ES2635621A1 - Coupling device between a manual bicycle and a wheelchair (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

The invention describes a coupling device (1) between a wheelchair (100) and a manual bicycle (200) and, where the chair (100) comprises a front bar (110) essentially vertical and the bicycle (200) comprises a substantially vertical rear bar (210), comprising: a lower jaw (2) for coupling to the bar (210), wherein the lower jaw (2) comprises a rail (21) which, when said lower jaw (2) is coupled to the bar (210), it has a lateral direction; an upper jaw (3) for coupling to the bar (110); and a body (4) rigidly fixed to the upper jaw (3) and comprising a lower sliding guide (41) engageable with the rail (21) of the lower jaw (2), so that the sliding of the guide (41) along the rail (21) adjusts the position of the lower jaw (2) relative to the upper jaw (3). (Machine-translation by Google Translate, not legally binding)

Description

Coupling device between a manual bicycle and a wheelchair

5 OBJECT OF THE INVENTION

The present invention pertains in general to the field of auxiliary elements attachable to a wheelchair.

The object of the present invention is a novel device designed to couple any manual bicycle to any wheelchair in a simple, fast way, and without the need of any external help from the user.

BACKGROUND OF THE INVENTION

15 There are currently various coupling devices designed to attach a manual bicycle to a wheelchair. However, these known coupling devices have disadvantages mainly of two types.

20 First, some of them require actions that cannot be carried out from the wheelchair itself. Obviously, this constitutes a significant inconvenience when the user of the chair has injuries that prevent him from getting up, since in that case he would need the help of a second person to connect and disconnect the manual bicycle to the wheelchair.

25 Secondly, in most cases the connecting device is designed for fixing to certain particular models of wheelchairs. Indeed, each wheelchair manufacturer markets its own hand bike, and therefore each hand bike has a binding device specifically designed for coupling to the chair

30 wheels from the same manufacturer. As a consequence, if a user changes a wheelchair, he could no longer use a manual bicycle that he bought specifically for the previous chair, being forced to also change a manual bicycle.

Next, some examples of patent documents describing 35 coupling devices between a wheelchair and such a manual bicycle are described.

Document US5501480 describes a coupling system between a manual pedaling device and a wheelchair that is formed by an auxiliary frame for the wheelchair. This auxiliary frame has an elongated shape and is attached to the rear of the wheelchair frame pivotally. However, a major drawback of this coupling system is that it would not be possible for the user to perform the coupling itself. Indeed, the assembly of this system requires a wide range of movement (access to the back of the chair, for example) that is not available to all wheelchair users.

US6669222 describes a folding unicycle for connection to a wheelchair. This unicycle has a positioning and fixing support adaptable to a horizontal bar of the wheelchair frame to form a tricycle-like assembly. However, this device has the disadvantage that it is not adaptable to most wheelchairs on the market, since not all of them have the horizontal bar of the frame to which the unicycle is fixed.

DESCRIPTION OF THE INVENTION

The present application solves the above problems thanks to a new coupling device that allows the coupling between a wheelchair and a manual bicycle regardless of the models of both. In addition, this coupling device has been designed to be connected and disconnected from both elements by the user of the wheelchair without having to get up, which avoids the need for external help.

Indeed, the inventors of the present application have discovered that virtually all current wheelchair models have a pair of essentially vertical front bars, and that virtually all current models of manual bicycles have a pair of essentially vertical rear bars. Well, taking this into account, the inventors of the present application have determined that the upper area of these bars is ideal for the connection between the chair and the bicycle and is also accessible to the user of the wheelchair without help. from another person Accordingly, the present invention describes a coupling device specially designed for joining an essentially vertical front bar of the chair with an essentially vertical rear bar of the hand bike.

This new coupling device allows the chair to be connected to the bicycle in such a way that the problems of the prior art devices are solved. The assembly and disassembly is simple and is within reach of a person sitting in the chair, thus allowing the user of the chair to do it without having to get up or make large displacements of the trunk. In addition, it can be mounted on almost any existing manual bicycle, so you can replace the coupling system that is standard. Additionally, this coupling device has been designed with a structure that is solid enough to withstand a possible impact during use.

Note that, in this document, the terms "front" and "rear" should be interpreted taking into account the natural direction of movement of the wheelchair and the manual bicycle. That is, the connection between the wheelchair and the manual bicycle is made between the front side of the chair and the rear side of the bicycle. On the other hand, the "longitudinal" direction refers to the horizontal direction of natural movement of the chair and the bicycle, and the "lateral" direction refers to a horizontal direction perpendicular to the longitudinal direction.

The present invention is directed to a manual coupling device between a manual bicycle and a wheelchair, provided that the wheelchair comprises at least one essentially vertical front bar and the manual bicycle comprises at least one essentially vertical rear bar. In this context, the term "essentially" refers to the fact that small deviations in relation to the vertical are possible both in the case of the rear bar of the hand bike and in the front bar of the wheelchair with respect to their respective natural position of use. For example, wheelchair structures are known whose frame includes a pair of almost vertical front bars although somewhat inclined backwards at an angle of up to about 10 °. These types of bars are considered in this document as "essentially vertical".

The coupling device of the invention basically comprises three elements: a lower jaw, an upper jaw, and a body that interconnects the upper jaw and the lower jaw. Each of these elements is described in more detail below.

a) Lower jaw

The lower jaw is configured for coupling to the rear bar 4

essentially vertical of the manual bicycle. In addition, the lower jaw comprises a rail which, when said lower jaw is coupled to the rear bar of the manual bicycle, has a lateral direction. This lane allows the coupling between a wheelchair and a manual bicycle that have different widths in their respective pairs of vertical bars.

In principle, the lower jaw could be designed in different ways as long as it allowed its coupling to an essentially vertical bar. However, in a particularly preferred embodiment of the invention the lower jaw is formed by a first lower jaw piece where the rail is located and a second lower jaw piece coupled to the first piece by means of a guide rod and a locking means . Thus, the lower jaw includes an essentially vertical housing intended to receive the rear bar of the bicycle, and then the first and second lower jaw pieces approach each other along the guide rod and are fixed by means of the Locking means to catch the rear bar of the bicycle between them.

The blocking means could also be designed in different ways, although in a preferred embodiment of the invention it is a locking rod provided with teeth fixedly attachable to an orifice of said second piece. That is, it is a locking system similar to that of a conventional flange where, when the second lower jaw piece is pressed in the direction of the first lower jaw piece to cause entrapment between both of the essentially vertical bar, successive teeth locking are introduced in the hole of the second piece and being coupled in it so that they do not allow its subsequent extraction. Thus, once the lower jaw has been coupled to the essentially vertical rear bar of the manual bicycle, it is fixed in that position. The bicycle is therefore ready for coupling / decoupling to the wheelchair at any time.

In another preferred embodiment of the invention, the lower jaw rail has open ends to allow entry and exit of the body guide. Indeed, as will be described later in this document, the rail of the lower jaw is arranged to receive a guide of the body of the device, which is in turn fixed to the upper jaw that is connected to the wheelchair. Therefore, to allow the decoupling of the chair and the manual bicycle, the jaw rail

Bottom has open ends to allow the guide to either exit to uncouple chair and bike, or enter to attach chair and bike. It is a very simple and quick coupling / decoupling means, and being located near the seat of the chair at its front, very accessible to the user.

b) Upper jaw

The upper jaw is configured for coupling to the essentially vertical front wheelchair bar.

According to a particularly preferred embodiment of the invention, the upper jaw is formed by a first upper jaw piece, a second upper jaw piece, and an opening-closing mechanism fixed to the body that allows the first and second to be zoomed in or out. upper jaw parts for attachment to the front wheelchair bar. In addition, to facilitate the grip with the front wheelchair bar, preferably the first and second upper jaw pieces have vertical cylindrical interior surfaces. Therefore, the upper jaw comprises an essentially vertical housing between the first and second upper jaw pieces configured to receive the front wheelchair bar, and subsequently the actuation of the opening-closing mechanism in the direction compresses said jaw pieces upper one against the other to firmly catch said front bar.

In principle, the opening-closing mechanism can be configured in different ways. In a preferred embodiment of the invention, a mechanism has been designed that does not require the application of much force so that it can be handled by the wheelchair users themselves with mobility problems. Specifically, the opening-closing mechanism preferably comprises:

-

A first lever arm having a first end fixed so

rotating to the body and a second end equipped with a grip.

-

At least one second arm that has a first fixed end of

rotational way to the second upper jaw piece and a second

end rotatably attached to the first lever arm.

With this configuration, the rotation of the first lever arm when the gripping means is actuated causes the second upper jaw piece to approach or move away from the first upper jaw piece, which allows the coupling or decoupling of said upper jaw to the front wheelchair bar. That is, the movement of the first lever arm fixed to the body drags the second jaw piece thanks to the second arm that is connected between the first arm and the second upper jaw piece. Since the first upper jaw piece is integral with the body, this movement causes the second upper jaw piece to approach or move away from it, which allows the front wheelchair bar to be firmly trapped.

In addition, this opening-closing mechanism can be located on one side of the upper jaw pieces, so that they have an open vertical side. Thanks to this, it is possible to insert or remove the essentially vertical front bar of the wheelchair through a movement in the lateral direction. Note that this movement in the lateral direction also allows the guide of the lower jaw rail to be removed, which will be described in more detail below. Therefore, in order to decouple the manual bicycle from the wheelchair, the user only has to operate the opening-closing mechanism of the upper jaw so that the upper jaw parts cease to firmly compress the front bar of the chair, since then pull the coupling device sideways. The upper body and the jaw are separated from the wheelchair, while the lower jaw is fixed to the essentially vertical rear bar of the bicycle.

In another preferred embodiment of the invention, the opening-closing mechanism of the upper jaw further comprises a pair of holes aligned in projections of the body for the introduction of a locking pin that prevents rotation of the first lever arm.

c) Body

The body is rigidly fixed to the upper jaw and comprises a lower sliding guide attachable to the rail of the lower jaw, such that by sliding the guide along the rail it can be adjusted in

lateral direction the position of the lower jaw relative to the upper jaw. That is, thanks to this guide the device of the invention can couple chairs and bicycles whose respective essentially vertical bars are arranged in different positions. In fact, normally wheelchairs comprise two essentially vertical front bars respectively left and right, and manual bicycles also comprise two essentially vertical rear bars respectively left and right. However, the separation distance between these respective pairs of bars may be different. The rail allows modifying the relative position of the lower jaw, which will be coupled to the rear bar of the bicycle, and the upper jaw, which will be coupled to the front bar of the chair, thereby providing the device of the invention with a great versatility

In addition, in an especially preferred embodiment of the invention, one end of the body that protrudes above the upper jaw comprises a horizontal-lateral cylindrical stud to rest on a curved portion of an upper end of the front bar of the wheelchair. Indeed, note that normally the essentially vertical front bar of a wheelchair curves backwards at its upper end until it becomes an essentially horizontal bar that supports the user's seat. The device of the present invention incorporates the pin to provide additional support to the body in case it is necessary to swing the chair so that the front part is raised during its connection with the bicycle. In addition, the positioning of the device near the upper end of the essentially vertical front bar of the chair ensures that the opening-closing mechanism of the upper jaw will be accessible to the user of the chair.

In another preferred embodiment of the invention, the body guide has an essentially cylindrical shape complementary to a cylindrical shape of the lower jaw rail, so that the guide can rotate about an axis parallel to the lower jaw rail. In fact, as mentioned above, the body guide is inserted into the rail of the lower jaw which is coupled to the bicycle bar to allow a lateral direction adjustment of the lower jaw with respect to the upper one. Additionally, due to the possibility that it is necessary to tilt the chair for the reason described above, the shape of the guide and the rail are chosen so that a certain turn in one direction is also allowed.

vertical plane

The operation of this device would be fundamentally the following. First, the lower jaw is fixed to the rear bar of the manual bicycle. To do this, insert the bar into the housing of the first jaw and, after placing the jaw at the appropriate height of said bar, the second jaw piece is pushed against the first jaw piece until the bar is firmly caught between them. The locking means operates automatically, with the last tooth of the locking rod being coupled to the hole of the second jaw piece so that the lower jaw as a whole is rigidly fixed to the rear bar of the bicycle. This action is carried out only the first time that the bicycle is to be attached to the chair, the lower jaw being normally attached to the rear bar of the bicycle, although it can be disassembled if disassembly is necessary. The rest of the connection procedure can be done by the wheelchair user himself without getting out of the chair. To do this, grab the upper body-jaw assembly with one hand and connect it laterally at the same time to the front bar of the chair and the lower jaw. That is, in the same movement, the guide of the lower end of the body is introduced laterally into the horizontal side rail of the lower jaw and the essentially vertical front bar of the chair is introduced into the vertical separation space between the first piece and the second upper jaw piece. If the device includes a support stud, the jaw body assembly is pulled up vertically to support the stud in the curved portion of the upper end of the chair bar. Once placed in its final position, the user activates the opening-closing mechanism of the upper jaw through the lever. The upper jaw pieces approach each other, firmly trapping the chair bar between them. Finally, a locking pin can be placed to prevent the opening-closing mechanism from accidentally opening during use. Once the exercise is finished, the user only has to re-actuate the opening-closing mechanism in the opposite direction to separate the upper jaw pieces and thus release the bar, and then simultaneously laterally extract the bar and the guide.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows a perspective view of a device according to the present invention.

Fig. 2 shows another perspective view of a device according to the present invention.

Fig. 3 shows a perspective view of a wheelchair to which they are attached 5 individual parts of the device of the invention formed by body-jaw assemblies higher.

Fig. 4 shows a perspective view of a manual bicycle to which parts of the device of the invention formed by the lower jaw are coupled.

10 Fig. 5 shows a detailed perspective view of a device of the invention by connecting a manual bicycle to a wheelchair.

Fig. 6 shows a perspective view of a manual bicycle coupled to a 15-wheel chair by means of a device according to the present invention.

Fig. 7 shows another perspective view of a manual bicycle coupled to a wheelchair by means of a device according to the present invention.

20 PREFERRED EMBODIMENT OF THE INVENTION

Figs. 1 and 2 show perspective views of the device (1) of the invention. The device (1) consists essentially of three parts: lower jaw (2), upper jaw (3), and a body (4) configured to interconnect the upper jaw (3)

25 to the lower jaw (2).

The lower jaw (2) is formed by a first piece (22) of lower jaw, a second piece (23) of lower jaw, a guide rod (24), and a locking rod (25). The first and second pieces (22, 23) have two pairs of aligned holes 30 in which the ends of the guide rod (24) and the locking rod (25) are inserted. The guide rod (24) is preferably smooth, and serves to guide the movement of the first and second lower jaw pieces (22, 23) when they approach or move away from each other. Between the lower jaw pieces (22, 23) there is an essentially vertical housing designed to receive a vertical bar (210) to which the jaw (2)

35 bottom is fixedly coupled by means of the locking rod (25).

The locking rod (25) has a plurality of teeth having an inclined side and another perpendicular to the direction of the rod itself (25). The operation of the locking rod (25) is similar to that of a conventional flange. When the second lower jaw piece (23) approaches the first lower jaw piece (22), the teeth of the locking rod (25) pass through the hole of said lower jaw piece (23) because they slide along its inclined side. However, the opposite side perpendicular to the direction of the rod itself (25) prevents the second lower jaw piece (23) from being separated from the first lower jaw piece (22) in the opposite direction. Thanks to this, it is possible to permanently fix the lower jaw (2) to the rear bar of a manual bicycle (200). Fig. 4 shows a perspective view of a manual bicycle (200) comprising two essentially vertical rear bars (210) to which lower jaws (2) are fixed.

The lower jaw (2) further comprises a rail (21) that is part of the first jaw piece (22). This rail (21) is arranged so that, when the jaw

(2)

Bottom is coupled to an essentially vertical bar (210) as shown in Fig. 4, it is oriented in a lateral horizontal direction, that is, perpendicular to the natural direction of movement of the bicycle (200). As will be described in detail below, this rail (21) is configured to receive inside a sliding guide (41) of the body (4) to which the upper jaw (3) is fixed, so that it allows the modification of the relative position of said upper jaw (3) relative to the jaw

(2)

 lower.

The upper jaw (3) is formed by a first piece (31) of upper jaw, a second piece (32) of upper jaw, and an opening and closing mechanism (33). The first piece (31) of upper jaw is rigidly attached to the body (4), and can even be an integral part thereof. The second upper jaw piece (32) is connected to the opening-closing mechanism (33) so that it can cause it to approach or move away from the first upper jaw piece (31) to trap the front bar (110) between them. ) essentially vertical of a wheelchair (100).

The opening-closing mechanism (33) is formed by a first lever arm (331) provided at its free end with a gripping means (331a), in this case a ball. The opposite end is rotatably connected to a body surface (4) opposite the position of the first and second (31, 32) upper jaw pieces. The opening-closing mechanism (33) also has a pair of second lever arms (332) that have a

end rotatably connected to the first lever arm (331) and an opposite end also rotatably connected to the second upper jaw piece (32).

Thanks to this configuration, when the user moves the first lever arm (331) by actuating the ball (331a), the movement of said first lever arm (331) is transmitted to the second jaw piece (32). through the pair of second lever arms (332), and consequently the second jaw piece (32) opens or closes. In addition, the opening-closing mechanism (33) has a pair of projections of the surface (4) of the body to which the end of the first lever arm (331) is fixed, which are provided with holes (333) for the introduction of a pin (334) or similar. The holes (333) are arranged in a position such that the pin (333) is perpendicular to the first lever arm (331) and adjacent thereto when it is in the closed position.

The introduction of this pin (333) therefore blocks the opening-closing mechanism (3) in the closed position in which the first and second jaw pieces (31, 32) are rigidly fixed to the vertical bar (110) of the wheelchair. Fig. 3 shows a perspective view of a wheelchair (100) comprising two essentially vertical front bars (110) to which upper jaws (3) and their respective bodies (4) are fixed.

The body (4) is the part that interconnects the lower jaw (2) and the upper jaw (3) when the device (1) is in a position of coupling the bicycle (200) to the chair

(100) of wheels. In this example, the body (4) has an essentially flat shape that has a central portion to which the upper jaw (3) is fixed on the one hand (specifically, to which the first piece (31) is rigidly fixed of the upper jaw), and on the other hand the opening-closing mechanism (33) of said upper jaw (3). The upper body portion (4) comprises a stud (42) protruding perpendicularly from its surface so that, when the upper jaw (3) is fixed to a chair (100), it has a lateral direction. This pin (42) will rest on the upper curved area of the bar (110), which, as seen in Fig. 3, undergoes a gradual transition through a curved section from vertical to horizontal. The lower portion of the body (4) comprises a guide (41) having an essentially cylindrical shape. This guide

(41) is arranged for sliding coupling to the rail (21) of the lower jaw

when the bicycle (200) is attached to the chair (100). 12

Fig. 5 shows a detailed side perspective view of the device (1) of the invention in a state in which a manual bicycle (200) is coupled to a wheelchair (100). As can be seen, the upper jaw (3) has been rigidly fixed to the bar

(110) of the wheelchair (100) through the opening-closing mechanism (33). The pin

(334) is inserted into the holes (333) to prevent the first lever arm (331) from being inadvertently displaced and releasing the rod (110) in an undesired manner. The lower jaw (2) is in turn rigidly fixed to the essentially vertical bar (210) of the manual bicycle (200). The body (4) is slidably coupled to the jaw

(2) lower through the guide (41, not visible in Fig. 5) inserted in the rail (21). Figs. 6 and 7 show perspective views of a bicycle (200) and a wheelchair (100) connected by means of this device (1).

Therefore, the use of this device (1) is fundamentally as follows. First, it is necessary to fix the lower jaw (2) to the essentially vertical rear bar (210) of the manual bicycle (200). To do this, said vertical bar (210) is introduced into the housing that exists between the first and second lower jaw pieces (22, 23) and said jaw (2) is located lower than the desired height. Next, the second upper jaw piece (23) is pushed in the direction of the first lower jaw piece (22), thereby firmly trapping the bar (210) between them. The locking rod (25) prevents the second jaw piece (23) from being able to retract, whereby the lower jaw (2) is rigidly fixed to the bar (210) of the bicycle (200). The bicycle (200) is thus ready to be connected to the wheelchair (100) by the user of the wheelchair (100) quickly and easily.

To perform this coupling, the user of the wheelchair (100), without getting up from the chair (100), holds the assembly formed by the body (4) and the upper jaw (3) and moves it in a lateral direction to achieve the introduction of the guide (41) into the rail (21) of the lower jaw (2) and simultaneously the introduction of the bar (110) of the chair

(100) in the vertical space that separates the first and second pieces (31, 32) of upper jaw. The pin (41) must rest on the curved portion of the upper end of the bar (110) which has an almost horizontal direction. Once the upper body assembly (4) and jaw (3) are placed in this position, the user operates the first arm

(331) lever through the ball (331a) in the direction of closing the upper jaw (3). The second upper jaw piece (32) moves closer to the first piece

(31) of upper jaw and so that the bar (110) is firmly trapped between 13

both. Once the first lever arm (331) is in the closed position, the user inserts the pin (334) into the holes (333) to prevent said first arm (331) from moving. The device (1) is thus locked in its closed position. The user repeats the operation in the device (1) on the opposite side of the chair (100), thus being fixed completely securely to the bicycle (200).

Claims (8)

1. Manual coupling device (1) between a wheelchair (100) and a bicycle 5 (200) manual and, where the wheelchair (100) comprises at least one essentially vertical front bar (110) and the manual bicycle (200) comprises at least one bar (210) essentially vertical rear, characterized in that it comprises: a lower jaw (2) for coupling to the essentially vertical rear bar (210) of the manual bicycle (200), where the lower jaw (2) comprises a rail (21) that, when said lower jaw (2) is coupled to the rear bar (210) of the manual bicycle (200), it has a lateral direction; - an upper jaw (3) for coupling to the essentially vertical front bar (110) of the wheelchair (100); and -a body (4) rigidly fixed to a first piece (31) of the jaw (3) 15 and comprising a sliding lower guide (41) attachable to the rail (21) of the lower jaw (2), such that by sliding the guide (41) along the rail (21) it can be adjusted in lateral direction the position of the lower jaw (2) relative to the upper jaw (3). Device (1) according to claim 1, wherein the lower jaw (2) is formed by a first lower jaw piece (22) where the rail (21) and a second jaw piece (23) is located. bottom coupled to the first piece (22) by means of a guide rod (24) and a locking means (25), so that the first and second lower jaw pieces (22, 23) can approach each other at stem length (24) of 25 guide and be fixed by means (25) of blocking. 3. Device (1) according to claim 2, wherein the locking means (25) is a locking rod provided with teeth fixedly attachable to an orifice of said second piece (23). Device (1) according to any one of the preceding claims, wherein one end of the body (4) protruding above the upper jaw (3) comprises a horizontal-lateral cylindrical pin (42) to rest on a curved portion of an upper end of the front bar (110) of the chair (100) wheels. 5. Device (1) according to any of the preceding claims, wherein the guide (41) of the body (4) has an essentially cylindrical shape complementary to a cylindrical shape of the rail (21) of the lower jaw (2), so that the guide (21) can rotate about an axis parallel to the rail ( 21) of the lower jaw (2). 5 6. Device according to any of the preceding claims, wherein the rail (21) of the lower jaw (2) has open ends to allow entry and exit of the guide (41) of the body (4). 7. Device (1) according to any of the preceding claims, wherein the 10 upper jaw (3) is formed by the first upper jaw piece (31) fixed to the body (2), a second upper jaw piece (32), and a closing opening mechanism (33) fixed to the body (4) that It allows the second jaw piece (32) of the upper jaw to be zoomed in or out from the first piece (31) of the upper jaw for attachment to the front bar (110) of the wheelchair (100). 8. Device (1) according to claim 7, wherein the first piece (31) and the second piece (32) of upper jaw have vertical cylindrical interior surfaces. A device (1) according to any one of claims 7-8, wherein the opening opening mechanism (33) of the upper jaw (3) is formed by a first lever arm (331) having a first end rotatably fixed to the body (4) and a second end provided with a gripping means (331a); - at least one second arm (332) having a first end rotatably fixed to the second upper jaw piece (32) and a second end rotationally fixed to the first lever arm (331), so that the rotation of the first lever arm (331) when the gripping means (331a) is actuated causes the second jaw piece (32) of the upper jaw to be moved closer or further away from the first jaw piece (31) for the upper jaw coupling or 30 decoupling said jaw (3) superior to the front bar (110) of the wheelchair (100). 10. Device (1) according to claim 9, wherein the mechanism (33) of opening-closing is located on one side of the upper jaw pieces (31, 32), so that they have an open vertical side. 11. Device (1) according to any of claims 9-10, wherein the mechanism (31) for opening-closing the upper jaw (3) further comprises a pair of holes (333) aligned on projections of the body ( 4) for the introduction of a pin (334) lock that prevents rotation of the first lever arm (331).