Abstract:
A method and apparatus for alignment of a rear axle of a motorcycle, whereby measurement is made of the relative positions of each end of the axle with respect to the axle mounting structure, thereby reducing the time necessary for aligning the axle, and increasing the accuracy of the alignment.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates generally to motorcycle maintenance, and more specifically, to a method and gauge for alignment of a motorcycle rear axle. 
         [0003]    2. Description of Related Art 
         [0004]    In any wheeled vehicle it is important that the proper alignment of the wheels be maintained for safe and efficient operation of the vehicle. This is especially true for two wheeled vehicles, such as motorcycles, due to the danger of harm to the operator in the event of an accident. For many motorcycles, including most chain and belt driven models, the axle of the rear wheel is adjustable in order to allow adjustment of the tension on the chain or belt to a specified parameter. The rear axle may be prone, however, to misalignment due to the adjustability of the axle. When the rear axle is misaligned, excessive wear may be caused to drive-train components and the tires, and the handling characteristics of the motorcycle may be impaired, potentially increasing the likelihood of an accident. 
         [0005]    One method of aligning the rear axle involves counting the number of threads visible on the exposed shaft of one or more of the rear axle adjustment screws or bolts. This method is problematic because it is inaccurate, tedious, and time-consuming. 
         [0006]    These problems are exacerbated by the frequency with which the rear axle may need to be adjusted or removed for repairs or proper maintenance of the motorcycle&#39;s components. Each time the rear axle is adjusted or removed, large amounts of time may be required to adjust the position of the rear axle to ensure that there is a proper amount of tension on the chain or belt, and that the rear axle is properly aligned. 
         [0007]    It is desirable, therefore, to provide a method of aligning the rear axle of a motorcycle that is more accurate and that can be accomplished in less time, thereby reducing or eliminating the disadvantages of known methods of aligning the rear axle during routine safety checks or after maintenance and/or repairs. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    Briefly described, in a preferred embodiment, the present invention overcomes the above-mentioned disadvantages and meets the recognized need for such a method and device by providing a motorcycle rear axle alignment gauge comprising a housing, a probe movably engaged with the housing, and an indicator operably engaged with the probe. 
         [0009]    According to one aspect of the preferred embodiment, the housing includes at least one portion adapted to abut a reference portion of the motorcycle. 
         [0010]    According to another aspect of the preferred embodiment, the indicator comprises a rotating needle. 
         [0011]    According to another aspect of the preferred embodiment, a scale is arranged around a peripheral portion of a face of the housing. 
         [0012]    According to another aspect of the preferred embodiment, the indicator comprises an electronic display. 
         [0013]    According to another aspect of the preferred embodiment, the gauge may be calibrated. 
         [0014]    Accordingly, a feature and advantage of the present invention is its ability to quickly and accurately ascertain a distance between an end of a rear axle adjustment screw and a portion of a motorcycle frame. 
         [0015]    Another feature and advantage of the present invention is its ability to quickly and accurately compare the position of a first side of an axle with a position of the second side of the axle. 
         [0016]    Another feature and advantage of the present invention is its ability to quickly and accurately align an axle of a motorcycle. 
         [0017]    According to another aspect, the present invention comprises a method of aligning a rear axle of a motorcycle comprising the steps of measuring a first position of a first rear axle adjustment device relative to a first portion of an axle-mounting structure of a motorcycle, and adjusting the first rear axle adjustment device to align the rear axle of the motorcycle. 
         [0018]    These and other objects, features, and advantages of the invention will become more apparent to those ordinarily skilled in the art after reading the following Detailed Description and Claims in light of the accompanying drawing Figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Accordingly, the present invention will be understood best through consideration of, and reference to,  FIGS. 1-6 , viewed in conjunction with the Detailed Description of the Preferred Embodiment referring thereto, in which like reference numbers throughout the various Figures designate like structure and in which: 
           [0020]      FIG. 1  is a front view of a preferred embodiment of the present invention; 
           [0021]      FIG. 2  is a front partial cutaway view of the preferred embodiment of the present invention; 
           [0022]      FIG. 3  is a side view of a rear axle of a motorcycle; 
           [0023]      FIG. 4  is a partial cutaway view of the preferred embodiment of the present invention shown in use; 
           [0024]      FIG. 5  is a side view of a rear axle of a motorcycle according to an alternative design; and 
           [0025]      FIG. 6  is a front view of the preferred embodiment shown in use with the motorcycle of  FIG. 5 . 
       
    
    
       [0026]    It is to be noted that the drawings presented are intended solely for the purpose of illustration and that they are, therefore, neither desired nor intended to limit the invention to any or all of the exact details of construction shown, except insofar as they may be deemed essential to the claimed invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    In describing preferred embodiments of the present invention illustrated in  FIGS. 1-6 , specific terminology is employed for the sake of clarity. The invention, however, is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. 
         [0028]    In that form of the preferred embodiment of the present invention chosen for purposes of illustration,  FIG. 1  shows gauge  100 . Gauge  100  preferably comprises indicator  110  which is preferably operably connected to probe  120 , and further comprises housing  130 . More specifically, probe  120  is preferably slidably engaged with sleeve  121  such that probe  120  is free to travel, at least within a range, in a direction of the longitudinal axis of probe  120  and sleeve  121 , as indicated by arrow  140 . Probe  120  preferably comprises first end  120   a , adapted to contact a first reference surface, and a second end, not shown, disposed within casing  111 . Casing  111  may further optionally be rotatable with respect to sleeve  121 . Sleeve  121  is preferably attached to casing  111  such that sleeve  121  is, at least selectively, not separable from casing  111 . As such, when sleeve  121  is not separable from casing  111 , the second end of probe  120  is preferably in operable engagement with indicator  110  such that movement of probe  120  in the direction of arrow  140  relative to sleeve  121  (and thus casing  111 ), indicator  110  moves in the direction of arrow  150  to indicate a value proportional to such movement of probe  120 . The form of the operable engagement may take any of a variety of forms, such as geared, pivotal, levered, direct, rotational, or other mechanical form of engagement as will be understood by one skilled in the art. Alternatively, the engagement can be inductive, magnetic, resistive, optical, or other electronic or non-contact engagement configured and arranged to convert movement of probe  120  to a change in a value indicated by indicator  110 . 
         [0029]    A preferred one of such engagement forms includes teeth disposed along a length of the second end of probe  120  in engagement with a rotatable gear, wherein movement along the longitudinal axis of probe  120  in the direction of arrow  140  translates to rotation of the gear, and needle  113  in fixed connection with the gear, such that rotation of the gear in response to motion of probe  120  causes rotation of needle  113  in the direction of arrow  150 . In such an embodiment, indicator  110  preferably includes scale  117  disposed on face  115  retained in casing  111 . It should be understood, however, that indicator  110  may alternatively comprise a digital or analog electronic display, such as an LCD. 
         [0030]    Regardless of the specific structure utilized to translate movement of probe  120  to an indication, indicator  110  preferably includes a calibration feature. In the preferred embodiment, indicator  110  preferably includes calibration portion  119  in the form of a button. Operation of calibration portion  119 , such as by pushing the button, preferably disengages probe  120  from needle  113  such that a position of needle  113  relative to scale  117  may be adjusted independent of the movement of probe  120 . Preferably, operation of calibration portion  119  takes the teeth of probe  120  out of engagement with the rotatable gear. Thus, for a given position of probe  120 , the position of needle  113  relative to scale  117  may be adjusted to a predetermined position, such as a position associated with a zero mark of scale  117 . Alternatively, however, other calibration portions may be implemented. One such alternative calibration portion comprises a rotatable face  115 , whereby rotation of face  115  adjusts a position of needle  113  relative to scale  117 . Another alternative calibration portion comprises threaded fastener  139  in threaded engagement with housing  130  such that loosening threaded fastener  139  allows adjustment of a position of sleeve  121 , and, thus first end  120   a  of probe  120  for a give position relative to sleeve  120 , relative to housing  130 . Subsequent tightening of threaded fastener  139  preferably retains sleeve  121  in fixed engagement with housing  130 . 
         [0031]    Now referring to  FIG. 2 , gauge  100  is shown with sleeve  121  in fixed engagement with housing  130  due to threaded fastener  139  being in a tightened position, thereby retaining sleeve  121  in friction force fixed engagement with a sidewall of bore  231 . When sleeve  120  is in such fixed engagement with housing  130 , a position of needle  113  relative to scale  117  due to a position of first end  120   a  of probe  120  within bore  230  indicates a distance D between first end  120   a  of probe  120  relative to forward surface  233  of housing  130 . 
         [0032]    Now referring to  FIG. 3 , motorcycle  300  includes rear tire  320  and rear wheel  321 , rotatably connected thereto by rear axle  301 . For proper operation, rear axle  301  must be maintained in a proper alignment relative to rear axle mounting structure  303 , in which rear axle  301  is carried. Furthermore, rear axle  301  must be maintained in a proper position within an adjustment portion, such as slot  307 , of rear axle mounting structure  303  in order to maintain a proper tension of belt (or chain)  310 . 
         [0033]    In use, gauge  100  may preferably be used to determine whether rear axle  301  is in proper alignment by comparing measurements of a position of each side of a rear axle  301  within respective slots, such as slot  307 . In order to make such a determination, a user may first adjust a drive-train side of axle  301  within a drive-train side adjustment slot using a drive-train side rear axle adjustment device so as to provide a proper or desired tension on a belt or chain of the drive-train. The user may then preferably measure a position of a first side of an axle within a slot by contacting forward surface  233  with a reference surface of a drive-train side rear axle mounting structure in which the drive-train side adjustment slot is disposed, thereby contacting first end  120   a  with a reference surface of the drive-train side rear axle adjustment device. The user may then read a first value indicated on indicator  110  representing a distance between the reference surface of the drive-train side rear axle adjustment device and the reference surface of the drive-train side rear axle mounting structure. The user may then measure a position of a second side of the axle by contacting forward surface  233  with reference surface  403  of the other rear axle mounting structure  303 , thereby contacting first end  120   a  with reference surface  405  of the other rear axle adjustment device  305 . The user may then read a second value indicated on indicator  110  representing a distance between reference surface  405  and reference surface  403  (equal to distance D of  FIG. 2 ). If the first value and the second value are equal, then the user may determine that rear axle  301  is in proper alignment due to the respective lengths of the drive-train side rear axle adjustment device and rear axle adjustment device  305  being equal. If the first value and the second value are different, however, the user may adjust rear axle adjustment device  305 , for example by tightening or loosing, in order to align rear axle  301  until a value of a measurement of the position of rear axle  301  in slot  307  is equal to the first value. 
         [0034]    Alternatively, the user may determine whether rear axle  301  is in proper alignment by measuring a position of a first side of rear axle within a first slot by contacting forward surface  233  with a reference surface of a drive-train side rear axle mounting structure in which the drive-train side adjustment slot is disposed, thereby contacting first end  120   a  with a reference surface of the drive-train side rear axle adjustment device. The user may then optionally calibrate gauge  100  such that the value indicated is a predetermined value, such as zero. Such calibration may be accomplished by rotating face  115  such that needle  113  points to, or otherwise indicates, a zero value of scale  117 . Alternatively, an electronic zeroing may be performed by activating a calibration portion of an electronic circuit comprising indicator  110 . Once gauge  100  has been calibrated, the user may then measure a position of a second side of rear axle  301  by contacting forward surface  233  with reference surface  403  of the other rear axle mounting structure  303 , thereby contacting first end  120   a  with reference surface  405  of the other rear axle adjustment device  305 . The user may then read a second value indicated on indicator  110  representing a distance between reference surface  405  and reference surface  403 . If the second value is equal to zero, then the user may determine that the axle is properly aligned, and if the second value is not zero, the user may adjust rear axle adjustment device  305  until a value of zero is indicated when forward surface  233  is contacted with reference surface  403  and when first end  120   a  is contacted with reference surface  405 . 
         [0035]    Now referring to  FIGS. 5 and 6 , motorcycle  500  according to an alternative design is shown. Motorcycle  500  preferably includes rear axle  501 , rear axle mounting structure  503 , rear axle adjustment device  505 , slot  507 , tire  520 , wheel  521 , and chain  510 . According to the alternative design, rear axle adjustment device  505  is arranged on a forward side of rear axle  501 , thus, reference surface  603  of rear axle mounting structure  503  is likewise disposed on a forward side of rear axle  501 . As will be understood by one skilled in the art, numerous similar alternative designs are possible, and use of gauge  100  according to the method described hereinabove is contemplated with motorcycles according to such similar alternative designs. 
         [0036]    According to an alternative embodiment of the present invention, the housing of the gauge may include a bend, a flexible portion, or other modification which allows the probe to be contacted with the reference surface of the rear axle adjustment device and the forward surface of the housing to be contacted with the reference surface of the rear axle mounting structure more easily, and preferably without interference between other parts of the gauge, such as the indicator or casing, and other parts of the motorcycle. Such a modification may also preferably allow the user to more easily read the value indicated, or handle and maneuver the gauge. 
         [0037]    Having, thus, described exemplary embodiments of the present invention, it should be noted by those skilled in the art that the within disclosures are exemplary only and that various other alternatives, adaptations, and modifications may be made within the scope and spirit of the present invention. Accordingly, the present invention is not limited to the specific embodiments as illustrated herein, but is only limited by the following claims.