Patent Publication Number: US-2013239395-A1

Title: Multi-part locking nut

Description:
CLAIM OF PRIORITY 
     This application claims priority from Provisional Application Ser. No. 61/611,850, filed on Mar. 16, 2012, the entirety of which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Locking fasteners and locking fastener assemblies are used to prevent loosening of a threaded fastener in a fastener joint. There are many types of threaded joints in which loosening of a fastener is undesirable. One example to which the principles of the present disclosure may be applied is an axle assembly of a vehicle, including automobiles, heavy trucks, trailers or other transportation devices as well as construction equipment. 
     In a typical axle assembly, axle bearings are supported between an axle or spindle and a wheel hub or spindle support to permit rotation of a vehicle wheel. An axle bearing nut is used to hold the components together. Usually, the axle bearing assembly is encased with grease and sealed so that outside contaminates, which can lead to premature bearing wear and failure, cannot enter the bearing assembly. Moreover, in order to extend bearing life, the nut must be installed properly and tightened to the proper torque to avoid excessive axial bearing load or, alternatively, excessive free play. In addition, after assembly, it is important to prevent loosening of the axle bearing nut to avoid bearing failure or even the dangerous loss of a wheel. 
     Existing locking assemblies provide a limited number of adjustment positions. As a result, if an installer is not careful during alignment of the pin with the washer, part of the pin could scrape against the sides of the washer, causing metal shavings to fall with the sealed bearing assembly. Thus, there exists a need for a locking nut assembly which has virtually limitless alignment positions using holes instead of slots which also prevents misalignment of a pin with a washer. 
     There is also a need for a lock nut assembly which does not require a sight gage for alignment. 
     Other aspects of the disclosure will become apparent upon a further reading of the following detailed description taken in conjunction with the drawings. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with one aspect of the disclosure, a multi-part locking nut assembly has a nut having a raised center portion and a flange having a plurality of holes thereof. A washer has a protrusion which is matingly received by a notch in a spindle. The washer has a plurality of holes therethrough. At least one locking pin is slidably received by one of the plurality of holes of the nut and one of the plurality of holes of the washer. A resilient biasing member retains the locking pin in place. 
     A method of assembling a lock nut includes the steps of assembling a washer on a spindle by aligning a protrusion of the washer with a groove on the spindle; threading a lock nut onto the spindle until the nut contacts the washer; aligning at least one hole in the nut with at least one hole in the washer; inserting a locking pin through a hole of the washer and the hole of the lock nut; and inserting a resilient biasing member onto the nut to retain the locking pin onto the nut and washer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a locking nut assembly in an assembled configuration in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is an exploded view of the lock nut assembly of  FIG. 1 ; 
         FIG. 3  is an exploded perspective view of the lock nut assembly of  FIG. 1 ; 
         FIG. 4A  is a top plan view of a lock nut of  FIG. 1 ; 
         FIG. 4B  is a side elevational view of the lock nut of  FIG. 4A ; 
         FIG. 5A  is a top plan view of a lock washer of  FIG. 1 ; 
         FIG. 5B  is a side elevational view of the lock washer of  FIG. 5A ; 
         FIG. 6A  is a top plan view of a snap-ring for the lock nut assembly of  FIG. 1 ; 
         FIG. 6B  is a side elevational view of the snap ring of  FIG. 6A ; 
         FIG. 7A  is a top plan view and a side elevational view of a pin or pin used in the assembly of  FIG. 1 ; 
         FIG. 8A  is a top plan view of a snap ring for the assembly of  FIG. 1  in accordance with another aspect of the disclosure; and 
         FIG. 8B  is a side elevational view of the snap ring of  FIG. 8A . 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Referring to the figures,  FIGS. 1-8  illustrate a locking nut assembly in accordance with a preferred embodiment of the disclosure. These figures show one example of the assembly only and other dimensions and sizes are contemplated by the disclosure. 
     Referring now to  FIG. 1 , a perspective view of the components of one embodiment of the locking fastener assembly  10  of the present invention in an assembled configuration is shown. The locking fastener assembly  10  includes a lock nut  12 , at least one locking pin  14  (preferably two pins), a retainer washer  16 , and a snap ring  18 . 
     Referring now to  FIGS. 2 and 4 , the nut  12  has a flange  20  with multiple through holes  22 , wherein the locking pins or pins  14  are received. The nut is shown as having ten through holes  22  (five on each side), but other numbers and positions of holes are contemplated by the disclosure. The nut  12  also can have a raised central portion  13  having internal female threads  15  formed therein. In order to give the nut  12  high shear strength, it is preferred that nut  12  is made out of a metal with HRC 28-32 (preferably AISI 1141 or 1045 alloy steel). However, other alloys of steel and hardnesses are contemplated by the disclosure. 
       FIGS. 4A and 4B  show the lock nut  12  having a plurality of notches  50  formed in raised portion  13  that receive a wrench or other tightening tool (not shown) for tightening and loosening the nut  12  by rotation clockwise or counter-clockwise on the threads formed on spindle  40  ( FIG. 3 ). Notches or grooves  50  also receive the snap ring  18 . 
     As shown in  FIGS. 2 and 5A  and  5 B, the retaining washer  16  has a tab or key  32  formed by two recesses or grooves  33  which protrudes at least slightly into the inner center opening  35  of the washer which is matingly engageable with a corresponding axial slot or key way  34  in spindle  40  ( FIG. 3 ), the spindle  40  also having axial threads  44 . When the key  32  engages with slot  34 , the washer  16  is prohibited from rotational movement around spindle, but is allowed to move axially in a longitudinal direction along slot  34 . The retaining washer  16  also includes holes  30  spaced evenly (about 15° apart) around the periphery of the retaining washer  16 . In a preferred embodiment, there are 24 such holes. However, one with skill in the art will appreciate that there can be fewer or greater holes, depending on the particular use of the locking fastener assembly  10  and the desired amount of locking locations. The holes are of such dimensions (such as about 0.3 inches in diameter or so) that a locking pin  14  can pass therethrough. It is preferred that the retaining washer  16  comprise alloy steel that can be oil quenched and tempered. Various alloys of steel are contemplated by the disclosure. 
     Preferably, to allow for proper alignment, one of the holes  22  in the nut flange  20  is closely aligned with one of the holes  30  formed in washer  16 . Due to the large number (24) of holes  30  in the washer, a virtually limitless number of alignment positions can be achieved by aligning a hole  22  in the nut with a hole  30  in the washer. Furthermore, the holes  30  are sized such that slight misalignment between holes  30  and holes  22  is compensated for and the pin  14  is able to slide through both holes. The axial movement or alignment is capable of adjustment of less than 0.0005 inch. 
     Referring now to FIGS.  2  and  6 A- 6 B, snap-ring  18  is used to retain the locking pins or pins  14  in place. The snap-ring has two opposed ends  19  and  21  which are resiliently biased to a “closed” position as seen in  FIG. 6A . To “open” the ring, a tool is inserted into openings  23 ,  25  formed in ends  19 ,  21  to pry the ends apart to slide the ring over portion  13  of nut  12 . The snap-ring has a thickness of about 0.100 inches and is preferably fabricated of high carbon spring steel with a hardness of 45-50 HRC. However, other hardnesses of steel are also contemplated by the disclosure. 
     Referring now to  FIGS. 8A and 8B , a snap ring  60  in accordance with another embodiment of the disclosure is shown. The snap ring  60  has two opposed ends  62 ,  64  which are resiliently biased to the “closed” position shown in  FIG. 8A . To “open” the rings, a tool is inserted into openings  66 ,  68  found in ends  62 ,  64  to pry the ends apart to slide rings over portion  13  of nut  12 . The snap ring has a thickness of about 0.100 inches and is preferably fabricated of high carbon spring steel with a hardness of 45-50 HRC. However, other hardnesses of steel are also contemplated by the disclosure. The snap ring  60  has a plurality of inner ridges  70  formed on inner edge  71  extending into centered opening  72  and a plurality of notches or grooves  74  formed on outer edge  75 . The ridges and grooves are preferably in alignment with each other and can be evenly spread along the circumference of the snap ring. The ridges and grooves are used to facilitate bending or stretching of the snap ring to slide the ring over portion  13  of nut  12 . 
     Referring now to FIGS.  2  and  7 A- 7 B, locking pin or pin  14  has a head  27  and body  29  and is preferably fabricated of alloy steel preferably having a hardness of RC 40-46. However, other hardnesses are contemplated by the disclosure. The pin can be zinc phosphate and oil coated. 
     Operation of the present disclosure is accomplished as follows: 
     First, the washer  16  is assembled on the spindle  40 , aligning the washer key  32  with the keyway  34  on the spindle. The flanged nut  12  (flanged side to the keyed washer) is threaded on the spindle until the nut contacts the surface of the washer. The nut is torqued to achieve required torque or bearing preload. 
     Alignment of holes  22  in the flange of the locknut with the holes  30  in the lock washer is then checked. If alignment is correct, two pins  14  are inserted in the opposing aligned holes  22 ,  30 . The snap ring  18  is then inserted into snap ring groove  50  in the nut body. The snap ring serves to retain the pins and does not allow the pins to fall out of the assembly. 
     If the nut assembly requires adjustment to align the holes, the nut  12  can be backed off and readjusted, or tightened further, to within torque or preload limits of the assembly, and stopped where a set of holes  22  of the nut align with the holes  30  in the washer. A maximum adjustment of 3 degrees radially from the original setting or an advancement (or loosening) of the nut (along the centerline of the threads) by no more than about 0.000463 inches (0.01176 mm) may be required. 
     After readjusting, the two pins  14  are assembled in opposing (and aligned) holes  22 ,  30  and the snap ring  18  is applied or inserted into the snap ring groove in the nut body to retain the pins. 
     Bearing adjustment and/or tightening specifications always have a tolerance that will allow this fine adjustment to obtain optimal bearing life or joint integrity. 
     The above noted adjustment features are calculated for a part that has 18 threads per inch (TPI) (2.548 inch—18 TPI). Parts having threads that are different in pitch may require different, but similar, hole patterns. 
     With a part having 18 TPI the nut will advance about 0.055555 inch per 360 degrees of rotation. If the part is turned about 15 degrees (which matches hole spacing in the lock washer) the nut will advance about 0.002315 inch. The spacing of the holes on the flange of the locknut is about 18 degrees (i.e., 3 degrees different than the lock washer). The holes on both the washer and the locknut of a given thread will always be on the same bolt circle, which allows the holes to align and the locking pins to be inserted. The 3 degree difference allows for a maximum adjustment opposing pin alignment of 3 degrees with a maximum nut advancement of only 0.000463 inches (i.e., about 0.0005 inches). 
     The exemplary embodiment has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the above description or the equivalents thereof.