Abstract:
A system for use in measuring an end play of a wheel hub assembly includes a follower configured to extend through an opening in a cover connected to a wheel hub. The cover covers the wheel hub such that the cover inhibits access to an end of a shaft of the wheel hub assembly, and the follower is configured to contact the end through the opening. The follower is received in a holder engageable with the cover such that the follower is movable relative to the cover and the holder to allow the follower to extend from the holder to contact the end of the shaft. A frame has a cavity receiving a measurement probe extending outwardly from the cavity. The probe contacts the follower and is configured to measure movement of the follower to determine endplay of the bearing assembly on the shaft. The frame includes a plurality of legs extending from the frame to a hub mounted on the shaft and coupled to the bearing to support the frame relative to the hub.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. Ser. No. 13/091,890, filed on Apr. 21, 2011, titled “Systems and Methods for Measuring Bearing Endplay”, and published as U.S. Publication No. US20120079893A1 on Apr. 5, 2012. 
    
    
     This application also relates to U.S. application Ser. No. 13/019,583, filed Feb. 2, 2011, titled “Systems and Methods for Adjusting Bearing Endplay”, and published as U.S. Publication No. US20120079922A1 on Apr. 5, 2012, U.S. application Ser. No. 12/951,727, filed Nov. 22, 2010, titled “Systems and Methods for Measuring Bearing Endplay”, and published as U.S. Publication No. US20120079892A1 on Apr. 5, 2012, U.S. application Ser. No. 12/492,826, filed Jun. 26, 2009, titled “Systems And Methods For Preloading A Bearing And Aligning A Lock Nut”, issued as U.S. Pat. No. 8,316,530 on Nov. 27, 2012, U.S. application Ser. No. 11/341,948, filed Jan. 27, 2006, and titled “Method And Apparatus For Preloading A Bearing,” issued as U.S. Pat. No. 7,559,135 on Jul. 14, 2009, U.S. application Ser. No. 11/354,513, filed Feb. 15, 2006, and titled “Method, Apparatus, and Nut for Preloading a Bearing”, issued as U.S. Pat. No. 7,389,579 on Jun. 24, 2008, and U.S. Provisional Application No. 61/388,806, filed Oct. 1, 2010, and titled “Systems and Methods for Preloading a Bearing and Aligning Lock Nut”, each of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates, generally, to methods and apparatus for preloading antifriction bearings in drive trains, particularly, to preloading and adjusting bearings while monitoring the preload being applied. 
     BACKGROUND OF THE INVENTION 
     Various means have been devised to simplify the adjustment of axle bearings, specifically, truck axle bearings. It is generally accepted that in some bearing installations, for example, axle bearings, the life of the bearing will be optimized if the adjustment is made for a slight axial compressive deflection, for example, about 0.003 inches (where this amount is the compressive deflection of the two bearings combined), which is often referred to as “a three thousandths preload.” Typical prior art methods of creating these preloads are obtained by applying specified torques to the bearing assembly, for example, by tightening the nut that retains the bearings. However, for several reasons, it is typically extremely difficult to achieve such preload settings under actual in-field conditions, such as in a mechanic shop. For example, the assembly of a heavy truck wheel onto a wheel hub assembly is a relatively cumbersome procedure that hinders the mechanic. Moreover, the wheel hub assembly always includes at least one inner seal, usually a lip type of seal, which can impose a resistive drag torque component to the preload torque, particularly when the seal is new. 
     In one example, a user may tighten a nut holding a bearing on a shaft to a particular torque and then such nut may be loosened to a particular position by referencing an index mark on a face of the nut a particular distance. Such a nut could be turned a particular portion of a rotation by referencing such a marking, e.g., half a turn. Such an adjustment is a particularly inexact procedure given that wheel nut adjustment is desired to have precision of 0.001 of an inch while the degree of rotation of a nut as described is relatively inexact. 
     Lock nut systems using a single nut are often utilized to retain a wheel or hub assembly, including axle bearings, on a shaft. Such lock nut systems may be connected to a shaft and inhibit rotation of a retaining nut relative to such shafts. For example, such systems are often utilized on motor vehicles, such as axles and wheel ends. Typically, a lock nut will be engageable with a locking member or keeper which inhibits movement of the nut relative to the shaft. The locking member may include a protruding portion which extends into a slot or receiving portion of a shaft. The locking member may also engage the nut such that there is little or no movement between the nut and shaft. 
     Thus, a need exists for providing accurate and repeatable procedures and devices for providing and adjusting bearing preload and for adjusting lock nut systems configured to retain preloaded bearings. 
     SUMMARY OF THE INVENTION 
     The present provides, in a first aspect, a system for use in measuring an end play of a bearing of a wheel hub assembly which includes a follower configured to extend through an opening in a cover connected to a wheel hub. The cover covers the wheel hub such that the cover inhibits access to an end of a shaft of the wheel hub assembly, and the follower is configured to contact the end through the opening. The follower is received in a holder engageable with the cover such that the follower is movable relative to the cover and the holder to allow the follower to extend from the holder to contact the end of the shaft. A frame has a cavity receiving a measurement probe extending outwardly from the cavity. The probe contacts the follower and is configured to measure movement of the follower relative to the wheel hub to determine endplay of a bearing of the hub assembly on the shaft. The frame includes a plurality of legs extending from the frame to a hub mounted on the shaft and coupled to the bearing to support the frame relative to the hub. 
     The present invention provides, in a second aspect, a method for determining an endplay of a bearing of a wheel hub assembly mounted on a shaft which includes extending a follower through an opening in a hub cover covering a hub of the wheel hub assembly and extending away from the hub The follower contacts an end of the shaft. A plurality of legs of an endplay measuring apparatus is connected to the hub of the hub assembly mounted on the shaft. A measuring probe is received in a cavity of a frame of the apparatus. The probe contacts the follower. A force is applied to the apparatus to move the hub in a first axial direction until a cessation of movement of the hub. A first measurement of the probe is determined. A force is applied on the apparatus in a second axial direction opposite to the first axial direction until a second cessation of movement of the hub. A second measurement of the probe is determined after the second cessation of movement. A movement of the follower by the probe is determined to determine an endplay of the bearing by comparing the first measurement to the second measurement. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention will be readily understood from the following detailed description of aspects of the invention taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a perspective view of a system for measuring endplay on a bearing of a wheel hub assembly mounted on a shaft in accordance with the present invention; 
         FIG. 2  is a side cross-sectional view of the system of  FIG. 1 ; 
         FIG. 3  is a side cross-sectional view of the follower, holder and hub cover of  FIG. 1 ; and 
         FIG. 4  is a perspective view of the follower and holder of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In accordance with the principals of the present invention, systems and methods for adjusting bearings mounted on a shaft are provided. In an exemplary embodiment depicted in  FIG. 1 , a system  10  for measuring end play is mounted on a wheel hub assembly  20 . 
     Wheel hub assembly  20  is an assembly that would typically be found on a front or rear axle of a cab or tractor of a tractor-trailer, or an axle of a trailer. However, aspects of the invention are not limited to use for vehicle bearings. As will generally be understood by those skilled in the art, aspects of the invention may be used to service bearings and bearing assemblies in any machine or device that employs bearings, including, but not limited to: power trains, transmissions, machine components, on and off-road vehicles, aircraft wheels, marine drives, spacecraft, conveyor rolls, and windmills, among others. According to aspects of the present invention, system  10  may be used in these and any other assembly for which bearing preload and/or endplay is desired, for example, any assembly that utilizes thrust and radial load carrying bearings that are indirectly mounted. 
     As shown in  FIGS. 1-2 , for example, wheel hub assembly  20  includes a wheel hub or, simply, a hub  12 , a threaded, spindle, axle, or a shaft  14 . As is typical, shaft  14  is mounted on two antifriction bearings and shaft  14  includes an exposed end  13 , which is typically threaded on the outside diameter and is partially hollow at the end. A retaining nut  11  ( FIG. 2 ) may be threaded to exposed end  13  to retain hub  12  thereon. 
     As shown in  FIG. 2 , as is typical of bearings, outboard bearing  16  includes an inner race (or cone)  15 , an outer race (or cup)  17 , a plurality of rollers  22 , and a roller cage  24 . Similarly, an inboard bearing  19  includes an inner race (or cone) (not shown), an outer race (or cup) (not shown), a plurality of rollers (not shown), and roller cage (not shown). The details of an inboard bearing and an outboard bearing are described and depicted in co-owned U.S. Pat. No. 7,303,367, issued Dec. 4, 2007 (application Ser. No. 11/029,531 filed Jan. 5, 2005), entitled “Lock Nut System”; U.S. Publication No. 2007/0177829A1, published Aug. 2, 2007, (application Ser. No. 11/341,948 filed Jan. 27, 2006), entitled “Method and Apparatus for Preloading a Bearing”; and U.S. Pat. No. 7,389,579, issued Jun. 24, 2008 (application Ser. No. 11/354,513, filed Feb. 15, 2006), entitled “Method, Apparatus, and Nut for Preloading a Bearing”, the entirety of which are incorporated herein by reference. 
     As depicted in FIGS. 5-8 of co-owned U.S. Provisional Application No. 61/388,806, filed Oct. 1, 2010, entitled “Systems and Methods for Preloading a Bearing and Aligning Lock Nut”, for example, retaining nut  11  may be a locking nut as disclosed in co-owned U.S. Pat. No. 7,303,367 (application Ser. No. 11/029,531 filed Jan. 5, 2005), entitled “Lock Nut System”; U.S. Publication No. 2007/0177829A1 (application Ser. No. 11/341,948 filed Jan. 27, 2006), entitled “Method and Apparatus for Preloading a Bearing”; and U.S. Pat. No. 7,389,579 (application Ser. No. 11/354,513, filed Feb. 15, 2006), entitled “Method, Apparatus, and Nut for Preloading a Bearing”. In another example, a retaining nut could be a locking nut as disclosed in U.S. Pat. No. 3,762,455 to Anderson Jr. In the conventional art, retaining nut  11  typically is used to secure a wheel (e.g., wheel  200 ,  FIG. 3 ) or hub assembly to non-rotating axle or spindle  14 . However, in aspects of the present invention, retaining nut  11  may be useful in varying the preload and/or endplay of bearing  16 . Bearing  16  may be a tapered roller bearing, or aspects of the invention may be applied to other types of antifriction bearings for which it is desirable to provide preload and/or endplay, for example, spherical roller bearings, deep groove ball bearings, and the like. 
     As described above, it is desirable for an adjustment to be provided to a bearing assembly such that a desired amount of endplay is present. After retaining nut  11  is tightened on the shaft to a particular predetermined torque (e.g., using a torque wrench), the standard procedures call for a loosening of say ¼ turn to create a desirable endplay of bearing  16  on shaft  14 . All typical adjustment procedures require that said endplay be measured with a dial indicator to assure a safe adjustment had been achieved. 
     System  10  may include a frame  30  formed of a plurality of cross members  35 . Frame  30  may be connected to a handle  40  at one end of system  10  by connecting legs  45 . Frame  30  may also be connected to pressing legs  50  which may extend from frame  30  away from handle  40  and to wheel hub  12  as depicted in the figures. Pressing legs  50  may be connected to wheel hub  12  at wheel lugs  60 . Connecting tabs  55  may be connected to, or monolithic relative to, pressing legs  50  and may be aligned in a direction substantially perpendicular to pressing legs  50 , such that connecting tabs  55  may be received under lug nuts  70  threaded onto wheel lugs  60 . Pressing legs  50  may be substantially parallel to each other and may be connected to wheel hub  12  such that the legs are substantially parallel to the axis (i.e., longitudinal axis) of shaft  14 . Connecting legs  45  may also be substantially parallel to the axis of shaft  14 . Each connecting leg and pressing leg on a same side of frame  30  may be monolithic to, or connected to, one another. The cross members (i.e., cross members  35 ) may be connected on each side thereof to at least one of pressing legs  50  and connecting legs  45 . 
     A hubcap  80  may be connected to hub  12  via screws  81  or other connecting mechanisms as is known in the art. A follower  82  may be received in a holder  85  which is received in an opening  83  through hubcap  80  such that holder  85  is connected to, or contacts, hubcap  80  to inhibit movement of holder  85  through opening  83  toward shaft  14 . A resilient member  86  (e.g., a spring) may be connected to follower  82  and holder  85  such that a distal end  84  of follower  82  is biased toward shaft  14  and away from probe  90 . As used herein, follower refers to any structure, or part of a structure, which contacts shaft  14  and extends to holder  85  such that the follower extends through the holder toward handle  40 . A dial indicator or probe  90  may be received in a cavity  95  of frame  30  such that probe  90  is stationary relative to frame  30  and a remainder of system  10 . For example, probe  90  may be connected to cross members  35  in any number of ways, such as by welding or by mechanical fasteners. Frame  30  may include an opening  32  to allow user to view a display  34  of a dial indicator of probe  90 . 
     A probe tip  100  of a probe stem  99  may contact follower  82  when follower  82  is received in holder  85  such that end  83  of follower  82  contacts shaft  14 . Probe tip  100  may be aligned in a direction substantially parallel to an axis of shaft  14 . For example, an axis of probe tip  100  may be substantially aligned with the longitudinal axis of shaft  14 . 
     When a measurement of endplay of hub assembly  20 , including wheel hub  12  and bearing  16 , is desired, a user may grasp handle  40  and push in a first direction toward hub  12  until no further forward motion occurs. Probe  90  may then be reset to a known setting (e.g., ‘zeroed’) to allow a measurement by probe  90  which it is in contact with follower  82 . The user may then pull in a second direction on handle  40  until no further reverse motion of hub  12  occurs. The user may then view display  34  to determine a measurement of the movement of hub  12  relative to the follower as determined by the movement of probe  90  which is in contact with the face of the follower. The movement by the probe signals a distance on the display which indicates the endplay of wheel hub  12  and bearing  16 . The difference between a movement after forward motion of the hub ceases to that after reverse motion of the hub ceases provides an indication of the endplay of bearing  16 . The components of system  10  (e.g., the connecting legs, extending legs, handle, tabs, and frame) may be sufficiently rigid to allow the application of a force (e.g., in a forward and reverse axial direction relative to shaft  14 ) to handle  40  to transfer such force to hub  12  to allow the motion of hub  12  in a forward and reverse direction to allow the measurement of the endplay as described. 
     Further, as described above probe  90  is connected to frame  30 . The connection of probe  90  to frame  30  may be fixed as described above or could be adjustable. For example, probe  90  may be connected to a plate  33  which has screws or other connectors received in slots of frame  35  such that probe  90  may be adjusted to a particular position and tightened by the screws or fasteners to frame  35  if further adjustment is desired. 
     After the measurement of endplay described above (or prior thereto) it may be desirable to tighten nut  11  to adjust such endplay. As depicted in  FIG. 1 , openings  52  may be present between connecting legs  50  on opposite sides of system  10 . A user may insert a wrench (not shown) into one of openings  52  to engage the wrench with a nut  11  to adjust an endplay of bearing  16  and hub  12 . Prior to any such adjustment, however, hubcap  80  is removed to allow access of a wrench to nut  11 . 
     As described above and depicted in  FIG. 1 , endplay may be measured by system  10  with tabs  55  placed on wheel hub  12  and held in place by wheel lugs  60 . In another example, tabs  55  could be received on top of wheel  200  connected to hub  12  as depicted in  FIG. 3  of co-owned U.S. application Ser. No. 12/951,727. In a further unillustrated example, follower  80  could be replaced by a follower of a different axial dimension or thickness to accommodate a height of hubcap from a hub or a dimension of a opening (e.g., opening  83 ) through a hubcap (e.g., hubcap  80 ), or another structure mounted on hub  12  which restricts access to shaft  14  by a system for measuring end play (e.g., system  10 ). As described above, handle  40  may be grasped by a user and a force may be applied thereto to move bearing  16  and hub  12  to a first position followed by a “zeroing” of the probe and then movement to a second position. During the application of force to the first position and movement from the first position to the second position, handle  40  may be utilized to rotate system  10  and thus hub  12  and bearing  16 . This rotation insures roller alignment of the bearing such that the measured endplay is accurate for the circumference of hub  12  and bearing  16 . Also, pressing legs  55  are located on opposite sides of system  10  and are located about 180° apart relative to the axis of shaft  14 . The positioning of such pressing legs substantially equally distant from one another and connected to handle  40  via connecting legs  45  promotes an equidistant application of force to hub  12  and bearing  16  when a force is applied to handle  40  described above such that twisting of the hub is minimized and an accurate measurement of endplay may be achieved and an off-center loading of the bearing may be avoided. Handle  40  may also extend substantially perpendicularly relative to the axis of shaft  14  and may extend through the axis to opposite sides of such axis as depicted in the figures. In particular, handle  40  may connect to connecting legs  45 , and connecting legs  45  may extend substantially parallel to the axis of shaft  45  and pressing legs  50  may also extend substantially parallel to the axis of shaft  45  such that connecting legs  50  may contact hub  12 . As described above, pressing legs  50  may connect to tabs  55  which extend substantially perpendicularly to pressing legs  50 . It will be understood by one skilled in the art that pressing legs  50  could connect to hub  12  in any number of other ways while satisfying the objectives of the invention. 
     Although aspects of the present invention were described above with respect to their application to wheel hub assemblies, for example, truck wheel hub assemblies, it is understood that aspects of the present invention may be applied to any vehicle, machine, or component having at least one bearing. 
     While several aspects of the present invention have been described and depicted herein, alternative aspects may be effected by those skilled in the art to accomplish the same objectives. Accordingly, it is intended by the appended claims to cover all such alternative aspects as fall within the true spirit and scope of the invention.