Abstract:
The present invention discloses a seal and a method of sealing dynamic shaft applications. The seal comprises an inner portion, an outer portion, a faceplate, and at least one flexible member located between the inner and outer portions. The method comprises providing a dynamic shaft assembly containing a bore for receiving a seal, providing a unitized seal, and placing the unitized seal on the shaft, thus sealing the assembly so that lubricants may not escape, and foreign material may not enter. The unitized seal can provide permanently lubricated sealed bearings in severe service conditions such as rollers and idlers of track-driven vehicles and agricultural equipment.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This Application is a Divisional of U.S. patent application Ser. No. 09/855,001, filed May 14, 2001, which is a Continuation-in-Part of U.S. patent application Ser. No. 09/690,524, filed Oct. 17, 2000 (now U.S. Pat. No. 6,406,026, issued Jun. 18, 2002), which is a continuation of U.S. application Ser. No. 08/937,427, filed Sep. 25, 1997 (now U.S. Pat. No. 6,186,507, issued Feb. 13, 2001); and U.S. patent application Ser. No. 09/855,001, filed May 14, 2001 is also a continuation-in-part of U.S. patent application Ser. No. 09/618,619, filed Jul. 18, 2000 (now U.S. Pat. No. 6,466,228, issued Oct. 15, 2002), which is a continuation-in-part of U.S. application Ser. No. 08/937,427, filed Sep. 25, 1997 (now U.S. Pat. No. 6,186,507, issued Feb. 13, 2001), all of the above which are herein incorporated by reference in their entirety. 

   FIELD OF THE INVENTION 
   The present disclosure is related to the field of seals for sealing dynamic shafts. The apparatus are particularly related to the field of unitary combination lip and sleeve seals. More specifically, this is an improved seal adapted for use in severe duty applications including construction equipment, agricultural machinery, track driven vehicles, and other applications where oil or grease must be held in contact with dynamic shaft assemblies. This seal and other seals of this type must also operate as excluder seals to keep lubricated surfaces free from corrosives, acids, other chemicals, dirt, mud, dust, abrasives, water and other contaminants. This seal incorporates design features that enhance performance (compared to usual original equipment seals) when installed on shafts that have been slightly damaged by normal wear. This seal can also be used as a roller or idler seal for track driven vehicles. 
   BACKGROUND OF THE INVENTION 
   The present seal structure yields a very important benefit that has eluded other persons skilled in the art. It can be retrofitted to existing, worn machinery to enhance the protection of costly lubricated machine components. This seal can replace existing seals, and the performance of this seal exceeds that of all other standard-sized, commercially available, conventional, lip and sleeve type seals. The only commercially available type of seal with performance comparable to this embodiment is the dual cone face seal. It is known by those in the art that dual cone face seals have the disadvantage of overall size that significantly restricts their use. The seal disclosed here overcomes that disadvantage. 
   Conventional unitized lip and sleeve seals are much thinner than dual cone face seals. Since this seal can be installed as a direct replacement for ordinary seals, it can be specified and used without making any modifications to the design of an existing machine. The shaft, the bore, and the housing in which the seal operates are identical whether the present seal or conventional seals are used. Wherever dual cone face seals are desired, the machine must have been originally designed specifically for their use. Dual cone face seals cannot fit into all of the machine locations because of design constraints. 
   It is an object of the invention to teach the structure and method of using a retrofittable severe duty seal for a shaft. 
   It is a further object of this disclosure to show a method useful for sealing bearings in shaft-mounted dynamic rollers used in track-driven vehicles. 
   Another object is to provide a seal that may be useful in any application where a shaft and shaft bearing or bushing surfaces may be exposed to mud, dust, abrasives, cement, submersion, abrasive liquids or other substances that could damage relative dynamic mechanical components. 
   Another object hereof is to disclose a seal that lasts longer than previously known conventional seals adapted for severe duty applications. 
   Another object of the present disclosure is to make essentially all of the important benefits of a dual cone face seal available in a physically smaller assembly. 
   It is an object to make essentially all of the important benefits of a dual cone face seal available in an assembly having the same physical dimensions as a conventional single lip or double lip seal. 
   Another object hereof is to provide a method for sealing a shaft and bearing assembly using a seal as an excluder seal, as a grease seal, as an oil seal, and as a seal for other liquids at low and moderate pressures. 
   Another object of this disclosure is to provide a method for using a seal having a shaft-contacting sleeve that enables the seal to be installed on and to operate reliably with shafts having imperfections such as those ordinarily caused by wear and use. 
   Another object is to provide a method of sealing a shaft and bearing assembly, using an unitary seal structure that both improves reliability, and makes seal installation easier compared to installation of seals that are composed of two or more separable parts. 
   These and further objects of the apparatus taught in accordance with this specification, the claims, and the figures are set forth below. 
   SUMMARY OF THE INVENTION 
   The availability of a seal having the superior performance characteristics of an embodiment according to the present disclosure in a package the size of ordinary seals gives additional freedom to designers of heavy machinery and severe duty assemblies. Many new design possibilities are made available by this seal because of the unitized style of the seal and the small width requirements as compared to dual cone face seals. 
   An important benefit of the seal disclosed is that it can create permanently lubricated shaft and bearing assemblies that can withstand severe use. This seal may enable equipment manufacturers to improve the performance of their machinery by reducing maintenance requirements. It is believed that existing vehicles and other machines can be retrofitted advantageously by replacing the original re-greasable seals with this new permanently lubricated seal. The lifetime of the new seal can last substantially longer than current lip seals. It is to be understood, however, that the present seal can be used to seal in either oil or grease and to substantially exclude all environmental contaminants that do not attack the materials from which the seal is manufactured. 
   The present disclosure shows a retrofittable, radial lip seal for sealing a paired shaft and bore assembly rotatable with respect to one another, the seal having a sleeve that may be disposed coaxially on the shaft, and a casing that may be disposed coaxially around the sleeve. The sleeve and casing have an inner end (oil or grease side) that would normally be in contact with the grease, oil, or other fluid to be contained within a housing, and an outer end (dirt side) opposite. The sleeve has a bore that may have an elastomeric coating. The seal also has seal case adapted for fitting into a bore, such as a bore that is formed through a roller end plate, the wall of a housing, or other securement. One or more circular elastomeric faceplate-contacting excluder lips extend coaxially opposite the oil side from a flange outer face. 
   The case is formed from a generally cylindrical case body having an outside surface, or outside diameter, that may be disposed within a bore and in contact with the wall of the bore. An elastomeric coating may be affixed to the outside of the case body. By coating the outside of the metal case body with an elastomeric coating or layer, it is possible for the seal to securely fit a bore that has become slightly damaged through use. 
   A resilient layer may cover the outside of the case to improve sealing in conditions where soft, damaged, or other less than optimal bore conditions exist that would impair reliable sealing with a steel outer case surface. In applications that might expose the sealed materials to corrosion, it is preferred to cover with resilient rubberized material all of the portions of the seal case that are likely to contact the corrosive agents. 
   The case elastomeric coating is formed with a chamfer to minimize the likelihood that the seal will be damaged during installation. One or more optional radial case relief channels may be formed in the case elastomeric coating. A relief channel may reduce the tendency of the elastomeric coating to form a bulge that could cause the seal to become unseated and move axially after installation. It is also possible to provide radial ribs on the outer surface of the case elastomeric coating for the purpose of providing desired installation properties. 
   A generally planar circular faceplate has an inside surface, an outside surface, and a central aperture slightly larger than the inside diameter of the sleeve. The plane of the inner faceplate surface is disposed generally perpendicular to the seal sleeve and case. An elastomeric portion, or faceplate wiper ring, can be attached to the faceplate at the central aperture so that the faceplate wiper ring extends between the faceplate and the shaft. The faceplate wiper ring has an internal diameter that allows it to contact the shaft and thereby exclude contaminants from the remainder of the seal and the sealed components. In another embodiment, the elastomeric portion, or faceplate wiper ring, can be attached to the case end of the faceplate to contact the inner diameter of the bore. 
   The sleeve bore is preferably coated with an elastomeric, or rubberized, coating to make it possible to obtain adequate sealing performance when the shaft condition is substandard due to wear, eccentricity, or other causes. A sleeve radial channel may be formed generally midway between the sleeve inner end and the sleeve outer end. The channel relieves shear tension that may develop during installation. The result is that it is easier to install the sleeve and the potential for damage to the sleeve during installation is reduced. 
   Chamfers are provided at both the inner end and at the outer end of the sleeve bore to reduce the potential for damage to the seal, the shaft, or the housing during installation. In addition, the inner end of the case outer surface is chamfered to make insertion of the sleeve through the housing easier and less likely to damage the dust lips or other components. 
   Flange peripheral lip and face lips may be formed in the same molding operation that is used to mold the sleeve bore elastomeric coating. The face lips may be designed with shapes similar to those of the peripheral lip and the three dust lips. However, an alternative design for the face lips is disclosed herein. The undercut face lips are adapted to provide superior performance in severe duty operating conditions. The advantage accrues because the undercut lip inside surface responds with increasing pressure in response to contact with materials that would penetrate the seal. The other lips contact the mating seal surface at distinctly different approach angles and with quite different elastomer shapes and configurations. 
   A sealing lip may also be employed in the seal. The sealing lip can be biased either against the seal sleeve or seal case. In one embodiment, a garter spring is used to bias the sealing lip. One embodiment does not have a sealing lip. Another embodiment has one sealing lip, and a third embodiment has more than one sealing lip. 
   An alternative form of the embodiment replacing the main sealing lip is favored for some very dirty applications, such as in agricultural machinery, or in applications where the width of the seal is severely limited due to the assembly configuration. One example in which the alternative embodiment of the seal can be used is in cultivator hub wheels. This type of equipment does not typically have much room for a seal around the bearing, and contains only grease in the assembly. In the alternative embodiment, the main sealing lip and the garter spring are replaced by at least one radial wiper, or excluder lip. In addition, the two sleeve contacting dust lips may also be eliminated in this alternative embodiment. The flat lip design may be less susceptible to catastrophic damage by the infiltration of small amounts of foreign materials than are the usual main seal lip and garter spring sets. It is also possible to produce the design with more lips; for example, a triple or quadruple lip design may be desired in some applications. Eliminating the garter spring and main sealing lip portions allows the seal to have a width of 5 mm inside the bore. This seal replaces typical triple lip seals commonly used in such applications, wherein the sealed portion must constantly be filled with grease to force out the grease, because it has either leaked out, or contains foreign material (e.g., dirt, dust, etc.), because those seals do not effectively keep the materials out. In contrast, the seal of the alternative embodiment does not have to be regreased, and is virtually maintenance free, because it effectively excludes foreign material from entering the sealed area, and does not allow the grease to leak out of the sealed area. 
   It is preferred to have the inner side of the faceplate smoothly finished to reduce wear on the face lips of the seal. Likewise, the outer surface of the sleeve, the sleeve flange inner face, and other any lip-contacting surfaces may be finished to a condition of low surface roughness to reduce the amount of wear to which the various elastomeric excluder and seal lips are subjected. For this reason, it is generally preferred to make the sleeve, case, and faceplate of metal such as stainless steel, carbon steel, or similar materials. It is to be understood, however, that the sleeve, case, and faceplate may be made from other metals and also from non-metallic materials. 
   In seals of this nature, the seals are normally described by reference to the cross-sectional configuration. The seal of the present embodiment may readily be manufactured in sizes between 0.5 inches and 26 inches with other sizes available on request. By way of example only and without any limitation on the configuration of embodiments of this disclosure, a representative seal may have an inside (shaft) diameter of 3⅛″, an outside (bore) diameter of 4⅛″, with an overall width of about 1″. The various dimensions do not scale proportionately. For example, the same type of seal may be manufactured for a 6¼″ shaft diameter but still have an overall width of 1″ and be designed to fit into a 7¾″ bore. Seals adapted to various purposes may vary in width from less than ⅛″ to over 1″ but generally have a width between ¼″ and ¾″. 
   It is to be understood, as well, that many different formulations of the elastomeric, or rubberized, elements may function satisfactorily. Viton®, nitrile, carboxylated nitrile, polyacrylate, ACM, fluoroelastomers, and silicone compounds are known to provide useful operational characteristics when adapted for incorporation within the seal presently disclosed. Other materials may also be incorporated to confer chemical resistance, extreme temperature resistance, expanded operating pressure range, wear resistance, or other desired properties to the final seal assembly. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  shows a cross-sectional profile of an embodiment of a retrofittable severe duty seal for a shaft according to the present disclosure. 
       FIG. 2  shows a cross-sectional profile of another embodiment of the retrofittable severe duty seal for a shaft. 
       FIG. 3  shows a cross-sectional profile of another embodiment of the retrofittable severe duty seal for a shaft. 
       FIG. 4  shows a cross-sectional profile of another embodiment of the retrofittable severe duty seal for a shaft. 
       FIG. 5  shows a cross-sectional profile of another embodiment of the retrofittable severe duty seal for a shaft. 
       FIG. 6  shows a cross-sectional profile of another embodiment of the retrofittable severe duty seal for a shaft. 
       FIG. 7  shows a cross-sectional profile of another embodiment of the retrofittable severe duty seal for a shaft. 
       FIG. 8  shows a cross-sectional profile of another embodiment of the retrofittable severe duty seal for a shaft. 
       FIG. 9  shows a cross-sectional profile of another embodiment of the retrofittable severe duty seal for a shaft. 
       FIG. 10  shows a representative assembly of a type that is adapted for receiving the retrofittable seal of  FIGS. 1-3 . 
       FIG. 11  shows a representative assembly of a type that is adapted for receiving the retrofittable seal of  FIGS. 4-7  and  8 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   Referring now to the various figures of the accompanying drawing,  FIG. 1  depicts a cross-sectional profile of an embodiment of the retrofittable severe duty seal  20  fitted onto a shaft  21 . A cylindrical sleeve  22  component is disposed coaxially over, and in contact with, the shaft  21  so that when installation is complete, the sleeve  22  is affixed to the shaft  21 . The sleeve inner end  24  extends into the sealed region, normally a housing or containment for oil or grease used to lubricate gears, bearings, or other moving parts. 
   To simplify nomenclature in this specification, the side or end or surface of a component that is oriented toward the lubricants, lubricated components, or other media from which it is desired to exclude dust, water, mud, and other environmental contaminants may be referred to using the terms “inner,” “inward,” “inside,” and similar terms. The words “outer,” “outward,” “outside” and similar terms may be used to refer to a side, end, or surface of a component that is oriented away from the sealed region, toward the exterior of a housing, or toward the unsealed overall environment into which a shaft extends. 
   Between the sleeve inner end  24  and the sleeve outer end  26 , the sleeve bore  28  may optionally be coated with an elastomeric coating  30 . The optional sleeve bore elastomeric coating  30  is desirable because it may prevent leakage from between the seal  20  and the shaft  21  even when the shaft is worn, damaged, or otherwise imperfect. 
   The sleeve flange  32  extends radially outwardly from the sleeve outer end  26  and has a sleeve flange outer edge  34  at its outer periphery. At least one, and preferably two, face lips  36  extend coaxially outwardly from the sleeve flange  32  outer face  38  and a perimeter lip  40  extends radially outwardly from the sleeve flange outer edge  34 . The sleeve bore elastomeric coating  30 , the face lips  36 , and the perimeter lip  40  may be integrally formed and bonded to the sleeve  22  in a single injection molding operation. 
   A seal case  50  is disposed coaxially outside the sleeve  22 . The seal case  50  has a generally cylindrical case body  52  designed so that the case outside surface  54  can fit into and seal against a bore in a housing or flange through which the shaft  21  to be sealed extends. In one embodiment, the case outside surface  54  can be coated with a case elastomeric coating  56 . The seal  20  is less likely to leak when installed in a damaged bore if the optional case elastomeric coating  56  is provided. The case body  52  has a case inner surface  58  that may be smoothly finished in the region near the case outer end  60  if the perimeter lip  40  will contact it. 
   The case inner end  62  is axially opposite the case outer end  60  and the case skirt  64  that extends radially outwardly from the case outer end  60 . 
   A case inner flange  66  extends radially inwardly from the case body  52  toward the sleeve  22 . The case inner flange  66  has a circular central aperture through which the shaft  21  and sleeve  22  fit. When the case inner flange  66  is drawn or otherwise made from the case body  52  it is possible to simultaneously form a case reinforcement  68  with a double layer of the material from which the case body  52  is made. 
   A main sealing lip  70  may attach to the case inner flange  66  and extend both axially inwardly and radially inward from the case inner flange  66 . The main sealing lip  70  contacts the sleeve outer surface  72  to form the primary sealing element by which the contents of the sealed volume are prevented from transferring to the outside of the assembly. The main sealing lip  70  is optionally biased against the sleeve outer surface  72  by a garter spring  74 . The sleeve outer surface  72  may be polished or otherwise finished to reduce wear of the main sealing lip  70 . For higher pressure applications, the garter spring  74  can be a high pressure garter spring, and the sleeve  22  can be constructed of a hardened metal in order to create a seal that functions under high pressure. 
   Additional optional sealing elements are situated axially outwardly from the main sealing lip  70 . These additional dust lips may extend between the case body  52 , particularly the case inner flange  66 , and the sleeve outer surface  72 . 
   A mid-sleeve dust lip  75  may be located generally between the case inner flange  66  and the sleeve outer surface  72 . A forward sleeve dust lip  76  may be disposed against the sleeve outer surface  72  at a location close to the sleeve flange  32 . A case flange dust lip  77  may extend from the case inner flange  66  to contact the sleeve flange  32 . The case elastomeric coating  56 , the main sealing lip  70 , the mid-sleeve dust lip  75 , the forward sleeve dust lip  76  and the case flange dust lip  77  may be integrally formed and bonded to the case body  52  and case inner flange  66  in a single injection molding operation. 
   On the inner end of the case body  52 , the case elastomeric coating  56  can be finished with a case elastomeric coating chamfer  78  to make it easier to install the seal  20  without distortion or damage. A case outside diameter relief channel  79  can be formed in the case elastomeric coating  56 . The optional relief channel  79  relieves axial shear stresses from the case elastomeric coating  56  that may be induced by the process of installing the seal  20  into a bore. 
   In one embodiment, as shown in  FIG. 1 , three main sub-assemblies, the sleeve  22 , the case  50 , and the faceplate  81  can be interconnected to form a complete seal  20 . These three sub-assemblies are normally made primarily of steel or other metal that is shaped, worked, and polished using conventional metalworking techniques and commercially available equipment. It may be advantageous to smooth the metal surfaces that are contacted by the various elastomeric components to obtain a metal finish having low surface roughness. Carefully shaped and molded elastomeric compounds may be bonded to the metal components in the configurations shown in the accompanying drawings. It is possible to form the elastomeric components and attach them to the metal structures in a variety of ways. In one embodiment, injection molding is used for these purposes. 
   Final assembly of the seal  20  is performed by carrying out four additional steps. First, water-resistant grease  80 , such as Esso Beacon 325™ is packed to fill all of the voids between the lips and between the case inner flange  66  and the case skirt  64 . Second, the sleeve  22  is inserted into the seal case  50  so that the sleeve flange dust lip  77  contacts the sleeve flange  32  and the perimeter lip  40  contacts the perimeter lip-contacting case inner surface  58 . Third, grease  80  is packed into the interstices between the individual face lips  36  and also between the perimeter lip  40  and the outermost of the face lips  36 . Fourth, the faceplate  81  is affixed to the case skirt  64  by crimping or other means to complete the assembly and unitizing process. 
   After the faceplate  81  is attached to the case skirt  64 , the faceplate inner side  82  contacts the face lips  36  and the sleeve flange inner face  84  is brought into contact with the case flange dust lip  77 . 
   An optional elastomeric faceplate wiper ring  86  can be bonded to a central aperture in the faceplate  81  coaxial with, and through which, the shaft  21  extends. The periphery of the faceplate  81  may be finished with a peripheral faceplate crimp edge  88  for crimping over the case skirt  64  when the faceplate  81  is attached by crimping. 
   A sleeve radial channel  90  is preferably formed within the sleeve bore elastomeric coating  30  to relieve shear as the seal  20  is fitted to a shaft. The sleeve  22  can be finished with a sleeve outer end chamfer  92  and a sleeve inner end chamfer  94  to reduce the potential for tearing of the sleeve bore elastomeric coating  30  and for distortion of the sleeve  22  during installation of the seal  20 . Likewise, the seal case  50  may be fitted with a case inner end chamfer  96  to reduce damage to the case elastomeric coating  56  when the case is fitted with elastomeric coating and to prevent case distortion in embodiments without case elastomeric coating  56 . 
   In one embodiment, the face lips  36  can be sharply angled radially inwardly with an acute point at the innermost portion of each of the face lips  36 . In order to form a lip having such a shape, it may be necessary to include a face lip undercut angle  98  that is less than 90 degrees to obtain the desired performance characteristics. The face lips  36  may be formed having a generally triangular cross-section. 
     FIG. 2  shows an embodiment wherein the single main sealing lip  70  and garter spring  74  shown in  FIG. 1  are replaced with a triple lip main seal  100 . It may be desirable to also eliminate the mid-sleeve dust lip  75  and the forward sleeve dust lip  76  from embodiments having the main sealing lip  70  replaced by the triple lip main seal  100 . This embodiment is especially useful for situations in which the space allowed for a seal in the assembly is less than approximately ¼″, and where the lubricant contained in the sealed area is grease, such as in cultivator hub wheels. 
     FIG. 3  shows an alternative embodiment of the seal  20  wherein the spacing relationship between the dust lips  75 ,  76 ,  77  is modified slightly from the relationship depicted in  FIG. 1 . 
     FIG. 4  depicts a cross-sectional profile embodiment of a flangeless retrofittable severe duty seal  20  fitted onto a shaft  21 . The absence of a flange where the faceplate attaches to the casing allows the seal to fit into a bore space better than the seal embodiment shown in  FIG. 1 . Like the flanged embodiment, a cylindrical sleeve  22  component is disposed coaxially over, and in contact with, the shaft  21  so that when installation is complete, the sleeve  22  is affixed to the shaft  21 . The sleeve inner end  24  extends into the sealed region, normally a housing or containment for oil or grease used to lubricate gears, bearings, or other moving parts. 
   Between the sleeve inner end  24  and the sleeve outer end  26 , the sleeve bore  28  may optionally be coated with an elastomeric coating  30 . The optional sleeve bore elastomeric coating  30  is desirable because it may prevent leakage from between the seal  20  and the shaft  21  even when the shaft is worn, damaged, or otherwise imperfect. 
   Like the embodiment shown in  FIG. 1 , a sleeve flange  32  extends radially outwardly from the sleeve outer end  26  and has a sleeve flange outer edge  34  at its outer periphery. At least one, and preferably two, face lips  36  extend coaxially outwardly from the sleeve flange  32  outer face  38  and a perimeter lip  40  extends outwardly from the sleeve flange outer edge  34 . The sleeve bore elastomeric coating  30 , the face lips  36 , and the perimeter lip  40  may be integrally formed and bonded to the sleeve  22  in a single injection molding operation. 
   A seal case  50  is disposed coaxially outside the sleeve  22 . The seal case  50  has a generally cylindrical case body  52  designed so that the case outside surface  54  can fit into and seal against a bore in a housing or flange through which the shaft  21  to be sealed extends. In one embodiment, the case outside surface  54  can be coated with a case elastomeric coating  56 . The seal  20  is less likely to leak when installed in a damaged bore if the optional case elastomeric coating  56  is provided. The case body  52  has a case inner surface  58  that may be smoothly finished in the region near the case outer end  60  if the perimeter lip  40  will contact it. 
   The case inner end  62  is axially opposite the case outer end  60 . An insert  100  (if there is more than one insert, a “first” or “medial” insert  100 ) may be introduced within the case  50  through the case inner end  62 . The medial insert  100  as shown in  FIG. 4 , has an outer surface, an insert inner end  102  and an outer end  104  that are securely disposed against the case inner surface  58  and the case outer end  60 . 
   A first insert flange  105  extends radially inwardly from the case body  52  toward the sleeve  22 . The first insert flange  105  has a circular central aperture through which the shaft  21  and sleeve  22  fit. Positioning the insert  100  within the case body  52  reinforces the structure with a double layer of the material from which the case body  52  is made. In addition, the insert flange  105  stiffens the case body  52 . Alternatively, as is shown in  FIG. 5 , the flange  105  can be drawn or otherwise made from the case body  52 , making it possible to simultaneously form a case reinforcement with a double layer of material from which the case body  52  is made. 
   It may be desirable to coat the case contacting insert  100  surface  102  with an elastomer coating  106  opposite the first insert inside cylindrical surface  108 . The elastomer coating  106  may extend to the insert flange bore  110  and may also be used to integrally form the seal lip  112  and excluder lips. 
   The secondary sealing lip  112  (in configurations having multiple inserts, otherwise it is the primary sealing lip) attaches to the case medial, or first, insert flange  105  and extends both axially inwardly and radially inward from the first insert flange  105 . The sealing lip  112  may be biased radially inwardly by a garter spring  114 . 
   An optional second, or oil side, cylindrical insert  116  may also be fitted within the case body  52 . An oil side insert outer surface  118  can be disposed against the case body inner surface  58  with the second insert inner end  122  proximate the case inner end  62  and the second insert outer end  124  adjacent the first insert inner end  102 . An oil side flange  126  extends radially inwardly toward the sleeve  22  and has affixed to it the elastomer coating  128  that also coats the oil side flange bore  130 . One or more oil side excluder lips  132  and the primary seal  70  may be formed integrally from the elastomeric coating  128  applied to the insert  116 . 
   The primary seal lip  70  contacts the sleeve outer surface  72  to form the sealing element by which the contents (generally fluids) of the sealed volume are prevented from transferring to the outside of the assembly. A biasing spring  74  may urge the main seal lip  70  against the sleeve outer surface  72 . 
   Likewise, the secondary sealing lip  112  is optionally biased against the sleeve outer surface  72  by a garter spring  114 . The sleeve outer surface  72  may be polished or otherwise finished to retard wear of the elastomeric elements. Additional contaminant excluding elements are situated axially outwardly from either or both the primary seal lip  70  and or the secondary sealing lip  112 . These additional dust lips (also called excluder lips) may extend between the case body  52  or from the inserts  100 ,  116  disposed within the case body  52  and brought into contact with the sleeve outer surface  72  or the inner side of the sleeve flange  32 . 
   A mid-sleeve dust lip  75  may be located generally between the first insert flange  105  and the sleeve outer surface  72 . A forward sleeve dust lip  76  may be disposed against the sleeve outer surface  72  at a location close to the sleeve flange  32 . A sleeve flange dust lip  77  may extend from the first insert flange  105  to contact the sleeve flange  32 . The case elastomeric coating  56 , the main sealing lip  70 , the mid-sleeve dust lip  75 , the forward sleeve dust lip  76  and the sleeve flange dust lip  77  may be integrally formed and bonded to the first insert  100  in a single injection molding operation. 
   On the inner end of the case body  52 , the case elastomeric coating  56  is finished with a case elastomeric coating chamfer  78  to make it easier to install the seal  20  without distortion or damage. A case outside diameter relief channel  79  is formed in the case elastomeric coating  56 . The optional relief channel  79  relieves axial shear stresses from the case elastomeric coating  46  that may be induced by the process of installing the seal  20  into a bore. Application of grease  80  to the shaft  21  or bore during installation is generally not recommended. 
   Three main sub-assemblies, the sleeve  22 , the case  50 , and the faceplate  81  are interconnected to form a complete seal  20 . These three sub-assemblies are normally made primarily of steel or another metal that is shaped, worked, and polished using conventional metalworking techniques and commercially available equipment. It may be advantageous to smooth the metal surfaces that are contacted by the various elastomeric components to obtain a metal finish having low surface roughness. Carefully shaped and molded elastomeric compounds are bonded to the metal components in the configurations shown in the accompanying drawing. It is possible to form the elastomeric components and attach them to the metal structures in a variety of ways, such as injection molding. 
   Final assembly of the seal  20  is performed by carrying out four additional steps. First, water-resistant grease  80 , such as Esso Beacon 325™ is packed to fill all of the voids between the lips and between the inserts  110 ,  116 . Second, the sleeve  22  is inserted into the seal case  50  so that the sleeve flange dust lip  77  contacts the sleeve flange  32  and the perimeter lip  40  contacts the perimeter lip-contacting case inner surface  58  or an equivalent cylindrical inner surface. Third, grease  80  is packed into the interstices between the individual face lips  36  and also between the perimeter lip  40  and the outermost of the face lips  36 . Fourth, the inserts  100 ,  116  are secured within the seal case  42  by crimping or other means to complete the assembly and unitizing process. 
   After the sleeve  22  is fitted within the seal case  50 , the faceplate inner side  82  contacts the face lips  36  and the sleeve flange inner face  84  is brought into contact with the sleeve flange dust lip  77 . 
   An optional elastomeric faceplate wiper ring  86  can be bonded to a central aperture in the faceplate  81  coaxial with, and through which, the shaft  21  extends. 
   A sleeve radial channel  90  is preferably formed within the sleeve bore elastomeric coating  30  to relieve shear as the sleeve  20  is fitted to a shaft. The sleeve is finished with a sleeve outer end chamfer  92  and a sleeve inner end chamfer  94  to reduce the potential for tearing of the sleeve bore elastomeric coating  30  and for distortion of the sleeve  22  during installation of the seal  20 . Likewise, the seal case  50  may be fitted with a case inner end chamfer  96  to reduce damage to the case elastomeric coating  56  when the case is fitted with elastomeric coating and to prevent case distortion in embodiments without case elastomeric coating  56 . A case crimp  97  is used to prevent the inserts  100 ,  116  from becoming dislodged during installation and operation. 
   It is believed preferable for the face lips  36  to be sharply angled radially inwardly with an acute point at the innermost portion of each of the face lips  36 . In order to form a lip having such a shape, it may be necessary to include a face lip undercut angle  98  that is less than 90 degrees to obtain the desired performance characteristics. The face lips  36  may be formed having a generally triangular cross-section. 
     FIG. 5  shows an embodiment wherein the seal  20  is fitted with a single insert  100  and sealing lip  70 . Although there may be some loss of ruggedness in this configuration, the countervailing considerations are that the seal can have a narrower profile, lower cost, lighter weight, lower rolling resistance, and still has excellent performance and durability. 
     FIG. 6  shows an alternative embodiment of the seal  20  wherein a triple lip main seal  120  is used in place of the single lip primary seal  70  with garter spring  74 . Otherwise, the configuration is similar to that depicted in  FIG. 4 . The triple lip seal  120  may allow a narrower profile, but will often require a seal configuration that has more radial space (i.e. increased height). 
     FIG. 7  shows another embodiment of the invention having a flexible filtering material  134  located between the faceplate  81  and the outside face  38  of the sleeve flange  32 . In one embodiment, the flexible filtering material  134  is a piece of wool felt. In another embodiment, the flexible filtering material is a synthetic filtering material. The filtering material  134  is suspended between the outside face  38  of the sleeve flange  32 , and the inside face of the faceplate. The flexible filtering material  134  may rotate with the sleeve flange  32 , or may remain stationary with the faceplate  81 . In an embodiment employing the flexible filtering material  134 , the end of the sleeve flange  34  may extend towards the sealed region to be approximately parallel with the sleeve  22 , forming a flange  35 , so that the face lips  36  and the perimeter lip  40  may contact the inner face  108  of an insert  105 . 
   A retaining lip  37  may be formed adjacent to the face lips  36 , to help to hold the filtering material  134  in place. In one embodiment, the retaining lip  37  is made at least in part with an elastomeric material. Also in this embodiment, the end of the faceplate  136  may extend towards the sealed region to form a flange  138  that can help to hold the filtering material  134  in place. 
   The seal shown in  FIG. 7  can be modified to employ other characteristics described for the other embodiments of the present invention. For instance, the seal of  FIG. 7  could employ a case skirt, such as that shown in  FIGS. 1-3 , and the faceplate  81 , as a separate piece from the case  56 , can be crimped to the case skirt to form a connection. The main sealing lip  70  can also be replaced by a triple lip seal, as shown in  FIGS. 2 and 6 . The seal can also employ a second insert and a secondary sealing lip as shown in  FIG. 4 . 
     FIG. 8  shows another embodiment of the seal of the present invention. The seal shown in  FIG. 8  is an inverted example of the seals depicted in  FIGS. 4-7 . The seal of  FIG. 8  is useful for applications having a stationary shaft and a rotating bore section, such as in a tread driven vehicle. 
   A cylindrical sleeve  22  component is disposed coaxially over, and in contact with, the shaft  21  so that when installation is complete, the sleeve  22  is affixed to the shaft  21 . The sleeve inner end  24  extends into the sealed region, normally a housing or containment for oil or grease used to lubricate gears, bearings, or other moving parts. 
   Between the sleeve inner end  24  and the sleeve outer end  26 , the sleeve bore  28  may optionally be coated with an elastomeric coating  30 . The optional sleeve bore elastomeric coating  30  is desirable because it may prevent leakage from between the seal  20  and the shaft  21  even when the shaft is worn, damaged, or otherwise imperfect. 
   A seal case  50  is disposed coaxially outside the sleeve  22 . The seal case  50  has a generally cylindrical case body  52  designed so that the case outside surface  54  can fit into and seal against a bore in a housing or flange through which the shaft  21  to be sealed extends. In one embodiment, the case outside surface  54  can be coated with a case elastomeric coating  56 . The seal  20  is less likely to leak when installed in a damaged bore if the optional case elastomeric coating  56  is provided. The case body  52  has a case inner surface  58  that may be smoothly finished if the main sealing lip  70  and dustlip  75  are to be in contact with the inner surface  58 . 
   A case flange  150  extends radially inwardly from the case outer end  60  and has a case flange outer edge  152  at its outer periphery. The case flange  150  has a circular central aperture through which the shaft  21  and sleeve  22  fit. At least one, and preferably two, face lips  36  extend coaxially outwardly from the case flange  150  outer face  154  and a perimeter lip  40  extends radially inwardly from the sleeve flange outer edge  152 . The case outside surface elastomeric coating  30 , the face lips  36 , and the perimeter lip  40  may be integrally formed and bonded to the case  50  in a single injection molding operation. 
   The sleeve inner end  24  is axially opposite the sleeve outer end  26 . An insert  140  (if there is more than one insert, a “first” or “medial” insert  140 ) may be introduced within the sleeve  22  through the sleeve inner end  24 . The medial insert  140  as shown in  FIG. 8 , has an outer surface, an insert inner end  156  and an outer end  158  that are securely disposed against the sleeve outer surface  72  and the sleeve outer end  26 . 
   A first insert flange  142  extends radially outwardly from the sleeve body  22  toward the case  50 . Positioning the insert  140  within the sleeve body  22  reinforces the structure with a double layer of the material from which the sleeve body  22  is made. In addition, the insert flange  142  stiffens the sleeve body  22 . Alternatively, the flange  142  can be drawn or otherwise made from the sleeve body  22 , making it possible to simultaneously form a sleeve reinforcement with a double layer of material from which the sleeve body  22  is made. 
   It may be desirable to coat the sleeve contacting insert  146  surface with an elastomer coating  160  opposite the first insert inside insert surface  144 . The elastomer coating  160  may extend outward from the end of the insert flange  148  and may also be used to integrally form the seal lip  70  and excluder lip  132 . 
   The seal shown in  FIG. 8  can optionally have a secondary sealing lip (in configurations having multiple inserts, such as numeral  112  in  FIG. 4 , otherwise it is the primary sealing lip), which attaches to the sleeve medial, or first, insert flange  140  and can extend both axially inwardly and radially outward from the first insert flange  140 . The sealing lip may be biased radially outwardly by a garter spring  74 . 
   An optional second, or oil side, cylindrical insert (such as numeral  116  in  FIG. 4 ) may also be fitted within the seal body  22 . All of the features of the second insert as described in  FIG. 4  may apply to the seal of  FIG. 8 , except that it would be inverted. For instance, the insert would be attached to the sleeve  22  instead of the case, and the lips and flanges would extend radially outward from the sleeve. 
   The primary seal lip  70  contacts the case inner surface  58  to form the sealing element by which the contents (generally fluids) of the sealed volume are prevented from transferring to the outside of the assembly. A biasing spring  74  may urge the main seal lip  70  against the case inner surface  58 . 
   Likewise, an optional secondary sealing lip (not shown) is optionally biased against the case inner surface  58  by a garter spring. The case inner surface  58  may be polished or otherwise finished to retard wear of the elastomeric elements. Additional contaminant excluding elements are situated axially outwardly from either or both the primary seal lip  70  and or the optional secondary sealing lip. These additional dust lips (also called excluder lips) may extend from the sleeve body  22 , or from the insert  140  disposed within the sleeve body  22  and brought into contact with the case inner surface  58  or the inner side of the case flange  154 . 
   A mid-sleeve dust lip  75  may be located generally between the first insert flange  142  and the case inner surface  58 . Other optional lips, such as a forward sleeve dust lip may be disposed against the sleeve outer surface at a location close to the case flange  150 . A case flange dust lip may also extend from the first insert flange  142  to contact the case flange  150 . The case elastomeric coating  56 , the main sealing lip  70 , the mid-sleeve dust lip  75 , and other optional lips, such as the forward sleeve dust lip and the sleeve flange dust lip, may be integrally formed and bonded to the first insert  140  in a single injection molding operation. 
   On the inner end of the case body  52 , the case elastomeric coating  56  is finished with a case elastomeric coating chamfer  78  to make it easier to install the seal  20  without distortion or damage. A case outside diameter relief channel  79  is formed in the case elastomeric coating  56 . The optional relief channel  79  relieves axial shear stresses from the case elastomeric coating  46  that may be induced by the process of installing the seal  20  into a bore. Application of grease  80  to the shaft  21  or bore during installation is generally not recommended. A sleeve crimp  162  is used to prevent the insert  140  from becoming dislodged during installation and operation. 
   A sleeve radial channel  90  is preferably formed within the sleeve bore elastomeric coating  30  to relieve shear as the sleeve  20  is fitted to a shaft. The sleeve is finished with a sleeve outer end chamfer  92  and a sleeve inner end chamfer  94  to reduce the potential for tearing of the sleeve bore elastomeric coating  30  and for distortion of the sleeve  22  during installation of the seal  20 . Likewise, the seal case  50  may be fitted with a case inner end chamfer  96  to reduce damage to the case elastomeric coating  56  when the case is fitted with elastomeric coating and to prevent case distortion in embodiments without case elastomeric coating  56 . 
   The seal also has a faceplate  81  similar to the seals in  FIGS. 1-7 , where the faceplate inner face  82  contacts the excluder lips  36 . In a seal having a stationary shaft and a rotating bore, the faceplate is operably coupled to the sleeve  22 . The end of the faceplate  85  can have a wiper ring  86  attached to it. In one embodiment, the wiper ring is constructed at least in part with an elastomeric material. 
     FIG. 9  shows an embodiment of the invention, wherein the seal case  50  extends inward to form a sleeve  164  that can be used as a housing for a bearing  166  or a bearing holder (not shown). The seal  20  can be any seal designed to fit onto a rotating shaft, such as the seals depicted in  FIGS. 1-7 . Once a bearing  166  is inserted into the housing  164 , the entire unit can be inserted into a bore. 
     FIG. 10  shows a representative application in which the seal  20  may be installed, specifically, a worm gear drive assembly  201 . The seal  20  is fitted into the bore of a housing  202  to seal a bearing  204  from outside contaminants and to prevent lubricants from leaking out of the housing  202  around the output shaft  206  of the worm gear drive assembly  201 . The seal  20  depicted in  FIG. 10  is a flanged seal, such as those depicted in  FIGS. 1-3 . However, any of the seals and combinations of elements of the seals depicted in any of the  FIGS. 1-7  may be used in this application. 
     FIG. 11  shows a representative application in which the seal  20  may be installed, specifically, a roller assembly  210 . The seal  20  in  FIG. 11  can be any of the seals depicted in the above figures. In  FIG. 11 , the seal is a flanged seal, such as those depicted in  FIGS. 1-3 . The roller  210  is retained on a stub shaft  212  secured with any known stub fastener assembly  213 , for example screw fasteners that retain a plate. The roller  210  may be comprised of an end cap  214 , opposite a seal cover  216  held in place by cover fasteners  218  such as cap screws that engage, either directly or indirectly, a roller load-contacting peripheral surface  220  situated between the end cap  214  and the seal cover  216 . By way of illustration only, and not by way of limitation, a stub shaft  212  may have a shoulder  222  and the end cap  214  may have a shoulder  223  also between which against which a distal roller bearing  224  may fit when affixed to the shaft  212 . Adjacent the roller bearing  224  and opposite the shaft shoulder  222 , a retainer  226  may be installed on the shaft  212  to prevent the roller  210  from detaching. 
   A coaxial spacer  228  can be fitted between the distal roller bearing  224  and a medial roller bearing  230 . A cover shoulder  232  urges the medical roller bearing  230  against the spacer  228 . The seal  20  is fitted into the cover bore  234  to prevent loss of lubricant and to exclude contaminants from the bearings  224   230 . 
   From the foregoing, it may be readily understood by those skilled in the art that the embodiments disclosed are applicable to industry and mechanical power transmissions generally, and to machinery and vehicles that are operated in severe environments, particularly. Incorporation of the present embodiment into new and existing equipment is expected to substantially reduce the maintenance requirements of many types of construction and agricultural equipment. 
   To use the seals as described, a dynamic shaft assembly is provided, wherein a housing containing the assembly has a bore through which the assembly extends. A seal  20  as described above is coaxially fitted onto the shaft, and is designed so that the case body  52  can fit into and seal against the bore, thus sealing the bearing, and preventing lubricants from escaping the assembly, and foreign materials from entering. 
   Changes and modifications in the specifically described embodiments can be carried out without departing from the scope of the invention which is intended to be limited only by the scope of the claims. 
   With regard to means for fastening, mounting, attaching or connecting the components of the present invention to form the seal as a whole, unless specifically described otherwise, such means are intended to encompass conventional fasteners such as nut and bolt-type connectors, threaded connectors, snap members, clamps and the like, rivets, toggles, pins and the like. Components may also be connected by welding, friction fitting or deformation, if appropriate. Electrical connections, if any, for use in or during the process, may be made using appropriate electrical components and connection methods, including conventional components and connectors. Suitable computers, microprocessors and the like may be used in the method. Unless specifically otherwise disclosed or taught, materials for making components of the present invention are selected from appropriate materials such as metal, metallic alloys, fibers, plastics and the like, and appropriate manufacturing or production methods including casting, extruding, molding and machining may be used. 
   Any references to front and back, right and left, top and bottom and upper and lower are intended for convenience of description, not to limit the present invention or its components to any one positional or spacial orientation. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.