HK1061890B - Unitized tone ring assembly - Google Patents

Description

Integrated tone ring assembly

Cross reference to related applications

This application is a continuation-in-part application of co-pending U.S. patent application No. 10/012,880 filed on day 11, 2 of 2001.

Background

The invention relates to an assembly comprising a so-called tone ring or exciter ring and a magnetic sensor device. More particularly, the present invention relates to a portion of a vehicle or other mechanical component adapted to produce a varying voltage output signal during variable speed rotation, which signal is detected by a sensor or sensor device connected to the rotating portion.

The tone ring preferably has a plurality of splines, blades or bosses separated by spaces or grooves, and may be a simple cylinder having magnetic rubber strips molded or otherwise secured thereto. At variable speeds, the boss or magnetic strip passes through a fixed sensor, which generates a speed change signal in the sensor, giving an indication of the rotational speed of the shaft to which the tone ring is attached.

The assembly is primarily intended for vehicles, wherein the rotational speed, in particular the change in rotational speed, of two or more shafts is detected for various purposes. This includes applications in ABS (anti-lock braking system), differential start or control, traction control, all wheel drive control, vehicle stability, etc. Furthermore, the invention may be used in other applications, such as sensing the rotational speed of a power output shaft, or other power transmission device including one or more rotating shafts.

In the past, the tone ring was secured to the axle or other rotating member in a press-fit orientation, as was the case with a bearing or seal. This method is also cumbersome in the best case and impossible to implement in the worst case. Other methods of attaching the tone ring to the rotating mechanism include assembling the tone ring with a bearing, hub or ring gear, the tone ring being attached to the rotating part. These methods are sometimes unsatisfactory because the shaft is subject to deflection in use, and for other reasons, particularly when the bearing/sensor system is too rigid to accommodate such deflection of the shaft in use.

Other tone rings or schemes related to tone rings involve mounting forces that may tend to damage the tone ring or transducer. Still other tone rings may lack integral features wherein a means is provided to prevent axial movement of the tone ring beyond certain limits, or a retainer is installed to determine the position of the tone ring, at least approximately.

If a tone ring assembly could be provided that is integrated, as a systematic approach, a simplified assembly would result. Also, it would be highly desirable if a tone ring could be made so that the mating parts could be installed with low force, particularly if a configuration were made so that after installation, the tone ring could grip the shaft more tightly than during initial installation. There are some preferred constructional features whereby it is easier to initially locate the tone ring on the shaft without compromising the final necessary clamping of the shaft. In other words, the force required to mount the tone ring on the shaft may be minimal initially due to geometry or surface texture.

In particular, it would be advantageous if a tone ring were provided in connection with a portion of the shaft that experiences little or no deflection during use. It would be highly desirable if these advantages could be achieved in a design that provides at least one, and preferably several, axial oil passages in use.

It is also desirable to provide a unitized retainer in the form of a sleeve having radially inner and outer portions that engage and encapsulate a radial flange of the tone ring, or the entire tone ring itself, allowing only a limited range of axial movement between the retainer flange and the tone ring flange, or limited movement of the entire tone ring. Alternatively, the integrated retainer ring may be made from a stamped steel piece or formed from a tough plastic such as Delrin @.

It is therefore an object of the present invention to provide an improved tone ring assembly capable of generating a voltage output by rotation, preferably in the form of a sleeve having a plurality of bosses, recesses, teeth or magnets, which signal an associated magnetic sensor or susceptor as the bosses or magnets of the tone ring rotate past the sensor. The term "tone ring" or the like means not only a single ring member but also a plurality of rings operating in coordination with sensors connected or linked to a speed differential computer and a feedback mechanism.

It is another object of the present invention to provide a tone ring assembly that is spaced from the bearings or seals but is connected to the axle shaft supported on these bearings.

It is a further object of the present invention to provide a tone ring assembly which is sufficiently flexible and positioned so that it can accommodate limited axle deflections during use, as well as limited axial clearance in such axles.

It is a further object of the present invention to provide a tone ring and retainer which can be initially installed with acceptable human and machine controlled force, positioned in the axle tube or housing with an installation tool, and then slid over the tone ring with the desired human and machine controlled force, and just past the position in which it is in effect in use, to permit an axially inner axle retainer or "C" clip to be installed in the axle groove. Thereafter, when the axle shaft is moved axially slightly outwardly, the clip and tone ring are centered and axially aligned.

It is a further object of the present invention to provide a tone ring and retainer design that can be positioned in an area of the shaft that experiences minimal deflection during use.

It is a further object of the present invention to provide a unified design for simple and relatively safe assembly.

A complementary object of the present invention is to provide a tone ring which is easy to install and thereafter produces a more secure grip on the shaft by virtue of the expansion of the rubber in response to the assembly and/or subsequent application of lubricant.

It is a further object of the present invention to create a tone ring design having an inner or maximum diameter that includes oil passages, a diameter that is adapted to expand into ribs or splines that contact the shaft, and finally, a small portion of the innermost diameter that is adapted to initially contact the corresponding shaft.

It is another object of the present invention to provide a design compatible with the axle configuration that allows sufficient axial travel of the axle to allow a retainer or "C" clip to be dropped into place over the axially inner end of the axle, after which the axle can be pulled out a few millimeters to place the clip, thus loading the thermoplastic or thermoset washer when the tone ring is slightly slid out of the "home" position on the axle. The gasket may also be eliminated if the retaining ring or tone ring flange is made of a thermoplastic or thermoset material.

It is a further object of the present invention to provide a tone ring which is axially located within the seal and bearing but is axially located by virtue of the engagement between the confronting retainer flange and the powder metal sleeve flange. It is initially held radially by ribs of the inner diameter on the tone ring and is thereafter held more firmly in place by virtue of the lubricant causing expansion of these radial ribs. This may occur over several steps or stages, if desired. Alternatively, the powder metal flange may be eliminated, or the powder metal tone ring/flange combination may be two or more pieces that are assembled or molded.

It is a further object of the present invention to provide a substantially axial width of the tone ring teeth so that the position of the sensor relative to the tone ring accommodates any variations in stack-up or axial clearance tolerances in use.

It is another object of the present invention to provide a tone ring that fits over the minimum machined diameter of an axle shaft, leaving a larger associated diameter for accommodating bearings and oil seals, respectively, and allowing for the assembly of parts within the axle tube.

It is a further object of the present invention to provide a tone ring assembly which, in itself, permits a desired or proper assembly sequence of the axle shaft, seals, bearings and tone ring. The tone ring assembly may also be reused after field disassembly.

It is another object of the present invention to provide a tone ring assembly that allows oil to pass through the tone ring along one or two paths.

Another object is to provide a textured surface on some or all of the ribs on the tone ring so that the ribs can effectively "hold" oil or grease close to the shaft for ease of installation or better lubrication.

It is also an object of the present invention to employ various processes, such as Electrical Discharge Machining (EDM) or chemical etching, to roughen or create a textured surface to the mold used to make the rubber member, thereby imparting a textured surface on the interior of the ribs or splines in the final molded article.

The present invention achieves these and other objects inherent in the invention by providing an assembly comprising a rotatable tuning or exciter ring capable of producing a variable voltage output by rotation relative to a magnetic sensor, and ribs on its inner diameter, the assembly comprising an optional radial flange, an optional abutment washer with radial oil passage spaces, a retainer ring having at least one radial flange, one or more oil passage means, the respective sensor being adapted to sense a speed change signal when a boss or magnet on the tuning ring passes the sensor.

Specifically, the present invention provides a tone ring assembly for use on a rotating machine part, said tone ring assembly comprising: a rotatable tone ring including a plurality of axially extending ribs of reduced diameter on an inner diameter thereof for abutting engagement with said rotating machine portion, said ribs defining axial spaces of increased diameter therebetween, thereby providing a passageway for oil to pass axially through said tone ring assembly; a stationary magnetic sensor assembly disposed in opposed proximity to said tone ring surface, said stationary magnetic sensor being adapted to sense rotation of said tone ring and produce a voltage output that varies with changes in the speed of rotation of said tone ring; a retainer having at least one radial flange to prevent substantially axial movement of the tone ring.

Preferably, said tone ring further includes an air gap between radially opposed portions of said body and said radial flange of said tone ring body to permit maximum axle deflection without contacting the flange on said retainer.

These and other objects of the invention will in fact become more apparent when reference is made to the following detailed description of the preferred embodiments of the invention, which is illustrated by way of example and shown in the accompanying drawings, in which like reference numerals designate corresponding parts throughout.

Brief Description of Drawings

FIG. 1 is a perspective view in the form of a tone ring and retainer, showing these parts in an assembled condition, the view being taken from the axially inner end of the tone ring;

FIG. 2 is a fragmentary exploded perspective view of the tone ring assembly of FIG. 1, the view being taken from the axially outer end to illustrate the component parts of the retainer, the preferred washer form, and various details of these components and the tone ring;

FIG. 3 is a fragmentary exploded perspective view of the tone ring assembly of FIGS. 1 and 2 showing the retainer, as well as the washer and tone ring, in two parts, the view being taken from the axially inner end thereof;

FIG. 4 is a horizontal cross-sectional view of the tone ring assembly, including the retainer, washer and tone ring in a mounted position within and along the axle housing, and showing the seal and bearing in a position surrounding the axle;

FIG. 5 is a fragmentary view with portions broken away and illustrates an alternative embodiment of the invention;

FIG. 6 is a fragmentary view with portions broken away showing an embodiment of the invention in which the sensor is located on a window or opening in the collar;

FIG. 7 is a perspective view looking toward the inside of the tone ring, showing the stepped portion of certain ribs or splines on the inner diameter of the tone ring;

FIG. 8 is an enlarged view of one of the ribs, including the stepped portion shown in FIG. 7;

FIG. 9 is a view taken from the inside of the tone ring body showing a textured portion of the innermost surface of the mounting ribs or splines on the inner diameter of the tone ring; and

FIG. 10 is an enlarged view of a portion of one of the ribs of FIG. 9 showing details of the textured surface thereof.

Description of The Preferred Embodiment

Although the tone ring may be embodied in a number of applications, including automotive and non-automotive applications, such as power take offs, generators, etc., a detailed description of the tone or field ring assembly and its ancillary components such as detectors or sensors will first be given in an application wherein a vehicle drive axle rotates the tone ring, the sensors being located in fixed positions in the axle tube housing, just radially away from or beyond the surface of the tone ring, the tone ring being maintained in fixed positions due to contact between an optional flange on the tone ring and the retainer flange, preferably with an optional gasket between the tone ring and the retainer.

Referring now in detail to the drawings, FIGS. 1-4 illustrate a tone ring assembly, generally designated 10, preferably axially located in a bearing in an axle tube housing assembly, generally designated 12, with a sensor 14 retained in an opening, generally designated 16, in the housing assembly 12.

The tone ring assembly body, generally designated 18, includes an axial extension 20, a radial flange 22 defined by axially inner and outer surfaces 24, 26, and a radially outermost stepped surface, generally designated 28. The body generally designated 18 includes a radially outer surface generally designated 30 on the axial extension 20, the axial extension 20 being axially inwardly defined by alternating radially extending lands 32 and grooves 34 which preferably extend axially in parallel.

The radial flange 22 has a stepped surface 28 having therein a large diameter surface 35 and a small diameter surface 36 for passage of oil. The tone ring body 18 includes a rubber portion therein, generally designated 38, which includes a beveled lead-in area 40. In addition, there are a plurality of axially extending ribs 46, each of which includes a lead-in zone 44.

The ribs 46 are separated by axially extending slots 48. The ribs 46 snugly engage the outer diameter 49 of the axle 50, engaging an intermediate sized axle portion 52 having a diameter slightly larger than the axial axle interior 53 and smaller than a portion 54 engaging a bearing inner diameter 56, generally designated 58.

The illustrated bearing 58 includes a roller member 60, and an outer cage 64. The actual type of bearing may vary, for example, the rollers 60 may be interfitted with the shaft, or there may be no bearing cage or gas locator.

Oil may pass axially from the differential (not shown) through the groove 48 in the tone ring 18 to the bearing 58 and a seal generally designated 66. Although not an essential part of the present invention, seal 66 typically includes a cap or stamp 68, and a rubber main edge 70. The seal shown has an auxiliary or dust-tight edge 71 which is usual in vehicle axles, but this is not strictly necessary.

Once the tone ring body 18 is finally mounted in place on a portion 52 of the shaft 50, it cannot measure movement in the axial direction. In addition to being retained by friction of the ribs 46, the body 18 is retained in its final axial position by a retaining ring of a tone ring, generally designated 75. Preferably, but not necessarily, the retainer ring, generally designated 75, is formed of two pieces, a radially thicker serrated outer shroud, generally designated 76, and a radially thinner inner shroud, generally designated 78.

The radially inner shroud 78 includes an axially extending portion 80 and a radially inwardly extending stop flange 82, while the outer shroud generally designated 76 (into which the thinner inner shroud 80 is pressed) includes a radially inwardly extending stop flange 83 and a generally axially extending portion 84, the extending portion 84 including a corrugated outer surface portion generally designated 88. Thus, the housing portion generally designated 76 includes both a raised portion 90 that mates with the bore 92 and a depressed portion 94 that allows oil to pass axially therethrough. There is also a scalloped cut-out 97 or relief in the radial flange 83 of the retainer ring 75. Thus, oil may flow within body 18 or between tone ring 18 and retainer ring 75. The result of the final assembly of the parts is a retainer having a U-shaped cross-section with flanges 82, 83 that prevent unwanted axial movement of the tone ring 18 in both directions.

Referring now to another preferred feature of the present invention, a gasket, generally designated 96, is captured between the radial flange 82 of the inner housing 78 and the axially outer surface 26 of the radial flange 22 of the tone ring 18.

The washer 96 includes a continuous inner portion 98 and a plurality of teeth 100 separated by spaces 102. Preferably, the teeth 100 include beveled ends 104 and flat axially inner and outer surfaces 106, 108 to facilitate engagement between the radial flange 82 of the radially inner shroud 78 and the axially outer surface 26 of the tone ring radial flange 22.

The tone ring body 18 also has a groove 110 or relief adjacent the radial flange 22 to provide additional clearance between the body 18 and the radial flange 83 of the retainer 75.

The assembly of the tone ring with its mating parts is a fairly straightforward operation. The axle 50 includes a smaller diameter portion 53 through most of its length. However, as the axle shaft 50 approaches its axially outer end, the diameter increases slightly at 52, and the axle shaft 50 includes another step toward a larger diameter surface 54 terminating before a flange, generally designated 57.

The sensor, generally designated 14, is properly positioned relative to the boss and recess of the tone ring body 18 at this time or later. It can be inserted at any time because it does not interfere with the tone ring. Retainer 75 is then placed in bore 92 with a light press fit while the tone ring body is retained within the retainer. The tone ring is held so that it does not tip excessively and is thus positioned to receive the axle. No other means is required to guide the axle into position within the body 18. Next, the bearing 58 is positioned, its outer retainer 64 is pressed into the just slightly larger bore 95, and finally the cap 68 of the seal 66 is pressed into the largest bore 101.

The axle shaft 50 is then gradually inserted until it engages the tone ring on the inner diameter rib 46 of the tone ring. The tone ring then prevents further inward movement of the axle shaft 50 due to the engagement between the radial flange 83 of the retainer ring 75 and the flange surface 24 of the tone ring, and the axle shaft 50 is gradually pushed axially inward (upward as viewed in FIG. 4) until the innermost end of the axle shaft receives a C-clip (not shown) to hold the axle shaft in place. Thereafter, the axle is axially retracted by a few millimeters so that the C-clip is properly engaged and positioned in the differential. This moves the tone ring slightly downward as viewed in fig. 4, ensuring that the axially outer surfaces 108 of the washer teeth 100 engage the retainer flange and, if desired, sliding the tone ring body 18 slightly axially inward relative to the axle shaft, ensuring that the body is properly seated on the washer 96 against the retainer flange 82. Thus, the mounting is self-aligning and self-centering, which is highly desirable. Once installed, another axle shaft can be reinserted in use by simply pushing it into position within the tone ring body, typically by hand. Of course, if the original axle has been removed, it can be reinserted into the tone ring.

The materials from which the tone ring is made for this purpose are conventional. For example, the tone ring itself may be made of a ferromagnetic powder metal that is molded into shape and then sintered into the desired final form. Other materials may be used, but powder metal technology is preferred because it provides deeper square lands and grooves, as well as cost effective magnetic performance. Embedding metal in plastic, including axially embedding magnetic strips, and then covering with hardenable synthetic rubber or plastic, may also be employed.

The rubber used to form the ribs 46 and surrounding material is EPDM or other suitable synthetic rubber such as those known as Nitrile (NBR), HNBR, FKM, AEM, ACM or other synthetic rubbers or two or more of these rubbers. Plastics or thermosets may also be employed in other suitable forms as described above. The rib portion is an elastomer, which is a mixture of NBR and EPDM. The ribs 46 and surrounding portions 40, 42 of the elastomer may be coated with a dry PTFE material for lubrication and the substrate may be made of a thermoplastic or thermoset material. For lubrication, a wet lubricant, such as oil, grease, or an alkyl ammonium phosphate, may be placed on the inner diameter of the tone ring. Both parts of the collar are preferably made of mild steel, but plastic may also be used.

The gasket is an insulating, lubricious material such as Delrin or acetal material, but could be replaced with a low friction coating on the retainer ring or tone ring flange, or both, or eliminated. The gasket may be made of plastic.

The collar is conveniently manufactured in two pieces, a thinner inner piece and a thicker outer piece, but may be manufactured in one piece. The illustrated form has corrugations in one part of the collar which are then combined with a thinner flat portion to form the radial flange. The rubber material used to form the ribs 46 is of a type that swells in oil or grease, including oil with extreme pressure additives. Thus, when the tone ring is attached to the axle, it is easy to position, but after the tone ring has been positioned for a certain time, the oil further expands the rubber, keeping the tone ring more firmly positioned.

Alternatively, the radial flange of the tone ring is an assembled metal flange made of a different material than the rest of the tone ring body.

Alternatively, the tone ring body is made of a powder metal material and the radial flange is made of a stamped metal material or plastic.

Several other configurations may be provided as an alternative design. In one of the simplest possible configurations and as shown in FIG. 5, the tone ring, generally designated 18a, may simply not have a radial flange, and the simplest retaining ring approach is now provided to ensure that the tone ring does not excessively move axially on the axle shaft when installed. In contrast, in the body 20a of the tone ring 18a, there is a groove 110a, and a flange 82a extends into the groove 110 a. In this configuration, the axial extent of the tone ring may be much greater than the axial extent of the retainer ring in the first embodiment, but the bore 92a has an axial flange 80 pressed therein. The sensor 14a is located in one of the openings 16 a. Thus, a unified construction is also provided.

Another alternative configuration is shown in fig. 6. Here, there is no groove or flange, but the retainer 78b is allowed to span the entire axial length of the tone ring with two flanges 82b, thereby limiting axial movement of the body 18 b. Of course, in such a configuration, it may be desirable to provide an opening or window 99 in a portion of the collar so that the sensor 14b can function properly.

As indicated above, the gasket may be eliminated and a lubricious coating may be placed in its place on the face of the radial flange 26 of the body, on the inner surface of the flange 82, or both. This expedient can be used in an effort to save costs, especially after installation, i.e. with little or no significant risk of axial movement of the tone ring in operation. In a further alternative, the gasket may be made of a block of hard grease, thus being suitable for melting after significant contact with the body radial flange and the retainer ring radial flange.

Importantly, there is at least one axial oil passage, and preferably several oil passages, in the tone ring assembly. The most advantageous way to provide these oil passages is to space the tone ring body from the axle shaft with a series of shallow ribs, and then also to provide passages in the washers, the retainer rings, and in the periodically aligned tone ring flanges to allow oil to pass through the parts. These useful methods provide for lubrication of bearings with oil from a differential.

The following is sometimes considered advantageous for convenient mounting of the axle: the inner diameter of the tone ring is particularly adapted to slide more easily on the shaft, but does not compromise the ability of the tone ring inner diameter to expand in the presence of oil, thereby tightly gripping the shaft. This can be achieved in two different ways, by way of example only.

Referring now to fig. 7 and 8, a modified tone ring, generally designated 200, and a retaining ring, generally designated 275, are shown. Other features of the tone ring, such as spaced lands and grooves on its outer diameter, are identical to the embodiments described above. There is only a difference in the configuration of the ribs 246. Here, the rib itself, about halfway along its extent, includes a reduced diameter portion generally designated 247 having a generally flat inwardly facing contact surface 250 and angled inlet and outlet surfaces 248, 249. The surface 250 is offset from the remaining ribs 246, typically about ten thousandths of an inch (0.010 inches). The surface 250 is about 5mm or 200 thousandths of an inch (0.200 inch) long. Typically, each third rib 246 includes a raised portion 247, although it is possible to have a raised portion 247 every fewer or greater number of ribs 246.

In use, the portions 247 of the ribs 246 in some instances make the tone ring easier to install. This is because only the raised portion 247 contacts the axle when mounted. However, when the on-axle grease or oil has the opportunity to react with the rubber, the rubber expands and secures the tone ring in a more locked position relative to the axle. The design of the raised portion is such that it includes two angled regions 248 and 249, protecting the raised portion of the boss from damage and accommodating axial movement during installation. As already noted, the ribs 246 lock into place more securely once the oil or grease reacts with the rubber.

Another way to achieve the same effect is illustrated in fig. 9 and 10. The tone ring, generally designated 300, is identical in all respects to the corresponding tone ring as shown in figures 1-3. The only exception to this identity is in the configuration generally designated 246. The spacing between the ribs 48 is the same and the texture of the textured modifying ribs 346 is the only difference in the tone rings.

Here, the surface referred to as 350 contains texture. The surface thus comprises a series of substantially flat portions lying in a plane, but also a very large number of smaller portions 354 having a random pattern of depressions or textures. The pattern shown in fig. 10 is for illustrative purposes only, and it will be understood that the portion having a slightly enlarged diameter or countersink is from 2 to 10 thousandths of an inch (0.002-0.010 inch), and preferably about 5 or 6 thousandths of an inch (0.005-0.006 inch). The method of manufacturing such a pattern in the molded rubber is relatively simple. The discharge machining (EDM) anode end on the die used to form the rib geometry was designed to be very rough, with the result that the die used to make the rubber article in this area exhibited a rough, textured appearance. Thus, the rubber formed or molded in this mold has a mirror image impression of the texture on the molding tool. Thus, the rib, generally designated 350, exhibits a textured feature on its inner surface. This texture may alternatively be obtained by chemical "etching" on the mold area. For example, an acid is used in selected areas to create "holes" similar to the EDM method.

When these assemblies have been installed, the textured portion creates a "cavity" to hold the remaining oil or grease against the axle. Thus, these "voids" retain the lubricant and effectively create a thin film thickness of lubricant between the rubber and the axle. This theoretically reduces the mounting force.

Thus, this more lubricated configuration may be preferred in some situations for ease of installation, particularly given the tolerances of axle manufacture, which are on the order of a few thousandths of an inch.

The simplest use of a tone ring assembly is for controlling the speed of a single shaft, such as the speed of an engine shaft. However, a more conventional application of the tone ring and its associated parts is in two-wheel drive vehicles, where feedback signals from sensors are sent to a computer and the relative speeds of the two axles are then determined. Such applications may be, for example, in ABS (anti-lock brake system), and in differential control systems.

The tone ring is most advantageous for use in four-wheel drive systems where the speed of each axle is desirably controlled by a computer having four or more inputs. Thus, the tone ring is useful not only in various braking systems, but also in traction control systems where, depending on the design of the system, the relationship of the front and rear wheel speeds must be determined instantaneously, and the relationship of the right and left wheel speeds must be measured instantaneously, and then corrected.

It will thus be seen that the present invention provides a tone ring assembly having a number of advantages and features, including those advantages and features explicitly noted herein, as well as others inherent in the invention. Having shown and described several embodiments of the article of manufacture of the present invention, it is to be understood that changes in the form of the device described will occur to those skilled in the art, and that such modifications and variations may be made without departing from the spirit of the invention and the scope of the appended claims.

Claims (41)

1. A tone ring assembly for use on a rotating machine part, said tone ring assembly comprising:

a rotatable tone ring including a plurality of axially extending ribs of reduced diameter on an inner diameter thereof for abutting engagement with said rotating machine portion, said ribs defining axial spaces of increased diameter therebetween, thereby providing a passageway for oil to pass axially through said tone ring assembly;

a stationary magnetic sensor assembly disposed in opposed proximity to said tone ring surface, said stationary magnetic sensor being adapted to sense rotation of said tone ring and produce a voltage output that varies with changes in the speed of rotation of said tone ring;

a retainer having at least one radial flange to prevent substantially axial movement of the tone ring.

2. A tone ring assembly as defined in claim 1, wherein said tone ring includes a tone ring body having a plurality of axially extending lands and grooves which are sensed by said fixed magnetic sensor.

3. A tone ring assembly as defined in claim 1, wherein said tone ring includes a tone ring body having a plurality of axially extending magnetic strips circumferentially spaced from one another, said magnetic strips being sensed by said stationary magnetic sensor.

4. A tone ring assembly as defined in claim 2, wherein said tone ring body includes a radial flange formed on an axially outer end thereof.

5. A tone ring assembly as defined in claim 2, wherein said at least one radial flange on said retainer is two.

6. A tone ring assembly as defined in claim 5, wherein said retainer is formed in two pieces, a generally L-shaped radial retainer inner portion and a generally L-shaped radial retainer outer portion, the two portions combining to form a U-shaped assembly having axially inner and outer radial flanges.

7. A tone ring assembly as defined in claim 6, wherein said retainer is a metal retainer that is press fit and locked together by two separate pieces.

8. A tone ring assembly as defined in claim 7, wherein said radially outer portion of said retainer is formed of a thicker metal than said radially inner portion of said retainer.

9. A tone ring assembly as defined in claim 1, wherein said retainer is made of a thermoplastic or thermoset material.

10. A tone ring assembly as defined in claim 1, wherein said ribs extending axially on said rotatable tone ring inner diameter have beveled end portions to facilitate mounting on an associated axle shaft.

11. A tone ring assembly as defined in claim 2, further comprising a washer, located in use between an end of said tone ring and a flange of said retainer, said washer being made of a low friction material.

12. A tone ring assembly as defined in claim 1, wherein said at least one radial flange of said retainer comprises an axially inwardly facing flange on said retainer coated with a low friction material.

13. A tone ring assembly as defined in claim 11, wherein said tone ring body further includes a radial flange portion adapted to engage the radial flange of said retainer, said radial flange portion having regions of different diameters, with relieved regions on the radial flange of said retainer, said spacer having a plurality of spaced apart teeth thereby permitting oil to pass through the relieved regions and said tooth regions.

14. A tone ring assembly as defined in claim 11, wherein said spacer is made of plastic.

15. A tone ring assembly as defined in claim 11, wherein said washer is made of a hard grease block.

16. A tone ring assembly as defined in claim 4, wherein the axially outermost portion of said radial flange on said tone ring body further comprises a low friction coating material.

17. A tone ring assembly as defined in claim 4, wherein said radial flange of said tone ring body is a fabricated metal flange made of a different material than the remainder of said tone ring body.

18. A tone ring assembly as defined in claim 11, wherein said washer is discontinuous on its outer diameter to permit oil to flow axially therethrough.

19. A tone ring assembly as defined in claim 1, wherein the material of at least said rib portion of said tone ring is an elastomer which is a blend of NBR and EPDM.

20. A tone ring assembly as defined in claim 1, wherein the material of said ribs on said tone ring is an elastomer selected from the group consisting of NBR, HNBR, EPDM, AEM and ACM.

21. A tone ring assembly as defined in claim 1, wherein said inner diameter of said tone ring includes a dry PTFE coating.

22. A tone ring assembly as defined in claim 1, wherein said ribs on said tone ring inner diameter are formed of a thermoplastic or thermoset material.

23. A tone ring assembly as defined in claim 1, wherein said inner diameter of said tone ring includes a wet lubricant coating.

24. A tone ring assembly as defined in claim 4, wherein said radial flange of said retainer includes cut-out portions to permit oil to pass therethrough.

25. A tone ring assembly as defined in claim 4, wherein said tone ring body has a stepped surface on said radial flange thereof.

26. A tone ring assembly as defined in claim 4, wherein said tone ring further includes an air gap between radially opposed portions of said body and said radial flange of said retainer to permit maximum axle deflection without contacting the flange on said retainer.

27. A tone ring assembly as defined in claim 1, wherein said tone ring assembly is attachable to a removable axle shaft and the axle shaft or another axle shaft is loaded into said tone ring assembly.

28. A tone ring assembly as defined in claim 4, wherein said tone ring assembly is mounted on the axle shaft and retained in position by virtue of an interference fit between said tone ring body and said flange on said retainer throughout the sequence of mounting the axle shaft.

29. A tone ring assembly as defined in claim 5, wherein said flange on said retainer engages a radial flange on said tone ring body and provides a self-aligning feature and a self-centering feature.

30. A tone ring assembly as defined in claim 5, wherein said flange on said retainer ensures accommodation of axial tolerances accumulated in the assembly of the axle shaft.

31. A tone ring assembly as defined in claim 1, wherein said retainer has two radial flanges and spans the entire axial width of the tone ring, said retainer having an opening in at least a portion of its axial extent to receive the sensor.

32. A tone ring assembly as defined in claim 2, wherein said tone ring body is formed of a powdered metal material and said radial flange of said tone ring body is formed of a different material than said tone ring body.

33. A tone ring assembly as defined in claim 2, wherein said tone ring body is formed of a powdered metal material and said radial flange of said tone ring body is formed of a stamped metal material.

34. A tone ring assembly as defined in claim 2, wherein said tone ring body is formed of a powder metal material and said radial flange of said tone ring body is formed of plastic.

35. A tone ring assembly as defined in claim 1, wherein at least one of said reduced diameter axially extending ribs includes a first portion and a second portion, said second portion being further of slightly reduced diameter so as to initially engage only said rotating mechanical portion, said first portion thereafter being adapted to contact more oil and grease to form a snug engagement with said rotating mechanical portion.

36. A tone ring assembly as defined in claim 35, wherein said at least one rib is a plurality of ribs.

37. A tone ring assembly as defined in claim 36, wherein the first two of every three of said axially extending ribs comprise a first portion and the third of every three comprise a first portion and a second portion, said second portion being further of slightly reduced diameter so as to initially engage only said rotating mechanical portion, said first portion thereafter being adapted to be in greater contact with oil and grease to form a snug engagement with said rotating mechanical portion.

38. A tone ring assembly as defined in claim 1, wherein at least one of said axially extending ribs includes a portion facing said rotating machine portion when said tone ring assembly is engaged with said rotating machine portion, said portion having a plurality of uneven surfaces and thereby a plurality of pockets for lubricant.

39. A tone ring assembly as defined in claim 38, said at least one rib being a plurality of ribs.

40. A tone ring assembly as defined in claim 39, wherein a third one of each three of said axially extending ribs includes a portion of further slightly reduced diameter.

41. A tone ring assembly as defined in claim 38, wherein at least one rib is molded in a mold having a rugged surface formed by electrical discharge machining or chemical etching.