Patent Publication Number: US-2004045400-A1

Title: Bicycle crank arm bearing bracket

Description:
BACKGROUND OF THE INVENTION  
       [0001] This invention relates to bicycle crank arm bearing brackets. More specifically, it refers to a pair of bearing brackets threadably engaged together within a shell housing and supporting an axle on bearings mounted within an outboard portion of each bearing bracket.  
       [0002] Conventional American style bottom brackets on bicycles are installed using a press tool to push bearing cups tightly into a bottom bracket. To repair failed bearings in the cups, the bracket and cups must be knocked out of their shell housing which is welded to the bike frame. This is an expensive and time consuming job which this invention seeks to improve upon. Because of the bracket configuration in American style bottom brackets the bearing cups sometime are too loosely or too tightly mounted in the bracket ends and as a result misaligned bearing could occur.  
       [0003] Patents that included threaded bearings supporting an axle engaged to crank arms include U.S. Pat. Nos. 2,280,936; 3,220,784; 5,209,581; and 5,233,885. Although these patents relate to unconventional means for removing bottom brackets, they do not provide a simple inexpensive system of removing bottom bracket parts. Such a system is needed in the bicycle industry.  
       SUMMARY OF THE INVENTION  
       [0004] The present invention provides a system for replacing bearings and other components of a crank arm bracket inexpensively and with less effort than accomplished heretofore. In addition, the bearings are consistently aligned with the axle. The crank arm bearing bracket of this invention has a cylindrical shell housing with a smooth annular inner surface accommodating a longitudinal axle having splines or other bicycle crank arm mounting portions at each end. The shell housing is fixed in place by being welded to the bicycle frame. A threaded male bracket and complimentary female bracket are threadably engaged around the axle within the shell housing. The ends of the axle project axially out from outboard ends of each bracket and can be splined or have other configuration to mount the crank arm. A bearing supports the axle within the outboard end of each bracket and an end cap holds the bearing perfectly aligned in place within the brackets. An irregular surface on an outer rim of each outboard portion of the brackets permits engagement of a wrench to separate the brackets. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0005] The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which:  
     [0006]FIG. 1 is an exploded view of the crank arm bearing bracket of this invention.  
     [0007]FIG. 2 is a perspective view of the crank arm bearing bracket assembled.  
     [0008]FIG. 3 is a perspective view of the shell housing welded to a bicycle frame.  
     [0009]FIG. 4 is a right side elevational view of a portion of the bicycle frame with the crank arms installed on the bracket axle splined ends. 
    
    
     DETAILED DESCRIPTION OF THE BEST MODE  
     [0010] Throughout the following detailed description, the same reference numerals refer to the same elements in all figures.  
     [0011] Referring to FIG. 1, the crank arm bearing bracket  10 , has a shell housing  12  welded to a bicycle frame  14  as seen in FIG. 3. An inner annular surface of the shell housing is smooth. A first end  16  of the shell housing  12  has a raised edge or flange  18  and likewise a second end  20  of the shell housing  12  has a raised edge or flange  22 . An axle  24  is centered within the interior of the shell housing  12  and is supported therein by bearings  26  and  28  which are mounted within an outboard portion  30  of a threaded bracket  32  and  34 , respectively. Bracket  32  has male threads on an inboard portion  36  and bracket  34  has female threads on an inner surface  38 . The brackets  32  and  34  are threadably engaged together inside shell housing  12 . Each bracket  32  and  34  have an irregular pattern  40  along an outer rim  41  of outboard portion  30 . Irregular pattern  40  is complementary to the inner portion of a wrench  42  which is used both to engage and disengage the brackets  32  and  34 .  
     [0012] Each end  44  and  46  of axle  24  has a splined configuration for engaging a crank arm  48  and sprocket  50  as seen in FIG. 4. Other configurations such as a rectangular or square end could be substituted. A standard foot peddle  52  is located at one end of the crank arm  48  distal from bearing bracket  10 . A flush mounted washer  54  and threaded bolt  56  inserted at each outside end of axle  24  hold the crank arm  48  on the axle  24 . A center sleeve  58  surrounds a mid-section  60  of axle  24  within the shell housing  12 . Each end of axle  24  has a threaded bolt hole  60  to accommodate threaded bolt  56 . End caps  62  are press fit into the outboard portions  30  of each bracket  32  and  34  to hold bearings  26  and  28 , respectively in place.  
     [0013] The crank arm bearing bracket  10  components are made from steel, brass or high strength aluminum. If a component such as bearings  26  or  28  fail, one merely has to use a wrench  42  to disengage the brackets  32  and  34  after removing bolt  56  and washer  54 . The end cap  62  easily snaps out to expose the bearing  26  or  28  for replacement. Upon re-engagement, the flanges  18  and  22  abut edges  64  and  66 , respectively to prevent over tightening of brackets  32  and  34 .  
     [0014] Other equivalent components can be substituted for the components disclosed herein to produce the same results in the same way.