Abstract:
A method for preloading a bearing includes releasably, threadably, and directly attaching an attaching member to a circumferential outside surface of an exposed end of a threaded shaft of an axle or spindle. A plurality of extensions extends from a frame and is moved axially toward a wheel hub assembly to apply the preload to the bearing in a distal direction past the attaching member toward the wheel hub assembly. The extensions are configured to contact at least one of a wheel hub or a bearing of the wheel hub assembly when the attaching member is directly attached to the threaded shaft. An automated adjustment mechanism is configured to move the frame and the plurality of extensions axially towards the wheel hub assembly to apply a preload to the bearing within the wheel hub assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. Pat. No. 9,618,049 issued on Nov. 4, 2017 (U.S. application Ser. No. 14/814,086, filed Jul. 30, 2015), and entitled “APPARATUS FOR PRELOADING A BEARING”, which is a continuation of U.S. Pat. No. 9,200,672 issued Dec. 1, 2015 (U.S. Ser. No. 14/305,673, filed Jun. 16, 2014), and entitled “METHOD, APPARATUS, AND NUT FOR PRELOADING A BEARING”, which is a continuation of U.S. Pat. No. 8,961,090 issued on Feb. 25, 2015 (U.S. Ser. No. 12/033,548, filed Feb. 19, 2008), and entitled “AXLE NUT”, which is a divisional Appl. of U.S. Pat. No. 7,389,579 issued on Jun. 24, 2008 (U.S. Ser. No. 11/354,513, filed Feb. 15, 2006), entitled “METHOD, APPARATUS, AND NUT FOR PRELOADING A BEARING”, the entire disclosures of which are incorporated herein by reference. 
     This application is also related to U.S. Pat. No. 8,359,733 issued Jan. 29, 2013 (U.S. Ser. No. 12/492,926 filed Jun. 26, 2009), entitled “METHODS FOR PRELOADING A BEARING”, the disclosure of which is incorporated by reference herein. 
     This application is also related to U.S. Pat. No. 7,303,367 issued Dec. 4, 2007, (U.S. Ser. No. 11/029,531, filed Jan. 5, 2005, entitled “LOCK NUT SYSTEM” the disclosure of which is incorporated by reference herein. 
     This application is also related to U.S. Pat. No. 7,625,164 issued Dec. 1, 2009 (U.S. Ser. No. 11/738,041, filed Apr. 20, 2007, entitled “LOCK NUT SYSTEM”, the disclosure of which is incorporated by reference herein. 
     This application is also related to U.S. Pat. No. 7,559,135 issued Jul. 14, 2009 (U.S. Ser. No. 11/341,948, filed on Jan. 27, 2006), entitled “METHOD AND APPARATUS FOR PRELOADING A BEARING”, the disclosure of which is incorporated by reference herein. 
     This application is also related to U.S. Pat. No. 9,200,673 issued on Dec. 1, 2005 (U.S. Ser. No. 14/305,830 filed on Jun. 16, 2014) concurrently filed herewith, entitled “LOCK NUT SYSTEM”, the disclosure of which is incorporated by reference herein. 
    
    
     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, 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. 
     One of the popular means of adjusting bearing preload by means of an applied torque is described in the literature provided by the Stemco Company, of Longview, Tex. (for example, Stemco form 571-2970) and further in instructions provided by Stemco (for example, Stemco part number 09-571-0006). These instructions are typically packaged with Stemco&#39;s axle spindle nuts. The accuracy of this and other prior art preloading methods is limited because they rely on the relationship between assembly torque and axial preload of the bearings, which will vary with variations in torsional resistance or friction of the nut against the face of the bearing, and will also vary with variations in torsional resistance or friction of the nut against the spindle thread, the nut against the bearing face, and the aforementioned lip seal present in the assembly. 
     Due to the limitations and disadvantages of these and other prior art bearing preloading methods and devices, there is a need to provide accurate and repeatable procedures and devices for providing and adjusting bearing preload. Aspects of the present invention overcome the limitations and disadvantages of the prior art and provide methods and apparatus for creating known, monitorable, uniform preload that is not subject to the inaccuracies of prior art methods and devices. Moreover, aspects of the present invention are easier to apply by a mechanic. 
     SUMMARY OF THE INVENTION 
     The present invention provides improved methods and apparatus for preloading bearings. In particular, the methods and apparatus of the present invention permit the mechanic to monitor the preload during the preloading procedure to more accurately determine the actual preload provided. One aspect of the invention is an apparatus for providing a preload to a bearing within a wheel hub assembly. The apparatus comprising a frame supporting a member to allow said frame to move relative to said member and in an axial direction, a plurality of extensions extending from said frame towards a wheel hub assembly, said extensions being configured to contact at least one of a wheel hub or a bearing of said wheel hub assembly when said member is attached to said threaded shaft, and an adjustment mechanism configured to move said frame and said plurality of extensions axially towards said wheel hub assembly to apply a preload form to a bearing within said wheel hub assembly. The plurality of extensions may be configured to contact said bearing of said wheel hub assembly. The adjustment mechanism may comprises an automated adjustment mechanism configured to automatically regulate the preload supplied to said bearing. 
     an apparatus for providing a preload on a bearing, the bearing having an inner race mounted to a shaft and an outer race mounted in a hub, the apparatus including a rod having a first end and a second end adapted to be removably mounted to the shaft; means for compressing the hub against the outer race of the bearing to provide the preload to the bearing, the means for compressing mounted to the rod; and a cylindrical frame positioned between the means for compressing the hub and the hub, the cylindrical frame having a first end adapted to receive a load from the means of compressing the hub and a second end adapted to transmit the load to the hub. In one aspect, the second end of the cylindrical frame contacts the hub. In another aspect, the second end of the cylindrical frame contacts an inner race of a bearing. In another aspect, the apparatus further comprises means for monitoring the preload on the bearing 
     Another aspect of the invention is a method for providing a preload on a bearing having an inner race mounted to a shaft and an outer race mounted in a hub, the method including mounting a rod to an end of the shaft; mounting a means for compressing the hub against the outer race of the bearing to the rod; and actuating the means for compressing the hub to compress the hub against the outer race of the bearing to provide the preload to the bearing. In one aspect, the method further comprises monitoring the preload on the bearing. 
     Another aspect of the invention is an apparatus for providing a preload to an inboard bearing having an inner race mounted to a shaft and an outer race mounted in a hub and for providing a preload to an outboard bearing having an inner race mounted to the shaft and an outer race mounted in the hub, the outboard bearing spaced from the inboard bearing, the apparatus including an outboard bearing retaining nut adapted to engage a threaded end of the shaft and contact the inner race of the outboard bearing to retain the preload on the outboard bearing; a rod having a first end and a second end adapted to be removably mounted to the shaft; a fluid-containing cylinder mounted to the rod, the cylinder having a cylinder housing mounted to the rod and a piston adapted to compress the hub against the outer race of the inboard bearing to provide the preload to the inboard bearing; an actuating nut threaded to the rod and adapted to compress the cylinder housing toward the piston; and a cylindrical frame positioned between the piston and the hub having a first end adapted to receive a load from the piston and a second end adapted to transmit the load to the hub and compress the hub against the inner race of the inboard bearing to provide the preload to the inboard bearing. In one aspect, the apparatus further comprises means for monitoring the pressure of the fluid in the fluid-containing cylinder. 
     A further aspect of the invention is an apparatus for precisely rotating a nut, the apparatus including a guide frame comprising a support ring having a first side adapted to contact a support and a second side opposite the first side; and a plurality of posts having first ends mounted to the second side of the support ring and second ends opposite the first ends; and a tool comprising a set of opposed tines adapted to engage flats on the nut; means for rotating the tines to rotate the nut; and at least two spaced stops adapted to engage at least one of the posts of the guide frame and limit the rotation of the nut to the predetermined angle defined by the two spaced stops. 
     A still further aspect of the invention is a method for precisely rotating a nut, the method including determining a desired precise rotation for the nut; providing a guide frame comprising: a support plate having a first side adapted to contact a support and a second side opposite the first side; and a plurality of spaced stops positioned on the support plate; providing a tool comprising: at least one set of opposed tines adapted to engage flats on the nut; and a plurality of spaced stops adapted to engage at least one of the spaced stops of the guide frame, the spaced stops positioned to limit the rotation of the tool to the desired precise rotation for the nut; mounting the tool to the nut wherein the plurality of tines engage flats on the nut and wherein the at least one stop on the tool engages at least one stop on the guide frame; and rotating the nut with the tool wherein at least one stop on the tool engages at least one stop on the guide frame wherein the nut is rotated the desired precise rotation. 
     A further aspect of the invention is a tool for precisely rotating a nut, the tool including: at least one set of opposed tines adapted to engage flats on the nut; means for rotating the plurality of tines to rotate the nut; at least one stop adapted to engage at least corresponding stop on a fixture mounted adjacent the nut to limit the rotation of the nut to a predetermined angle. In one aspect, the at least one stop on the tool comprises at least one of a post, pin, and recess. 
     A further aspect of the invention is an axle nut comprising a cylindrical body having a first end, a second end having a face adapted to bear against a surface, a longitudinal axis, and an outer surface engagable by a tool; a threaded through-hole directed substantially along the longitudinal axis of the cylindrical body; and at least one recess in the face of the second end of the cylindrical body, the at least one recess adapted to expose at least a portion of the surface the face bears against. In one aspect, the at least one recess comprises at least one arcuate recess, for example, a plurality of arcuate recesses equally spaced about the perimeter of the face. 
     Another aspect of the invention is an apparatus for providing a load on a bearing, the bearing having an inner race mounted to a shaft and the bearing retained on the shaft by a nut, the apparatus comprising a rod having a first end and a second end adapted to be removably mounted to the shaft; an adapter comprising a plate having a hole through which the rod passes and a plurality of extensions mounted to the plate and adapted to engage the inner race of the bearing with the nut in place; and means for providing a compressive load to the plate of the adapter whereby the load is provided to the inner race of the bearing with the nut in place. In one aspect, the plurality of extensions is pivotally mounted to the plate. In another aspect, the apparatus further comprises means for monitoring the load on the bearing. 
     A further aspect of the invention is a method for providing a load on a bearing having an inner race mounted to a shaft and the bearing retained on the shaft by a nut, the method comprising mounting a rod to an end of the shaft; without removing the nut, mounting a means for compressing the inner race of the bearing to the shaft; and actuating the means for compressing the inner race to compress the inner race to provide the load to the bearing. In one aspect, the means for compressing the inner race comprises an adapter having a plate and a plurality of extensions mounted to the plate, wherein mounting the means of compressing comprises mounting the adapter to the rod and the inner race. 
     A still further aspect of the invention is a fastener arrangement for retaining a bearing on a shaft, the bearing having an inner bearing race having an outer diameter, the fastener arrangement adapted to permit a bearing loading device to contact the inner bearing race, the fastener arrangement comprising a first threaded ring adapted to threadably mount to the shaft and engage the inner bearing race, the first threaded ring having an outer diameter less than the outer diameter of the inner bearing race and an outer surface engagable by a tool; a second ring adapted to mount to the shaft and engage the first ring and engage the shaft to prohibit relative movement between first ring and the shaft; and a third threaded ring adapted to threadably mount to the shaft and to contact the second ring, the third ring having an outer surface engagable by a tool; wherein when the first ring, second ring, and third ring are mounted to the shaft, the bearing is retained on the shaft and the inner bearing race is exposed and can be contacted by the bearing loading device. In one aspect, at least one of the first threaded ring and the third threaded ring comprises a threaded nut. 
     An even further aspect of the invention is a method for providing a load to a bearing having an inner race mounted to a threaded shaft, the inner race having an outer diameter, the method comprising threading a first threaded ring onto the threaded shaft whereby the threaded ring contacts the inner bearing race, the first threaded ring having an outer diameter less than the outer diameter of the inner; mounting a second ring to the shaft, the second ring adapted engage the first ring and engage the shaft to prohibit relative movement between first ring and the shaft; and threading a third threaded ring on to the shaft, the third threaded ring adapted to engage the second ring; and engaging the inner race with an apparatus adapted to provide the load to the inner race. In one aspect, the method further comprises monitoring the load on the inner race. In another aspect, the method further comprises, when the load on the inner race reaches about a predetermined load, tightening the first threaded ring against the inner race, for example, to maintain the predetermined load on the inner race. 
     These and other aspects, features, and advantages of this invention will become apparent from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings 
    
    
     
       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 perspective view of a wheel hub assembly having a bearing preloading apparatus according to one aspect of the invention. 
         FIG. 2  is a right side elevation view of the hub assembly shown in  FIG. 1 . 
         FIG. 3  is a right side elevation view, partially in cross section, of the assembly shown in  FIG. 1   
         FIG. 4  is a detailed view of the means for providing a preload shown in  FIG. 3  and identified by detail  4 . 
         FIG. 5  is a partial cross sectional view of another aspect of the invention for transferring a load to a bearing. 
         FIGS. 6A, 6B, and 6C  are partial axial elevation views of another aspect of the invention as viewed along the section lines  6 - 6  shown in  FIG. 4  with the addition of a typical tool according to one aspect of the invention. 
         FIG. 7  is a right side elevation view, partially in cross sectional, of another aspect of the invention. 
         FIG. 8  is perspective view of a wheel hub assembly having a bearing preloading apparatus according to another aspect of the invention. 
         FIG. 9  is a right side elevation view of the hub assembly shown in  FIG. 8 . 
         FIG. 10  is a right side elevation view, partially in cross section, of the assembly shown in  FIG. 8   
         FIG. 11  is a detailed view of the means for providing a preload shown in  FIG. 10  and identified by detail  11 . 
         FIG. 12  is perspective view of the bearing loading adapter shown in  FIG. 11 . 
         FIG. 13  is a side elevation view, partially in cross section, of the bearing loading adapted shown in  FIG. 12 . 
         FIG. 14  is top plan view of the bearing loading adapter shown in  FIG. 12 . 
         FIG. 15  is a perspective view of an axle nut according to another aspect of the invention. 
         FIG. 16  is a side elevation view, partially in cross section, of the axle nut shown in  FIG. 15 . 
         FIG. 17  is a side elevational view, partially in cross section and similar to  FIG. 11 , of an apparatus for applying or verifying a preload on a bearing according to another aspect of the invention. 
         FIG. 18  is a perspective view, partially in cross section, of a nut arrangement shown in  FIG. 17  according to another aspect of the invention. 
         FIG. 19  is an exploded perspective view the nut arrangement shown in  FIGS. 17 and 18 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is perspective view of a wheel hub assembly  10  having a bearing preloading apparatus  20  according to one aspect of the invention. In  FIG. 1 , some of a section of the hardware has been removed to reveal inner structure to facilitate disclosure of the invention.  FIG. 2  is right side elevation view of the wheel hub assembly  10  and preload apparatus  20  shown in  FIG. 1 .  FIG. 3  is a right side elevation view, partially in cross section, of the assembly shown in  FIG. 1 . For the sake of illustration, the wheel assembly that would typically be mounted to wheel hub assembly  10  is omitted. Wheel hub assembly  10  represents a typical wheel hub that may be found on any wheeled vehicle, for example, a wheel hub of truck, a front or rear axle of a tractor of a tractor-trailer, or an axle of a trailer. 
     The wheel hub assembly  10  shown in  FIG. 1  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, preloading apparatus  20  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 and 3 , typical wheel hub assembly  10  includes a wheel hub or, simply, a hub  12 , a threaded shaft, axle, or “spindle”  14 . As is typical, on spindle  14  are mounted two antifriction bearings  16  and  18  and spindle  14  includes an exposed end  13 , which is typically threaded. Spindle  14  typically includes a retaining nut  11  threaded to the exposed end  13 . Retaining nut  11  may comprise the locking nut disclosed in commonly owned copending U.S. application Ser. No. 11/029,531 filed on Jan. 5, 2005, the disclosure of which is incorporated by reference herein, or any other available retaining nut. In the conventional art, retaining nut  11  typically is used to secure a wheel (not shown) or hub assembly to a non-rotating axle  14 . However, in aspects of the present invention, retaining nut  11  may be useful in varying the preload and/or endplay of bearings  16  and  18 . Though bearings  16  and  18  are illustrated as tapered roller bearings, 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. In the following discussion and claims, bearing  16  may be referred to as the “outboard bearing” and bearing  18  may be referred to as the “inboard bearing.” 
     As shown in  FIG. 3 , 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, inboard bearing  18  includes an inner race (or cone)  19 , an outer race (or cup)  21 , a plurality of rollers  26 , and roller cage  28 . As shown in  FIG. 3 , the outer race  17  of outboard bearing  16  is positioned, for example, an interference fit, into a annular cavity  29  having a annular retaining flange  30 . Similarly, the outer race  21  of inboard bearing  18  is positioned into an annular cavity  31  having a retaining flange  32 . Also, the inner race  15  of outboard bearing  16  is positioned, for example, a sliding fit, onto the outside diameter of spindle  14  and the inner race  19  of inboard bearing  18  is positioned against a shoulder  34  of spindle  14 , which may be a sliding or interference fit to the spindle diameter. As such, any loads applied to hub  12  or spindle  14  are transferred to inboard bearing  18 . 
     According to some teachings in the art, outboard bearing  16  and inboard bearing  18  can be provided with at least some preload to enhance the performance or bearing life and the performance or life of wheel hub assembly  10 . For example, as described in the Timken Tech Tip, Volume 6, Issue 3 (copyrighted 2001) entitled “Preload in Wheel Bearings”[http://www.timken.com/products/bearings/techtips/PDFs/Vol6No3.pdf#search=‘Bearing %20Preload’],
         Slight preload [on wheel bearings] can improve bearing, seal, and tire life, but only if the entire process is in control. “In control” means that you actually know the bearing setting process will result in a consistent bearing setting range.
 
The Tech Tip continues,
   Unfortunately, neither dial indicators nor any other standard tool will tell a technician the amount of preload in a wheel end . . . . To date, there isn&#39;t anything available that will confirm that the bearing fastener is providing the correct preload setting.” [Emphasis added.]
 
In other words, one of the leading bearing suppliers in the world believes that conventional torquing methods and dial indicator methods have proven to be unsatisfactory means of providing preload and endplay. Specifically, prior art methods have been shown to provide unreliable and non-repeatable preloads and/or end play to bearings such as bearings  16  and  18 . Moreover, such experts in the field contend that “there isn&#39;t anything available” that can confirm a bearing preload. However, the preload assembly  20  according to aspects of the present invention provides such a device—a reliable, accurate, and repeatable means of providing preload and/or endplay adjustment to bearings such as bearings  16  and  18 . In addition, aspects of the invention provide means for monitoring the preload on the bearings to, for example, ensure that the desired preload is provided, in contrast to the unreliable and often inaccurate assumed preloading of the prior art.
       

     As shown in  FIGS. 1-3 , preload assembly  20  includes a rod or shaft  40  mounted for rotation within a housing or frame  42 , and a means  44  for compressing hub  12  against the outer race  21  of inboard bearing  18 , in which the means  44  for compressing is mounted to rod  40 . Means  44 , through housing  42  and hub  12 , provides a known and predetermined preload to bearing  18 . Housing  42  may be referred to as “the shoe” or “the foot” of preload assembly  20 . Rod  40  is adapted to attach to the exposed end  13  of shaft  14 , for example, by means of collar  46 , though other attachment means may be used. Means  44  may be mounted to rod  40  by means of adjustment nut  48  which may be threaded to rod  40  and provide a compressive load to means  44 . Nut  48  may be adapted to facilitate rotation of nut  48 , for example, nut  48  may include arms  50  or a hand wheel that can assist a mechanic while manually tightening or untightening nut  48 . 
     In one aspect, nut  48  may be adapted to be rotated by an automated tool, for example, a drill or stepper motor. For instance, nut  48  may be fashioned with a hex head or threads to engage an automated tool, for example, a torque motor. One such automated tool is disclosed in  FIG. 7 , discussed below. 
     Means  44  may be any means that is adapted to transfer the compressive load provided by nut  48  to hub  12  and outer bearing race  21  of bearing  18 . In one aspect, means  44  may simply comprise an extension of housing  42  whereby nut  48  contacts and compresses housing  42  against hub  12 , though, absent a means to monitor the load transmitted, such a system would not be as advantageous as other aspects of the invention. In another aspect of the invention, means  44  is not only adapted to transfer a load from but  48  to outer race  21 , but means  44  also provides a means for monitoring the compressive load transferred, for example, some means of direct or indirect indication of the load transferred to outer race  21 , that is, the preload on bearing  18 . 
     In one aspect of the invention, the indication of the compressive load transferred through means  44  may be provided mechanically, for example, by means of compression springs having a known spring constant, for example, coil springs or disc springs, and a deflection indicator, for example, a dial indicator, as is known in the art. In this aspect, the dial indicator may be mounted to detect and indicate the compression of one or more springs positioned in means  44  due to the advancement of nut  48 , and the compression load calculated from the deflection indicated and the known spring constant of the springs used. This aspect of the invention may provide a reliable and repeatable means for monitoring the preload provided to bearing  18 . 
     In another aspect of the invention, means  44  may provide an indication of the compression load transferred by nut  48  electronically, for example, by means of a load or pressure sensor, for instance, one or more strain gages or load cells positioned in means  44 . In this aspect of the invention, the load sensor may be wired to an appropriate processor and display to, for example, provide a digital readout of the compressive load to the mechanic operating preload device  20 . The transmission of signals from the sensor may also be practiced wirelessly, for example, by means of an RF signal. This aspect of the invention may also provide a reliable and repeatable means for monitoring the preload provided to bearing  18 . 
     In another aspect of the invention, means  44  may include at least one fluid, for example, a gas, such as air; or a liquid, such as, water, oil, or hydraulic fluid, the pressure of which can be detected and monitored, for example, by means of a pressure gage, pressure sensor, or a mechanical indicator. In one aspect, the fluid pressure may comprise the source of compressive load on bearing  18 . One apparatus that may be used to effect this aspect of the invention is shown in  FIG. 7 . The fluid may be retained in a cavity for example, a deformable cavity, such as a bladder or hose, for example, an air spring; or a cavity having rigid walls and at least one moveable wall, for example, as in a cylinder and piston. In one aspect, the deformable cavity or air spring may be made of molded rubber, somewhat like an inner tube, and the configuration of means  44  may be adapted accept the molded rubber when inflated and deflated. 
     When air is used as the fluid, the air may be provided by conventional “shop air” at a pressure of about 100 psig. The pressure of the fluid in the deformable cavity may be monitored by means of sensor or pressure gage, for example, a pressure gas mounted to a nozzle inserted the wall of the deformable or non-deformable cavity. In one aspect, a mechanical indicator may be activated, for example, a lever deflected when the desired fluid pressure in means  44  is reached advising the mechanic. One aspect of the invention having a means  44  having a fluid is illustrated in  FIGS. 1-3 .  FIG. 4  is a detailed view of the means  44  for providing a preload shown in  FIG. 3  and identified by detail  4 . 
     In the aspect of the invention shown in  FIG. 4 , means  44  comprises a housing  52  and a movable piston  54  mounted for axial movement in housing  52 . In this aspect of the invention, an internal cavity  56  is provided in housing  52  between the between housing  52  and piston  54 , for example, an annular cavity. Internal cavity  56  is at least partially filled, for example, substantially completely filled, with a fluid, for example, a gas, air, oil, water, and the like, that produces a hydrostatic pressure, P, when housing  52  is compressed by the advancement of nut  48  on rod  40 . Piston  54  may be provided with one or more seals  61  and  63 , for example, one or more wiper seals, to minimize or prevent the leakage of fluid from cavity  56 . Also, housing  42  may include an internal cavity  57 , which provides clearance for the displacement of piston  54  within housing  52 . In one aspect, a leakage path through housing  52  may be provided from cavity  57  to minimize or prevent buildup of fluid in cavity  57  which may interfere with the proper operation of piston  54 . Piston  54  may also be retained in housing  52  by means of a retainer or snap ring  55 . Housing  52  and piston  54  may be fabricated by machining from solid bar or plate stock, welded from bar or plate, forged, or cast. 
     As shown in  FIG. 4 , the compressive load applied by the advancement of nut  48  is transmitted to housing  52 , to the fluid in cavity  56 , to piston  54 , to cylindrical housing  42 , to hub  12 , and ultimately to the outer race  21  of bearing  18 . Thus, according to aspects of the invention, the hydrostatic pressure induced in the fluid in the cavity  56  by the advancement of nut  48  provides a direct indication of the preload on bearing  18 . 
     In one aspect, the pressure P in cavity  56  may be monitored, for example, continuously, by means of a pressure sensor or pressure gage. As shown in  FIG. 4 , pressure P in cavity  56  may be monitored by one or more pressure indicators  60  which is adapted to detect the pressure P in cavity  56  via a passage  58  in housing  52 . Pressure indicator  60  may be an analog or digital pressure gage. Pressure indicator  60  may be a pressure sensor adapted to detect the pressure P in cavity  56  and forward an electrical signal corresponding to the pressure P to a processor or controller adapted to display the pressure, record the pressure, energize a circuit in response to the pressure, and/or provide a signal to the mechanic, for example, a tone or bell that a pressure corresponding to a desired preload on bearing  18  has been achieved. 
     According to aspects of the invention, the pressure P and the corresponding geometry (for example, the inside and outside diameters of cavity  56 ) may be used by a mechanic to determine the preload on bearing  18 . For example, for a desired preload L (in pounds, Newtons) and a given area of piston  54  exposed to pressure P (in square inches, square meters), the desired pressure of the fluid in cavity  56  may be determined by the equation P=L/A, for example, in psi or Pascal. For example, when a preload of 6000 pounds lbs. (L) is desired to provide an compressive deflection of 0.003 inches on bearing  18 , and the outside diameter of annular cavity  56  is 3 inches and the inside diameter of cavity  56  is 1 inch, the target pressure, P, is calculated by
 
 P=L/A =(6000 lbs)/((π/4)(3 2 −1 2 ))=6000 lbs/(2π in 2 )=955 psig.  Equation 1
 
This pressure may now be used as the target pressure in cavity  56  and detected by pressure indicator  60  to provide the desired 0.003-inch compressive deflection for bearing  18 . According to aspects of the present invention, the pressure of the fluid in cavity  56  may be monitored to determine when the desired pressure P is achieved wherein the desired preload is provided to bearing  18 .
 
     In one aspect of the invention, one or more antifriction bearings may be provided for means  44 . For example, in one aspect, one antifriction bearing  62  may be positioned between nut  48  and housing  52  and another antifriction bearing  64  may be located between piston  54  and housing  42 . Bearings  62  and  64  may be roller-type bearings or reduced friction material bearings. For example, bearings  62  and  64  may comprise needle bearings or a material containing at least some PTFE, for example, DuPont&#39;s Teflon® PTFE or Saint-Gobain&#39;s Rulon® PTFE, or their equivalent. Bearings  62  and  64  may be retained by one or more retaining devices  65  and  66 , for example, one or more snap rings. 
     As shown in  FIGS. 1-4 , housing or frame  42  is adapted to transmit the compressive load provided by the advancement of nut  48  to hub  12 . In one aspect, housing  42  may be any structure adapted to transmit this load while not interfering with the movement and operation of nut  11  and collar  46 . In one aspect, housing or frame  42  comprises a cylindrical housing and may include at least one opening to permit access to nut  11  and collar  46 , for example, for servicing by a mechanic. In the aspect of the invention shown in  FIGS. 1-4 , housing  42  comprises an upper flange  70  adapted to receive the force transmitted by means  44 , a lower plate or ring  72  adapted to transmit a load to hub  12 , and a plurality of posts  74  spaced about flange  70  and ring  72  to transmit a load between flange  70  and ring  72 . In one aspect, flange  70  may be any plate adapted to engage piston  54  and posts  74 . Ring  72  may be any annular plate adapted to receive a load from posts  74 . In one aspect, the interface between ring  72  and hub  12  may be provided with an antifriction bearing, for example, a needle bearing or a PTFE-containing material, as described above with respect to bearings  62  and  64 . Posts  74  may comprise cylindrical posts, for example, circular cylindrical or rectangular cylindrical, extending from flange  70  to ring  72 . When housing  42  is provided as a cylindrical body, posts  74  may comprise sections of the cylindrical body remaining when openings are introduced to the cylindrical body. In one aspect, ring  72  may be omitted wherein posts  74  contact the surface of hub  12  directly. When ring  72  is omitted, posts  74  may be provided with means to reduce friction between the ends of post  74  and hub  12 . For example, the ends of posts  74  may be adapted to provide antifriction bearings or rollers or reduced friction materials, such as, a PTFE-containing material. Housing  42  may be machined from stock shapes, assembled by means of fasteners, fabricated by welding, forging, casting, or a combination thereof. 
     In one aspect of the invention, housing or frame  42  may be adapted to contact the inner race of outboard bearing  16 , that is, instead of contacting hub  12 , and transmit a preload to bearing  18 . For example, with reference to  FIG. 3 , in some wheel hub assemblies  10 , the diameter of retaining nut  11  may be smaller than the diameter of inner race  15  of outboard bearing  16  whereby access to inner race  15  is not obstructed by nut  11 . (In  FIG. 3 , the diameter of nut  11  is greater than the diameter of inner race  15  and thus inner race  15  cannot be directly accessed.) Under this condition, housing  42  may be sized or adapted to contact the inner race  15  whereby the compression load providing by advancing nut  48  may be transmitted to outboard bearing  16  via inner race  15  and from bearing  16  to hub  12  and to outer race  21  of inboard bearing  18 . That is, according to one aspect of the invention, a preload may be transferred to inboard bearing  18  by means of compression on the face of hub  12  or on the inner race  15  of bearing  16 . In one aspect, compressive deflection is imposed on both of bearings  16  and  18 . 
     According to aspects of the invention, the compressive load transmitted to the bearing  18  is transmitted through hub  12 . Therefore, at least some of the compressive deflection provided by the present invention will comprise deflection of hub  12 . Therefore, in some aspects of the present invention, when determining the compressive deflection of bearing  18  under preload, the deflection of hub  12  may also be considered. For example, a dial indicator mounted on, for example, housing  42  to detect the compression deflection of bearing  18  may also detect the deflection of hub  12 , depending upon the magnitude of the load and the stiffness of hub  12 . In one aspect of the invention, when deflection of hub  12  may effect the compressive deflection, the deflection measured can be normalized to or compensated for the hub stiffness, that is, hubs of varying stiffness may have varying deflections though the corresponding compressive deflection of bearing  18  will be substantially the same. However, any deflection of hub  12  will likely have little effect upon the compressive force transmitted to bearing  18 . 
     It will be apparent to those of skill in the art that the design of housing  42  may be modified whereby housing  42  may contact inner race  15 . For example, flange  70  and ring  72  may be reduced in diameter whereby ring  72  may contact inner race  15 . This alternative aspect of the invention is shown  FIG. 5 .  FIG. 5  illustrates a partial cross sectional view of an alternate design of housing  42  for transferring the compressive load from means  44  to bearing  18  via inner race  15  of outboard bearing  16 . In this aspect, the size of nut  111  on spindle  14  is smaller than nut  11  shown earlier, whereby an inner race  15  is exposed and can be contacted by a modified housing  142 . Inner race  15 , bearing  16 , and hub  12  are shown in  FIG. 5  for reference. In this aspect of the invention, the diameter of upper flange  70  is reduced to the diameter of upper flange  170  shown in  FIG. 5 , the diameter of ring  72  is reduced to the diameter of ring  172  shown in  FIG. 5 , and posts  74  are replaced with posts  174 . As a result, the compressive load can be transferred to inner race  15  of bearing  16 . In another alternative design of housing  42 , posts  74  may be angled or tapered inward toward the centerline of the assembly and the diameter of ring  72  reduced accordingly whereby ring  72  may contact inner race  15 . Other modifications to housing  42  to achieve this contact with inner race  15  will be apparent to those of skill in the art. 
     As discussed previously, rod  40  is adapted to attach to the exposed end  13  of spindle  14 . Though this may be effected by many conventional means, including welding and mechanical fasteners, in the aspect of the invention shown in  FIGS. 1-4 , rod  40  is attached to end  13  of spindle  14  by means of a collar  46 . In the aspect shown, collar  46  is mounted to rod  40  by means of internal threads  47  in collar  46  that thread onto external threads  49  on rod  40 . Collar  46  also includes a second set of internal threads  45  that engage external threads  51  on spindle  14 . In one aspect, only 2 or 3 external threads  51  need be engaged by collar  46 . According to one aspect, multiple collars  46  having varying diameters may be provided to accommodate varying diameters of spindle  14 . Each of these collars  46  may be adapted to engage external threads  49  on rod  40 . In one aspect, the movement of rod  40  may be limited by a collar or ring  76 , for example, a snap ring, mounted on rod  40 . 
     Rod  40 , housing  42 , collar  46 , nut  48 , arms  50 , housing  52 , piston  54 , and housing  42  may be fabricated from any conventional structural metal, for example, iron, steel, stainless steel, aluminum, titanium, nickel, magnesium, brass, or bronze, among others. 
     In one aspect of the invention, apparatus  20  may be used to apply and monitor a preload to inboard bearing  18 . In a typical procedure, the wheel (not shown) mounted to hub assembly  10 , for example, mounted to studs on hub  10 , as exemplified by stud  100  in  FIG. 3 . As shown in  FIG. 4 , apparatus  20  may be prepared by assembly and filling cavity  56  with a fluid, for example, oil, through one of the access ports  58  that is not occupied by pressure indicator  60 . Nut  11  may be loosened or hand tightened prior to mounting apparatus  20 , though any light load on nut  11  will typically be relieved with application of tension to spindle  14  by means of rod  40 . Apparatus  20  is then mounted to hub assembly  10  by attaching rod  40  to spindle  14  by means of collar  46 . As a result, housing  42  is brought into contact with hub  12 . Assuming a desired compressive deflection for bearing  18 , for example, 0.003 inches, and a corresponding preload, L, the desired target pressure in cavity  56  can be calculated by Equation 1. 
     The loading of bearing  18  is initiated by advancing, that, is tightening, nut  48 , against housing  52  via bearing  62 , for example, by means of arms  50 . The build up of pressure in cavity  56  as indicated by pressure indicator  60  may be monitored by the mechanic. The tightening of nut  48  continues until the target pressure is achieved. The hub assembly may be rotated at least once to provide proper seating of the rollers in bearing  18 . Once the target pressure is achieved in cavity  56 , and the desire preload is applied to bearing  18 , nut  11  may be tightened against inner race  15  to maintain the preload after apparatus  20  is removed. The desired tightening of nut  11  may be determined by monitoring the pressure in cavity  56  on pressure indicator  60 . For example, should the pressure begin to decrease during tightening of nut  11 , the nut may be tightened too much. The reduction in pressure means that the preload on bearing  18  is being relieved and transferred to nut  11  by the tightening of nut  11 . In one aspect of the invention the tightening of nut  11  can proceed until a decrease in pressure is observed. At that point, the tightening of nut  11  may be stopped, or nut  11  may be untightened slightly, for example, about ⅛ turn. Again, the hub assembly may be rotated at least once to provide proper seating of the rollers in bearings  16  and  18 . Upon completion of the preloading, apparatus  20  may be removed from wheel hub assembly  10  and, for example, the wheel remounted. Variations on this procedure while not deviating from the desired results may be apparent to those of skill in the art. 
     In another aspect of the invention, apparatus  20  may be used to adjust the endplay of a bearing. For example, in some bearing installations it is desirable to create an endplay for a bearing assembly, for example, an endplay of between about 0.001 inches and about 0.003 inches. For instance, see undated instructions entitled “ProTorq® Advanced Axle Spindle Nuts” flyer by Stemco, of Longview, Tex. Although procedures such as these which apply specified torques to the nut are intended to provide the specified endplay in the bearing, the inventor has found that the actual endplay provided by such procedures may vary dramatically. For example, the actual axial deflection of the bearings that results from the applied torque may vary due to, among other things, differences in torque resistance (or friction) between mating surface, for example, between nut  11  and the axle threads  15  and between the face of nut  11  and the surface of bearing  16 , among others. Further errors may be introduced by such torque-based procedures by misalignment of the bearing rollers that may occur in between steps in the specified procedures. Therefore, there is a need in the art to provide an accurate and repeatable means of providing bearing endplay. One aspect of the invention addresses this need. 
     Aspects of the present invention eliminate the inaccuracies that are inherent in prior art endplay adjustment procedures and can be used to provide accurate end play settings of as fine as 0.001 inches and 0.002 inches. With reference to the cross section shown in  FIG. 3 , one method of providing accurate endplay adjustment includes the following steps. Starting with a greased and assembled wheel end assembly  10  (this procedure may be practiced with or without the wheels present), nut  11  is unloosened or installed and only fastened hand tight. The apparatus  20  shown in  FIG. 1-4  is then mounted to the wheel hub assembly  10 . Specifically, rod  40  having means  44 , which comprises a fluid-containing housing  52 , is attached to axle  14  by means of collar  46 , and housing  42  is mounted to hub  12 . In this aspect of the invention, the fluid in housing  52  is assumed to be hydraulic fluid. According to this procedure, nut  48  is rotated and advanced, for example, by means of arms  50  to produce a target hydraulic fluid pressure of, for example, 1000 psig, in cavity  56  as indicated by pressure indicator  60 , for example, an analog pressure gage. The target pressure is typically predetermined by Equation 1 and the desired compressive deflection or endplay desired in bearing  18 . The target pressure will vary depending upon the size and type of bearings used and the size of cavity  56 , among other things. 
     The wheel hub assembly  10  is then rotated about spindle  14  at least one complete revolution, typically, at least three complete revolutions, to seat the rollers in inboard bearing  18 . (See Timken Tech Tip Volume 1, Number 6 entitled “Why oscillate or rotate a bearing” http://www.Timken.com/products/bearings/techtips/tip6.asp, the disclosure of which is incorporated by reference herein.) The pressure indicated by the pressure indicator  60  (that is, about 1000 psig) may vary as rollers  26  of inboard bearing  18  are seated by the rotation. If the pressure in cavity  56  deviates from the desired target pressure, the pressure in cavity  56  may be re-established by rotating nut  48 , for example, by means of arms  50 . The rotation of wheel assembly  10  about spindle  14  and the repressurization step may be repeated until rollers  26  of inboard bearing  18  are properly seated and the pressure indicted by pressure indicator  60  stabilizes to about the target pressure. It is understood that there may be slight variation in the pressure in cavity  56  due to slight misalignments (that is, the out of “squareness”) of the installed bearing, among other things. The rollers  26  of inboard bearing  18  are then substantially seated in inner race  19 . 
     Next, with the inboard bearing  18  properly seated by the above procedure, the endplay in outboard bearing  16  may be adjusted. While the target pressure (again, for example, about 1000 psig) is maintained in housing  52 , nut  11  is rotated and tightened, for example, with a hand held wrench, on spindle  14 , for example, slowly. During or after the tightening of nut  11 , wheel assembly  10  is rotated about spindle  14  whereby rollers  22  of outboard bearing  16  are seated in inner race  15 . The nut  11  is continued to be tightened until the pressure indicted by pressure indicator  60  just begins to drop. This drop in pressure indicates that the preload on inboard bearing  18  is being relieved by the compression of nut  11  against inner race  15  of outboard bearing  16 . Nut  11  is then loosened slightly to so that the target pressure is regained, and thus the preload on inboard bearing  18  is reestablished, that is, typically, without retightening nut  48 . This condition of adjustment, where the desired preload is established in the inboard bearing  18  and the compression of nut  11  on inner race  15  is such that any further tightening will unload the preload on inboard bearing  18 , according to one aspect of the invention, is referred to as “the load reference point.” Practicing aspects of the present invention, this load reference point can be fairly easily identified by feel by a mechanic. According to the invention, at this load reference point, the rollers in both outboard bearing  16  and inboard bearing  18  are properly seated and desired preload (that is, due to the 1000 psig pressure in housing  52 ) is applied to outer race  21  of inboard bearing  18 . 
     According to aspects of the invention, a method and an apparatus are provided by which the mechanic can accurately determine the load reference point for a bearing assembly. Aspects of the present invention are not prone to the variability of the preload due to the unknown and unpredictable frictional forces between mating surfaces, regardless of what the desired bearing preload and/or endplay setting. According to aspects of the invention, after establishing the neutral point position, the mechanic may relatively easily provide the desired adjustment of nut  11  that accurately achieves the desired bearing preload and/or endplay setting. 
     As is known in the art, a known preload, for example, the 6000 pounds in the example above, results in a known value of axial compression of a bearing, for example, an axial compression of 0.004 inches. According to aspects of the invention, in the load reference point position, where both bearings are correctly aligned and at zero preload on nut  11 , the preload on inboard bearing  18  will be captured by or transferred to nut  11  if nut  11  is loosened, for example, precisely 0.004″ from the load reference point. Therefore, according to aspects of the invention, the preload may be varied or the endplay provided by precisely controlling the rotation of nut  11 . One aspect of the present invention provides a method and apparatus for controlling the rotation of nut  11  to provide a desired preload or endplay. 
     According to one aspect of the invention, a method and an apparatus is provided of employing a calibrated wrench that can be used to accurately control the rotation of nut  11  to provide a desired preload or endplay. This method and apparatus are illustrated in  FIGS. 6A, 6B, and 6C .  FIGS. 6A, 6B, and 6C  are partial axial elevation views of the apparatus  20  as viewed along the section lines  6 - 6  shown in  FIG. 4  with the addition of a wrench  90 . For ease of illustration,  FIGS. 6A, 6B, and 6C  only illustrate the portion of housing or frame  42 , specifically ring  72  and posts  74 . These figures also illustrate the end of shaft  14  and nut  11  mounted on shaft  14 . 
     According to one aspect of invention, wrench  90  includes a handle  89  and two opposing tines  92  spaced to engage the opposite flats on nut  11 . Wrench  90  also includes at least one recess  94  positioned between tines  92 . Recess  94  includes two opposing end surfaces  91 ,  93  adapted to contact a post  74  and function as stops to the movement of wrench  90 . In one aspect, stops  91 ,  93  may be provided by one or more projections or bosses between tines  92  instead of one or more recesses  94 . In another aspect, the stopping surfaces may be provided by the closed ends of one or more slots  95  (shown in phantom) in ring  72  that are adapted to receive one or more pins  97  (also shown in phantom) projecting from beneath wrench  90 . The one or more slots  95  may vary in length to correspond to one or more angular rotations. Other adaptations of wrench  90  and/or ring  72  and posts  74  may be provided to provide the desired limitations in the rotation of nut  11 . Wrench  90  may have a thickness ranging from about 0.50 inches to about 1 inch or more. 
     As shown in  FIG. 6A , recess  94  may have a common centerline with handle  89 ; however, recess  94  may be located anywhere between tines  92 . In one aspect, a plurality of recesses  94 , for example, 3 or more recesses  94 , may be provided in wrench  90 . According to one aspect of the invention, the arc length separating the opposing ends  91 ,  93  of recess  94  is provided to limit the rotation of wrench  90  when wrench  90  is used to rotate nut  11  to provide the desired preload or end play. This aspect of the invention is more clearly illustrated by describing one procedure that may be used as shown in the sequence of steps illustrated by  FIGS. 6A, 6B , and,  6 C. 
     In this example, the size of the recess  94  in handle  90 , that is, the arc length between the ends  91 ,  93  of recess  94 , is provided whereby the rotation of wrench  90  provides a predetermined angular displacement, α. (As will be discussed below, this angular displacement, α, may be determined from the desired preload or endplay and the pitch of the threads on spindle  14 .) As shown in  FIG. 6A , wrench  90  may be mounted to nut  11  whereby tines  92  engage opposing flats of nut  11  and recess  94  accepts one of the posts  74  of housing  42 . As shown in  FIG. 6B , the engaged wrench  90  and nut  11  are held fixed by holding handle  89  and hub  12  is carefully rotated in a clockwise direction as indicated by arrow  96  until one end  91  of recess  94  contacts a post  74 . This contacting of end  91  of recess  94  upon post  74  establishes the base position for this angular adjustment of nut  11 . 
     Now, as shown in  FIG. 6C , hub  12  is fixed from further rotation, wrench  90  is rotated in a counter-clockwise direction—as indicated by arrow  98 —whereby the opposite end  93  of recess  94  contacts post  74 , and thus the rotation of nut  11  is limited to the arcuate spacing between the ends  91 ,  93  of recess  94 . Since the wheel hub  12  is typically substantially more massive than wrench  90  and nut  11 , hub  12  may simply be retained by hand, or other means, while rotating wrench  90  and nut  111 . However, due to the relative inertia of hub  12 , it may not be necessary for the mechanic to restrain hub  12  while rotating wrench  90  and nut  11 , while ensuring that rotation of the wrench is stopped when end  93  contacts post  74 . 
     It will be apparent to those of skill in the art that the desired angular rotation a of nut  11  is not the arcuate length between ends  91  and  93  of recess  94 , but, due to the diameter of posts  74 , the desired angular rotation a corresponds to the arcuate length between the center of posts  74  before and after rotation. 
     One example of the use of the method and apparatus described with respect to  FIGS. 6A, 6B, and 6C , is illustrated by the following example. This example assumes that the wheel hub assembly  10  has been adjusted whereby a compression of bearing  18  has been established of, for example, 0.004 inches, and bearings  16  and  18  are in their “load reference point.” It is also assumed that the desired endplay of bearing supports  16  and  18  is 0.001 inches and the threads on nut  11  and shaft  14  have a pitch of 12 threads per inch (that is, 1/12 inches per revolution), which is a common pitch for truck axles. The total required displacement of nut  11  to overcome the preload compression and obtain the desired endplay is 0.004+0.001=0.005 inches. For a 12 pitch thread, the required rotation of nut  11  is (0.005 inches)/( 1/12 inches/revolution)=0.060 revolutions of nut  11  to provide the desired endplay, which corresponds to (0.060 revolutions)×(360 degrees/revolution)=21.6 degrees. For a typical spindle thread pitch of 12 threads per inch, an accuracy of 0.001 inches relates to more that four degrees of rotation of nut  11  or wrench  90 , and that relates to an excursion of more than an eighth of an inch at the radial distance where post  74  is located. Therefore, by fabricating the recess  94  of handle  90  whereby angle α is, for example, 21.6 degrees, wrench  90  can be used in the procedure described above to provide the 0.001 inches of endplay desired in this example. Other examples of the use of wrench  90  will be apparent to those of skill in the art. 
       FIG. 7  illustrates a right elevation view, partially in cross section, of another arrangement  110  according to another aspect of the invention. In this aspect, fluid pressure in means  44  may provide the compressive load to bearing  18 . In this aspect, of the invention, instead of the compressive force provided by the advancing of a nut, such as nut  48  in  FIG. 3 , the compressive force provided by nut  48  may be supplemented by or replaced by the fluid pressure force provided to means  44 , for example, the fluid pressure provided to cavity  56  in housing  52  having piston  54 . In this aspect, the fluid pressure may be provided by conduit or hose  200 . Hose  200  may supply fluid, for example, hydraulic fluid, from a pressurized supply, for example, a pump. The fluid supplied to hose  200  may vary from 500 to 3000 psig. In one aspect, the fluid pressure provided through hose  200  may be the only supply of compressive force to bearing. In this aspect shown in  FIG. 7 , rod  40 , shown in  FIG. 3 , is replaced by rod  140 . Similar to rod  40 , rod  140  engages spindle  14  as described in other aspects of the invention. However, contrary to rod  40 , rod  140  includes a knob  145  that restrains means  44 , for example, through an antifriction bearing. Knob  145  may be knurled or include a hand wheel or one or more arms  50  similar to nut  48 . 
     The aspect of the invention shown in  FIG. 7  may be used to automatically regulate the compressive load on bearing  18 , for example, by regulating the pressure introduced to means  44  through hose  200 . In one aspect, the invention may include an automatic controller, for example, a PID controller, personal computer, or PLC controller adapted to regulate the pressure in hose  200 . For example, the predetermined preload or endplay and the parameters of the bearing being loaded may be entered into the controller and, after mounting rod  140 , housing  42  and means  44  to hub  12 , the controller may automatically ramp up the fluid pressure to provide the desired preload or to verify an existing preload. The aspect of the invention shown in  FIG. 7  may be suitable for production line applications, among others. 
     In one aspect, the fluid provided by hose  200  may be provided by pressure increasing device, for example, a pressure intensifier, that is, a device that converts one pressure to a higher pressure. For example, the pressure-increasing device may be provided with a pressure supply of, for example, 100 psig (for instance, shop air) and increased to, for example, 2000 psig hydraulic fluid, which is then supplied to hose  200 . Other sources of high-pressure fluid may be provided according to aspects of the invention. 
     It will also be understood that due to the variations in angle α that may be desired, for different bearings, different spindle pitches, and different endplays and preloads, among other things, many different wrenches  90  having recesses  94  of varying width may be provided. In one aspect of the invention, a plurality of recesses  94  of varying width or angle α may be provided in handle  90 . In another aspect of the invention, recess  94  in handle  90  may be adjustable by the operator, for example, the position of at least one end of recess  94  may be variable to provide for varying angles α. In another aspect, the width between tines  92  if wrench  90  may be variable to permit use of wrench  90  on nuts  11  of varying diameter. According to aspects of the invention, an adjustable wrench may be provided that can be calibrated for a desired preload and/or endplay values for a specific spindle and hub design. 
     Aspects of the invention may also be used to evaluate the preload or endplay on an existing bearing or bearing assembly. For example, an existing truck hub assembly may be evaluated for its existing preload and compared to the desired preload, and, if necessary, adjusted accordingly. First, the truck may be jacked up, if needed. (The hub may be allowed to cool, if necessary). Apparatus  20  may then be mounted to hub  12  and spindle  14  (with reference to  FIG. 4 ) and the means  44  actuated to introduce tension to spindle  14  and compression to hub  12 . (The wheel may be mounted to removed.) The means  44  may be regulated to, for example, vary the fluid pressure, to gradually increase the preload on bearing  18 . While the load is increased, a mechanic can repeatedly check the load on or the “tightness” of nut  11 . When nut  11  begins to loosen, the existing preload on bearing  18  has been met or exceeded. A comparison of the actual preload indicated by means  44 , for example, the fluid pressure, with the desired preload can then be made. Any adjustments to the preload, either higher or lower, can be made according to the procedures described above. 
     While one aspect of the present invention, in which the inboard bearing  18  is loaded through hub  12 , can provide a useful indication of the preload present in bearings  16  and  18 , for example, by assuming a predetermined distribution of load between bearing  16  and  18  and distributing the preload measured on bearing  18  accordingly, other aspects of the invention can provide an more accurate indication of the preload on bearings  16  and  18 . For example, the aspect of the invention illustrated and described with respect to  FIG. 5  above and the aspect of the invention illustrated and described with respect to  FIGS. 8 through 19  below, in which the loading of bearings  16  and  18  transmitted via bearing  16 . 
       FIG. 8  is perspective view of a wheel hub assembly  201  having a bearing preloading assembly  202  according to another aspect of the invention. As will be discussed more fully below, in contrast to the apparatus discussed above with respect to  FIGS. 1-5 , preloading assembly  202  introduces a load to the outboard bearing  16 , instead of to hub  12 . According to this aspect of the invention, contact with the inner race of the outboard bearing is accomplished by means of specially designed axle nut or an axle nut arrangement. Unlike prior art methods and devices, aspects of the invention permit mechanics to apply or confirm a preload to outboard bearing  16 . 
       FIG. 9  is a right side elevation view of the hub assembly  201  shown in  FIG. 8  and  FIG. 10  is a right side elevation view, partially in cross section, of the assembly shown in  FIG. 8 .  FIG. 11  is a detailed view of the means for providing a preload shown in  FIG. 10  and identified by detail  11 .  FIGS. 8-11  are views similar to those shown in  FIGS. 1-3  and include many of the structures shown in  FIGS. 1-3 , which are identified with the same reference numbers that appear in  FIGS. 1-3 . These structures may typically comprise the same structures having the same properties as those discussed above with respect to  FIGS. 1-5 . For example, hub assembly  201  in  FIGS. 8-11  includes a hub  12 , a threaded shaft, axle, or “spindle”  14 , an outboard antifriction bearing  16 , an inboard antifriction bearing  18 . As shown in  FIG. 10 , outboard bearing  16  includes an inner race (or cone)  15  and an outer race (or cup)  17 , and inboard bearing  18  includes an inner race (or cone)  19  and an outer race (or cup)  21 . 
     As also shown in  FIGS. 8-11 , wheel hub assembly  201  includes preload assembly  202  that, similar to preload assembly  20  shown in  FIGS. 1-5 , includes a rod or shaft  40  mounted to spindle  14  by means of collar  46 , and a means  244  for providing a compressive load to bearing  16 . Again similar to the aspects shown in  FIGS. 1-5 , means  244  of preload assembly  202  shown in  FIGS. 8-11  includes a nut  48  threaded to shaft  40 . Nut  48  may include arms  50  or a hand wheel to assist the operator in rotating nut  48 . Means  244  of preload assembly  202 , similar to means  44  discussed above with respect to  FIGS. 1-5 , may provide a compressive load to bearing  16  or means  44  may be any means that is adapted to transfer the compressive load provided by nut  248  to the inner race  15  of bearing  16 . In one aspect, means  244  provides a means for monitoring the compressive load transferred, for example, some form of direct or indirect indication of the load transferred to inner race  15 , as described above with respect to means  44 , for example, by means of compression springs, electronically, or by means of a fluid pressure sensor, such as pressure gage  60 . 
     According the aspect of the invention shown in  FIGS. 8-11 , the compressive load of nut  48  and/or means  244  is transmitted to bearing  16 , and to bearing  18 , by means of loading adapter  210 . In one aspect, loading adapter  210  works in conjunction with modified axle nut  220  to provide a load to inner race  15  of outboard bearing  16 . As described above, for example, with respect to  FIGS. 4 and 5 , conventional axle nuts, for example, axle nut  11  in  FIG. 5 , are typically larger in diameter than inner race  15  of bearing  16  whereby no direct physical contact can be made with race  15  to, for example, apply a load. Under some conditions, for example, as shown in  FIG. 5 , axle nut  11  may be smaller in diameter than inner race  15  where inner race  15  may be directly contacted, for example, by housing  142 , to provide a load. In the aspect of the invention shown in  FIGS. 8-11 , a specially designed axle nut  220  having a recess that exposes the surface of inner race  15  and permits contact by for example, loading adapter  210 . According to aspects of the invention, loading adapter  210  transmits the compressive load from nut  48  and/or means  244  to inner race  15  of bearing  16 , and thus to bearing  18 . In one aspect, where race  15  is exposed, load adapter  210  may be used with a conventional axle nut, for example, axle nut  11  in  FIG. 3 . However, when inner race  15  would be concealed by a conventional axle nut, modified axle nut  220  may be used according to aspects of the invention. 
     In contrast to other aspects of the invention, for example, those illustrated in  FIGS. 4 and 5 , the aspect of the invention shown in  FIGS. 8-11  may provide a more accurate and reproducible indication of an existing or desired preload on bearings  16  and  18 . For example, since the load applied, for example, via means  244 , is directed to bearing  16  and from bearing  16  to bearing  18 , the load monitored and indicated by means  244  is thus a more accurate indicator of the combined preload on bearings  16  and  18 , for instance, no load bearing relationship need be assumed regarding the relative preloads on bearing  16  and  18 . 
       FIG. 12  is perspective view of the bearing loading adapter  210  shown in  FIG. 11 .  FIG. 13  is a side elevation view of the bearing loading adapter  210  shown in  FIG. 12  and  FIG. 14  is top plan view of bearing loading adapter  210  shown in  FIG. 12 . As shown, adapter  210  includes a plate  211  and at least two extensions, fingers, or arms  212 ,  213  from plate  211 . In this aspect of the invention, extensions  212  and  213  are adapted to transmit the load applied to plate  211 , for example, by the compression of nut  48 , to the bearing  16 . As shown in  FIGS. 12-13 , plate  211  typically includes a through hole or bore  214  that is adapted to receive rod  40 , as shown in  FIG. 11 . Plate  211  may also include a raised boss  215  adapted to contact means  244  for example, adapted to contact piston  54  or bearing  64  (see  FIG. 4 ). In one aspect, extensions  212  and  213  may be moveable or deflectable to facilitate assembly of adapter  210  into engagement with bearing  16 . For example, extensions  212  and  213  may include any interface with plate  211  or modification to extensions  212  and  213  that permits extensions  212  and  213  to deflect to avoid interference with nut  11  or nut  220 . As shown in  FIGS. 12-14 , in one aspect, extensions  212  and  213  may be pivotally mounted to plate  211 . Plate  211  may include a pair of lugs or projections  216  having through holes  217  and extensions  212 ,  213  may include recesses  218  adapted to receive projections  216  and extensions  212 ,  213  may include through holes  219 . Pins  222  may be provided in holes  219  in extensions  212 ,  213  that engage holes  217  in projections  216  whereby extensions  212 ,  213  may rotate about pins  222  as indicated by double arrows  224  in  FIG. 13 . 
     Arms or extensions  212 ,  213  may include projections  225 ,  226 , respectively, for example, arcuate projections adapted to engage the arcuate shape of inner race  15  of bearing  16 . Arcuate projections  225 ,  226  may be radiused to provide the same curvature of inner race  15 , for example, a radius of between about 1¼ inches and about 3 inches. Projections  225 ,  226  may include shoulders  227 ,  228 , respectively, to assist in engaging race  15 . In one aspect, since pins  222  (which transmit the load from plate  211  to extensions  212 ,  213 ) may be located at a greater radial distance from the center of shaft  14  than the radial distance to the point of contact on inner race  15  (see  FIG. 11 ), shoulders  227 ,  228  may be provided to minimize or prevent contact of projections  225 ,  226  with nut  220 . This aspect of the invention may ensure that the compressive load applied by means  244  is transmitted to race  15  and not borne by nut  220 . Minimizing or preventing contact between extensions  212 ,  213  and nut  220  also permits nut  220  to be freely rotated without contact with extensions  212 ,  213 . 
     Although only two extensions  212 ,  213  are illustrated in  FIGS. 12-14 , according to one aspect of the invention, two or more extensions  212 ,  213  may be mounted to plate  211 . For example, three or more extension  212 ,  213  may be provided, for example, uniformly spaced about plate  211 . In one aspect, plate  211  may be a circular plate having two or more extensions  212 ,  213 . In one aspect of the invention, extensions  212 ,  213  may include spring-loaded mountings to plate  211  whereby extensions  212 ,  213  are biased into a position of engagement with race  215 . Adapter  210  and its components may be fabricated from any conventional structural metal, for example, iron, steel, stainless steel, aluminum, titanium, nickel, magnesium, brass, or bronze, among others. 
       FIG. 15  is a perspective view of an axle nut  220  according to another aspect of the invention.  FIG. 16  is a side elevation view, partially in cross section, of axle nut  220  shown in  FIG. 15 . As shown in  FIGS. 15 and 16 , nut  220  includes a cylindrical body  240  having a first end  241  and a second end  242  and a longitudinal axis  246 . Cylindrical body  240  may be a circular cylindrical body or a non-circular cylindrical body, for example, a polygonal cylindrical body, such as body having a triangular, square, pentagonal, hexagonal, or octagonal cross section, among others, having a plurality of flat sections, that is, “flats.” 
     Second end  242  includes a face  248  adapted to contact the face of inner race  15  (see  FIG. 11 ). Body  240  includes a threaded through hole or bore  250  directed substantially along the longitudinal axis  246  of body  240 . The threads of through hole  250  may comprise any conventional UN, UNC, UNF, UNJ, Acme, or other conventional thread. In one aspect, of the invention where nut  220  is used for a conventional truck axle, threaded through hole  250  may have 12 to 18 threads per inch UN threads. 
     According to aspects of the present invention, second end  242  of body  240  may include at least one recess  252  in face  248 . As described above, recess  252  in the face  248  exposes at least a portion of the mating surface against which nut  220  bears whereby a compressive load may be applied, for example, to apply a compressive load to the face of inner race  15  of bearing  16  (see  FIG. 11 ). As described above, this exposure of the face of race  15  permits a mechanic to apply and/or verify a preload on bearing  16 , for example, to verify a preferred “3 thousandths” preload discussed previously. 
     In the aspect of the invention shown in  FIGS. 15 and 16 , recess  252  is shown as a single annular or arcuate recess whereby a raised boss  254  is provided on second end  242 . However, according to one aspect of the invention, the at least one recess  252  may comprises one or more cavities in surface  248 , for example, one or more cavities evenly distributed about the perimeter of the second end  242 . For instance, in one aspect of the invention, recess  252  may comprise a plurality of arcuate recesses evenly distributed about the perimeter of second end  242  and adapted to expose the surface of the mating surface, for example, whereby two or more extensions on adapter  210 , for example, extensions  212 ,  213  in  FIG. 12 , may contact the mating surface, for example, the mating surface of bearing  16 . As shown in  FIG. 16 , the diameter of boss  254 , or the inside diameter of the plurality of recesses in second end  242  may have a diameter  255 . According to one aspect of the invention, diameter  255  is sized to provide sufficient support for inner race  15  while providing at least some exposure to the surface of race  15  whereby a loading device, for example, adapter  210 , may contact inner race  15 . For example, diameter  255  may be at least as large as the minimum “backing diameter” recommended by the manufacturer of bearing  16 . 
     As shown in  FIGS. 15 and 16 , first end  241  of body  240  may be adapted to accommodate a nut locking mechanism, for example, the nut locking mechanism disclosed in co-pending and commonly-assigned application Ser. No. 11/029,531 entitled “Lock Nut System” filed on Jan. 5, 2005, the disclosure of which is included by reference herein. For example, first end  241  of body  240  may include a counter bore  256  having a plurality of internal projections  258  and an annular groove  260 . Internal projections  258  may be gear teeth or spline teeth adapted to engage a locking device (not shown) and annular groove  260  may be adapted to retain a locking device retainer (not shown), such as described in co-pending application Ser. No. 11/029,531. In one aspect of the invention, no counter bore  256  or annular groove  260  may be provided in first end  241  whereby first end  241  may only comprise a flat surface interrupted by threaded through hole  250 . 
     Body  240  may also be adapted to be engagable by a tool, for example, a crescent wrench, spanner wrench, or socket, among other tools, whereby body  240  may be rotated as desired. In one aspect, as shown in  FIGS. 15 and 16  body  240  may comprise an outside surface  262  having at least one flat  264 , but typically a plurality of flats  264  adapted to engage a tool, such as a wrench or socket. In another aspect, body  240  may include at least one recess, hole, or slot adapted to engage a spanner-type tool. For example, in one aspect, outside surface  262  may include holes or slots (not shown) adapted to engage a spanner wrench. In another aspect of the invention, any other surface of body  240  may include recesses, holes, or slots adapted to engage a spanner-type wrench, for example, the surface of end  241  may include a plurality of equally spaced holes or the surface of counter bore  256  may include a plurality of equally spaced holes. Other adaptations of body  240  to facilitate engagement by a tool for rotating nut  220  will be apparent to those of skill in the art. 
     Nut or fastener  220  may be fabricated from any one or more the structural metals mentioned above, for example, carbon steel or stainless steel. Nut  220  may be fabricated by machining from a billet or plate, by forging or casting and then finished machining, or fabricated by conventional powder metallurgy techniques. In one aspect, when formed by powder metallurgy, the material may be FC 0208, or its equivalent. Nut  220  may also be surface hardened for example, induction hardened, carburized, or nitrided, among other surface hardening methods; in one aspect, the exposed surfaces on end  241  of nut  220  may be hardened, for example, induction hardened. 
     One method of providing a preload to an axle bearing and minimizing the likelihood of losing the preload is to provide a nut arrangement including a first load adjusting nut, a lock washer that prevents the load adjusting nut from loosening, and a second jam nut that bears against the lock washer to secure the lock washer in place. Such a hardware arrangement can be found in most conventional original equipment truck and trailer axles. However, in this prior art arrangement, the first load adjusting nut is typically at least as large in diameter as the inner race of the bearing to which it applied. Therefore, when employing such prior art nut arrangements, the inner race is typically not accessible by a bearing loading or verification device, such as aspects of the invention. However, the aspect of the invention shown in  FIGS. 17-19  addresses the limitations of the prior art bearing loading devices by, among other things, allowing access to the inner bearing race for loading and/or preload verification when a nut-lock washer-jam nut arrangement is provided. 
       FIG. 17  illustrates still another aspect of the invention for applying or verifying a load or preload to a bearing.  FIG. 17  is a side elevational view, partially in cross section, of an apparatus  300  for applying or verifying a load or preload on a bearing according to another aspect of the invention.  FIG. 17  is a view similar to  FIG. 11  and includes many of the structures that may have similar if not identical functions to those structures that appear in  FIG. 11 . These similar structures are identified in  FIG. 17  by the same reference numbers shown in  FIG. 11 . Some of these common structures shown in  FIG. 17  include wheel hub  12 , shaft  14  (shown in cross section in  FIG. 17 ), inner bearing  16  having inner race  15 , and means  244  having shaft  40 , coupling  46 , nut  48 , gage  60 , and adapter  210 . According to this aspect of the invention, apparatus  300  also includes a nut or fastener arrangement  270  that is an alternative to nut  220  shown in  FIG. 11 . Nut arrangement  270  includes a first internally threaded ring  272 , a second ring  274 , and a third threaded ring  276 . According to this aspect of the invention, nut arrangement  270  provides a means for ensuring a preload is maintained in bearing  16  while minimizing or preventing the removal of this preload, for example, during normal operation of the vehicle. In addition, arrangement  270  also provides access to inner race  15  whereby a bearing loading device, such as adapter  210 , may access the surface of inner race  15  to provide a desired load or preload to the inner race  15 . For example, close examination of  FIG. 17  with nut arrangement  270  installed, illustrates how a surface of inner race  15  can be contacted by extensions  212  of adapter  210 . 
       FIG. 18  is a perspective view, partially in cross section, of nut arrangement  270  shown in  FIG. 17 .  FIG. 19  is an exploded perspective view of the elements of nut arrangement  270  shown in  FIGS. 17 and 18 . As shown in  FIGS. 18 and 19 , nut arrangement  270  includes a first threaded ring or nut  272 , a second ring  274 , and a third threaded ring or nut  276 . As noted with respect to diameter  255  of nut  220  in  FIG. 16 , the outer diameter of ring or nut  272  may have a diameter sized to provide sufficient support for inner race  15  while providing at least some exposure to the surface of race  15  whereby a loading device, for example, adapter  210 , may contact inner race  15 . For example, the outer diameter of ring or nut  272  may be at least as large as the minimum “backing diameter” recommended by the manufacturer of bearing  16 . 
     Ring or nut  272  includes internal threads  273  adapted to threadably mount to shaft  14  and engage the inner bearing race  15  (see  FIG. 17 ). Ring or nut  272  includes an outer surface  278  that may be engagable by a tool, for example, a crescent wrench, spanner wrench, or similar tool. For example, as shown in  FIGS. 18 and 19 , the outer surface  278  of ring or nut  272  may include one or more grooves  279  engagable by a spanner-type wrench. Grooves  279  may also be slots, notches, holes, or other indentations in surface  278 . In lieu of or in addition to grooves  279 , the outer surface  278  of ring  272  may include projections, for example, one or more spokes, engagable by a tool or a mechanic. Also, according to an aspect of the invention, ring or nut  272  may have an outer diameter that is less than the outer diameter of inner race  15 , that is, whereby at least a portion of the longitudinal surface of race  15  is accessible for contact by, for example, adapter  210  (again, see  FIG. 17 ). Ring or nut  272  may also include means for engaging ring  274  to prohibit relative movement, specifically relative rotational movement, between ring  272  and ring  274 . For example, as shown in  FIGS. 18 and 19 , ring  272  may include one or more projections or pins  280  adapted to engage a hole or a recess in ring  274 . Pin  280  may be press or shrink fit into ring  272  or pin  280  may simply be punched into ring  272 . In one aspect of the invention, ring  272  may include a hole or a recess that accepts a projection or pin in ring  274 . Threads  273  may be any one of the threads mentioned above, but are typically 12 to 18 threads per inch UN threads. 
     Second ring  274  is also adapted to mount to shaft  14  (see  FIG. 17 ) and includes means for engaging ring  272  to prohibit relative movement between second ring  274  and first ring  272  and second ring  274  includes means for engaging shaft  14  to prohibit relative movement between second ring  274  and shaft  14 , specifically prohibit rotational movement. For example, as shown in  FIGS. 18 and 19 , ring  274  may include one or more holes or recesses, for example, through holes  282 . Through holes  282  are adapted to engage one or more pins or protections  280  in ring  272  to prohibit relative rotational movement between ring  274  and ring  272 . Again, in one aspect, ring  274  may include one or more pins or projections, similar to pin  280 , that are adapted to engage one or more holes or recesses in ring  272 . The means for engaging shaft  14  in ring  274  may comprise any recess or projection adapted to engage shaft  14 . For example, as shown in  FIGS. 18 and 19 , ring  274  may include one or more projections or key-type structures adapted to engage a recess in shaft  14 . For example, ring  274  may include one or more key-type projections  284  that are adapted to engage a slot or keyway  285  in shaft  14  (see  FIG. 17 ). In one aspect, arrangement  270  may include one or more separate individual keys that are adapted to engage one or more keyways in ring  274  and one or more keyways  285  in shaft  14 . 
     Third threaded ring or nut  276  includes internal threads  277  adapted to threadably mount to shaft  14  and engage second ring  274  (see  FIG. 17 ). Ring or nut  276  includes an outer surface  286  that may, similar to ring  272 , be engagable by a tool, for example, a crescent wrench, spanner wrench, or similar tool. For example, as shown in  FIGS. 18 and 19 , the outer surface  286  of ring or nut  276  may include one or more flats  287  engagable by a crescent-type wrench. In one aspect outer surface  286  may also include grooves, slots, notches, holes, or other indentations adaptable to be engaged by a spanner-type wrench. Threads  277  may be any one of the threads mentioned above, but are typically 12 to 18 threads per inch UN threads. 
     Ring  272 , ring  274 , and ring  276  may be fabricated from any one or more the structural metals mentioned above, for example, carbon steel or stainless steel. Ring  272 , ring  274 , and ring  276  may be fabricated by machining from a billet or plate, by forging or casting and then finished machining, or fabricated by conventional powder metallurgy techniques. In one aspect, when formed by powder metallurgy, the material may be FC 0208, or its equivalent. Ring  272 , ring  274 , and ring  276  may also be surface hardened for example, induction hardened, carburized, or nitrided, among other surface hardening methods. 
     As shown in  FIG. 17 , according to one aspect of the invention, nut arrangement  270  may be used to secure bearing  16  to shaft  14  while also providing access to the surface of inner race  15  of bearing  16  whereby a bearing loading device may contact inner race  15 . In one aspect, during a new installation or during servicing of an existing bearing, arrangement  270  permits access to inner race  15  by, for example, loading adapter  210 . In an original installation, after bearing  16  is mounted to shaft  14  and hub  12 , ring  272  may be threaded to shaft  14  and tightened, for example, hand tightened, against the exposed longitudinal surface of inner race  15 . The bearing loading apparatus  244  may then be mounted to shaft  14  as described above, for example, where rod  40  is engaged with shaft  14  by means of collar  46 , adapter  210  is mounted to rod  40  and inner race  15 , and housing  52  (having piston  54 ) and nut  48  are mounted to rod  40 . Then, according to aspects of the invention, a load may be applied to inner race  15 , for example, mechanically by turning nut  48  and/or hydraulically by introducing a pressurized fluid to housing  52 . The loading on inner race  15  may be monitored, for example, by means of pressure gauge  60 , until the desired loading on inner race  15  is provided. After a load is applied to race  15 , the hub assembly  12  may be rotated about shaft  14  to ensure proper seating of the rollers of bearing  16 . This rotation and seating may be practiced repeatedly to ensure proper seating. According to aspects of the invention, with the desired loading on inner race  15  provided, ring or nut  272  may be tightened, for example, by using a spanner wrench engaging grooves  279 , to maintain the desired loading on inner race  15 . 
     In one aspect, the rollers in bearings  16  and  18  may be properly seated by applying a roller-seating load to the inner race  15 , that is, a load sufficient to seat the rollers in bearings  16  and  18 . For example, a roller-seating load may correspond to a hydraulic pressure in housing  52  of between about 900 psig and about 1000 psig, as detected by gauge  60 . (In one aspect, this hydraulic pressure may correspond to a bearing load of between about 5000 pounds to about 6000 pounds, for example, as computed by Equation 1.) Again, hub  12  may be rotated one or more times while this seating load is applied to ensure proper seating of all the rollers. After proper seating of the rollers, the applied load may be reduced to a load corresponding to the desired preload on the bearings, for example, a load providing a few thousands inches preload. This desired preloading may be provided by between about 50 psig and 100 psig hydraulic pressure in housing  52  of means  244 . (In one aspect, this hydraulic pressure may correspond to a bearing load of between about 300 pounds to about 600 pounds, for example, as computed by Equation 1.) Once the desired preload is provided, ring or nut  272  may be tightened, for example, by hand or with a tool, to maintain the desired preload. 
     Apparatus  244  is then removed, and ring  274  can be mounted to shaft  14  whereby at least one through hole  282  engages one or more pins  280  on ring  272  and key  284  engages keyway  285  in shaft  14 . These interferences of ring  274  with ring  272  and shaft  14  substantially prohibit relative rotational motion between ring  272  and shaft  14  whereby the preload on inner race  15  is substantially maintained. Then, ring or jam nut  276  is threaded onto shaft  14  and tightened against ring  274  to secure ring  274  to shaft  14 . Other procedures and procedural modifications of this method will be apparent to those of skill in the art. 
     In another aspect, the preloading on a bearing of an existing hub assembly may be verified or evaluated with the wheel in place or removed. In this aspect of the invention, nut arrangement  270  may be mounted to shaft  14  whereby a preload may or may not be present on inner race  15  of bearing  16 . Third ring  276  and second ring  274  may be removed to obtain access to ring  272  whereby ring  272  may be rotated about shaft  14 , if necessary. In one aspect, where sufficient play between hardware is provided, third ring  276  and second ring  274  need not be removed. Also, when a nut such as nut  220  in  FIG. 11  is provided with a locking mechanism (for example, the locking mechanism disclosed in pending U.S. application Ser. No. 11/029,531), the locking mechanism need not be removed when sufficient play is available between hardware to detect loosening of the nut. 
     Apparatus  244  having rod  40 , adapter  210 , housing  52 , and nut  48  may then be mounted whereby adapter  210  engages inner race  15 . According to aspects of the invention, inner race  15  may be contacted by adapter  210  since the outer diameter of ring  272  is less than the outer diameter of inner race  15 . The loading on inner race  15  is then gradually increased, either mechanically or hydraulically. At the same time or alternating with the increase in load, the tightness of ring  272  against inner race  15  may be checked, for example, manually, to determine when the preload on inner race  15  is relieved by the applied load via adapter  210 . If nut or ring  272  becomes loose prior to achieving the desired preload for the specific bearing, the preload can be increased to the desired value, for example, as indicted by gauge  60 , and then ring  272  tightened to maintain the desired preload. If the preload on inner race  15  is satisfactory, that is, nut or ring  272  does not loosen until about the desired preload is achieved, nut or ring  272  can be tightened to maintain the desired preload. Should the actual preload exceed the desired preload, the load applied by apparatus  244  can be increased until ring or nut  272  becomes loose, and then the load reduced to the desired preload, and nut or ring  272  retightened to maintain the desired preload. Apparatus  244  may then be removed and rings  274  and  276  remounted according to the invention to ensure the desired preload is provided. 
     Again, the inventor underscores that though 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.