Abstract:
In a traditional hitched trailer there is no way to adjust the ride height of the trailer. Provided is an angular adjusting mechanism ( 13 ) for a suspension system ( 10 ) comprising a shaft ( 12 ) and a crank arm ( 20 ), the shaft ( 12 ) having a connecting end ( 14 ) connected to the crank arm ( 20 ), said angular adjusting mechanism ( 13 ) comprising a frusto-comcal shaped surface ( 16 ) provided on the connecting end ( 14 ) and pointing outwardly from said shaft ( 12 ), said surface ( 16 ) having an array of first cavities ( 18 ) arranged circumferentially, a frusto-comcal bore ( 22 ) proximate a first extremity of said crank arm ( 20 ), said bore ( 22 ) having an array of second cavities ( 24 ), said bore ( 22 ) being operative to mate with said surface ( 16 ) of said connecting end ( 14 ), and an interlocking element ( 30 ) partly positioned in one of said second cavities ( 24 ) and partly positioned in one of said first cavities ( 18 ) so as to lock said crank arm ( 20 ) at a predetermined angular position with respect to said shaft ( 12 ). Also, an improved torsion suspension system ( 10 ) including the above mentioned angular adjusting mechanism ( 13 ) is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is a National Stage of International Patent Application No. PCT/CA2009/000733, filed on May 25, 2009, which claims priority to U.S. Provisional Patent Application No. 61/055,700, filed on May 23, 2008, the contents of which are hereby incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to the field of hitched trailers for vehicles or various devices involving the use of a torsion suspension such as tensioning devices, motor bases, oscillating mounting, etc. More specifically, the invention relates to a torsion suspension for such trailers having an angular adjusting mechanism. The present invention also relates to an angular adjusting system for a torsion suspension. 
     BACKGROUND OF THE INVENTION 
     Torsion axles represent a way to provide some independent suspension to the wheels of vehicles. Torsion axles and torsion suspensions are commonly used with vehicles such as hitched trailers. Also, torsion axles and torsion suspensions can be used with various devices involving the use of a torsion suspension such as tensioning devices, motor bases, oscillating mounting, etc. 
     Such trailers are used in a wide variety of applications like hauling a recreational vehicle, transporting dirt or branches, moving furniture, etc. However, sometimes, the trailer is too high for the application such that it is difficult to place the object to be loaded on the trailer. Some other times though, the trailer is too low for the application, like when going off-road. 
     There is therefore a need to provide a way to either lower or raise the height of the trailer. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a torsion suspension system that overcomes or mitigates one or more disadvantages of known torsion suspension systems, or at least provides a useful alternative. Also, even though the following description is directed to a vehicle suspension system, it may be applied to various devices involving the use of a torsion suspension such as tensioning devices, motor bases, oscillating mounting, etc. 
     The invention provides the advantages of facilitating the adjustment of the height of a trailer by the angular adjustment of the suspension crank arms with respect to a shaft. 
     The invention also provides the advantages of facilitating the replacement of the crank arms from the shaft. 
     The invention also provide with the further preferred advantage of having a plane of symmetry allowing to define an universal crank arm either side of a suspension system. This gives an economical advantage of reducing production and inventory costs. 
     The invention is particularly and non limitatively useful with a torsion system for torsion axle/suspension as defined in Applicant&#39;s US patent application which is a national phase originating from the Applicant&#39;s International Patent Application PCT/CA2006/001901 the content of which is hereby incorporated by reference in its entirety. 
     More particularly, in this International Patent Application PCT/CA2006/001901, the Applicant describes a torsion system comprising: a housing adapted to be secured to a structural portion of a vehicle; a shaft having a core portion accommodated in the housing and defining at least one concavity in the core portion, the shaft having a connector end connected to a crank arm, the connector end protruding out of the housing; and an elastomeric member received in the concavity of the shaft, the elastomeric member having a geometry so as to at least partially fill the concavity and contact an inner surface of the housing; whereby a rotation of the crank arm results in a deformation of the elastomeric member. One of the advantages of this torsion system relates to the fact that the core portion do not have translational movements allowing the elastomeric member to be deformed only by rotational movement of the shaft. 
     Further in this International Patent Application PCT/CA2006/001901, the Applicant describes a method for inserting elastomeric members in a torsion system, comprising the steps of: positioning at least one unused elastomeric member on a shaft of a torsion system; manually inserting the shaft and the at least one unused elastomeric member in a housing of the torsion system; and locking support blocks to maintain the shaft and elastomeric member captive in the housing of the torsion system. 
     According to a first embodiment, the present invention relates to an angular adjusting mechanism for a suspension system comprising a shaft and a crank arm, the shaft having a connecting end connected to the crank arm, said angular adjusting mechanism comprising:
         a frusto-conical shaped surface provided on the connecting end and pointing outwardly from said shaft, said surface having an array of first cavities arranged circumferentially;   a frusto-conical bore proximate a first extremity of said crank arm, said bore having an array of second cavities, said bore being operative to mate with said surface of said connecting end; and   an interlocking element partly positioned in one of said second cavities and partly positioned in one of said first cavities so as to lock said crank arm at a predetermined angular position with respect to said shaft.       

     According to a second embodiment, the invention relates to a torsion suspension system comprising:
         a shaft having two opposed connecting ends, each one of said connecting ends having a frusto-conical shaped interface surface pointing outwardly from said shaft, said interface surface having an array of first cavities arranged circumferentially;   a pair of angular adjusting mechanisms, each one of said pair of an angular adjusting mechanisms being located at a respective connecting ends, each said angular adjusting mechanism having:
           a crank arm, said crank arm having a frusto-conical bore proximate a first extremity of said crank arm, said bore having a second cavity, said bore being operative to mate with said interface surface of said connecting end; and   an interlocking element, said interlocking element being partly positioned in said second cavity and partly positioned in one cavity of said array of said first cavities so as to lock said crank arm at a predetermined angular position with respect to said shaft. As a non limitative example, this second embodiment can be preferably useful when used as part of a tensioning device for a belt or a strap.   
               

     According to a third embodiment, the invention relates to a torsion suspension system comprising:
         a shaft having two opposed connecting ends;   two crank arms operatively connected to a different one of said connecting ends;
           an angular adjusting mechanism at each of said connecting ends, said angular adjusting mechanism being operative to angularly adjusting an angle of each of said two crank arms with respect to said shaft. As a non limitative example, this third embodiment can be preferably useful when used as part of a tensioning device for a belt or a strap.   
               

     According to a fourth embodiment, the invention relates to a torsion system comprising:
         a housing adapted to be secured to a structural portion of a vehicle;   a shaft having a core portion accommodated in the housing and defining at least one concavity in the core portion, the shaft having a connecting end connected to crank arm, the connecting end protruding out of the housing;   at least one elastomeric member having a geometry so as to at least partially fill the concavity and contact an inner surface of the housing, the rotation of the crank arm resulting in a deformation of the elastomeric member; and   an angular adjusting mechanism comprising:
           a frusto-conical shaped interface surface provided on the connector and pointing outwardly from said shaft, said interface surface having an array of first cavities arranged circumferentially;   a frusto-conical bore proximate a first extremity of said crank arm, said bore having an array of second cavities, said bore being operative to mate with said interface surface of said connecting end; and   an interlocking element partly positioned in one of said second cavities and partly positioned in one of said first cavities so as to lock said crank arm at a predetermined angular position with respect to said shaft. According to an alternative embodiment, an angular adjusting mechanism may be provided at both ends of the shaft.   
               

     According to a fifth embodiment of the invention, the connecting ends of any of the above mentioned embodiments may further comprise a screw for attaching said crank arm to said connecting end. More preferably, this screw is adapted to cooperate with a corresponding threaded bore provided in a corresponding connecting end, to press the crank arm against the connecting end and maintain the interlocking element in said first and second cavities. Optionally and not imitatively, a washer may be positioned between the head of the screw and the crank arm. 
     According to a sixth embodiment of the invention, the crank arm of any of the above mentioned embodiments may further comprise an axle proximate a second extremity of said crank arm, said axle being parallel to said shaft. Such an axle can be mounted to the crank arm according to any conventional techniques well known to a person skilled in the art. 
     According to a seventh embodiment of the invention, the interlocking element of any of the above mentioned embodiments may be tightly enclosed within a volume defined by one cavity of the first array of cavities and the cavity of the second cavities. Optionally, an array of several second cavities may be provided, allowing the user to select the second cavity he needs. 
     According to an eighth embodiment of the invention, the core portion may have a cross-shaped section with four of said concavity. More preferably, each of said concavity is defined by adjacent walls that form an obtuse angle to each other. An example of such an obtuse angle may be +5 degree with respect to a normal angle between said adjacent walls. When the core portion or the shaft comprising the core portion, is obtained by moulding techniques, such obtuse angles allows an easy removal from a mould. Advantageously, the core portion can be made of any appropriate material well known to a person skilled in the art, especially of aluminum, iron, iron alloys, etc. Steel is particularly preferred. Also, according to an optional and particularly preferred aspect, each intersection of adjacent walls may be rounded to improved mechanical characteristics of the core portion. 
     According to a ninth embodiment of the invention, the elastomeric members for each of the four concavities are an elongated member of generally trapezoidal cross-section. Obtuse angles of this trapezoidal cross-section are selected in order to fit with corresponding adjacent walls of a corresponding concavity of the core portion. Also, according to an optional and particularly preferred aspect, each intersection of adjacent walls of the member may be rounded in order to fit with rounded portions of the corresponding concavity. More preferably, these elastomeric members may be obtained by molding or extrusion according to techniques well known to persons skilled in the art. Also, chemical formulations of these elastomeric members may be similar to those already known in the art. 
     According to a tenth embodiment of the invention, the shaft may have a pair of supported surfaces at opposed ends of the core portion. More preferably, each of these supported surfaces is adjacent to flanges and forms a groove, the intersection of each of these supported surfaces with the flanges being rounded. 
     According to an eleventh embodiment of the invention, the torsion system may further comprise support blocks operatively supporting the supported surfaces in the housing such that the shaft is rotatable about its longitudinal axis. More particularly, the support blocks are paired at each said supported surface, each support block having an opening that is shaped to corresponds with a corresponding portion of a groove defines by the supported surfaces and flanges provided on said shaft. 
     According to twelfth embodiment of the invention, at least one of the pairs of support blocks is secured to the housing, and the support blocks maintain the shaft captive within the housing. Each of these support blocks cooperates with supported surfaces and flanges to prevent translation movements of the shaft with respect to the housing. 
     According to a thirteenth embodiment, the invention also relates to a method for inserting elastomeric members in a torsion system, said method comprising the steps of: positioning at least one unused elastomeric member on a shaft of a torsion system; manually inserting the shaft and the at least one unused elastomeric member in a housing of the torsion system; and locking support blocks to maintain the shaft and elastomeric member captive in the housing of the torsion system. 
     According to a fourteenth embodiment of the invention, the insertion of elastomeric members in the torsion system is preceded by the steps of: releasing the support blocks from maintaining the shaft and used elastomeric members captive within the housing of the torsion system; manually removing the shaft and the used elastomeric members from the housing; and separating the shaft from at least one of the used elastomeric members. 
     According to a fifteenth embodiment of the invention, the steps of removing and inserting elastomeric members involved a used elastomeric member and an unused elastomeric member of different hardnesses. More particularly, the step of manually locking the shaft also involves positioning the support blocks on the shaft, and much more preferably, the step of locking the support blocks involves passing at least one fastener transversely through at least a portion of the housing and at least a portion of at least one of the support blocks. 
     According to a sixteenth embodiment of the invention, the step of positioning at least one unused elastomeric member involves inserting the elastomeric member in a concavity of the shaft of the torsion system. 
     According to another embodiment, the invention relates to a trailer for being hauled by a vehicle, preferably a trailer, comprising:
         a body; and   a torsion suspension system as defined in any one of the above mentioned embodiments.       

     According to another embodiment, the invention relates to a strap of belt assembly, comprising a strap or a belt mounted on supporting rotationary members, and a tensioning device for tensioning said strap or belt on said rotationary members, said tensioning device comprising a torsion suspension system as defined hereinabove. 
     According to another embodiment, the invention relates to a use of a torsion suspension system as defined hereinabove, in a suspension of a vehicle. 
     According to another embodiment, the invention relates to a use of a torsion suspension system as defined hereinabove, 
     in tensioning device for a mobile belt or strap, or 
     in a motor base or 
     in an oscillating mounting. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       These and other features of the present invention will become more apparent from the following description in which reference is made to the appended drawings wherein: 
         FIG. 1  is an isometric view of a trailer on which a torsion suspension system in accordance with an embodiment of the present invention is mounted. 
         FIG. 2  is an isometric view the torsion suspension system of  FIG. 1 . 
         FIG. 3  is a cut away plan view along line III-III, of a portion of a shaft of the torsion suspension system of  FIG. 1  with a bore cavity provided in the crank arm for the interlocking element positioned in first alternative position. 
         FIGS. 4A ,  4 B and  4 C are respectively a plan view, a end view and a perspective view of a portion of a variant of the angulary adjusting system shown in  FIG. 3 . 
         FIGS. 5A and 5B  are respectively a plan view and a cut away plan view according to line VB-VB of a crank arm of the torsion suspension system of  FIG. 3 . 
         FIG. 6  is a cut away side view according to line VI-VI of the angular adjusting mechanism of the torsion suspension system of  FIG. 3  with a bore cavity provided in the crank arm for the interlocking element, and positioned in second alternative position. 
         FIGS. 7A , and  7 B are respectively a plan view and an end view of a variant of the angulary adjusting system shown in  FIGS. 4A to 4C . 
         FIG. 8  is a perspective view of Applicant&#39;s torsion system that is part of the prior art; 
         FIG. 9  is a perspective view of Applicant&#39;s shaft that is part of the prior art; 
         FIG. 10  is a cross sectional view of the shaft of  FIG. 9  along line X-X; 
         FIG. 11  is a perspective view of Applicant&#39;s elastomer member that is part of the prior art; 
         FIG. 12  is a perspective view of Applicant&#39;s block that is part of the prior art; 
         FIG. 13  is a plan view of a variant of the shaft of the angulary adjusting system shown in  FIGS. 4A to 4C ; 
         FIG. 14  is a side view of the angulary adjusting system shown in  FIG. 13 ; 
         FIG. 15  is a cross-sectional view of the angulary adjusting system shown in  FIG. 13 . 
         FIG. 16  is a perspective view of the angulary adjusting system shown in  FIG. 13 . 
         FIG. 17  is a top plan view of an elastomeric member designed to fit in a corresponding concavity of the angulary adjusting system shown in  FIG. 13 . 
         FIG. 18  is a front view of the elastomeric member of  FIG. 17 . 
         FIG. 19  is a front perspective view of the elastomeric member of  FIG. 17 . 
         FIG. 20  is a end view of the elastomeric member of  FIG. 17 . 
         FIG. 21  is a perspective view of the elastomeric member of  FIG. 17 . 
         FIG. 22  is a perceptive view of an improved block designed to fit with a groove of the shaft of  FIG. 13 . 
         FIG. 23  is a schematic view of an alternative use of an improved torsion system according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to a design of torsion suspension used on trailers and other similar vehicles. 
       FIG. 1  generally depicts a torsion suspension system  10  mounted on a trailer  11 . 
       FIG. 2  depicts in more details the torsion suspension system  10 . The torsion suspension system  10  comprises a shaft  12  having two opposed connecting ends  14 . Each one of the connecting ends  14  is equipped with an angular adjusting mechanism  13 . For example, as illustrated in  FIG. 3 , the angular adjusting mechanism  13  may have a frusto-conical shaped interface surface  16  that points outwardly from the shaft  12 . This is best shown in  FIGS. 3 and 6 , now concurrently referred to. The angular adjusting mechanism  13  may be carried partly by the shaft  12  and partly by a crank arm  20 . The interface surface  16  has an array of shaft cavities  18  arranged circumferentially. The shaft  12  may be optionally and not limitatively mounted within a housing  124  and provided with elastomeric members  125  and support blocks  126  according to Applicant&#39;s international application no. PCT/CA2006/001901. 
     The crank arm  20  is operatively connected to each one of the connecting ends  14 . Each crank arm  20  has a frusto-conical bore  22  at one extremity of the crank arm  20  as part of the angular adjusting mechanism  13 . This is best shown in  FIG. 5 , now concurrently referred to. The bore  22  has a bore cavity  24 . Both the interface surface  16  of the connecting end  14  and the bore  22  are designed to mate together. A screw  26  and a washer  28  may be used to attach the crank arm  20  to the connecting end  14 . In such case a threaded bore  26 A is provided. Other similar fastening systems may also be used. 
     Each connecting end  14  of the torsion suspension system  10  is further provided with a interlocking element  30 . The interlocking element  30  is partly positioned in the bore cavity  24  and partly positioned in one of the shaft cavities  18 . By doing so, the interlocking element  30  locks the crank arm  20  at a predetermined angular position with respect to the shaft  12 .  FIG. 6  depicts the angular position of the crank arm  20  with respect to the shaft  12 . 
     Advantageously, the crank arm  20  may further comprises an axle  32  proximate a second extremity of the crank arm  20 . The axle  32  is positioned parallely to the shaft  12  so that a wheel mounted on it would move up and down by rotating the shaft  12 . 
     In  FIGS. 4A ,  4 B,  4 C,  5 A and  5 B there is illustrated a particularly preferred variant of the angulary adjusting mechanism where cavities on the frusto-conical connecting end represent portions of a sphere, the interlocking element  30  is a sphere  25  (such as for example and not limitatively a bearing ball) and the bore cavity  24  is shaped to receive said sphere  25 . The distance between two neighboring cavities  18  corresponds to a given angulary position θ. The selection of a given cavity  18  by the sphere  25  determines the angulary position of the crank arm  20  with respect to the vehicle. The shaft  12 , the crank arm  20 , the sphere  25 , axle  32 , the interlocking element  30 , the screw  26  and the washer  28  can be made of any appropriate material, preferably of a metal such as aluminum, iron or iron alloys, more preferably of steel. 
     Also,  FIGS. 5A and 5B  further illustrate peripheric recesses  27  allowing to be engaged by a conventional puller in order to help to remove the crank arm  20  from the shaft  12 . To mount a crank arm  20  on the shaft  12 , one only have to align the cavity  24  with a proper cavity  18  in which an interlocking element  30  (e.g. sphere  25 ) is positioned, and then to screw the screw  26  into the threaded bore  26 A to press the washer  28  against the crank arm  20  and the bore  22  against the frusto-conical connecting end. To remove the crank arm  20  from the shaft  12 , the screw  26  is unscrewed, the washer is removed and a conventional puller may be optionally used to removed the crank arm from the frusto-conical connecting end. When a conventional puller is used, it may engage recessed  27  to allow a better anchoring of the puller on the crank arm  20 . 
     Also,  FIGS. 7A and 7B  further illustrate a variation of the shaft  12  where angulary adjusting mechanisms may be provided at both ends of the shaft. 
     It will be apparent to a person skilled in the art that various modifications could be brought to the present invention. For example, the interface surface  16  could be equipped with only one shaft cavity  18  while the bore  22  could be equipped with a plurality of bore cavities  24 . Optionally and not imitatively, the bone  22  may comprise an array of cavities  24 . According to a particularly preferred embodiment, the shaft  12  is an hollow housing  24  in which the shaft  12  is as defined in Applicant&#39;s International Patent Application no. PCT/CA2006/001901. 
       FIGS. 8 to 12  illustrate a prior version of a torsion system described in Applicant&#39;s International Patent Application no. PCT/CA2006/001901. More particularly, referring to those drawings, and more particularly to  FIG. 8 , a torsion system in accordance with an embodiment is generally shown at  120 . 
     The torsion system  120  is shown having a crank arm  121 . In the illustrated embodiment, the crank arm  121  is made of a tube of rectangular section, but may be a solid piece, a single machined or cast piece, etc. The crank arm  121  has a connector hole  122  at a free end so as to support a hub, or any other rod-like member compatible with the torsion system  120 . Alternatively, the crank arm  121  may incorporate a shaft, hub, or fastener at its free end. 
     A shaft  123  is connected at the opposed end of the crank arm  121 . The shaft  123  is enclosed in housing  124 . Elastomeric members  125  are positioned between the shaft  123  and the interior of the housing  124 . Support blocks  126  are provided at opposed ends of the shaft  123 . Some of the support blocks  126  are used in combination with fasteners, such as bolt  128  and nut  129  passing through the housing  124  at holes  127  to maintain the shaft  123  captive within the housing  124 . As other alternatives, a screw (not shown) can be bolted directly into the support block  126 , with or without tapping in the holes  127  of the housing  124  or in the support blocks  126 . Moreover, the support blocks can be end caps positioned at opposed ends of the housing or the like. 
     The housing  124  is the interface of the torsion system  120  with the structure of the vehicle. Although not shown, it is considered to provide the housing  124  with connection flanges on its outer surface, such that the torsion system  120  may be connected to the structure of the vehicle using bolts or like fasteners. Moreover, the housing  124  is illustrated as having a square cross-section, but other cross-sectional shapes are considered. Referring to  FIG. 9 , the shaft  123  is shown individually. The shaft  123  has a connector end  130 , by which it is connected to the crank arm  121 . Supported surfaces  131  are separated by a core portion  132 . A flange  133  is provided at the end of the shaft  123  away from the connector end  130 . In an embodiment, the crank arm  121  and the shaft  123  form an integral piece. 
     The core portion  132  is the portion of the shaft  123  that will be interfaced with the elastomeric members  125  ( FIG. 11 ). In the embodiment of  FIGS. 9 and 10 , the core portion  132  is a circular rod in which concavities  134  have been defined. The concavities  134  are receptacles in which a portion of the elastomeric members  125  are received. 
     Referring to  FIG. 10 , the core portion  132  is shown having four of the concavities  134 , such that the core portion  132  defines a cross-shaped section. Although the illustrated embodiment of the core portion  132  is shown with four concavities  134 , it is considered to provide any suitable number of concavities, starting with a single concavity. The number of elastomeric members  125  used will have a direct effect on the shock absorption level of the torsion system  120 . 
     Referring concurrently to  FIGS. 8 and 11 , one of the elastomeric members  125  is shown. The geometry of the elastomeric member  125  is defined so that the elastomeric member  125  matches the shape of one of the concavities  134 . Moreover, when accommodated in the concavity  134 , the elastomeric member  125  has two of its walls coplanar with the inner walls of the housing  124 . Accordingly, as shown in  FIG. 8 , a rotation of the shaft  123  about its longitudinal axis is opposed by the elastomeric member  125 . The elastomeric members  125  must be deformed for the shaft  123  to rotate about its longitudinal axis. The elastomeric material used is any suitable elastomer, such as a polymer, a rubber or the like. In one embodiment, the elastomer is urethane at a durometer hardness of 70, but a wide range of hardnesses are considered. It is considered to increase the length and/or diameter of the torsion system  120 , so as to increase the load capacity of the torsion system. In an embodiment, the elastomeric members  125  are extruded. The cross-shaped section of the core portion  132  as embodied in  FIG. 8  is advantageous in that all elastomeric members  125  have the same cross-section. Therefore, all elastomeric members  125  may be obtained by any appropriate processes such as for example extrusion or moulding. Preferably said elastomeric members  125  are extruded from a single extrusion. 
     It is pointed out that the configuration of the shaft  123 /elastomeric members  125  enables the torsion system  120  to be mounted without the shaft  123  being pre-stressed. Therefore, as opposed to the prior-art torsion axles and torsion suspensions, neither hydraulic presses nor freezing equipment are required to assemble the torsion system  120  of  FIG. 8 . 
     One contemplated solution to maintain the shaft  123  aligned within the housing  124  is the support blocks  126 . Referring to  FIG. 12 , the support blocks  126  are used in pairs to define a circular opening by the alignment of semi-cylindrical cavities  140 . Two pairs of the support blocks  126  are used to each accommodate one of the supported surfaces  131  of the shaft  123 . In  FIG. 12 , a throughbore  141  is provided in the support block  126 . The throughbore  141  is used with a fastener (e.g., bolt) or a rod, to maintain the support block in position within the housing  124 . The flange  133  at the end of the shaft ensures that the shaft  123  remains in alignment within the housing  124 . Although only the distal pair of support blocks  126  are provided with throughbores  141 , it is considered to also lock the proximal pair of support blocks  126  with fasteners/rods. Support blocks  126  prevent shaft  123  to have translation movements within the housing  124 , and allow the elastomeric material to be compressed only by the rotational movement of the shaft  123 . 
     As the torsion system  120  is readily assembled without presses and such equipment, it is considered to sell the torsion system  120  separate from the elastomeric members  125 . Therefore, elastomeric members  125  can be selected as a function of the shock absorption level desired. Moreover, elastomeric members  125  can be replaced when worn out, by simply removing the shaft  123  from the housing  124 . As such, the torsion system can be sold in a kit, with additional or replacement elastomeric members  125  being available to the customer such that the shock absorption level of the torsion system  120  may be changed. The elastomeric members  125  are inserted in the torsion system  120  by positioning the elastomeric member  125  on the shaft  123 . Whether or not the support blocks  126  are positioned on the shaft  123 , the latter is manually inserted with the elastomeric member  125  in the housing  124 . The support blocks  126  are locked to maintain the shaft  123  and elastomeric member  125  captive in the housing  124  of the torsion system  120 . The steps are reversed to remove the shaft  123  from the housing  124 , for instance to replace the elastomeric members  125 . 
     Referring now to  FIGS. 13 to 22 , the Applicant has made substantial improvements to the aforesaid torsion system for torsion axle/suspension described in its International Patent Application no. PCT/CA2006/001901. More particularly, according to the eighth embodiment of the invention, the shaft  223  has a core portion  232  may have a cross-shaped section with four of said concavity  234 , each of said concavity being defined by adjacent walls that forms an obtuse angle to each other. An example of such an obtuse angle may be +5 degree with respect to a normal angle between said adjacent walls. According to an optional and particularly preferred aspect, each intersection of adjacent walls may be rounded. Also, the shaft  223  has a connecting end  214  having an interface  216  provided with cavities  218 , and it has a threaded bore  226 A for receiving a screw. 
     More particularly, according to the eighth embodiment of the invention, the core portion  232  may have a cross-shaped section with four of said concavity  234 , each of said concavity  234  being defined by adjacent walls that forms an obtuse angle to each other. An example of such an obtuse angle may be +5 degree with respect to a normal angle between said adjacent walls. According to an optional and particularly preferred aspect, each intersection of adjacent walls may be rounded. 
     According to a ninth embodiment of the invention, the elastomeric members  225  for each of the four concavities  234  are an elongated member of generally trapezoidal cross-section. Obtuse angle of this trapezoidal cross-section are selected to fit with corresponding adjacent walls of a corresponding concavity  234  of the core portion  232 . According to an optional and particularly preferred aspect, each intersection of adjacent walls of the member may be rounded. More preferably, these elastomeric members  225  may be obtained according to techniques well known to persons skilled in the art such as, for example, by molding or extrusion. Also, chemical formulations of these elastomeric members  225  may be similar to those already known in the art. 
     According to the tenth embodiment of the invention, the shaft may have a pair of supported surfaces  231  at opposed ends of the core portion  232 . More preferably, each of these supported surfaces  231  is adjacent to flanges  233  and forms a groove  239 , the intersection of each of these supported surfaces with the flanges  233  being rounded. 
     According to the eleventh embodiment of the invention, the torsion system may further comprise support blocks  226  operatively supporting the supported surfaces  231  in the housing such that the shaft is rotatable about its longitudinal axis. More particularly, the support blocks  226  are paired at each said supported surface  231 , each support block  226  having an opening  240  that is shaped to correspond with a corresponding portion of the groove  239  defines by the supported surfaces  231  and the flanges  233 . The throughbore  241  illustrated in  FIG. 22  is similar to the throughbore  141  illustrated in  FIG. 12 . 
     According to the twelfth embodiment of the invention, at least one of the pairs of support blocks  226  is secured to a housing (similar to the housing  124  of  15   FIG. 1 ), and the support blocks  226  maintain the shaft  223  captive within the housing. Those support blocks  226  can be made of any appropriate materials such as plastic, metal, etc., and manufactured according to techniques well known in the art. 
     According to the thirteenth embodiment of the invention, a method for inserting elastomeric members  225  in a torsion system, comprising the steps of: positioning at least one unused elastomeric member on a shaft  223  of a torsion system; manually inserting the shaft  223  and the at least one unused elastomeric member  225  in a housing of the torsion system; and locking support blocks  226  to maintain the shaft  223  and elastomeric member  225  captive in the housing of the torsion system. 
     According to the fourteenth embodiment of the invention, the insertion of elastomeric members  225  in the torsion system is preceded by the steps of: releasing the support blocks  226  from maintaining the shaft  223  and used elastomeric members  225  captive within the housing of the torsion system; manually removing the shaft  223  and the used elastomeric members  225  from the housing; and separating the shaft  223  from at least one of the used elastomeric members  225 . 
     According to the fifteenth embodiment of the invention, the steps of removing and inserting elastomeric members  225  involved a used elastomeric member  225  and an unused elastomeric member  225  of different hardnesses. More particularly, the step of manually locking the shaft  223  also involves positioning the support blocks  226  on the shaft  223 , and much more preferably, the step of locking the support blocks  226  involves passing at least one fastener transversely through at least a portion of the housing and at least a portion of at least one of the support blocks  226 . 
     According to sixteenth embodiment of the invention, the step of positioning at least one unused elastomeric member  225  involves inserting the elastomeric member  225  in a concavity  234  of the shaft  223  of the torsion system. 
     Referring to  FIG. 23 , it is illustrated a schematic view of one of the possible alternative applications for suspension system according to the invention. More particularly, the suspension system is used in a tensioning device  301 . This suspension system has a housing  324  mounted on a frame  300  and comprises a rotating element  302  mounted on a crank arm  320 , and an angulary adjusting system as defined hereinbefore in any of the above-mentioned embodiments of the invention, for tensioning a belt  303  on rotating elements  305  and  307  (preferably pulleys) mounted on the frame  300 . More preferably, the second and third aforesaid embodiments are particularly suitable for tensioning a wide belt. In such case, the crank arm is provided with a pair of rotating elements  302 . 
     The present invention has been described with regard to preferred embodiments. The description as much as the drawings were intended to help the understanding of the invention, rather than to limit its scope. It will be apparent to one skilled in the art that various modifications may be made to the invention without departing from the scope of the invention as described herein, and such modifications are intended to be covered by the present description. The invention is defined by the claims that follow.