Patent Document

RELATED APPLICATIONS  
       [0001]    This application claims priority from earlier filed U.S. application Ser. No. 09/273,432, filed Mar. 22, 1999. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to vibratory devices such as vibrating screens for classifying aggregate and vibratory feeders for feeding aggregate to crushing and processing devices. More specifically, the present invention relates to an improved wheel case for housing the rotating components of the vibratory devices and for protecting those components from the loss of lubricant and/or from the ingress of contaminants.  
         BACKGROUND OF THE INVENTION  
         [0003]    Vibrating screen devices and vibrating feeder devices are generally well known in the art. On a typical vibrating screening device, a system of classifying screens are mounted to a frame which in turn is supported on a system of springs. At or near the center of the device is an eccentrically weighted shaft unit, typically having one, two, or three or more rotating and eccentrically weighted shafts. On a multi-shaft unit, the shafts may be counter-rotating such that the eccentric weights are oriented in the same direction twice each revolution. This causes the screen to vibrate, which aids the classifying effects of the screen device. On a vibrating feeder, a similar shaft unit vibrates the feed trough or chute, which “throws” the aggregate contained in the trough in a desired direction. An example of such a device can be found in U.S. Pat. No. 4,340,469 issued to Archer.  
           [0004]    The ends of the rotating shafts are supported by bearings, and each shaft includes a drive wheel or gear. The shaft drive gears are operatively coupled to an external drive motor. The eccentric weights are typically attached to the ends of the shafts adjacent the drive wheels. The bearings and the drive wheels require constant lubrication, and thus such components are disposed within a wheel housing or case containing a quantity of oil or other suitable lubricating fluid. The wheel case is typically bolted to the frame of the vibratory device.  
           [0005]    Historically, conventional cap screws have been used to secure the wheel case to the frame of the vibratory device. However, due to the constant vibration, coupled with the constant exposure of the cap screws to the lubricating oil, such conventional cap screws are subject to loosening. The loosened cap screws provide a convenient avenue for oil loss, and also provide a convenient avenue for the ingress of dirt, water, and other contaminants. Moreover, the cap screws are not readily accessible for the purposes of re-tightening.  
           [0006]    Accordingly, threadless fasteners have been used, such as the threadless fastener sold under the trade name Huckbolt® manufactured by the Federal Mogul Corporation. Such a fastener has a threadless collar that is pressed onto the bolt shank using hydraulic means. The collar engages a series of annular rings spaced along the bolt shank. Such bolts typically provide consistent clamping force and exhibit high resistance to loosening in most applications. However, such bolts may experience loosening when used in highly lubricated, vibrating environments, thus leading to the leakage problems outlined above. Such bolts are not easily re-tightened, and as outlined above, it is not easy to access the securing bolts in any event.  
           [0007]    In addition to the problems with oil loss and contaminant ingress, both of which lead to premature failure of the gears and/or the bearings housed within the wheel case, a loose bolt also causes the holes through the bolted components to enlarge, thus accelerating the loss of oil or the ingress of contaminants. Moreover, loose bolts permit small pieces of aggregate to become lodged between the various bolted components, rendering it impossible to securely bolt the components together without completely disassembling and cleaning the device.  
           [0008]    A similar leakage problem may be created where the spindles, which support the rotatable shafts, are secured to the frame. The spindles are typically disposed within the wheel case such that the shaft bearings are exposed to a constant supply of lubricating oil. Each spindle includes a mounting flange, and an O-ring seal may be provided under the mounting flange. However, the cap screws used to secure the spindle to the frame may loosen in a manner similar to the problem described above, leading to similar problems.  
           [0009]    As mentioned above, at least one of the shafts is operatively coupled to an external drive system. Typically, one of the shafts is extended through the wheel case cover for connection to a drive motor. This penetration through the wheel case must be sealed. Due to deflections at the end of the shaft caused by the extreme operating conditions, the end of the shaft typically experiences “runout” which typically causes premature breakdown of the seal. Although labyrinth seals have been employed, a typical labyrinth seal includes a weep hole for captured oil to escape back into the sealed area. Under the extreme operating conditions of the wheel case, in which the rotating eccentric weights contact the oil supply at velocities in excess of 5000 feet per second, the resulting oil agitation throws oil through the weep hole, causing lubricant loss. Consequently, the seal becomes one additional path of lubricant loss or contaminant ingress.  
           [0010]    Accordingly, an improved wheel case having an improved fastening system less prone to loosening and leakage is desired. It is also desired to have an improved wheel case which exhibits better lubricant retention characteristics than prior art wheel cases. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a fragmentary schematic elevational view of a vibratory device having a three shaft sealed wheel case attached to the vibratory device, the wheel case being shown with a portion cut away to reveal the wheels disposed therein;  
         [0012]    [0012]FIG. 2 is an enlarged fragmentary cross-sectional view taken along line  2 - 2  of FIG. 1 and illustrating a wheel case constructed in accordance with certain teachings of the present invention;  
         [0013]    [0013]FIG. 3 is a further enlarged fragmentary cross-sectional view of a sealed attachment bolt assembled in accordance with the teachings of the present invention;  
         [0014]    [0014]FIG. 4 is a fragmentary cross sectional view of another sealed attachment bolt constructed in accordance with the teachings of the present invention;  
         [0015]    [0015]FIG. 5 is a fragmentary cross sectional view of another sealed attachment bolt constructed in accordance with the teachings of the present invention;  
         [0016]    [0016]FIG. 6 is a fragmentary cross sectional view of another sealed attachment bolt constructed in accordance with the teachings of the present invention;  
         [0017]    [0017]FIG. 7 is a fragmentary cross sectional view of another sealed attachment bolt constructed in accordance with the teachings of the present invention;  
         [0018]    [0018]FIG. 8 is a fragmentary cross sectional view of another sealed attachment bolt constructed in accordance with the teachings of the present invention;  
         [0019]    [0019]FIG. 9 is an enlarged elevational view of a clipped washer for use with the attachment bolt of FIG. 8; and  
         [0020]    [0020]FIG. 10 is an enlarged fragmentary view similar to FIG. 2 but illustrating a seal around the penetration of the shaft through the wheel case housing constructed in accordance with the teachings of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    The embodiment described herein is not intended to be exhaustive or to limit the scope of the invention to the precise form disclosed. The following embodiment has been chosen and described in order to best explain the principles of the invention and to enable others skilled in the art to follow its teachings.  
         [0022]    Referring now to the drawings, an improved wheel case generally indicated by the reference numeral  10  is shown in FIGS. 1 and 2 in a preferred environment of use, namely, mounted on a vibrating screen device  12  of the type commonly employed in the art to process aggregate materials by classifying and/or separating the aggregate material according to size. Persons of ordinary skill in the art will recognize that the improved wheel case  10  may also be used on other devices, such as vibrating trough feeders, as well as other devices benefitting from the features to be discussed below.  
         [0023]    As shown in FIGS. 1 and 2, the vibrating screen device  12  typically includes a frame  14  supporting a deck  16  to which is mounted one or more classifying screens (not shown) of the type commonly employed for such purposes. A pair of opposing sidewalls  18  are secured to the frame  14 , and one or more shafts  20 , each housed in a housing  22 , are rotatably mounted to the frame  14  and extend between the sidewalls  18 .  
         [0024]    As shown in FIGS. 1 and 2, one or more shafts  20  are provided, for example shafts  20   a ,  20   b , and  20   c . It will be understood that only a single shaft  20  will be discussed in detail. The shaft  20  includes an end  24  which is rotatably mounted to a spindle  26  by a bearing assembly  28 . Attached to the end of the shaft  20  is wheel  29  having an eccentric weight  30  and a gear  32 , which gear  32  may be either a drive gear or a driven gear as required. Although only one end  24  of the shaft  20  it is shown, it will be understood that the other end (not shown) of the shaft  20  is substantially similar and is rotatably mounted to the opposing sidewall  18  of the frame  14  in a similar manner. The device  12  may also include a plurality of additional side members or stiffeners  34  as required.  
         [0025]    As shown in FIG. 2, the end  24  of the shaft  20 , along with the spindle  26 , the bearing assembly  28 , the eccentric weight  30  and the gear  32  are all disposed within the wheel case  10 . It will be understood that the wheel case  10  is adapted to contain therein a quantity of lubricating oil for the purposes of supplying lubricant to the bearing assembly  28 , the gear  32 , and to any other components housed within the wheel case  10  as required. It will also be understood that a portion of the eccentric weight  30  and/or a portion of the gear  32  comes into contact with, agitates, and distributes the oil about an interior  36  of the wheel case  10 .  
         [0026]    As shown in FIGS. 1 and 2, the wheel case  10  includes a housing  38  having a base  40 , a peripheral sidewall  42  extending outwardly away from the base  40 , and a cover  44  attachable to the sidewalls  42  so as to enclose the interior  36 . The cover  44  is preferably removable as would be known to those of skill in the art in order to gain access to the various components housed within the wheel case  10 . A plurality of attachment bolts  46  are provided for securing the wheel case  10  to the frame  14  (i.e., by securing the base  40  of the housing  38  to the sidewall  18  and the frame  14 ).  
         [0027]    Although a number of configurations are contemplated for the attachment bolt  46 , the preferred embodiment is shown in FIG. 3. Referring now to FIG. 3, the attachment bolt  46  shown therein includes an inner end  48  disposed inside the housing  38  of the wheel case  10 , an outer end  50  disposed outside the housing  38 , and an interconnecting shank  52 . The inner end  48  includes an inner contact surface  54 , while the outer end  50  includes an outer contact surface  56 .  
         [0028]    The bolt  46  is preferably a threadless bolt having a pressed on collar  58 , and preferably the bolt  46  is a threadless bolt sold under the trade name Huckbolt® and is manufactured by the Federal Mogul Corporation. Other suitable fasteners, especially other suitable threadless fasteners and/or other suitable fasteners which may be fastened with a desired pre-load tension on the bolt  46  may be employed, with the desired pre-load tension typically being designated by the manufacturer or otherwise determined using well known principles of mechanics. The collar  58  is preferably pressed on using a tool, such as a hydraulic tool, of the type commonly employed for such installations. The collar  58  is retained on the shank  52  by a plurality of annular rings  60  spaced along a portion of the shank  52 .  
         [0029]    A pair of compression control washers  62 ,  64  are provided. The washers  62 ,  64  are preferably 0.108 inches thick, and have a hardness in the range of 38-45 on the Rockwell “C” hardness scale. The washer  62  includes an aperture  66  which is greater than the diameter of the shank  52  so as to define an annular cavity  68  surrounding the shank  52 . The annular cavity  68  is sized to receive a resilient O-ring seal  70 . Similarly, the washer  64  includes an aperture  72  which is greater than the diameter of the shank  52  so as to define an annular cavity  74  surrounding the shank  52 . The annular cavity  74  is sized to receive a resilient O-ring seal  76 . The O-rings  70 ,  76  are preferably thicker than the thickness of the washers  62 ,  64 , and are preferably 0.140 inches thick. Still preferably, the O-rings may be manufactured of a resilient rubber compound, such as nitrile rubber.  
         [0030]    The washer  62  and the O-ring  70  are disposed adjacent the outer contact surface  56 , while the washer  64  and the O-ring  76  are disposed adjacent the inside contact surface  54 , inside the wheel case  10 . An additional washer  78  may be employed, but the use of such is optional.  
         [0031]    In operation, the housing  38  and the stiffeners  34  are positioned for attachment to the sidewall  18  of the frame  14  as shown in FIG. 3. The washer  62  and the O-ring  70  are positioned on the bolt  46  adjacent the outer contact surface  56 . The inner end  48  of the attachment bolt  46  is then inserted into the wheel case  10  from the opposite side of the sidewall  18 . The washer  64  and the O-ring  76  are placed along the shank  52 , and then the collar  58  is applied using the above-referenced tool in a known manner. The tool draws the inner end  48  (typically by pulling on a break-away portion, which is not shown but which is releasable along a frangible connection line  80 ). As stated above, the optional washer  78  may be included as shown.  
         [0032]    In the process of securing the bolt  46 , the inner and outer contact surfaces  54 ,  56  are drawn together, which compresses the O-rings  70 ,  76  such that they substantially fill their respective annular cavities  68 ,  74 . The ratio between the thickness of the O-rings  70 ,  76  and the thickness of their associated washer  62 ,  64 , allows for the O-rings to be compressed a desired amount to maximize their sealing capacities while preventing inadvertent damage to the O-rings via over-compression.  
         [0033]    The embodiment shown in FIG. 4 is similar to that shown in FIG. 3, but it excludes the inner washer  64  and the inner O-ring  76 , and excludes the optional washer  78 .  
         [0034]    The embodiment shown in FIG. 5 also is similar to that shown in FIG. 3, but it excludes the outer washer  62  and the outer O-ring  70 , and includes the optional washer  78 .  
         [0035]    The embodiment shown in FIG. 6 is similar to that shown in FIG. 5, but the inner washer  64  is sized such that the inner O-ring  76  is disposed in an annular cavity  65  defined in part by an outer perimeter  67  of the washer  64 . The embodiment of FIG. 6 also includes an optional washer  78 .  
         [0036]    The embodiment shown in FIG. 7 is similar to that shown in FIG. 6, but includes an outer washer  62  sized such that the outer O-ring  70  is disposed in an annular cavity  69  defined in part by an outer perimeter  71  of the washer  62 . The optional washer  78  is excluded.  
         [0037]    Referring now to FIGS. 8 and 9, an attachment bolt  146  is shown, such as an attachment bolt used to secure the spindle  26  to the frame  14  in an area of low lateral clearance. The bolt  146  is preferably a conventional cap screw, although other suitable fasteners may be employed. The bolt  146  includes an inner washer  164  having an aperture  172  defining with the bolt shank  152  an annular cavity  174 . A pair of compressible O-rings  176   a ,  176   b  are provided for insertion in the cavity  174  in stacked arrangement. The O-rings  176   a ,  176   b  will preferably have a stacked height totaling approximately 30% greater than the thickness of the washer  164 . It will be noted in FIG. 9, that the washer  164  includes a truncated side portion  180 , thereby permitting an inner end  150  of the attachment bolt  146  to be positioned in close proximity to an extended portion  182  of the spindle  26 , such that upon application of a torque to an outer end  148 , rotation of the bolt  146  is prevented. The O-rings  176   a ,  176   b  cooperate to prevent lubricant from leaking out of the wheel case  10  along the shank  152  of the bolt  146 .  
         [0038]    Referring now to FIG. 10, it will be appreciated that at least one of the shafts  20 , such as, for example, the shaft  20   b , will include a portion  100  extending out of the cover  44  of the wheel case  10  for operative engagement with an external drive source (not shown). Accordingly, the cover  44  includes an aperture  102  having a seal  104 . Preferably, the seal  104  is a labyrinth seal, such as a ProTech® labyrinth seal manufactured by J M Clipper. The seal  104  includes at least one weep hole  106 . An annular cylindrical baffle  108  is secured to an inner surface  109  of the cover  44 , and is spaced outwardly from and generally surrounds the aperture  102  and the seal  104 . It will be noted that the baffle  108  includes an inner end  110  which is disposed generally adjacent to the wheel  29  so as to define a relatively small and generally annular gap  112  therebetween.  
         [0039]    It will be appreciated that, during operation of the device  12 , splashing and otherwise agitated oil (not shown) is shielded from the seal  104 , the weep hole  106  and the aperture  102  by the annular baffle  108 . The sealing properties are enhanced by the relatively small size of the gap  112 .  
         [0040]    Numerous modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which come within the scope of the appended claims is reserved.

Technology Category: 4