Abstract:
A suspension system suitable for a trailer incorporates a device for limiting rotation of an axle received in an eye of a leaf spring. The leaf spring has a wrapped end defining the eye extending transverse to the leaf spring with a gap left between the leaf spring and the wrapped end thereof. The rotation limiting device is fixed to the axle and features a sleeve having a peripheral wall extending circumferentially about the axle inside the eye of the leaf spring and a tab projecting outward from the peripheral wall of the sleeve and extending in a direction parallel to the axis. The tab projects into the gap left between the leaf spring and the wrapped end thereof to block rotation of the axle and sleeve relative to the wrapped end of the leaf spring. Friction fit, adhesive, welding or multi-piece hardware fixing of the spring is avoided.

Description:
[0001]    This application claims the benefit under 35 U.S.C. 119(e) of U.S. provisional application Ser. No. 61/117,322, filed Nov. 24, 2008. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to suspension systems, and more particularly to a device for limiting relative rotation between a vehicle axle and a leaf spring eye wrap in which the axle is supported. 
       BACKGROUND OF THE INVENTION 
       [0003]    The international PCT application published under WO 02/42099, herein incorporated by reference, discloses a suspension system for a trailer, featuring a pair of leaf springs extending longitudinally of the trailer frame on respective opposite sides thereof. Each leaf spring is cantilevered with one end connected to the frame and its opposite otherwise free end secured to an axle of the trailer. This prior art application teaches that the an eye-forming wrapped around end of the leaf spring may be push-fitted, friction-fitted, adhered, puddle or full welded, bolted. clip-secured or clamp-secured to the axle to rigidly fix these two elements together to prevent relative motion therebetween. The fitted, adhered, and welded options are generally not easily serviceable without special equipment. Also, spring steel generally does not weld properly to steel axles. The bolted, clip-secured, and clamp-secured options require multiple hardware pieces causing increased complexity at greater cost. As a result, it is desirable to provide an alternative arrangement for mounting an axle within an eye wrap of a leaf spring in a way that prevents rotation of the axle within the spring eye. 
         [0004]    The solution proposed herein is not limited to use in the context of the light trailer suspension system taught in the aforementioned prior art patent application, and may be readily applied in other suspension contexts where it is desirable to limit or prevent rotation of an axle received in the eye wrap of a leaf spring. 
       SUMMARY OF THE INVENTION 
       [0005]    According to a first aspect of the invention there is provided a device for limiting rotation of an axle received in an eye of a leaf spring&#39;s wrapped end, the device comprising: 
         [0006]    a sleeve having a peripheral wall extending about an axis and dimensioned to fit circumferentially about the axle inside the eye of the leaf spring; and 
         [0007]    a tab projecting outward from the peripheral wall of the sleeve and extending in a direction parallel to the axis; 
         [0008]    whereby, with the sleeve fixed to the axle to extend thereabout within the eye of the leaf spring and the tab projecting into a gap left between the leaf spring and the wrapped end thereof, contact between the tab and the leaf spring blocks rotation about the axis of the axle and sleeve relative to the wrapped end of the leaf spring. 
         [0009]    Preferably there is provided a flange projecting outward from the peripheral wall of the sleeve at positions spaced from the tab about the axis. 
         [0010]    Preferably the flange is situated at an end of the sleeve 
         [0011]    Preferably the tab is integral with the peripheral wall of the sleeve. 
         [0012]    Preferably the tab is defined by a bent portion of the peripheral wall. 
         [0013]    Preferably the sleeve is split to form a break in the peripheral wall thereof and the bent portion of the peripheral wall is formed by an end thereof defined at a respective side of the break. 
         [0014]    Preferably the tab is bent back over itself between a proximate end of the tab connected to the peripheral wall of the sleeve and a distal end of the tab opposite the connection thereof to the sleeve. 
         [0015]    Preferably the tab smoothly curves from the proximate end of the tab to the distal end of the tab. 
         [0016]    According to a second aspect of the invention there is provided a suspension system comprising: 
         [0017]    a leaf spring having a wrapped end defining an eye extending along an axis transverse to the leaf spring with a gap left between the leaf spring and the wrapped end thereof; 
         [0018]    an axle received in the eye of the leaf spring; 
         [0019]    a rotation limiting device fixed to the axle and comprising a sleeve having a peripheral wall extending circumferentially about the axle inside the eye of the leaf spring and a tab projecting outward from the peripheral wall of the sleeve and extending in a direction parallel to the axis, the tab projecting into the gap left between the leaf spring and the wrapped end thereof to block rotation about the axis of the axle and sleeve relative to the wrapped end of the leaf spring by contact between the tab and the leaf spring. 
         [0020]    Preferably the rotation limiting device further comprises a flange projecting outward from the peripheral wall of the sleeve at positions spaced from the tab about the axis outside the eye on a respective side of the leaf spring. 
         [0021]    Preferably the flange is disposed on an inner side of the leaf spring opposite an end of the axle adjacent the leaf spring. 
         [0022]    Preferably the tab is bent about an end edge formed at the intersection of an inner surface of the leaf spring&#39;s wrapped end facing into the eye and an end surface of the leaf spring&#39;s wrapped end defining one side of the gap between the wrapped end and the leaf spring. 
         [0023]    Preferably the tab smoothly curves about the end edge. 
         [0024]    Preferably the rotation limiting device is welded to the axle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    In the accompanying drawings, which illustrate exemplary embodiments of the present invention: 
           [0026]      FIG. 1  is a perspective assembled view of a leaf spring pairing carrying an axle fitted with a rotation blocking sleeve device according to the present invention. 
           [0027]      FIG. 2  is a perspective exploded view of the leaf spring pairing, axle and sleeve device of  FIG. 1 . 
           [0028]      FIG. 3  is an isolated perspective view of the sleeve device of  FIG. 1 . 
           [0029]      FIG. 4  is a close-up perspective view of the assembly of  FIG. 1 , showing rotation blocking positioning of a tab of the sleeve device within a gap left at the end of an eye wrap of the leaf spring. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  shows an axle tube  10  received in a cylindrical eye opening extending transversely across a leaf spring  12  at a wrap-around end thereof defining the eye opening. This arrangement differs from prior art axle and leaf spring eye wrap assemblies in that a locking sleeve device  14  is fixed to the axle  10  to extending thereabout on the periphery thereof so as to fit concentrically between the coaxial eye wrap  16  and axle  10 . As described herein below in further detail, the locking sleeve device  14  is designed to limit rotation of the axle relative to the eye wrap of the leaf spring without requiring welding, bolting or clamping to the spring itself. 
         [0031]      FIG. 2  shows the assembly of  FIG. 1  in an exploded state. The axle tube  10 , the locking sleeve  14  and the eye wrap  16  of the leaf spring  12  are concentrically coaxial, as illustrated by their aligned positioning on common axis  18 . The locking sleeve  14  features a peripheral wall  20  closing substantially, but not fully, around the axis  18  along a circumferential cylindrical path thereabout, defining the generally cylindrical shape of the locking sleeve. The sleeve&#39;s peripheral wall  20  has an inner diameter dimensioned to fit its inner surface  20   a  against the outer peripheral surface  10   a  of the hollow cylindrical axle tube  10 . 
         [0032]    In a conventional manner, the eye wrap  16  of the leaf spring is formed by a wrapped end thereof extending along a circular path from where it integrally diverts from the elongate central portion  22  of the spring  12  so as to curve back over itself and nearly close fully around the cylindrical eye opening traversing the spring, but leaving a small gap  23  between a free distal end of the eye wrap  16  and a broad surface of the central portion of the leaf spring facing the side thereof to which the wrapped end curves. The outer diameter of the sleeve&#39;s uniform thickness peripheral wall  20  is dimensioned to fit its outer surface  20   b  adjacent to and face-to-face with the inner surface  24  of the eye wrap  16 , which is defined by the aforementioned broad surface of the spring  12  where it diverts from the portion of the broad surface at the central portion  22  of the spring to extend along a cylindrical path about the axis  18 . 
         [0033]    With reference to  FIGS. 3 and 4 , as the peripheral wall  20  of the sleeve  14  does not quite close fully about the axis  18 , a break  26  extending parallel to the axis  18  is left in the otherwise cylindrical peripheral wall. At one side of this break  26 , the peripheral wall  20  ends at a flat edge surface  20   c  lying on the peripheral wall&#39;s cylindrical path about the axis  18 . At the other side of the break  26 , the peripheral wall  20  is bent in a curving manner to form an integral tab  28  deviating from the peripheral wall&#39;s circularly cylindrical path about the axis  18  and projecting outward from the peripheral wall&#39;s cylindrical path. The tab  28  smoothly curves back over itself through more than ninety degrees but less than one hundred and eighty degrees so as to give the tab  28  a hook-like cross section in a plane normal to the axis  18 . 
         [0034]    With reference to  FIG. 4 , the tab  28  thus forms a hook or catch that wraps, bends or curves around an edge  30  formed at the intersection of the inner surface  24  of the leaf spring&#39;s wrapped end and an end surface  32  of the leaf spring&#39;s wrapped end defining one side of the gap  23  between this free end of the leaf spring&#39;s wrapped end portion and the broad surface of the leaf spring&#39;s central portion. A distal end  28   a  of the tab opposite its proximal end integrally connected with the peripheral wall  20  of the sleeve is thus disposed within the gap  23  of the eye wrap  16 . The cross section of the tab  28  is uniform along the axis  18  and features a short end portion linearly connecting the curved portion of the tab wrapped about the end edge  30  of the eye-wrap  16  to the distal end  28   a  of the tab  28 , this end portion of the tab extending generally along the broad surface of the leaf spring&#39;s central portion at the integral connection of the leaf spring&#39;s central portion  22  and wrapped end  16  between this broad surface and the end surface  32  of the eye wrap facing this broad surface. 
         [0035]    Still referring to  FIG. 4 , clockwise rotation of the sleeve  14  about the axis  18  is blocked by contact of the curved portion of the tab  28  with the end edge  30  of the eye wrap  16 , and opposite rotation of the sleeve  14  is blocked by contact of the curved portion or straight end portion of the tab  28  with the broad surface of the central portion  22  of the leaf spring or the integral inner surface  24  of the eye wrap  16 . Rotation of the sleeve  14 , and the axle  10  to which it is fixed, is thus prevented or at least limited to a very minute range created by allowance of small movement of the tab between contact with the eye wrap end edge  30  and contact with the broad surface of the leaf spring due to manufacturing tolerances. The sleeve can thus be welded to the axle and installed within the spring eye to position the tab  28  within the wrapped end eye gap  23 , thereby effectively preventing rotation of the axle relative to the spring eye without requiring welding to the spring itself or multi-piece bolting or clamping arrangements. The described spring eye, axle and sleeve arrangement may also be used as an alternative to leaf spring arrangements typically relying on a U-bolt and cradle arrangement to rigidly clamp an axle to an unwrapped or eye-lacking end of a different style of leaf spring. 
         [0036]    The illustrated embodiment of the sleeve  14  features an end rim or flange  34  projecting radially outward from the outer surface  28   b  of the peripheral wall  20  in a planar manner at one end face thereof. The flange  34 , like the peripheral wall  20 , extends nearly but not quite fully about the axis  18 , ending on either side of the break  26  in the peripheral wall. The flange  34  and the peripheral wall  20  are co-terminal at the flat edge surface  20   c , with the other end of the flange being situated at the integral joining of the peripheral wall  20  and the tab  28 , leaving the side of the tab  28  in a respective plane normal to the axis  18  exposed and free of direct connection to the flange  24 . 
         [0037]    In a suspension system of a trailer, using the context of the aforementioned PCT application to illustrate use of the locking sleeve  14 , a wrapped-end leaf spring may be mounted to the frame of the trailer on respective opposite sides thereof, each spring being cantilevered from an eye-free unwrapped end thereof, for example by rigid mounting of the spring to a respective longitudinal frame member of the trailer by bolting thereto through a pair of bolt holes  36  proximate the unwrapped end of the spring. With each spring extending in the trailer&#39;s longitudinal direction, the springs are aligned along this longitudinal direction to support a single axle in the two spring eyes, each of which is equipped with a locking sleeve of the type described herein above. The flanges of the two locking sleeve&#39;s are either each situated against the outer side of the respective spring, opposite the central vertical plane of the trailer, or each situated against the inner side of the respective spring, adjacent the central vertical plane of the trailer. This way, sliding of the axle in each direction along its own axis transverse to the trailer&#39;s longitudinal direction is blocked by contact between one of the locking sleeve flanges  34  and the respective annular end face of the respective spring&#39;s eye wrap. The sleeves thereby not only prevent rotational movement of the axle relative to the springs, but also sliding movement, therefore acting to fix the axle relative to the springs with a welded or multi-piece connection thereto. 
         [0038]    Preferably, the flanges of the two locking sleeve&#39;s are either each situated against the inner side of the respective spring, adjacent the trailer&#39;s central vertical plane extending the longitudinal direction thereof, so that installation of the spring can be effected by simply sliding the spring&#39;s eye onto the device over the respective end of the axle. In other words, preferably each flange is disposed on an inner side of the respective leaf spring, the inner side being opposite the respective wheel of the vehicle mounted on the nearest end of the axle adjacent and outside the leaf spring. The flanges of the two locking sleeve&#39;s are thus disposed between the two leaf springs disposed on opposite sides the trailer&#39;s central longitudinal plane, and accordingly between the two wheels carried on the axle outside the leaf springs. 
         [0039]    Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.