Abstract:
A finger-operated lever device to be installed on a handlebar of an All-Terrain Vehicle (ATV) or other applicable vehicle, for actuating a cable to cause acceleration of the internal combustion engine of the vehicle. The lever device includes a housing, an internal first lever assembly connectable to the cable, and an external second lever assembly. The external lever assembly and the internal lever assembly are connected so that user operation of the external lever assembly causes the internal lever assembly to rotate. The external lever assembly is divided into two portions, a support member and an extension member. The extension member can be adjusted at different angles to the support member, allowing the user to set the angle of the lever to most comfortably fit to his or her riding posture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/929,365, filed Jan. 20, 2014, which is incorporated herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a finger-operated lever device to be installed on a vehicle handlebar for actuating a cable of a vehicle, and particularly to a thumb throttle device designed to be installed on an ATV handlebar for accelerating and decelerating an All-Terrain Vehicle (ATV), where the position of the lever is adjustable so that the thumb can comfortably and safely access the lever regardless of the posture in which the user is riding the vehicle and gripping the handlebar. 
     BACKGROUND OF THE INVENTION 
     An All-Terrain Vehicle (ATV) is an open three-wheeled or four-wheeled vehicle that includes a seat and a steering handlebar, and that is designed for driving over very irregular terrain while also being capable of driving over asphalt. The experience of riding an ATV is unique for several reasons. In the first place, handlebar steering provides a very sportive driving experience, similar to that of driving a motorcycle or a mountain bike (MTB), but different in that the vehicle has three or four wheels instead of two. In the second place, the driver generally rides in a straddled position, further enhancing the sportive driving feeling. In addition, the driver can ride the ATV either sitting down or standing up, depending on the type of terrain or on his/her specific desire at any given moment. ATV&#39;s are thus versatile vehicles that provide many riding styles, although the use for which they are especially designed is to ride over rough terrain. 
     ATV&#39;s are usually provided with an internal combustion engine to power the vehicle and cause it to move. Such a combustion engine generally comprises one or more cylinders, inside each of which there is a combustion chamber and a movable piston. Internal combustion engines work in cycles. In each cycle, a mixture of fuel and air is injected into the combustion chamber; then, the piston moves towards the chamber and compresses the injected mixture; the fuel explodes (a spark can be provided therefor), causing the piston to move outwards from the combustion chamber. A crank shank converts the longitudinal outward and inward movement of the pistons into a rotational movement that is eventually transmitted to the tractor wheels. The combustion engine further includes a throttle valve or other valve capable of adjusting the amount of fuel or air in the mixture. Adjusting the amount of fuel or air in the mixture causes the motor to accelerate or decelerate, depending on whether the fuel/air ratio is increased or decreased. A user-operable mechanism, external to the engine, allows the user to act on the valve in order to accelerate or decelerate the motor. Normally, the user-operable mechanism for accelerating an ATV is included in the handlebar, in further resemblance to motorcycles, and is connected to the throttle valve or other applicable fuel-, air- or mixture-regulating valve by a cable. 
     Various types of user-operable handlebar accelerating mechanisms are known in ATV&#39;s present in the market. For instance, the user-operable mechanism can consist of a turnable gripping portion capable of pulling the aforementioned cable. The turnable gripping portion is usually on the right side of the handlebar so that the user can accelerate or decelerate the vehicle by rotating the gripping portion using his/her right hand. Although traditionally used in motorcycles, mechanisms based on a turnable gripping portion can result quite uncomfortable to use in ATV&#39;s, particularly when the user is standing up, as they force the user&#39;s wrist to flex upwards excessively in order to accelerate the vehicle. Alternatively, the user-operable handlebar mechanism can consist of a lever that is actuated by the user&#39;s thumb and that is capable of pulling the aforementioned cable. Such a mechanism is sometimes referred to as thumb throttle. Thumb throttles are advantageous in that they require less or no movement of the user&#39;s wrist. However, they present the drawback of the user having to slightly ungrasp the handle to allow for his/her thumb to press the lever. Because of this, thumb throttles can be uncomfortable and even dangerous to use, especially when riding in a standing position, and particularly when performing a riding modality known as ATV Cross. In said modality, the user performs jumps with the ATV, and thus needs to strongly hold on to the handlebar in order not to fall off of the vehicle; in such riding conditions, having to soften the grip in order to press the thumb lever can result very dangerous and even fatal. 
     Accordingly, there remains a need in the art to provide a safe and comfortable user-operable handlebar mechanism for actuating a cable, such as a cable for operating a throttle valve for accelerating an ATV or other vehicle provided with an internal combustion engine. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the deficiencies of the known art and the problems that remain unsolved by providing a finger-operated lever device to be installed on a vehicle handlebar for actuating a cable of the vehicle. For instance, the finger-operated lever device can be installed on a handlebar of an All-Terrain Vehicle (ATV) in order to actuate on the cable that in turn actuates the throttle valve of the internal combustion engine. The device of the present invention provides comfortable access to the user&#39;s thumb or finger by including a finger-operable lever whose position within the device can be varied, allowing the user to adjust the position of the lever to a position that best suits the posture in which the user is riding the ATV, so that the lever is easy and safe to operate regardless of the user&#39;s posture. 
     In accordance with one embodiment of the present invention, the invention consists of a finger-operated lever device to be installed on a vehicle handlebar for actuating a cable of a vehicle, comprising: 
     a housing, comprising a handlebar-receiving area for at least partially embracing a portion of the handlebar, an inner space delimited inside the housing, and a cable opening for allowing a cable to pass between the inner space and the outside of the housing; 
     a first lever assembly, arranged in the inner space of the housing, the first lever assembly comprising a hinged end and a pivotable end, the hinged end being hinged along a first rotation axis, and the pivotable end providing a fastening area for connecting a cable; 
     a second lever assembly, arranged at least partially outside of the housing and extending from the housing so that a user can operate the second lever assembly with at least one finger, wherein the second lever assembly is non-rotationally connectable to the hinged end of the first lever assembly. 
     In a second aspect, the lever device further includes a rod extending from the second lever assembly to the hinged end of the first lever assembly, and rotationally coupled to the second lever assembly and to the hinged end so that the first lever assembly, the rod and the second lever assembly are jointly rotatable about the first rotation axis, wherein the rod extends through a through hole in the housing. 
     In another aspect, through hole is provided with at least one bearing to facilitate rotation of the rod within the through hole in the housing. The at least one bearing can include a needle bearing. 
     In another aspect, the second lever assembly includes a support member and an extension member, the support member being non-rotationally connectable to the hinged end of the first lever assembly, wherein the extension member protrudes outwardly from the housing allowing for the extension member to be operated by a user&#39;s finger, the extension member being rotatable relative to the support member about a second rotation axis, wherein the extension member is lockable to the support member in different rotational positions. 
     In another aspect, the second rotation axis is parallel to the first rotation axis. 
     In another aspect, the extension member comprises an extension body portion and an extending handle, the extension body portion facing the support member and comprising at least two pin-receiving spaces capable of becoming alternately aligned with a pin-receiving space of the support member, the second lever assembly further comprising a pin arrangeable within the pin-receiving space of the support member and within a pin-receiving space of the extension body portion, preventing rotation of the extension member with respect to the support member. 
     In another aspect, the pin-receiving spaces of the extension body portion comprise longitudinal cylindrical grooves on an outer surface of the extension body portion, and the pin-receiving space of the support member comprises a longitudinal cylindrical groove on an outer surface of the support member. 
     In another aspect, the extension body portion is movable with respect to the support member in the direction of the second rotation axis, and the extension body portion is spring biased against the support member so that the pin-receiving spaces of the extension body portion are biased to radially face the pin-receiving space of the support member. 
     In another aspect, the extension body portion comprises a longitudinal through hole forming a barrel hinge connection with a rod longitudinally coupled to the support member. 
     In another aspect, the rod is threaded to the support member. 
     In another aspect, the rod is terminated in a shoulder, the shoulder comprising an inner surface and an outer surface, the extension body portion including a compression spring housed in the longitudinal through hole of the extension body portion and applying a longitudinal expansion force between the inner surface of the shoulder and an opposing inner surface of the extension body portion. 
     In another aspect, the lever device further comprises a rod extending from the support member to the hinged end of the first lever assembly, and rotationally coupled to the support member and to the hinged end so that the first lever assembly, the rod and the support member of the second lever assembly are jointly rotatable around the first rotation axis. 
     In another aspect, the support member is rotationally and longitudinally coupled to the rod by at least one transverse screw, allowing the support member to be adjusted and locked to the rod in different rotational and/or longitudinal positions. 
     In accordance with another embodiment of the present invention, the invention consists of a finger-operable lever device to be installed on a vehicle handlebar for actuating a cable of a vehicle, comprising: 
     a housing, comprising a handlebar-receiving area for at least partially embracing a portion of the handlebar, an inner space delimited inside the housing, and a cable opening for allowing a cable to pass between the inner space and the outside of the housing; 
     a first lever assembly, arranged in the inner space of the housing, the first lever assembly comprising a hinged end and a pivotable end, the hinged end being hinged about a first rotation axis, and the second end providing a fastening area for connecting a cable; 
     a second lever assembly, arranged at least partially outside of the housing, wherein the second lever assembly comprises a support member and an extension member, the support member being non-rotationally connectable to the hinged end of the first lever assembly, and wherein the extension member protrudes outwardly from the housing allowing for the extension member to be operated by a user&#39;s finger, the extension member being rotatable relative to the support member about a second rotation axis, wherein the extension member is lockable to the support member in different rotational positions. 
     Introducing yet another embodiment of the invention, the present invention consists of a finger-operated lever device to be installed on a vehicle handlebar for actuating a cable of a vehicle, comprising: 
     a housing, comprising a handlebar-receiving area for at least partially embracing a portion of the handlebar, an inner space delimited inside the housing, and a cable opening for allowing a cable to pass between the inner space and the outside of the housing; 
     a first lever assembly, arranged in the inner space of the housing, the first lever assembly comprising a hinged end and a pivotable end, the hinged end being hinged along a first rotation axis, and the second end providing a fastening area for connecting a cable; 
     a second lever assembly, arranged at least partially outside of the housing, wherein the second lever assembly comprises a support member and an extension member, the support member being non-rotationally connectable to the hinged end of the first lever assembly, and wherein the extension member protrudes outwardly from the housing allowing for the extension member to be operated by a user&#39;s finger, the extension member being rotatable relative to the support member about a second rotation axis, wherein the extension member is lockable to the support member in different rotational positions; and 
     a rod extending from the second lever assembly to the hinged end of the first lever assembly, and non-rotationally coupled to the support member of the second lever assembly and to the hinged end so that the first lever assembly, the rod and the second lever assembly are jointly rotatable about the first rotation axis, wherein the rod extends through a through hole in the housing. 
     These and other aspects, features, and advantages of the present invention will become more readily apparent from the attached drawings and the detailed description of the preferred embodiments, which follow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The preferred embodiments of the invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the invention, in which: 
         FIG. 1  presents a first perspective view of an exemplary lever device according to the invention. 
         FIG. 2  presents a second perspective view of the lever device of the previous figure; 
         FIG. 3  presents the lever device of  FIG. 1  mounted on a vehicle handlebar; 
         FIG. 4  presents a first exploded view of the lever device of  FIG. 1 , showing the inner space and the first lever assembly; 
         FIG. 5  presents a second exploded view of the lever device of  FIG. 1 , revealing the rod that connects the second lever assembly to the first lever assembly, and the components of the second lever assembly; 
         FIG. 6  presents a third exploded view, similar to that of  FIG. 5  but shown from a different angle; 
         FIG. 7  presents a cross-sectional view of the second lever assembly according to a cross-sectional plane containing the second rotation axis; 
         FIG. 8  presents a perspective view of the second lever assembly being unlocked to readjust the position of the extension member; 
         FIG. 9  presents a cross-sectional view of the second lever assembly according to a cross-sectional plane that is perpendicular to the second rotation axis; 
         FIG. 10  presents a cross-sectional view of the lever device, according to a cross-sectional plane that is perpendicular to the first rotation axis and passes through the first lever assembly; 
         FIG. 11  shows a cross-sectional view of the lever device, according to cross-sectional plane  11 - 11  of  FIG. 10 . 
     
    
    
     Like reference numerals refer to like parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure, which is defined by the claims. For purposes of description herein, the terms “upper”, “lower”, “left”, “rear”, “right”, “front”, “vertical”, “horizontal”, and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     The illustrations of  FIGS. 1 and 2  show two different perspective views of an exemplary embodiment of the invention, consisting of a finger-operated lever device  100  for pulling or releasing a cable that actuates a throttle valve or other similar mechanism for accelerating a combustion engine of an ATV. The cable is not shown in the figures. 
     The lever device  100  consists mainly of a housing  110  inside which many of the lever device components are housed and concealed. The housing  110  includes a handlebar-receiving area  120 , for receiving the ATV handlebar, not shown. In the present embodiment, the handlebar-receiving area  120  is a through hole delimited by a concave surface  124  comprised in a main body  114  of the housing  110  and by a separable cover  128  that fastens to the main body  114 . The illustration of  FIG. 3  shows the lever device  100  attached to a handlebar  500  by having fitted the handlebar  500  against the concave surface  124  and by having fastened the separable cover  128  onto the main body  114  of the housing  110  so that the separable cover  128  keeps the handlebar  500  in place. Therefore, the device  100  of the present embodiment fully embraces the perimeter of the handlebar  500 . Alternative embodiments are contemplated, however, in which the device only partially embraces the handlebar, for instance by comprising a clipping or clamping connection to the handlebar. 
     Turning again to  FIGS. 1 and 2 , the housing  110  of the present embodiment includes a second separable cover  130  that is attached to the main body  114  of the housing  110  by hex screws  134 . The illustration of  FIG. 4  shows a partially exploded perspective view of the device  100 , where the second separable cover  130  is separated from the main body  114 , revealing an inner space  140  delimited inside the housing  110 . The housing  110  further comprises a cable opening  150 , as better shown in  FIGS. 1, 3 and 4 , for allowing a cable to pass between the inner space  140  and the outside of the housing  110 . The cable  510  is shown only in  FIG. 3 . 
     As best shown in  FIGS. 1, 3 and 10 , the cable opening  150  can be provided within a connector  152 . In different embodiments of the invention, the connector  152  can optionally be provided with an internal thread, an external thread, a flange, an inward clipping protuberance, an outward clopping protuberance, or other applicable mechanical fastener or combination thereof for engaging a connector carried by the cable  510 . For instance, as best shown in  FIG. 10 , the connector  152  of the present embodiment presents a central bore  154  and two internal wider cavities  156  for the passing through of the cable  510 , and for housing and longitudinally retaining a connector carried by the cable  510 . 
     As depicted in  FIG. 4 , the device  100  further comprises a first lever assembly  160  arranged in the inner space  140  of the housing  110 . The first lever assembly  160  includes a hinged end  164  and a pivotable end  168 . The hinged end  164  is hinged along a first rotation axis  170 , allowing the first lever assembly  160  to rotate around the first rotation axis  170 . The pivotable end  168 , in turn, provides a fastening area  180  for connecting the cable. When the first lever assembly  160  is caused to rotate around the rotation axis  170 , the pivotable end  168  pulls or releases the attached cable. 
     The device  100  further includes a second lever assembly  190 , arranged at least partially outside of the housing  110 . The second lever assembly  190  comprises a support member  200  and an extension member  210 . The support member  200  is non-rotationally connected to the hinged end  164  of the first lever assembly  160 . By non-rotationally connected it is understood that the support member  200  and the hinged end  164  are connected so that they to rotate jointly around the rotation axis  170 . For instance, in the present embodiment, a rod  220  is non-rotationally connected to and extends through the support member  200 , further extending through the main body  114  of the housing  110  and into the inner space  140 , inside which a non-rotationally-symmetric end  224  of the rod  220  engages with a matching aperture  166  of the hinged end  164 , as is shown in  FIG. 4  and also in the cross-sectional view of  FIG. 10 . Such an arrangement allows rotation of the support member  200  to cause rotation of the first lever assembly  160 . In turn, the extension member  210  is connected to the support member  200  and protrudes outwardly from the housing  110  so that a finger can comfortably push the extension member  210 . The extension member  210  is non-rotationally connected to the support member  200  so that rotation of the extension member  210  causes a joint rotation of the support member  200  and thus, as has been explained, a rotation of the first lever assembly  160 . According to the invention, the extension member  210  is lockable to the support member  200  in different rotational positions for adjusting the position of the extension member  210  with respect to the support member  200 . In other words, the support member  200  and the extension member  210  can be non-rotationally connected forming different angles, allowing the angle at which the extension member  210  protrudes outwardly from the housing  110  to be varied and adapted to the user&#39;s riding or driving posture. 
     The non-rotational correction between the support member  200  and the rod  220  is achieved through transverse screws  226 , which are radially arranged through the support member  200  and extend to the outer surface of the rod  220 , not shown, slightly biting into the outer surface. Biting into the surface is enough to lock the support member  200  to the rod  220  and thus to prevent the support member  200  from moving relative to the rod  220  in any direction (i.e., neither rotationally nor longitudinally). The screws  226  can be unthreaded, allowing the user to adjust the relative rotational and/or longitudinal position between the support member  200  and the rod  220 , and thus to adjust the relative position of the second lever assembly  190  relative to the main body  114 . For instance, the user can slightly unthread the screws  226 , pull out the support member  200  to a more comfortable position, and thread the screws  226  back in to once again lock the support member  200  to the rod  220 . In an exemplary practical application, a user having a longer thumb might have to adjust the support member  200  longitudinally along the rod  220  so that the support member  200  is placed closer to the main body  114  than a user having a shorter thumb. 
     In the present embodiment, as shown in  FIG. 3 , the extension member  210  is rotatable with respect to the support member  200  relative to a second rotation axis  230  that is parallel to the first rotation axis  170 . Such an arrangement provides a comfortable and intuitive adjustment of the extension member  210 , as the direction in which the user must rotate the second lever assembly  190  in order to accelerate is the same as the direction in which the user must rotate the extension member  210  in order to adjust its position relative to the support member  200 . Thus, if the user adjusts the rotational position of the device  100  on the handlebar  500  so that the second lever assembly  190  is comfortably reached and the user can thus comfortably accelerate the vehicle, the user will also be able to adjust the position of the extension member  210  equally comfortably. 
     The illustrations of  FIGS. 5 and 6  show two additional perspective views of the device  100 , where the device is shown again partially exploded in order to reveal components in the area of the second lever assembly  190 . As shown in the figures, the extension member  210  comprises an extension body portion  240  and an extending handle  250 . The extension body portion  240  faces the support member  200  and comprises at least two pin-receiving spaces  242 , shown in  FIG. 6 , capable of becoming alternatively aligned with a pin-receiving space  202  of the support member  200 , which is shown in  FIG. 5 . The second lever assembly  190  further comprises a pin  260  ( FIG. 5 ) that allows locking the extension member  210  in a determined position relative to the support member  200 . For this purpose, the pin  260  is arranged inside the pin-receiving space  202  of the support member  200  and a pin-receiving space  242  of the extension body portion  240 , preventing rotation of the extension member  210  with respect to the support member  200  around the second rotation axis  230 . 
     Preferably, as shown, the pin-receiving spaces  242  of the extension body portion  240  are longitudinal cylindrical grooves, as shown in the figures. The grooves are formed on an outer surface  246  of the extension body portion  240 . By longitudinal, it is understood that the cylindrical grooves are arranged so that the cylinder axes are parallel to the second rotation axis  230 , i.e., to the rotation axis between the extension member  210  and the support member  200 . Similarly, the pin-receiving space  202  of the support member  200  is a longitudinal cylindrical groove on an outer surface  206  of the support member  200 . The pin-receiving spaces  202 ,  242  being cylindrical allows using a cylindrical pin  260 . The pin-receiving spaces  202 ,  242  and the pin  260  being cylindrical in shape allows them all to be manufactured at reasonable cost. 
     In addition, the extension body portion  240  comprises a longitudinal through hole  270  forming a barrel hinge connection with a rod  280  that is, in turn, longitudinally coupled to the support member  200 . By longitudinally coupled it is understood that the rod  280  is connected to the support member  200  and does not vary its longitudinal position in relation to the support member  200  during normal use of the device  100 . A barrel hinge connection between the support member  200  and the extension body portion  240  provides a robust and durable articulated connection between the extension member  210  and the support member  200  of the second lever assembly  190 . 
     For instance, in the present embodiment, the rod  280  is a separate member, as shown in  FIGS. 5 and 6 , that has a threaded portion  282 . The support member  200  includes a corresponding threaded bore  208 , into which the threaded portion  282  of the rod  280  is threaded, allowing the rod  280  to become longitudinally coupled to the support member  200 . 
     In the present embodiment, the extension body portion  240  is movable with respect to the support member  200  in the direction of the second rotation axis  230 . In addition, the extension body portion  240  is spring biased against the support member  200  so that the pin-receiving spaces  242  of the extension body portion  240  are biased to radially face the pin-receiving space  202  of the support member  200 . Such an arrangement allows the extension member  210  to be easily unlocked, rotated and locked to the support member  200  for readjustment of the relative position of the extension member  210  and the support member  200 . In the present embodiment, as best shown in  FIG. 7 , the rod  280  is terminated in a shoulder  286 , the rod  280  and the shoulder  286  thus forming a shoulder bolt, where the shoulder  286  comprises an inner surface  290  that faces the rod  280  and an outer surface  294  opposite to the inner surface  290 . The extension body portion  240  further includes a spring  300  housed in the longitudinal through hole  270  of the extension body portion  240 . The spring  300  is a compression spring that is compressed between the inner surface  290  of the shoulder  286  and an opposing inner surface  310  of the extension body portion  240 , and thus applies an expansion force on both surfaces  290 ,  310 . Because the rod  280  is longitudinally coupled to the support member  200 , the position of the inner surface  290  relative to the support member  200  does not vary. In consequence, the spring expansion force pushes the extension body portion  240 , and thus the extension member  210 , against the support member  200 , to maintain the aforementioned pin lock mechanism in a locked state. 
     The illustration of  FIG. 8  allows for better understanding of the aforementioned pin-based locking mechanism. In normal operating conditions, the extension member  210  is biased against the support member  200  by the spring  300  (not shown) located inside the extension body portion  240 , as has been explained above with reference to  FIG. 7 . In the normal operating conditions, the extension member  210  is rotationally locked to the support member  200  by the pin  260 , as is further illustrated in the cross-sectional view of  FIG. 9 . Thus, when the user operates the extending handle  250  of the extension member  210 , the following components rotate jointly around the first rotation axis  170 : the extension member  210 , the support member  200 , the rod  220 , and the first lever assembly  160  housed in the inner space  140  of the housing  110 . Therefore, in the normal operating conditions, rotation of the extension member  210  causes the first lever assembly  160  to pull the cable. This being said, the illustration of  FIG. 8  presents a situation in which, parting from the normal operating conditions, the user is readjusting the relative position of the extension member  210  and the support member  200  in order to vary the angle at which the extending handle  250  protrudes outwardly from the handlebar (for instance, in the event that the user wishes to ride in a standing position instead of in a sitting position and wishes to readjust the position of the extending handle  250  accordingly). In order to readjust, the user pulls out the extension member  210  as indicated by arrow  320  by exerting an outward force that has overcome the inward biasing force of the spring. The pin-receiving spaces  242  are moved rearwards so that the pin  260  disengages from the specific pin-receiving space  242  inside which it was engaged in the normal operating condition. In consequence, the extension member  210  is now free to rotate with respect to the support member  200  and around the second rotation axis  230 , as indicated by arrow  330 . The user then turns the extension member  210  to the desired new angle, and stops exerting the outward force in the direction of arrow  330 . The inner spring  300  ( FIG. 7 ) pushes the extension body portion  240 , and thus the extension member  210 , back towards the support member  200 , causing the pin  260  to engage in a different pin-receiving space  242 . The extension member  210  is thus locked in a new rotational position around the second rotation axis  230 . 
     In a further aspect of the invention, as shown in  FIGS. 4, 5 and 11 , the rod  220  that connects the second lever assembly  190  to the first lever assembly  160  extends through a through hole  340  in the housing  110 . The end  224  of the rod  220  is engaged with the corresponding aperture  166  of the hinged end  164  of the first lever assembly  160 , as has been explained. On the other side of the hinged end  164 , a cap  350  is fixed by a screw  360 , as best shown in  FIG. 11 , securing the rod  220  to the first lever assembly  160 . The through hole  340  is provided with at least one bearing  370  to facilitate rotation of the rod  220  within the housing  110 . In the embodiment shown, the device specifically comprises two needle bearings  370 . 
     The above-described embodiments are merely exemplary illustrations of implementations set forth for a clear understanding of the principles of the invention. Many variations, combinations, modifications or equivalents may be substituted for elements thereof without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all the embodiments falling within the scope of the appended claims.