WO2013046175A1

WO2013046175A1 - Clamp with inclined tightening for a male terminal

Info

Publication number: WO2013046175A1
Application number: PCT/IB2012/055203
Authority: WO
Inventors: Antonio Falchetti
Original assignee: Mta S.P.A.
Priority date: 2011-09-30
Filing date: 2012-09-28
Publication date: 2013-04-04
Also published as: ITMI20111759A1

Abstract

The present invention concerns an inclined clamp for a male terminal comprising: - a clamping ring (5) having an axis (Z-Z) suitable for being inserted on a male terminal according to an insertion direction extending along the axis (Z-Z), two jaws (20, 21) connected to the clamping ring (5) and being able to come closer together along a direction (X-X) perpendicular to said insertion direction (Z-Z) for clamping the clamping ring (5) on the male terminal, at least one of said two jaws (20, 21) being mobile; clamping means (30) comprising a clamping member (31) being able to rotate around a clamping axis (B-B) so as to move said jaws (20, 21) from a distant position to a close position, said clamping axis (B-B) being inclined with respect to a plane (P) perpendicular to said direction (X-X) so as to identify with said plane (P) an angle (a) different from the right angle, said clamping means (30) moreover comprising a clamping plate (33) having a clamping surface (33a) lying on a plane perpendicular to said clamping axis (B-B) on which said clamping member (31) is suitable to act; guiding means (40) cooperating with said clamping means (30) and with said two jaws (20, 21) so as to guide the movement of said two jaws (20, 21) along said clamping direction (X-X). The clamp moreover comprises consent means (53, 150) which cooperate with the clamping member (31), said consent means (53, 150) being mobile between a locking position, suitable for preventing the rotation of said clamping member (31), and a consent position, suitable for allowing the rotation of said clamping member (31) when the clamp (1) is completely inserted on the male terminal.

Description

CLAMP WITH INCLINED TIGHTENING FOR A MALE TERMINAL

DESCRIPTION

The present invention concerns a clamp with inclined tightening for a male terminal.

In particular, the present invention refers to a clamp with an inclined tightening screw.

The clamp according to the present invention can be applied for connecting to one pole of a battery. In this case, the male terminal is a pole of the battery whereas the clamp is connected to one or more utilities of a motor vehicle.

In accordance with a different application, the clamp according to the present invention can be applied when earthing electrical and/or electronic devices. In this case, the male terminal is a ground terminal that is fixed to a structure acting as grounding, whereas the ground connection of the devices to be earthed is connected to the clamp through an electric cable. The structure acting as grounding can be, for example, the body of a motor vehicle, in particular of an automobile.

The clamp substantially comprises a body that is equipped with a clamping ring that is connected to two jaws which can come closer together so as to clamp the clamping ring on the male terminal. The clamping operation is carried out by rotating a clamping nut with respect to a screw that engages the body of the clamp.

The inclined clamp has a clamping nut that can rotate around a clamping axis that is inclined with respect to a plane that is perpendicular to the axis of the clamping ring.

During the clamping operation of such a clamp there can be some drawbacks. On one hand the clamping force acts on a plane that is inclined with respect to the axis of the ring and this can lead to a displacement or twisting of the jaws or of other parts of the clamp which could negatively affect the maintaining of the contact between the clamp and the terminal over time.

One solution is described in international patent application PCT no. WO2010/044111 of the Applicant which illustrates a clamp for a male terminal with inclined tightening, in which the clamping means for moving the jaws have a clamping member that rotates around a clamping axis that is inclined with respect to the axis of the clamping ring. The clamping means comprise guiding means that cooperate with the jaws so as to guide the movement of the jaws from the distant position to the close position.

In such a way, during the clamping operations, the guiding means make it possible to avoid twisting of the clamp jaws.

In this specific field, it is moreover considered necessary to provide a clamp that is equipped with a consent system that ensures that the clamp is locked on the battery terminal only if the clamp is mounted correctly and therefore suitably fitted on the male terminal and engaged with the battery terminal.

Some solutions of safety system for the clamp with inclined tightening are known, however these are particularly complex and relatively costly.

The purpose of the present invention is that of providing a clamp with inclined tightening that is equipped with consent means that are suitable for ensuring that the clamping operation is carried out correctly after the clamp has been mounted correctly on the male terminal for an optimal operation over time.

A further purpose is to provide consent means that are easy to handle, that can be actuated easily and that have limited bulk.

Another purpose is to provide a clamp with inclined tightening that can be easily reused.

Such a purpose is achieved with a clamp with inclined tightening for a male terminal made according to claim 1.

The characteristics and the advantages of the present invention shall become clearer from the following detailed description of an embodiment, given as an indication and not for limiting purposes with reference to the attached drawings, in which:

- figure 1 shows a perspective view of a clamp in accordance with the present invention, with consent means in the locking position,

-figure 2 shows a perspective view of the clamp of figure 1, with the consent means in the consent position,

-figure 3 shows an exploded perspective view of the clamp of figure 1, -figures 4 and 5 show section views of the clamp of figures 1 and 2, respectively,

-figure 6 shows a top view of the clamp of figure 1,

-figures 7 and 8 show two different side views of the clamp of figure 1.

With reference to the attached figures, a clamp in accordance with the present invention is wholly indicated with reference numeral 1.

The clamp 1 comprises a conductor body 3 and clamping means 30 and it is inserted on a male terminal 8 that projects from a resting surface 2 according to an axis Z-Z.

In accordance with the embodiment shown in the attached figures, the conductor body 3 is obtained through punching, coining and bending starting from a plate made from electrically conductive material, such as brass or copper alloy with high electrical conductivity and good mechanical resistance associated to good pliability. Alternatively, the conductor body can be a melted block of alloy or another kind.

The conductor body 3 comprises a clamping ring 5 having axis Z-Z and suitable for being inserted on the male terminal 8 according to an insertion direction that projects along the axis Z-Z. In the rest of the description we shall refer, in a non- limiting manner, to a battery terminal, being it understood that the clamp of the present invention can be used on any male terminal.

In accordance with the embodiment shown in the figures, the clamping ring 5 comprises an upper open ring 6 and a lower open ring 7 having two opposite end portions, 6a, 6b and 7a, 7b, respectively, that can be moved closer together so as to clamp the clamping ring 5 around a battery terminal, when the clamp 1 is mounted on the battery terminal. Each open ring 6, 7, is made up of two opposite arms 6', 6" and 7', 7" which end in the end portions 6a, 6b and 7a, 7b.

The conductor body 3 is obtained starting from a plate (not shown in the figures) which is folded so that the lower ring 7 is arranged below the upper ring 6, parallel to it and axially aligned with it.

The clamp 1 comprises a first jaw 20 and a second jaw 21, that are connected to the clamping ring 5 and are able to move closer to one another so as to clamp the clamping ring 5 on the male terminal 8. In one embodiment, the first jaw 20 is mobile whereas the second jaw 21 is fixed. In particular, the first jaw 20 is mobile from and towards the second jaw 21.

Alternatively, the two jaws 20, 21 can both be mobile.

The first jaw 20 is fixedly attached to the end portions 6a, 7a whereas the second jaw 21 is fixedly attached to the end portions 6b, 7b.

In accordance with one embodiment, the upper ring 6 and the lower ring 7 are joined to one another through the two jaws 20, 21. In particular, the first jaw 20 comprises an upper wall 20a that is joined to the upper end 6a of the ring 6, a lower wall 20b joined to the lower end 7a of the ring 7 and a side wall 20c that joins the upper and lower walls 20a, 20b, on the opposite side from the rings 6, 7. In the same way, the second jaw 21 comprises an upper wall 21a that is joined to the upper end 6b of the ring 6, a lower wall 21b that is joined to the lower end 7b of the ring 7 and a side wall 21c that joins the upper and lower walls 21a, 21b, on the opposite side from the rings 6, 7.

The walls 20a, 20b, 20c and 21a, 21b, 21c define a housing 23, that projects along a direction X-X, the function of which shall be described in the rest of the description.

The clamping means 30 act on the two jaws 20, 21, cooperating with one of the two jaws 20, 21, so as to move such jaws 20, 21 from a distant position to a close position along a clamping direction X-X so as to clamp the clamping ring 5 on the battery terminal 8.

The clamping means 30 comprise a clamping member 31 that can rotate around a clamping axis B-B so as to move the two jaws 20, 21 between said positions. In particular, the clamping axis B-B is inclined with respect to a plane P that is perpendicular to the axis Z-Z of the clamping ring 5, so as to identify with the plane P an angle a that is different from a right angle.

Preferably, the angle a is comprised between 15° and 75°. More preferably, the angle a is comprised between 30^° and 60°. Even more preferably, the angle a is about The clamping means 30 moreover comprise a clamping plate 33 that is obtained starting from a plate (not shown in the figures) that is suitably machined, having an upper clamping surface 33a that lies on a plane that is perpendicular to the clamping surface B-B on which the rotary clamping member 31 is able to act. The clamping plate 33 is substantially symmetrical with respect to a plane that is perpendicular to the upper surface 33a passing through a longitudinal axis A- A which intersects the clamping axis B-B.

In one embodiment, the rotating clamping member of the clamping means 30 comprises a tightening screw 31 having a head 130 for rotating such a tightening screw 31 and suitable for engaging the clamping plate 33, and a leg 135. In order to simplify the overall representation of the clamp 1, the tightening screw 31 shown in the attached figures is schematised without its threading. However, it is obvious that such a tightening screw 31 can be equipped with a threading (not shown in the figures).

The clamping plate 33 comprises an opening 34 for the leg 135 of the tightening screw 31 to pass, which is defined by an elongated slot, which projects along the longitudinal axis A-A. In such a case, a washer can be arranged between the head 130 of the tightening screw 31 and the opening 34.

The clamping means 30 are configured so as to allow the relative movement between the clamping plate 33 and tightening screw 31 not only along the clamping axis B-B but also along the plane on which the upper surface 33a of the clamping plate 33 lies to move said clamping plate 33 between a locking position and a consent position, as shall become clearer in the rest of the description.

The clamp 1 moreover comprises said guide means 40 which cooperate with the two jaws 20, 21 so as to guide the movement of the jaws 20, 21 along the clamping direction X-X on the plane P, between the distant and the close position. Since the movement of the two jaws 20, 21 occurs on the plane P perpendicular to the axis Z-Z of the clamping ring 5, the jaws 20, 21 are locked without any twisting on the two jaws 20, 21 or on the clamping ring 5.

Moreover, the guide means 40 cooperate with the clamping means 30 so as to guide the movement of the two jaws 20, 21 on the plane P along the clamping direction X-X. In one embodiment, the guiding means 40 comprise a slide with a body that projects along the clamping direction X-X and having the shape of an isosceles trapezoid. In particular, the slide 40 comprises two walls, an upper wall 42 and a lower wall 43 that are parallel to one another, an inclined wall 44 for connecting the two walls 42, 43 and a bottom wall 45, which is also inclined so as to engage the fixed jaw 21. The inclined wall 44 lies on a plane that is perpendicular to the clamping axis B-B and therefore parallel to the plane on which the upper surface 33a of the clamping plate 33 lies. On the opposite side of the inclined wall 44, the bottom wall 45 has abutment means 46 so as to allow the engagement of the slide 40 with the fixed jaw 21. In this case, the abutment means 46 are in the form of a peripheral flange that projects from the planes of the walls 42, 43, 45, transverse to the direction X-X. In order to guide the movement of the jaws 20, 21 on the plane P, the two walls 42 and 43 lie on respective planes that are parallel to the plane P and engage the respective upper and lower walls 20a, 21 a, 20b, 21 b of the two jaws 20, 21.

In the inclined plane 44 there is a threaded hole 41 that is suitable for receiving the end portion of the leg 135 of the tightening screw 31.

During the clamping, the rotation of the tightening screw 31 determines a screwing of the screw 31 in the threaded hole 41 and therefore a movement of the head of the screw 31 towards the inclined wall 44 along the axis B-B, by means of the slide 40 engaged with the second jaw 21, there is a movement of the first jaw 20 mobile on the plane P along the clamping direction X-X from the distant position to the close position so as to clamp the clamping ring 5 on the battery terminal 8.

In order to ensure that the clamping member 31 engages with the guiding means 40 only when the clamp 1 is inserted correctly on the battery terminal 8, the clamp 1 also comprises consent means. In other words, the consent means make it possible to clamp the clamp 1 and have the purpose of preventing the clamp 1 from being locked in an erroneous manner on the male terminal 8 when the clamp 1 is not perfectly mounted or when the clamp 1 is disengaged from the male terminal 8.

The consent means cooperate with the clamping member 31 and are mobile between a locking position, that is suitable for preventing the rotation of the clamping member 31, and a consent position, that is suitable for allowing the rotation of said clamping member 31 when the clamp 1 is completely inserted on the male terminal 8.

In accordance with one embodiment, the consent means are fixedly connected to the clamping plate 33.

The clamping plate 33 is a plate that is mobile with respect to the clamping ring

5 along the plane on which the upper surface 33a lies passing from a locking position to a consent position, corresponding to the locking position and consent position of the consent means, respectively.

The clamping plate 33 comprises an abutment element 145 that juts out at the bottom with respect to the plane of the upper surface 33a and projects at the bottom of the jaw 20 with which the clamping plate 33 cooperates. Such an abutment element 145 cooperates with the resting surface 2 of the male terminal 8, during the insertion of the clamping ring 5 on the male terminal 8, so as to move the clamping plate 33 from the locking position to the consent position.

The consent position 145 is substantially "L"-shaped with a first part which projects along a direction that is parallel to the axis Z-Z and with the end folded in a substantially perpendicular manner with respect to the first part thus facing the clamping plate 33 and in particular the lower wall 20b of the first jaw 20.

In such a way, when the consent element 145 is arranged in the blocking position at least one part of the consent element 145 projects below the plane parallel to the plane P and comprises the lower wall 20b of the first jaw 20, as illustrated in figures 1 and 4. Whereas, when the allowing element 145 is arranged in the consent position its end moves closer to the lower wall 20b, as illustrated in figures 2, 5. In some embodiments, in the consent position, the end of the consent element 145 can abut against the lower wall 20b and be interposed between the lower wall 20b and the support element 2. In such a case, the lower wall 20b can have a recess, not illustrated in the figures, which is a housing seat for the lower end of the consent element 145.

The consent means comprise a locking element 150 that is provided on the clamping plate 33 and is suitable for preventing the rotation of the tightening screw 31 when the consent means are in the locking position and allowing the rotation of the tightening screw 31 when the consent means are in the consent position. In accordance with one embodiment, the locking element 150 is positioned opposite to the abutment element 145 with respect to the plane of the upper surface 33a.

The locking element 150 cooperated with the clamping member 31 when the clamping plate 33 is in the locking position. The locking element 150 is, in the example, substantially an appendage of the clamping plate 33 and defines an anti- rotation element that is arranged so as to engage the head 130 of the tightening screw 31, in the example one side of the head 130, when the clamping plate 33 is in the locking position, so as to prevent the rotation of the tightening screw 31, and for disengaging the head 130 of the tightening screw 31, when the tightening screw is in the consent position, so as to allow the rotation of the tightening screw 31. In some embodiments, the locking element 150 is an element that prevents the user from engaging the clamping member 31 with a suitable tool thus preventing the clamping operation to be carried out.

Advantageously, according to one embodiment, the upper ring 6 of the clamping ring 5 comprises, near to the end 6a, an undercut 160 that is suitable for defining a guide element for the clamping plate 33.

The consent means further comprise an elastic element 53 that is equipped with means 56, 57 for hooking to the clamping plate 33 and being mobile between a locking position and a consent position.

The clamping plate 33 cooperates with the elastic element 53 so as to increase the load of the elastic element 53 when the clamping plate 33 is moved from the locking position to the consent position during the insertion of the clamping ring 5 on the male terminal 8.

In particular, the elastic element 53 is suitable for guiding the clamping plate 33 from the consent position to the locking position during the extraction of the clamping ring 5 from the male terminal 8.

Indeed, the clamping plate 33 comprises engagement means 36, 37 that are suitable for engaging the hooking means 56, 57 so as to guide the movement of the elastic element 53 from the locking position to the consent position.

In one embodiment, the locking element 53 is a spring inserted in the leg 135 of the tightening screw 31 the branches of which 54, 55 are substantially arranged on top of one another in an "X"-shape. The free ends of the two branches 54, 55 are thus folded on the same side with respect to a resting plane of the coils and in an opposite manner with respect to one another and such as to define with the branches 54, 55 said hooking means 56, 57 so as to engage the spring 53 with the clamping plate 33.

In the embodiment illustrated, the spring 53 is preloaded by arranging the branches 54 and 55 over one another in the "X"-shape so that the coils can be fitted on the leg 135 of the screw 31 without clamping the leg itself. The preloaded spring 53 defines the locking position.

The engaging means 36, 37 are defined by a first through slit 36 and a second through slit 37, that are arranged symmetrically with respect to the longitudinal axis A- A according to transverse directions with axes that intersect with one another and with the longitudinal axis A- A. The first slit 36 and the second slit 37 allow the sliding housing of said hooking means 56, 57 of the spring 53 and their respective coming closer and moving away from one another in a guided fashion from the locking position to the consent position.

The spring 53 is operatively associated with the clamping plate 33 in such a way that for a translation of the clamping plate 33 along the plane of the upper surface 33a there is a sliding of the first and of the second hook 56, 57 of the spring 53 in the slits 36, 37 from the upper ends 36a, 37a to the lower ends 36b, 37b, respectively.

The spring 53, preloaded so as to define the locking position, has the first and the second hook 56, 57 that are close together and arranged at the upper ends 36a, 37a with the coils inserted in the leg 135 of the tightening screw 31. In the consent position, the spring 53 has the first and the second hook 56, 57 away from one another, and arranged at the lower ends 36b, 37b. In such a position the spring 53 is loaded.

According to the present invention, during a correct mounting of the clamp 1 on the male terminal 8 along the direction Z-Z, the abutment element 145, abuts along the direction Z-Z against the resting surface 2 of the male terminal 8. The clamping plate 33 is thus moved by the abutment element 145 passing from the locking position to the consent position. Such a movement makes it possible in particular to move the locking element 150 away from the head 130 of the screw 31 for tightening making it possible to clamp the clamp 1 on the male terminal 8. Moreover, the movement of the clamping plate 33 which substantially occurs along the direction of the plane of the upper surface 33a makes it possible to guide the hooking means 56, 57, which fixedly connected inside respective slits 36, 37, slide from the upper end 36a, 37a to the respective lower ends 36b, 37b indeed loading the spring 53 which passes from the locking position to the consent position.

Advantageously, therefore, during a possible extraction of the clamping ring 5 from the male terminal 8, according to an extraction direction which occurs along the axis Z-Z in a direction that is opposite the direction of insertion, the elastic element 53 is loaded and is moved from the consent position to the locking position. The elastic element 53 is fixedly connected to the clamping plate 33 through the hooking means 56, 57 and guides the clamping plate 33 from the consent position to the locking position. The locking element 150 thus goes in abutment against said tightening screw 31 so as to stop the rotation of the clamping member.

The longitudinal dimensions L of the slits 36 and 37 are related to the height H of the abutment element 145 of the clamping plate 33 and relate, moreover, to the elastic load of the spring 53.

As can be appreciated from what has been described, the clamp according to the present invention makes it possible to avoid the mentioned drawbacks with reference to the prior art.

In this case, the clamping of the clamp is carried out thanks to the consent of the locking element which occurs with the correct translation of the clamping plate on the upper surface following a correct mounting of the clamp on the male terminal. Moreover, the clamp can be locked without twisting of the two clamping jaws which move on a plane that is perpendicular to the axis of the clamping ring.

Furthermore, the elastic element of the consent means makes it possible for there to be a correct positioning of the clamping plate during a possible extraction of the clamping ring from the male terminal, making it possible for there to be an optimal reuse of the clamp which can be advantageously inserted in a male terminal without changing its functionality.

Of course, a man skilled in the art, with the purpose of satisfying contingent and specific requirements, can bring numerous modifications and variants to the clamp according to the invention described above, all moreover covered in the scope of protection of the invention as defined in the following claims.

Claims

1. A clamp (1) with inclined tightening for a male terminal comprising:

- a clamping ring (5) having an axis (Z-Z), said clamping ring (5) being adapted to be inserted on a male terminal (8) along an insertion direction extending along said axis (Z-Z),

- two jaws (20, 21) connected to said clamping ring (5) and being able to be mutually approached along a direction (X-X) perpendicular to said inserting direction (Z-Z) to tighten the clamping ring (5) on the male terminal (8), at least one of said jaws (20, 21) being movable;

- clamping means (30) comprising a clamping member (31) pivo table around a clamping axis (B-B) to move said jaws (20, 21) between a moved away position and an approached position, said clamping axis (B-B) being inclined with respect to a plane (P) perpendicular to said direction (X-X) in order to form with said plane (P) an angle (a) different from the right angle, said clamping means (30) further comprising a clamping plate (33) having a clamping surface (33a) laying on a plane perpendicular to said clamping axis (B-B) on which said clamping member (31) is adapted to act;

- guiding means (40) cooperating with said clamping means (30) and with said two jaws (20, 21) to guide the movement of said two jaws (20, 21) along said clamping direction (X-X);

characterised in that said clamp (1) comprises permission means (53, 150) cooperating with said clamping member (31), said permission means (53, 150) being movable between a locking position, suitable for preventing said clamping member (31) from rotating, and a permission position, suitable for allowing said clamping member (31) to rotate when the clamp (1) is completely inserted on the male terminal (8).

2. A clamp (1) according to claim 1, wherein:

- said clamping member (31) comprises a tightening screw (31) having a head (130) to set said tightening screw (31) in rotation,

- said permission means (53, 150) comprise a locking element (150) which is provided on said clamping plate (33) and which is arranged to prevent the rotation of said tightening screw (31) when said permission means (53, 150) are in the locking position and to allow the rotation of said tightening screw (31) when said permission means (53, 150) are in permission position.

3. A clamp (1) according to claim 2, wherein said locking element (150) defines an anti-rotation element arranged to engage the head (130) of the tightening screw (31) when the permission means (53, 150) are in the locking position, so as to prevent the rotation of the tightening screw (31), and to disengage the head of the tightening screw (31) when the permission means (53, 150) are in the permission position, so as to allow the rotation of the tightening screw (31).

4. A clamp (1) according to any one of claims 1 to 3, wherein said permission means (53, 150) are arranged to prevent a user from engaging said clamping member (31) with a tool when the permission means (53, 150) are in the locking position.

5. A clamp (1) according to any one of claims 1 to 4, wherein said permission means (53, 150) are provided on said clamping plate (33), said clamping plate (33) cooperating with one of said two jaws (20, 21) and with said clamping member (31) and being interposed between said clamping member (31) and the jaw (20) with which said clamping plate (33) cooperates.

6. A clamp (1) according to any one of claims 1 to 5, wherein said clamping plate (33) is a plate movable, with respect to said clamping ring (5), along said plane on which said upper surface (33a) lies, between a locking position and a permission position, said clamping plate (33) comprising an abutment element (145) projecting from the bottom of said jaw (20), said abutment element (145) cooperating with a bearing surface (2) of said male terminal (8) to move said clamping plate (33) between said locking position and said permission position.

7. A clamp (1) according to claim 6, wherein said permission means comprise a locking element (150) which is provided on said clamping plate (33) and which is arranged opposite to said abutment element (145) with respect to the plane of said upper surface (33a), said locking element (150) cooperating with said clamping member (31) when said clamping plate (33) is in said locking position.

8. A clamp (1) according to any one of claims 1 to 7, wherein said permission means further comprise an elastic element (53) provided with means (56, 57) to be hooked to said clamping plate (33), said clamping plate (33) cooperating with said elastic element (53) to move said elastic element (53) from a locking position to a permission position in order to increase the load of said elastic element (53) when said clamping plate (33) is moved from said locking position to said permission position.

9. A clamp (1) according to claim 8, wherein said clamping plate (33) has a first through slot (36) and a second through slot (37) suitable for slidably housing said hooking means (56, 57), said elastic element (53) being suitable for guiding said clamping plate (33) from said permission position to said locking position during the extraction of said clamping ring (5) from the male terminal (8) along the insertion direction (Z-Z).

10. A clamp (1) according to claim 8, wherein said clamping member comprises a tightening screw (31) having a head (130) to rotatably operate said tightening screw (31) and a shank (135) suitable for engaging said clamping plate (33) and said guiding means (40), said clamping plate (33) comprising an opening (34) for the passage of said shank (135).

11. A clamp (1) according to claim 10, wherein said elastic element (53) comprises a torsion spring interposed between said jaw (20) and said clamping plate (33), said spring (53) comprising coils engaged with said shank (135) of said screw (31) and branches (54, 55) adapted to define said hooking means (56, 57), said clamping plate (33) comprising a first through slot (36) and a second through slot (37) suitable for slidably housing said hooking means (56, 57) to guide and load said spring (53) shifting from said locking position to said permission position.

12. A clamp (1) according to claim 11, wherein said spring (53) in said locking position is unloaded by having said hooking means (56, 57) being approached each other at the upper ends (36a, 37a) of said engaging means (36, 37), said spring (53) in said permission position is loaded by having said hooking means (56, 57) being arranged away from each other at the lower ends (36b, 37b) of said engaging means (36, 37).

13. A clamp (1) according to one or more of claims 10 to 12, wherein said guiding means (40) have a slider extending along the direction (X-X) and comprising a tilted wall (44) cooperating with said clamping plate (33) through a hole (41) adapted to receive said shank (135) of said tightening screw (31), said slider further comprising a bottom wall (45) adapted to engage the jaw (21) that does not cooperate with said clamping plate (33).