Abstract:
The problem of damage sustained to a traction device and the extendable traction elements thereof due to tire-roadway interaction forces exerted on the traction elements while extended over the tire tread area is solved by resiliently coupling a traction assembly within a tire rim to permit movement and repositioning of the traction assembly relative to the rim and biasing back to the original position. Preferably the traction assembly is mounted to a traction hub through a resilient coupling, and with the traction hub permitted to rotate relative to the rim. Also preferably, the invention provides for full retraction and extension of the curved traction elements by use of a linear actuator. The present device delivers increased traction in slippery conditions while protecting the traction device and surrounding mechanics from damage due to the impact of roadway forces, and the device is effectively stowed within the rim when not in use.

Description:
RELATED APPLICATION DATA 
       [0001]    This application is a continuation-in-part of patent application Ser. No. 12/214,608 filed on Jun. 20, 2008, which claims priority to provisional application No. 60/936,590 filed on Jun. 21, 2007. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates to an automatic traction device to increase traction in snow, ice, or other slippery conditions, and more particularly to a means to protect the traction device from damage due to tire-roadway interaction forces. 
         [0004]    2. Description of the Related Art 
         [0005]    In snow, ice or other slippery conditions a driver may choose to supplement the traction of a standard tire with snow chains, or preferably a retractable automatic traction device that can be fitted within a rim and configured to extend a plurality of traction elements over the tread area of a tire. Examples of an automatic traction device are disclosed in Kahen U.S. Pat. No. 7,174,935 and Kahen US 2006/0096683, the disclosures of which are incorporated herein by this reference. 
         [0006]    It is known that the interaction area or contact zone between the road and tire is a high stress region, with multiple tire-roadway interaction forces. These tire-roadway interaction forces can be caused by the weight and speed of the vehicle exerted on the rolling tires through rough road conditions, potholes and other changes in road conditions that can cause impact forces. The traction elements are designed to extend over portions of the tire tread, between the roadway and tread, covering the tread in spaced strips radially about the tire within this high stress region. 
         [0007]    If the tire, with the traction elements extended thereover, encounters rough road conditions or potholes, the traction elements can be resultantly impacted and deflected due to the impact forces. If the traction element is rigidly coupled to the body of the automatic traction device, a substantial deflection could cause damage to the traction element or the traction device body, or both. Even repeated smaller deflections can cause fatigue and eventual failure over time or given life cycle. Since the traction elements are designed with a degree of stiffness to remain extended over the tread with substantial stability, they may absorb these forces well. 
         [0008]    A large deflection could potentially damage parts of the traction device, such as the gearing, motor and other internal parts. A large enough deflection could also shear the traction element, causing it to fly off the tire with great velocity, having the potential to cause damage to cars or people. Therefore, traction device failure is undesirable not only for financial reason but also for safety reasons. 
         [0009]    Although, the traction devices in the above-mentioned prior art references permit the traction element to extend over the tread area and selective retract off the tread area, they lack design provisions to absorb or otherwise address these tire-roadway interaction forces. Other automatic traction devices also fail to address this shortfall, such as the traction device disclosed in U.S. Pat. No. 5,540,267 to Rona. Rona&#39;s grip assemblies are rigidly coupled to the central hub, so all of the deflection is absorbed through the grip assemblies. A substantial force could easily deflect the grip assemblies to the point of breakage or damage to the other components. 
         [0010]    Yet another shortcoming of previous attempts to mate an automatic traction device to a tire rim, such as in US 2006/0096683, is the inability to permit full retraction of the curved traction elements within the rim when the curvature of the curved traction elements is greater than the curvature of the inner diameter surface of the rim when measured cross sectionally through the central axis, the curvature being defined as the inverse of the radius. If the curvature of the curved traction element is greater than the rim&#39;s curvature, then the curved traction element&#39;s retraction will be hindered by contact with the rim. Basically, the rim does not provide the necessary clearance and the traction element does not yield. This limits the design options available for the rims and traction elements. 
         [0011]    Accordingly, there has been a long-felt need in the art for an automatic traction device that is not adversely affected by the impacts on the traction elements due to tire-roadway interaction forces. This device should respond to the impacts with the roadway without substantial or catastrophic damage to the traction element, the device, the vehicle or nearby people. This system should also respond to impact forces from multiple directions. 
       OBJECTS 
       [0012]    It is an object of the present invention to provide an improved automatic traction device that substantially prevents damage due to tire-roadway interaction forces; 
         [0013]    It is a further object of the present invention to provide an improved means to couple the traction assemblies on the traction device, such that the coupling elastically deflects and absorbs transmitted forces; 
         [0014]    It is a further object of the present invention to provide an improved traction device that permits translation and rotation of the traction assembly with multiple degrees of freedom; 
         [0015]    It is yet a further object of the present invention to provide a biasing means to restore the traction assembly back to or near its previous position after being elastically deflected or translated or rotated due to roadway or other forces; and, 
         [0016]    It is yet a further object of the present invention to provide an improved traction device that provides a means to accommodate the traction elements when in a retracted mode. 
         [0017]    These and other advantages and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention. 
       SUMMARY 
       [0018]    The present invention is directed to a novel automatic traction device for preventing damage to the device and its components, as well at surrounding objects and people due to tire-roadway interaction forces. The present invention provides a means to elastically couple the traction assembly to the traction device to permit nondestructive elastic deflection, or translation and rotation with multiple degrees of freedom. The present invention also provides a biasing means to restore the traction assembly back to or near its original position. Additionally, the present invention also provides a means to accommodate the traction elements when in a retracted mode without undue interference with the retraction operation. 
         [0019]    The problem of damage sustained to a traction device and the extendable traction elements thereof due to tire-roadway interaction forces exerted on the traction elements while extended over the tire tread area is solved by resiliently coupling a traction assembly within a tire rim to permit the repositioning of the traction assembly relative to the rim. In a preferred embodiment of the present invention a traction device is provided with a traction assembly having said traction element slidably fitted therein and being resiliently coupled within the rim to permit the repositioning of the traction assembly in response to a tire-roadway interaction force exerted on and transmitted through the traction element while extended over a tire tread. As an option, the traction assembly may be resiliently coupled by a resilient coupling means. 
         [0020]    As used in this specification and the appended claims, the term “tire-roadway interaction force” means forces exerted on the traction elements due to the tire contacting a driving surface or the traction element contacting the driving surface. Likewise, the terms “traction device” and “automatic traction device” mean a device attached to the rim of a vehicle and configured to selectively extend a traction element over a tire tread to increase traction in slippery conditions. Again, likewise, the terms “traction element” and “curved traction element” mean the retractable portion of the traction device that can be selectively extended and retracted, having traction enhancing means at a free end which is configured to overlie the tire tread. Also, likewise, the terms “rim” and “wheel” mean any number of devices configured to support a tire through the hermetic engagement of the tire to a rim flange, whether the rim is made of two or more pieces, usually with a cylindrical sleeve supported by a central disc or spokes, or one piece, often made by a casting or forging process. 
         [0021]    Yet another preferred embodiment of the present invention the traction device includes a traction hub coupled to a rim, a traction assembly with a traction element slidably fitted within, and a resilient coupling means that joins the traction assembly to the traction hub. This resilient coupling means permits the traction assembly to deflect relative to the traction hub, in response to tire-roadway interaction forces exerted on the traction elements. These forces are transmitted through the traction elements and thereafter substantially absorbed by the resistive deflection of the resilient coupling means. 
         [0022]    The traction hub is preferably mounted to the rim within the cylindrical sleeve of the rim, preferably on the inner side of the wheel. The outer diameter of the traction hub is generally smaller than the rim inner diameter or cylindrical sleeve inner diameter to provide clearance therebetween, for the radial mounting of at least one and preferably a plurality of traction assembly, each having one traction element slidably fitted therein. 
         [0023]    Optionally, a torsion spring or other biasing means may be used to bias the traction assembly towards the rim inner diameter. A torsion spring may be installed over the pin of the leaf, to provide a rotational bias about the pin to urge the traction assembly towards the rim inner diameter. The torsion spring may optionally, have two legs each having attached at a terminus a ball configured to mate within a respective socket on the traction hub outer diameter to form a ball and socket joint at each leg. This arrangement provides a degree of control to the overall deflection of the resilient coupling and biases the traction assembly as discussed, yet still facilitates deflection of the traction element with multiple degrees of freedom. 
         [0024]    Mechanically, the traction element is coupled to the traction hub by the resilient coupling means, the torsion spring serves to maintain a bias towards the traction assembly&#39;s original position, basically bringing the traction assembly back to an equilibrium position after the force induced repositioning. The torsion spring follows the repositioning of the traction assembly through all six degrees of freedom over which motion is permitted by the resilient coupling means, including translation in three axes and rotation about three axes. 
         [0025]    In an alternate embodiment, the traction hub is rotatably coupled to the rim about common wheel rotation axis through a rotatable coupling, permitting the rotation of the traction hub in response to tire-roadway interaction forces. It is important to note that the rotation is permitted only when a substantial force is transmitted through the traction elements; free spinning rotation is not usually desired. Therefore the rotatable coupling may preferably provide resistive rotation through a variety of common means, such as a bearing or other appropriate means. Optionally, in the case wherein the traction assembly is biased towards the rim inner diameter, the traction assembly may include a roller on the housing configured to contact the rim inner diameter to substantially prevent the traction assembly from abrading the rim inner diameter during rotation 
         [0026]    In yet another embodiment of the present invention, resilient coupling means is an elastomeric leaf, in a similar manner of a leaf in a standard hinge, being configured to be secured to the traction hub at a fixed end arid pivotally coupled to the traction assembly at a free end through a pin; except, unlike a standard hinge leaf, the elastomeric leaf is flexible, being made from rubber or other similar elastic material. The pin can either be integrally formed with the elastomeric leaf or be a separate component, such as a metal pin. The elastomeric leaf permits the rotation of the traction assembly about a tangent to the hub and also provides flexibility is multiple directions through the elastic deformation of the elastomeric leaf. The elastomeric leaf should be designed so that it can provided resistive deflection in response to forces without sustaining substantial permanent deformation. Optionally, the resilient coupling means can be a compression spring or other appropriate spring. 
         [0027]    In yet another embodiment of the invention a means for accommodating a curved traction element of a traction device mounted within an inner diameter of a tire rim is provided. The traction device is configured to selectively extend the curved traction element over the tread of the tire and selectively retract the curved traction element within the inner diameter. The means for accommodating a curved traction element permits the retraction of the curved traction element without dysfunctional interference between the rim and the curved traction element. 
         [0028]    Optionally this means for accommodating a curved traction element could be a recess formed on the inner diameter and configured to provide clearance for a portion of the curved traction element while retracted. Basically, because the curvature of the curved traction elements is greater than the curvature of the inner diameter surface of the rim the curved traction element&#39;s retraction will be hindered by contact with the rim if not for the recess. The recess provides the necessary clearance for the curved traction element to fully retract. This clearance may optionally be annular to provide all of the traction elements appropriate clearance, even in the case of the traction hub rotating, carrying the traction assemblies and traction elements through an arcuate path, necessitating an annular clearance, such as a trough about the inner diameter or sleeve. 
         [0029]    In yet another optional embodiment, the means for accommodating a curved traction element comprises a curved traction element with a free end and a secured end configured to deform when retracted upon contact with the inner diameter. The free end of the curved traction element is configured to extend over the tire tread to provide enhanced traction, while the secured end is slidably joined within the traction assembly. The traction assembly is designed to permit the passage of the curved traction element therethrough, so that the secured end contacts the inner diameter of the rim, deforming and deflecting as a result. 
         [0030]    To permit adequate flexure of the secured end of the traction element, the secured end can be made of a different material than the free end. The material chosen for the secured end is preferably more flexible than the remainder of the traction element. In other words, the Young&#39;s modulus of the free end material is greater than the Young&#39;s modulus of the secured end material. This flexibility permits the device to be used with industry standard rims without substantial modification. 
         [0031]    A method for preventing damage to a traction device due to a tire-roadway interaction force exerted on an extendable traction element thereof is also provided. This method includes resiliently coupling a traction assembly within a rim and permitting the repositioning of the traction assembly from an initial position in response to the tire-roadway interaction force. Optionally, the method can include the further step of urging the traction assembly back to said original position in the absence of said tire-roadway interaction force. Optionally, a further step may include providing a traction hub with the traction assembly resiliently mounted thereon and permitting the rotation of the traction hub relative to the rim in response to the tire-roadway interaction force. Yet another optional step may include providing a recess within an inner diameter of the rim configured to provide clearance for a portion of the extendable traction element while retracted within the rim. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0032]      FIGS. 1A-B  is are perspective views of the preferred embodiment of the present invention, showing the traction assembly and the resilient coupling means with the traction element in the retracted and extended modes; 
           [0033]      FIG. 2A-E  are perspective views of the preferred embodiment of the present invention, showing the traction assemblies coupled to the traction hub through the resilient coupling means and showing the axes of rotation and translation; 
           [0034]      FIG. 3  is an exploded perspective view of an optional embodiment of the present invention, showing how the hub is assembled within a standard rim arrangement; 
           [0035]      FIG. 4  is an exploded perspective view of an optional embodiment of the present invention, showing how the hub is assembled within a custom two piece rim arrangement; 
           [0036]      FIGS. 5A-B  are cross-sectional views of the present invention shown installed on a custom two piece rim arrangement, showing the extended and retracted modes with a motor driven traction element; 
           [0037]      FIGS. 6A-B  are cross-sectional views of the present invention shown installed on a custom two piece rim arrangement, showing the extended and retracted modes with an actuator driven traction element; 
           [0038]      FIGS. 7A-C  are cross-sectional views of the optional embodiment of the present invention shown installed on a standard or OEM rim arrangement, showing the extended and retracted modes and the deformable traction element; 
           [0039]      FIG. 8  is an exploded perspective view of the traction assembly of the present invention, showing the actuator driven option; and 
           [0040]      FIG. 9  is an exploded perspective view of the traction assembly of the present invention, showing the motor driven option. 
           [0041]      FIG. 10  is a perspective view of the optional embodiment of the traction assembly of the present invention, showing the magnetic actuator driven traction element. 
           [0042]      FIG. 11  is a cross-sectional view of the optional embodiment of the present invention, showing the magnetic actuator, showing the magnetic actuator driven traction element in the extended position. 
           [0043]      FIG. 12  is a cross-sectional view of the optional embodiment of the present invention, showing the magnetic actuator, showing the magnetic actuator driven traction element in the retracted position. 
       
    
    
     LISTING OF REFERENCE NUMERALS of FIRST-PREFERRED EMBODIMENT 
       [0000]    
       
         
           
             traction device  20   
             traction element  22   
             portion  23   
             traction assembly  24   
             housing  25   
             resilient coupling means  26   
             biasing means  28   
             pin  30   
             elastomeric leaf  32   
             slot  33   
             torsion spring  34   
             ball  36 ,  38   
             free end  40   
             fixed end  42   
             traction hub  44   
             roller  46   
             socket  48   
             ball and socket joint  50   
             industry standard rim  52   
             custom rim  54   
             tire  56   
             hub  58   
             tire tread  60   
             rotatable coupling  62   
             traction hub outer diameter  64   
             rim inner diameter  66   
             annular recess  68   
             motor  70   
             actuator  72   
             means  74   
             curved traction element  76   
             secured end  78   
             free end  80   
             free end material  82   
             secured end material  84   
             housing half  86   
             roller pin  88   
             sleeve  90   
             first leg  92   
             second leg  94   
             counterbalance  96   
             drive gear  98   
             guide roller  100   
             hole  102   
             drive  104   
             axis  104 ,  106 ,  108 ,  110   
             solenoid  120   
             power lead  122   
             coil spring  124   
             pivoting arm  126   
             joint  128   
             solenoid rod  130   
             pivot  132   
             pin  134   
             hinge  136   
           
         
       
     
       DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0099]    Looking first at  FIGS. 1A and 1B , the traction assembly  24  containing the traction element  22  is shown uninstalled from the traction device  20  and rim for the sake of clarity.  FIG. 1A  shows the traction element  22  in the retracted mode; and  FIG. 1B  shows the tractions element  22  in the extended mode. These modes will be described more specifically in the description of  FIGS. 5A-B . The preferred embodiment of the resilient coupling means  26  is shown, with the elastomeric leaf  32  attached to the housing  24  through pin  30 , which permits rotation of the traction assembly  24  about the pin  30 . The biasing means  28  is preferably a torsion spring  34 , although other means to bias the traction assembly are available for use. The torsion spring is installed about the pin  30 , on both sides, each leg of the torsion spring  34  has attached a ball  36  and  38 . The traction assembly  24  is configured to slidably move the traction element  22  through an arcuate path controllably from the retracted to the extended modes, or vice versa. The fixed end  42  of the elastomeric leaf  32  is configured to be attached to the traction hub  44  (see  FIG. 2 ), while the free end  40  is coupled to the traction assembly  24  through the pin  30  passing through the housing  25 , to permit the traction assembly  24  to pivot. The free end  40  is permitted to flex relative to the fixed end  42 . 
         [0100]    Turning now to  FIGS. 2A-E , the assembled traction device  20  is shown with the traction hub  44  at the center, with eight exemplary traction assemblies  24  mounted radially about the traction hub  44 , although any number of traction assemblies  24  may be mounted. The traction device  20  is shown ready to be installed within a rim. The traction assemblies  24  are each coupled to the traction hub  44  by the elastomeric leaf  32  installed through the slot  33 . One potential means to secure the fixed end  42  (hidden) to the traction hub  44 , is by a common fastening means, such as a nut and bolt. The traction assembly  24  is permitted to move relative to the traction hub  44  with multiple degrees of freedom, as illustrated by the three curved arrows representing rotation about a vertical and two horizontal axes. 
         [0101]    Looking particularly at  FIGS. 2B-E , the traction device is shown with the axes that motion is permitted over. The traction element itself is permitted to move with six degrees of freedom, essentially translation in three axes and rotation in three axes. The traction hub  44  itself is also permitted to rotate with one degree of freedom, carrying the traction assemblies along. In  FIG. 2B , an axis  104  passes through the traction assembly  24  with an arrow at each end, representing translation along that axis  104  and a curved, double-ended arrow indicating rotation about that axis  104 , representing two degrees of freedom for the traction assembly  24 . Likewise, two more degrees of freedom are visually indicated in  FIG. 2C  through axis  106  and in  FIG. 2E  through axis  108 , for a total of six degrees of freedom. The traction hub  44  rotates with one degree of freedom about axis  110 . 
         [0102]    The torsion spring  34  is shown with the balls  36  and  38  installed within the sockets  48  to create two ball and socket joints  50 . It can be seen that the torsion spring is arranged to bias the traction assembly  24  away from the traction hub  44 , pivoting about the pins  30 . The traction hub  44  is preferably open-ended drum shaped to permit mounting on the inner side of the rim, to permit clearance for the brakes and other mechanics. 
         [0103]      FIG. 3  shows the present traction device  20  in an exploded view, along with a tire and industry standard rim  52 . The traction device  20  is designed to fit within the industry standard rim  52 , without interference with the normal function of the car&#39;s equipment. 
         [0104]      FIG. 4  alternative shows a traction device  20 , again in exploded view with the tire  56  and a custom rim  54 . A custom rim  54  is one that is designed specifically for use with the traction device  20 , providing clearances and design features that will be later described. A hub  58  can be attached to the custom rim  54 , or it can be crafted as a one-piece design. 
         [0105]    A cross section of the traction device  20  installed on a custom rim  54  can be seen in  FIGS. 5A and 5B , the traction element  22  optionally driven by a motor  70  (as seen in  FIG. 9 ), such as a stepper motor or the like.  FIG. 5A  shows the traction element  22  in the retracted mode. In the retracted mode, a portion  23  of the traction element  22  can be seen lying within an annular recess  68 , which provides clearance so that the traction element  22  may freely retract without impacting the custom rim  54  or other interference. A rotatable coupling means  62  permits the traction hub  44  to rotate relative to the custom rim  54 . This can be any number of means that permits rotation, such as a bearing or series of bearings. 
         [0106]    The traction assembly  24  is installed between the outer diameter  64  of the traction element  44  and the inner diameter  66  of the custom rim  54 . The elastomeric leaf  32  attaches the traction assembly  24  to the traction hub  44 . As previously described, the torsion spring  34  biases the traction assembly towards the inner diameter  66  to push the roller  46  against the inner diameter  66 , with the roller  46  preventing abrasion between the traction assembly  24  and the inner diameter  66  when the traction hub  44  rotates relative to the custom rim  54 . The torsion spring  34  also acts to bias the traction assembly  24  towards an original position. 
         [0107]    Moving to  FIG. 5B , the traction element  22  is seen in the extended mode, where it partially overlies the tread  60  of the tire  56  to provide enhanced traction. The design of the traction element  22  is curved in profile so that it can easily tuck away within the custom rim  54  when not in use, or extended over the tread  60  when in use. The arcuate path between the extended and retracted mode may be visually interpolated by comparing  FIG. 5A  with  FIG. 5B . 
         [0108]    Yet another option is seen in  FIGS. 6A and 6B , showing the option of driving the traction element  22  by use of an actuator  72 . A variety of actuators  72  may be chosen, such as electromechanical actuators, hydraulic actuators, or other appropriate actuator device. 
         [0109]    When viewing  FIGS. 7A-7C , an optional variation if the present invention can be seen in use with an industry standard rim  52 .  FIG. 7C  shows an optional curved traction element  76 , in this exemplary embodiment, comprised of two different materials, a free end material  82  and a secured end material  84 . To permit flexing of the secured end  78  while maintaining the at least semi rigidity of the free end  80 , the Young&#39;s modulus of the free end material  82  is greater than the Young&#39;s modulus of the secured end material  84 . The advantage of the more flexible secured end  78  can be seen in  FIG. 7A , where the curved traction element  76  is in the retracted mode and the secured end  78  is touching the inner diameter  66  of the standard rim  52 , being deflected down as a result. Instead of the curved traction element  76  impacting the inner diameter  66  with dysfunctional interference, the secured end  78  is permitted to bend upon contacting the inner diameter  66 , allowing the full retraction of the curved traction element  76 . 
         [0110]    Other embodiments are also available to create a curved traction element  76  that permits the flexure of the fixed end  78 , such as a change in the material cross section to permit a localized weakness to permit bending thereat or the hinging of the secured end  78  to the free end  80 , again to permit flexure at the hinge. Likewise, while maintaining the inventive concept of the present invention, many other optional embodiments are available for utilization that permit the deflection of the fixed end  78 . 
         [0111]      FIGS. 8 and 9  show the traction assembly  24  in an exploded view,  FIG. 8  showing the actuator  72  option and  FIG. 9  showing the motor  70  option. Looking first at  FIG. 8 , two housing halves  86  comprise the outer shell or housing  25  of the traction assembly  24 . A roller  46  may be mounted about a roller pin  88 , held in place on the traction assembly  24 . In this case, two pins  30  are each inserted through a respective hole  102  in the elastomeric leaf  32 ; each pin  30 , in turn is supported by the housing  22 , to permit the traction assembly to rotate about the pin. The torsion spring  34  is supported about the pins  30  and has two legs, the first leg  92  and second leg  94  with a ball  36  and  38  at the terminus of each leg  92  and  94  respectively. Each leg  92  and  94  is inserted into a sleeve  90  for engagement to the balls  36  and  38 . The actuator  72  drives the traction element  22 . 
         [0112]    The motor  70  driven variation shown in  FIG. 9  is substantially similar to the actuator  72  version, except the motor  70  support mechanisms, such as the drive  104 , the drive gear  98 , the guide rollers  100 , and the counterbalance  96 . The counterbalance serves to enhance the rotational balancing of the entire assembly of the rim  52 , the tire  56  and the traction device  20 . 
         [0113]      FIGS. 10-12  show an alternate embodiment of the present traction device  20 , where a linear actuator or solenoid  120  drives the traction element  22 , rather than a geared motor. The linear actuator can be any of a variety of devices which produce a linear force, such as a linear motor and the like. The benefit of the solenoid  120  is that traction element  22  can be quickly deployed over the tire tread  60  without the mechanical difficulties associated with geared deployment. Road debris and dirt may collect within the teeth of the geared system and slow or prevent deployment, and reduce motor  70  life. The traction assembly  24  is fastened to the traction hub  44  through a pin  134 , which holds the elastomeric leaf  32  to the traction assembly  24 . A pivoting arm  126  is attached by a pivot  132  to the pin  134 . The pivot arm  126  is free to rotate about the pin  134 . On the opposing end of the pivoting arm  126  is a joint  128  upon which the solenoid  120  rotates. In one example solenoid  120 , an eyelet fitting on the solenoid  120  mates with a clevis on the pivoting arm  126 . 
         [0114]    The solenoid  120  can be attached to the joint  128  through a coil spring  124 . The coil spring  124  prevents vibrations and impacts on the traction element  22  from being transmitted to the pivoting arm  126 . In this way, the solenoid  120  is vibrationally isolated from pivoting arm  126 , which prevents damage to the pivoting arm  126  and the remainder of the connected parts. A power lead  122  is connected to a control means (not shown) which receives a signal to deploy or retract the traction elements  22 . If the solenoid  120  is a push tubular solenoid, when power is not provided to the solenoid  120  it is normally retracted. If power is supplied to the solenoid  120  through the power lead  122 , then the rod  130  extends. A single control means may be utilized for all traction devices  20  installed on each of the tires, such that a command to deploy the traction elements  22  will deploy all traction elements  22  within each traction device  20 . Alternatively, multiple control units may be utilized to control the deployment of the traction elements  22  individually or by tire. Power or control signals from the non-rotating body of the vehicle may be provided to the rotating traction device  20  through a rotating electrical connector, such as a slip ring or other suitable means. 
         [0115]    A solenoid rod  130  connects the solenoid  120  to the traction element  22  through a hinge  136 , which permits the solenoid rod  130  to pivot relative to the traction element  22 . Therefore, the solenoid is connected with the traction assembly  24  by the cylinder end and to the traction element  22  by the rod  130  end. In the retracted state, shown in  FIG. 12 , the pivoting arm  126  is rotated towards the inner diameter of the rim  52  and the solenoid rod  130  is retracted within the cylinder of the solenoid  120 .  FIG. 11  shows the solenoid rod  130  fully extended. Because the solenoid rod  130  is connected to the traction element  22  through the hinge  136 , as the rod  130  extends it pushes the traction element  22  to the extended or deployed position; and as the rod  130  retracts, it pulls the traction element  22  back into the retracted position. The pivoting arm  126  provides articulation, such that the pivoting arm  126  rotates downward, as seen in  FIG. 11 , to permit the solenoid  120  to act on the traction element  22  within the small confines of the area between the traction assembly  24  and the rim  52 . Roller  46 , shown as a spherical roller, maintains a set minimum clearance between the traction assembly  24  and the rim  52 , and permits the rotation of the traction device  20  relative to the rim  52 . 
         [0116]    While particular forms of the invention have been illustrated and described, it will also be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited except by the claims.