Abstract:
A device for changing the drive belt in a machine having power transmitted by a trapezoidal flexible drive belt, a circular adapter plate for attachment to the terminal end of the shaft having the pulley having the spring means having an attachable compressor with a bail and a connector yoke, the connector yoke being shaped approximating a semi-circular flattened annulus, the inner radius being sized to fit about the adapter plate carried on the shaft, the outer being sufficiently larger to provide the necessary strength and provide for the attachment of the bail; the bail being pivotally attached to the yoke and having a planer graspable handle and an offset bearing pad, the bearing pad extending outwardly from the plane of the bail and affixed proximate the pivotal attachment to the connector yoke forming the “L” shape of the bail, the bearing pad further being adapted to engage the extension of the movable sheave of pulley with the spring means.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to snowmobile maintenance and more particularly to the changing drive belts on snowmobiles and other machines using variable ratio drive belts. The recent popularity of snowmobiles for winter recreation has increased the number of both snowmobiles and snowmobilers. This has brought less experienced and less mechanically inclined people to the sport of snowmobiling. This surge in popularity, has brought one unintended consequence with the less experienced operators, more drive belts are becoming inoperative in the field.  
           [0002]    The operation of a typical snowmobile involves the transmission of the power of the engine through a variable ratio drive belt and thence to the track. In the transmission of the power developed by the engine of a snowmobile, it is conventionally transmitted through a flexible, usually composite rubber, belt to a counter shaft and thence through a drive chain to the flexible track of the snowmobile that engages the snow or other surface that the snowmobile is riding upon.  
           [0003]    Additionally, the belt drive uses variable diameter pulleys to provide a variable drive ratio to providing gear reduction to have increased power for starting and providing no gear reduction to allow a sufficiently high top speed and acceptable fuel economy. Usually, the variable ratio is accomplished using a pair of pulleys having a movable side or flange so that when the flanges of the pulley are separated, the effective diameter of the pulley is reduced, and when the flanges of the pulley are moved together, the pulley diameter is increased so that with the pair of pulleys working in concert, the drive ratio can be changed over a fairly wide range. This allows a snowmobile to have a reduction to a low drive ratio allowing the engine to develop sufficiently high revolutions to produce power to both start the snowmobile from a stopped position and negotiate a steep incline successfully and as the load decreases, and the speed increases, a lower drive ratio to provide the snowmobile with a sufficiently speed for economical cruising.  
           [0004]    While the current drive belts are relatively long lived, the belts are a wear item and periodically wear out and must be replaced. The replacement of the drive belt involves a certain amount of strength, skill, and, all too frequently, frustration. Were the life of the drive belts predictable and a user judicious in performance of preventive maintenance, all of the belt changes could be performed in the comfort of an inside shop where a complete set of tools is available as part of scheduled maintenance. However, reality is that the life of a drive belt is unpredictable and may break or otherwise become unusable at any time, all too frequently, in the field miles away from a shelter or service facility. Upon this unpleasant occurrence, the user must replace the belt in the cold and the snow, often without adequate tools to assist him in performing the repairs. The unpleasant task is further complicated by the necessity of wearing gloves or mittens as protection from the cold weather.  
           [0005]    The conventional method of changing belts involves manually forcing the sheaves of the drive pulley apart and holding the sheaves in this position while removing the old belt and then placing the new belt onto the pulleys while still holding the sheaves apart. Often, the user has difficulty separating the sheaves of the pulley and once the sheaves are separated, and the old belt removed, the sheaves are allowed to go back together and they must be again separated to install the new belt. Users, occasionally, will attempt to wedge a tool or other object between the sheaves of the pulley to keep the sheaves separated while changing belts. This procedure can work quite well in some circumstances, but, can lead to scoring the pulley sheave which significantly increases the wear and reduces the life of subsequent belts. The only solution being to replace a rather expensive pulley.  
           [0006]    The invention disclosed herein is a tool which separates the sheaves of the drive pulley and holds the sheaves in a separated position from the end of the pulley thereby making it much easier and more convenient to change a drive belt while eliminating the scoring or defacing problems inherent with use of a tool to pry the sheaves apart directly. The invention acts only on the shroud of the pulley and not on the faces of the pulley.  
         SUMMARY OF THE INVENTION  
         [0007]    When changing a drive belt on a snowmobile or the like, if the old drive belt has not broken, it must first be removed by forcing the flanges of the one pulley apart to reduce their effective diameter so that both the drive pulley and the driven pulley are at a minimum effective diameter so as the drive belt can be removed. The flanges of the drive pulley are typically held together by springs and the tension of these springs must be overcome and the flanges held apart to remove the drive belt. If the flanges are then allowed to come back together, they must be reopened to allow the installation of a new belt. While this task is difficult to do in a warm shop with the snowmobile on a bench, it can become nearly impossible in the cold with the snowmobile nestled down in the snow. This is particularly true where the user must wear gloves or mitts as protection from the cold.  
           [0008]    The invention disclosed herein is a tool that allows a user to easily and readily urge the flanges of a drive pulley apart and hold the flanges apart while removing the defective drive belt and replacing the drive belt with a new drive belt. More particularly, the invention includes a small circular adapter plate that is attached to the terminal end of the shaft carrying the drive pulley and a pivoting tool having a yoke that engages the adapter plate and locates the tool so as that the user can actuate the handle to move the drive pulley flanges apart and hold the pulley flanges apart to change the drive belt and after replacing the drive belt with a new drive belt, release the handle, and thereby allow the pulley flanges to be urged together by the spring and return to their resting position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    Figure One is an overall perspective view of the adapter plate and compressor.  
         [0010]    Figure Two is another overall perspective view of the adapter plate and compressor as shown from a different viewpoint.  
         [0011]    Figure Three is a plan view showing the adapter plate exploded away from the drive pulley with the sheaves of the drive pulley in an adjacent position.  
         [0012]    Figure Four is a plan view showing the adapter plate attached to a drive pulley and the drive pulley sheaves separated.  
         [0013]    Figure Five is an overall perspective view of a variable ratio drive pulley system with the adapter plate attached to the drive pulley. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]    Looking first to Figure One, which shows the belt changing tool  10  which consists of the adapter plate  12  and the separator  14 . The adapter plate  12  is a circular disk having a central attachment opening  16  for attaching the adapter plate  12  to the pulley shaft  18 , as shown in Figure Two. Figure Three shows the adapter plate  12  exploded away from the pulley  20  with the attachment bolt  22  partially removed. As can be seen, the adapter plate  12  has larger diameter outer flange  24  and a reduced diameter inner flange  26 .  
         [0015]    The separator  14  has a yoke  30  and a handle  32  which are pivotally joined through a hinge means  34 . The yoke  30  may be of any selected shape, and is preferably semi-circular in shape having an inner periphery  36  sized to fit closely about the inner portion  26  of the adapter plate  12 . The outer periphery  38  or the yoke  30  may be of any selected shape and is preferably a smooth shape. The outer periphery  38  is spaced away from the inner periphery  36  a sufficient distance such that the yoke  30  material has sufficient strength so that the yoke  30  does not deform in use. Of necessity, the distance and therefore the width of the yoke  30  will vary depending on the choice of construction materials and the particular application.  
         [0016]    The handle  32  may be of any suitable shape so as to be graspable by the user and is pivotally attached to the hinge means  34  of the yoke  30 . The handle  32  further has a pair of offset ears  40  formed on the end adjacent the hinge means  34 . The offset ears  40  may terminate in a rounded ramp or any other suitable shape and preferably have at least one roller  42  mounted on the terminal end of each ear  40 . The offset ears  40  are located approximately at right angles to the handle  32  so that when the handle  32  is moved in a direction as indicated by “A” in Figure two, the ears  40  move from a location coplanar with the yoke  30  to a location spaced away from the plane of the yoke.  
         [0017]    The separator  14  may be constructed from any suitable material having sufficient strength such as metal, certain high strength polymers, or glass filled plastics. The rollers  42  may be constructed of the same or of a different material than the separator  14 . The surface of the rollers  42 , however, must be sufficiently hard so as to not deform as the rollers  42  are pressed against the drive pulley housing  44 .  
         [0018]    The adapter plate  12  when attached to a pulley shaft  18 , as shown in Figure Four, provides an inner flange  26  sized to be slightly smaller than inner periphery  36  of the yoke  30  so that the yoke  30  may be placed over the inner flange  26  and retained thereat by the outer flange  24  thusly retaining the yoke  30  longitudinally with respect to the pulley shaft  18 . In most variable ratio drive systems, the terminal end of the pulley shaft  18  is conventionally drilled and tapped to receive a bolt  22  and the adapter plate  12  may be attached merely by turning a bolt  22  into the existing threads, if, however, the pulley shaft  18  is not so drilled and tapped, the pulley shaft  18  must be drilled and tapped before the adapter plate  12  may be attached.  
         [0019]    In the preferred embodiment of the belt changing tool  10 , the adapter plate  12  may be constructed of aluminum alloy, iron, polymer, or other such material. The adapter plate  12  may be machined from a single billet of aluminum or constructed from two circular pieces of aluminum fused together. When constructed from two pieces of aluminum, a first piece is formed the outer flange  24  and the second piece forming the inner flange  26  with concentric center holes formed in each piece. The two pieces forming the adapter ring may be joined by welding, spot welding, adhesives, or other suitable means. The center hole of the second piece forming the inner flange  26  is sized to accept the shank of the attachment bolt  22 . The center hole  16  in the first piece forming outer flange  24  of the adapter plate  12  may be the same size as the center hole of the second piece forming the inner flange  26 , or is preferably a larger diameter to receive the head of the attachment bolt  22  thus recessing the head of the attachment bolt  22 .  
         [0020]    Similarly, in the preferred embodiment of the belt changing tool  10 , the separator  14  is constructed of aluminum alloy. Both the yoke  30  and the handle  32  are fabricated from 0.25 inch aluminum alloy stock. The yoke  30  is cut to a suitable shape, having an inner periphery  36  diameter approximating the diameter of the inner flange  26  so that the yoke  30  fit about the inner flange  26  and be retained by the outer flange  24  the outer periphery  38  may be any suitable shape, and it is convenient to form the outer periphery  38  concentrically circular. The width of the yoke  30  is increased near the ends forming tabs  46  and a slot  48  is formed therein to receive the handle  32 . The tabs  46  are further drilled to receive the hinge means  34 . The preferred hinge means  34  is simply a pin of sufficient strength passing through the tabs  46  and the handle  32 , a readily available pin is a roll pin. When roll pins are used, the hole  47  in the yoke tabs  46  is sized to be an interference fit with the roll pin. Roll pins are well known and readily available in many sizes from many different sources.  
         [0021]    The handle  32  may be similarly fabricated from 0.25 inch aluminum alloy stock. When first cut from aluminum stock, the handle  32  can be a flat strip with its offset ears  40  formed at the respective ends. The handle  32  is then bent to have a semicircular portion  50  located approximately equidistant from each end. The handle  32  is also sufficient length so that a straight portion  52  separates the semicircular portion  50  from the offset ears  40 . The semicircular portion  50  is formed to a radius so that the terminal ends  54  of the handle  32  are spaced apart a distance equal to the spacing of the yoke slots  48  so that the terminal ends  54  bearing the offset ears  40  are received in the yoke slots  48 . The terminal ends  54  are also drilled to receive the pivot point of the hinge means  34 . When roll pins are used as the hinge means  43 , the holes (not shown) are sized to allow the roll pins to easily turn in the hole.  
         [0022]    The rollers  42  are similarly fabricated from 0.25 inch aluminum alloy stock. While only one roller is needed per offset ear  40 , it is preferred to use two rollers  42  per offset ear  40 . Each roller  42  is fabricated as a disk and is drilled with a center hole  56 . The center hole  56  is sized to interferingly receive a roll pin  58  as an axle. Thus, a slightly larger hole may be formed in each offset ear  40  and a roll pin  58  placed therein, and rollers  42  pressed onto each end of the roll pin  58  to form the roller  42  pair.  
         [0023]    It is understood that when the belt changing tool  10  is fabricated, that it is not necessary that the component parts be machined, but, that the component parts may be molded or otherwise fabricated.  
         [0024]    In its operation, the user selects an appropriately sized belt changing tool  10  for his snowmobile or other application. If necessary, the pulley shaft  18  is drilled and tapped to receive an attachment bolt  22 . The attachment bolt  22  is passed through the central attachment opening  16  of the adapter plate  12 , as shown in FIG. 3. The attachment bole  22  is threaded into the pulley shaft  18  and that adapter plate  12  is drawn adjacent the pulley shaft  18 , as shown in FIG. 4 completing the installation. The separator may then be stored on the snowmobile where it is readily available when needed.  
         [0025]    The discussion of operation will with regard to changing a belt  60  on a snowmobile, it being understood, that the procedure is similar and equally applicable when the drive belt is used on another apparatus. When in the operation of the snowmobile, or other apparatus, the belt  60  is either broken, worn, or otherwise requires changing, any shrouds or housings that need to be opened to access the drive pulleys  18  are opened or removed. The separator  14  is hinged to the position as shown in FIG. 2 and placed over the adapter plate  12  so that the inner periphery  36  of the yoke  30  is adjacent the inner flange  26  of the adapter plate thus retaining the separator  14  longitudinally with respect to the pulley shaft  18  by the outer flange  24  of the adapter plate  12 . At this time, the sheaves  62  of drive pulley  64  are in an adjacent position as shown in FIG. 3. The handle  32  the separator  14  is moved in a direction as shown by arrow “A” in FIG. 2 moving the rollers  42  from the plane of the yoke  30  allowing the rollers to bear on the drive pulley housing  44  and thence move and hold the pulley sheaves  62  in a spaced apart position, as shown in FIG. 4, against the tension of the drive pulley springs  65 .  
         [0026]    When the drive pulley  64  is held with the sheaves  62  spaced apart it has a minimum effective diameter, and the worn drive belt  60  can be removed and replaced by a new drive belt  60 . After the new drive belt  60  is placed over the drive pulley  64  and the driven pulley  63 , the handle of the separator  14  is moved in the direction as shown by arrow “B” in FIG. 2 moving the rollers  42  substantially into the plane of the yoke  30  and allowing the sheaves  62  of the drive pulley  64  to return to approximately their adjacent position, as shown in FIG. 3. The sheaves  62  will not return to this adjacent position because the belt  60  is usually wedged partway down the sheaves  62  and will hold the sheaves  62  somewhat apart until the drive pulley  64  is rotated allowing the drive belt  60  to climb to a position near the periphery of the drive pulley.  
         [0027]    With the belt change completed, the user removes the device  10 , closes any shrouds or housings that had been previously opened, and the snowmobile may be started and driven again.  
         [0028]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize changes may be made in form and detail without departing from the spirit and scope of the invention.