprises a tow bar having a tow ball thereon, and wherein the tow hitch adapter comprises a housing having a cylindrical part for accommodating the tow ball in a direction transverse to the centre line of the housing, wherein a first circular-round passage opening for the tow ball is situated in a casing of the housing, which first passage opening transverse to the centre line merges into a second narrower circular-round passage opening for accommodation of a neck portion of the tow hitch.

The invention furthermore provides a tow hitch or tow hitch adapter intended and suitable for a said assembly according to the invention.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of a number of exemplary embodiments shown in the attached drawings, in which:

Figure 1 shows a view in perspective of a tow hitch according to the invention and a first embodiment of a tow hitch adapter according to the invention, in locked condition;

Figure 2 shows a view in perspective according to figure 1 , in which some parts have been left out;

Figure 3 shows a cross-section in perspective of the tow hitch and the tow hitch adapter according to figure 1 ;

Figure 4 shows a cross-section in perspective of the tow hitch including tow hitch adapter according to figures 1 , 2 and 3, in placed yet unlocked condition;

Figure 5 shows a top view in perspective of the tow hitch according to figure 1 ;

Figure 6 shows a bottom view in perspective of the tow hitch according to figure 1 ; Figure 7 shows a bottom view in perspective of the tow hitch adapter according to figure 1 ;

Figure 8 shows a view in perspective of the tow hitch according to figures 1 -6 having above it a second embodiment of a tow hitch adapter according to the invention that is a part of a bike rack;

Figure 9 shows a view in perspective of the tow hitch and the tow hitch adapter according to figure 8, in which some parts have been left out;

Figure 10 shows a bottom view of the passage opening in the housing of the tow hitch adapter according to figures 8 and 9;

Figures 1 1 -16 show the consecutive steps for placing the tow hitch adapter according to figures 8-10 onto the tow hitch;

Figure 17 shows a view in perspective of an adapted embodiment of the second embodiment of the tow hitch adapter in the placement position;

Figure 18 shows a cross-section of the tow hitch adapter according to figure 17, and the operative position on the tow hitch; and

Figures 19 and 20 show longitudinal sections of the tow hitch adapter, in the placement position and the operative position, respectively.

DETAILED DESCRIPTION OF THE DRAWINGS

Figures 1 -7 show a first embodiment of the tow hitch 1 and a tow hitch adapter 10 according to the invention. Figures 1 -3 show the tow hitch 1 having a tow bar 2 and a tow ball 3. On the tow ball 3 a detachable tow hitch adapter 10 has been attached that is provided with a holder 1 1 with which accessories can be connected, such as for instance a bike rack. The tow hitch adapter 10 can also be a part of the accessory itself.

The tow hitch adapter 10 is placed on the tow ball 3 in placing direction S, wherein the tow hitch adapter 10 clamps an upper side 32 (shown in dots) and a lower side 9 of the tow ball 3 between a hood- shaped support 14 at the holder 1 1 and two claws 16 connected to the holder 1 1 , respectively. In the upper side 32 of the tow ball 3 a tapering square locking hole 5 is situated in which a correspondingly formed square locking pin 12 at the hood-shaped support 14 extends.

The holder 1 1 is fork-shaped, wherein the holder 1 1 has tow side walls 33 in between which a chamber 24 is defined. The hood-shaped support 14 forms one unity with the side walls 33 of the holder 1 1 . In both side walls 33 a long slot 25 is situated extending in longitudinal direction in placing direction S.

The tow hitch adapter 20 has a lever 20 having a head 34 and a handle 35, wherein the head 34 is situated in the chamber 24 and the handle 35 protrudes from the chamber 24. The lever 20 is journalled in the holder 1 1 by means of a axle 23 through the head 34, wherein the axle 23 extends transverse to the placing direction S through the lever 20, the long holes 25 and the holes 36 in the claws 16.

The claws 16 each extend into one of two slots 26 that are situated in the placing direction S in the hood-shaped support 14. Due to play of the axle 23 in the long holes 25 and the position of the claws 16 in the slots 26 a guided shifting of the claws 16 with respect to the holder 1 1 is possible whereas rotation of the claws 16 about the axle 23 is blocked.

Figures 3 and 4 show a cross-section of the tow hitch 1 with tow hitch adapter 10 according to figure 1 in the locked and unlocked condition, respectively, of the tow hitch adapter 10. The lever 20 has a first abutment surface 27 on the head 34 and a second abutment surface 28 which is at an angle of 45° to the first abutment surface 27. Both abutment surfaces 27, 28 are parallel to the centre line of axle 23. The normal distance between the first abutment surface 27 and the centre line of axle 23 in this case exceeds the normal distance between the second abutment surface 28 and the centre line, as a result of which the abutment surfaces 27, 28 are eccentric to the axle 23. Via a rounded corner 22, the first abutment surface 27 merges into the second abutment surface 28 of the lever 20.

In locked condition the first abutment surface 27 abuts an abutment surface 29 of the hood-shaped support 14, whereas in unlocked condition the second abutment surface 28 abuts the abutment surface 29 of the hood-shaped support 14. Due to the eccentric position of the axle 23 with respect to the first and second abutment surface 27, 28 of the lever 20, according to figure 3, the tow ball 3 is clamped between the claws 16 and the hood-shaped support 14, whereas according to figure 4 the claws 16 are apart from the lower side 9 of the tow ball 3. Due to the parallel abutment of the first abutment surface 27 of the lever 20 to the abutment surface 29 of the hood- shaped support 14, and due to the force exerted during clamping the tow ball 3 via the claws 16 in the placing direction S, the lever 20 remains blocked in the locked position according to figure 3.

Figure 5 shows the upper side 32 of the tow ball 3 with locking hole 5 in more detail. The locking hole 5 has four level side walls 7 wherein the corners between the side walls 7 have been rounded. At the upper side 32 the tow ball 3 has a levelling 6 which is situated around the locking hole 5. Due to the levelling 6 and the tapering locking hole 5 edges 8 of the locking hole 5 are blunt as a result of which the tow hitch 3 has an upper side 32 that is not sharp.

Figure 6 shows the lower side 9 of the tow hitch 3 in more detail. The tow ball 3 has an annular abutment surface 4 around the tow bar 2 which abutment surface 4 is at least partially situated transverse to the placing direction 9. The claws 16 engage onto the annular abutment surface 4 and optionally onto the tow bar 2 for extra stability.

Figure 7 shows the tow hitch adapter 10 with the locking pin 12 according to figure 1 in more detail. The locking pin 12 has four level side walls 13, wherein the corners between the side walls 13 have been rounded. The locking pin 12 as regards shape corresponds with the locking hole 5 in the tow ball 3, as a result of which a play-free engagement can be effected between the locking pin 12 and the locking hole 5. The hood-shaped support 14 has a concave inner surface 30 around the locking pin 12 which inner surface as regards shape corresponds with the upper side 32 of the tow ball 3. Around the locking pin 12 the inner surface 30 has a levelling 15 for abutment to the levelling 6 on the tow ball 3. The claws 16 has a curved abutment surface 19, which as regards shape corresponds with the annular abutment surface 4 of the tow ball 3.

The operation of the tow hitch adapter 10 is as follows. The lever 20 is placed in the unlocked position as shown in figure 4. Subsequently the tow hitch adapter 10 is placed with the claws 16 over the tow ball 3 in the placing direction S in figure 1 , so that the claws 16 with their abutment surface 19 come to lie under the tow ball 3. The claws 16 can move apart according to arrow 31 in figure 6 for allowing the tow ball 3 to pass through, for instance by a telescopic action of axle 23.

When placing the tow hitch adapter 10 over the tow ball 3 the locking pin 12 falls into the locking hole 5 of the tow ball 3, wherein the concave inner surface 30 of the hood-shaped support 14 comes to lie on and abut the tow ball 3.

Subsequently the lever 20 is moved from the unlocked position according to figure 4 to the locked position according to figure 3, as a result of which the abutment surfaces 19 of the claws 16 due to the eccentric position of the first and second abutment surfaces 27, 28 are shifted towards and against the lower side 9 of the tow ball with respect to the axle 23.

By clamping the tow ball 3 between the claws 16 and the hood-shaped support 14, movements or translations of the tow hitch adapter 10 with respect to the tow hitch 1 are blocked. Due to the engagement of the locking pin 12 into the locking hole 5 hinging or rotation of the tow hitch adapter 10 about the tow ball 3 of the tow hitch 1 in a vertical plane is blocked due to shape-closure, despite the ball shape of the tow ball 3. Due to the square shape of the locking pin 12 and the locking hole 5 particularly rotations about the centre line of the locking pin 12 are blocked due to shape-closure, as a result of which accessories as regards position can reliably be attached to the tow ball 3. The locking hole 5 and the locking pin 12 may therefore, optionally in combination with the tow hitch adapter 10 itself, also be a part of a stabilisation system between a towing and a towed vehicle, such as a caravan by a car. In that case the stabilisation bars and the permanent connections to the car that are common for that purpose are no longer necessary. In an alternative embodiment of the tow hitch adapter, some play remains between the upper side 32 and the levelling 6 of the tow ball 3 on the one hand and the concave inner surface 30 and the levelling 1 5 of the hood-shaped support on the other hand, after placing the tow hitch adapter and the tow ball 10, as a result of which by operating the lever 20 a press fit is effected between the tapered locking pin 1 2 and the locking hole 5.

In yet another alternative embodiment of the tow hitch adapter only one fork-shaped claw is attached to the holder which claw when placing the tow hitch adapter on the tow hitch 1 engages under the lower side 9 of the tow ball 3 up to middle of the tow bar 2, wherein due to the fork-shape of the claw it is prevented that the claw slides off in the direction of the tow ball 3 when the tow hitch adapter is closed and/or loaded.

Figure 8-16 show the tow hitch 1 according to figures 1 -6, and a tow hitch adapter 100 according to a second embodiment of the invention. The tow hitch adapter 100 forms a part of a metal bike rack 101 , that has been constructed with U-shaped cross girders 102 for supporting bikes and longitudinal girders 103 that are connected to the housing 1 10 of the tow hitch adapter 100.

The tow hitch adapter 100 as shown in figure 8 is in a coupling position above the tow hitch 1 , wherein the plane of the bike rack 101 is at an angle Y of approximately 45 ° to the ground. When coupling the bike rack 101 it is placed with the tow hitch adapter 100 in direction A downwards over the tow hitch 1 , in a placement position, after which the bike rack 101 is swung in direction B with respect to the tow hitch 1 into its horizontal operative position. In order to lock this operative position an upright handle 133 on the tow hitch adapter 100 is swung in direction D into its locking position. The tow hitch 1 , the tow hitch adapter 100 and its operation are shown in detail in figures 9-16.

As shown enlarged in figure 9 the tow hitch adapter 100 comprises a cylindrical housing 1 10 having a centre line or axis of rotation T, that has been closed off with a left metal end plate 1 1 1 and a right metal end plate 1 12 that have been pressed parallel to each other in the housing 1 10. In the middle at the lower side, the housing 1 10 has a passage opening 134 having a round, wider part 1 55, for freely allowing the tow ball 3 of the tow hitch 1 through, which in a direction transverse to the centre line T merges into a round, narrower part 136 of which the diameter is adapted to the diameter of the neck portion 2 in order to snugly accommodate it. In the shown coupling position in direction A the wide part 1 55 faces straight downwards. The passage opening is shown in bottom view in figure 10.

Between the left end plate 1 1 1 and the right end plate 1 12 the housing 1 10 consecutively comprises two cup springs 1 13, 1 14 situated against each other and having a high spring stiffness, a metal positioning disk 1 15 through which a compression spring 160 has been passed, a left metal clamping disk 1 19, a metal holder 139 having a locking pin 140 and a clamping spring 1 50, a right metal clamping disk 130, and a metal threaded shaft 132. The positioning disk 1 15, the left clamping disk 1 19 and the right clamping disk 130 have an outer diameter that is adjusted to the inner diameter of the housing 1 10, under narrow tolerances, such that said parts are only able to shift in the direction of and rotate about the centre line T of the housing 1 10.

The positioning disk 1 15 is situated against the right cup spring 1 14, and in the circumferential surface facing the housing 1 10 comprises a recess that is not shown in which an elevation, extending in the direction of the centre line, extends at the inner wall of he housing 1 10. Due to this engagement the positioning disk 1 15 rotates in direction B along with the rotation in the direction B of the housing 1 10 about the centre line T.

In a rotation-symmetrical way on both sides with respect to the centre line T, the positioning disk 1 1 5 has a total of two inclined surfaces 1 16 only one of which is shown in the figure. The inclined surfaces 1 16 merge into lowered surfaces 1 17 and raised end surfaces 1 18, as a result of which two lowerings have been formed in the circumferential surface 170 of the positioning disk 1 1 5 which circumferential surface faces the left clamping disk.

In the middle, the positioning disk 1 1 5 has an opening for passing the compression spring 160 through. The compression spring 160 on the one side abuts the left end plate 1 1 1 and on the other side the left clamping disk 1 19, which is thus pre-biassed in direction C to the second clamping disk 130. On both sides of the centre line T also in a rotation-symmetrical way, the left clamping disk 1 19 has two inclined surfaces 120, only one of which is shown, that merge into support surfaces 121 and end surfaces 122 which together form cams 210 that can be snugly accommodated in the said lowerings in the circumferential surface 170 of the positioning disk 1 15.

The left clamping disk 1 19 and the right clamping disk 130 at their upper side are provided with straight slots 137, 138 that extend in the direction of the centre line T and in which the rectangular holder 139 is situated. The holder 139 is confined between the slots 137, 138 and the inner wall of the housing 1 10, and can only be slid in the direction of the centre line T with respect to the left and right clamping disk 1 19, 130. The slide bearings thus provided block a mutually opposite rotation of the left clamping disk 1 13 and right clamping disk 130. The left clamping disk 1 19 and the right clamping disk 130 comprise a left accommodation opening 1 19 and a right accommodation opening 131 for partial accommodation of the tow ball 3 of the tow hitch 1 . The centres of the accommodation openings 123, 131 are eccentric to the centre line T, in the direction of the passage opening 134.

In the middle of the holder 139 the square locking pin 140 that tapers towards the passage opening 134 has been formed which as regards shape and dimensions corresponds with the locking pin 12 of the tow hitch adapter 10 according to the first embodiment of the invention described above. On both sides of the holder 139 stops 161 have been formed which due to the pre-biassing in the compression spring 160 in the shown coupling position of the tow hitch adapter 100 are held in abutment with the left and right clamping disk 1 19, 130. The stops 161 limit the mutual position of the disks 1 19, 130 in the direction of the locking pin 140. The left clamping disk 1 19 is provided at the lower side with a bevel 124 which in the pre-biassed position slopes to the outer edge of the wide part 155 of the passage opening 134.

The clamping spring 150 is secured around the holder 139, and has tow semi-circular spring lips 1 51 , 152 which define a clamping space for the tow ball 3, which is aligned with the accommodation openings 123, 131 of the clamping disks 1 19, 130.

The right clamping disk 130 is provided with a threaded hole 141 in which the threaded shaft 132 extends. The threaded shaft 132 is journalled in the right end plate 1 12 and is connected to lever 133. By operating the handle 133, the right clamping disk 130 is urged in the direction D in the direction of the left clamping disk 1 19.

The tow hitch adapter 100 furthermore comprises retainers or pre- biassing devices that are not shown for positioning the rotatable left and right clamping disks 1 19, 130 to the shown coupling position, such that the centre line of the locking pin 140 in the shown stand-by position is concentric to the wide part 1 55 of the passage opening 134.

The operation of the tow hitch adapter when placing on the tow hitch 1 is shown in detail in figures 1 1 -16.

In consecutive figures 1 1 and 12 the tow hitch adapter 100 is placed from above in direction A on the tow ball 3 of the tow hitch 1 . In this inclined placement position the bike rack 101 is at an angle Y of approximately 45° to the ground (see figure 8). When placing the tow hitch adapter 100 the tow ball 3 is passed through the wide part 1 55 of the passage opening 134, wherein the lips 151 , 152 of the clamping spring 150 move apart in direction E and partially around the tow ball 3, and the locking pin 140 is snugly accommodated in the locking hole 5. The length of the lips 1 51 , 1 52 is dimensioned such so as to firmly retain the locking pin 140 and thus the holder 139 in the locking hole 5.

When moving downwards in direction A the left clamping disk 1 19 is also moved away from the tow ball 3 in direction C by the bevel 124, after which the accommodation openings 123, 131 partially accommodate the tow ball 3. At the end of the movement in direction A the left clamping disk 1 19 and the lips 151 , 152 are moved back in opposite direction C and E, respectively, in the direction of the tow ball 3, as shown in figure 12. During these movements back a snapping sound is audible and the engagement can be felt, which to the user is a confirmation that the tow ball 3 is correctly accommodated in the housing 1 10 and the placement position is reached.

Subsequently, as shown in figure 13, the bike rack 101 and thus the housing 1 10 is swung downwards to the operative position in direction B (also see figure 8) with respect to the tow ball 3. The inclined surfaces 1 16, 120 of the positioning disk and the left clamping disk 1 19 as a result move, if necessary over each other, to past each other, as a result of which the support surfaces 1 21 move against the circumferential surfaces 170 of the positioning disk 1 15 and the movement of the left clamping disk in direction F is limited. Moreover the narrow part 136 of the passage opening 134 is moved against the neck 2 and under the tow ball 3 of the tow hitch 1 , as a result of which the tow ball 3 is confined. The inserted locking pin 140 on the one hand and the abutment against the neck 2 of the tow hitch 1 on the other hand, due to the weight of the bike rack 101 , are already capable of ensuring a firm, shape-closed connection with the tow hitch 1 , wherein the clamping disks 1 19, 130 and the clamping spring 1 50 exert a slight clamping onto the ball 3.

Subsequently, as shown in figure 15, the handle 133 is swung downwards in direction D (also see figure 8), as a result of which the right clamping disk 130 is forcefully urged in direction G towards the blocked left clamping disk 1 19 and the cup springs 1 13, 1 14 are biassed by the small, joint movement of the left clamping disk 1 19 and the positioning disk 1 15 in the direction of the left end plate 1 1 1 it causes. The tow ball 3 is then firmly clamped on both sides by the edges of the accommodation opening 137, 131 . The clamped position is shown in figure 16.

In said clamped or locked operative position the clamping disks form an extra connection in addition to the connection formed by the locking pin 140 and by the narrower part 136 of the passage opening 134. The tow hitch adapter 100 can be detached from the tow hitch 1 by consecutively pulling the handle 133 upwards in opposite direction and subsequently moving the bike rack 101 in opposite direction B from the ground, after which it can be detached in the direction A from the tow hitch 1 . Movements B and A can be carried out in one continuous - action.

Alternative to the use of the rotation in direction B and swinging the handle in direction D, both blocking the in this example left clamping disk 1 19, and urging the left and right clamping disk 1 19, 130, can occur simultaneously or consecutively during swinging the bike rack 101 in direction towards the operative position. This may for instance be possible when several inclined segments are used in the said inclined surfaces 1 16 and 120, namely having a steep section as already used, and a less steep section, such as in accordance with the pitch of the threaded shaft 132, for during the last part of the motion B firmly clamping the tow ball. The handle 133 then is not necessary.

The tow hitch adapter 100', as shown in figure 17, is slightly adjusted in comparison with the tow hitch adapter 100 according to figures 8- 16. The parts with comparable action are therefore indicated by corresponding reference numbers.

The housing 1 10' of tow hitch adapter 100' is connected to a hollow longitudinal girder 103' having a recess 190. A hook 180 extends through the recess 190, which hook hinges to the longitudinal girder 103' by means of pin 182 and which via an opening 174 is movable in the upper side of the housing 1 10' to an elevation 173 at the upper side of the holder 139' and extending through the opening 174. The hook 180 having a U-shaped cross-section, is at the lower side provided with two recesses 181 in which elevation 173 of the holder 139' can be snugly accommodated.

The hook 180 is pre-biassed with a volute spring 183 against the holder 139'. The recesses 181 are placed such that they are able to block the swinging motion of the holder 193, and thus the locking pin, the positioning disk 1 1 5' and the right clamping disk 130' about the centre line T in the operative position of the bike rack 101. In this embodiment the holder 139' is bearing mounted in recesses in the upper sides of the positioning disk 1 15' and the right clamping disk 130'.

The axle 230 of the left clamping disk 1 19' is slidably passed through the left end plate 1 1 1 ', wherein the compression spring 1 60' presses against the a first shoulder part 171 of the clamping disk 1 19'. The left clamping disk 1 19' extends through the positioning disk 1 1 5' with the axle 230, wherein the cup springs 1 13', 1 14' are situated between the positioning disk 1 1 5' and a second shoulder part 172.

The positioning disk 1 15' has a total of four cams 210' equidistantly positioned along the circumference, which cams depending on the rotation position about centre line T' rest against the end plate 1 1 1 ' (in the operative position) or fall through a total of four accommodation openings 220 in the left end plate 1 1 1 ' (in the placement position). In the latter position the left clamping disk 1 19' is able to move away from the right clamping disk 130' under the pre-biassing of the compression spring, for allowing the tow ball 3 through, wherein the tow ball 3 moves along the bevel 124' that lies receded with respect to the passage opening 134.

As shown in figures 19 and 20 a dirt-blocking synthetic protective bush 200 is situated at the inside of the housing 1 10' which bush is able to move along with the swinging motion of the holder 139'. Against the left end plate 1 1 1 ' a synthetic hood that is not shown can be placed which counteracts the penetration of dirt through for instance the accommodation openings 220 along the axle 230. By clamping the tow ball 3 between the clamping disks 1 19, 130 movements or translations of the tow hitch adapter 100, 100' with respect to the tow hitch 1 are blocked. Due to the engagement of the locking pin 140 into the locking hole 5 hinging or rotation of the tow hitch adapter 100, 100' about the ball 3 of the tow hitch 1 in a vertical plane is blocked due to shape-closure, despite the ball shape of the tow ball 3. Due to the square shape of the locking pin 140 and the locking hole 5 particularly rotations about the centre line of the locking pin 140 are blocked due to shape-closure. Accessories may thus as regards position be reliably attached on the tow hitch 3. The locking pin (locking body), therefore acts like a form lock between the adapter with accessory and the tow hitch.

The locking pin 12, 140 also functions as a orientating pin for orienting the tow hitch adapter 1 , 100, 100' with respect to the tow hitch 1 and thus with respect to the vehicle, also in the placement position.