Abstract:
A unitary sleeve lip seal can be used to provide permanently lubricated sealed bearings in severe service conditions such as the track pins of track-driven vehicles and agricultural equipment. The seal has a labyrinthine exclusion path and multiple dust lips contacting the sleeve in addition to the main sealing lip. A garter spring encircling the main sealing lip may enable the seal to operate at moderately elevated pressures. The sleeve has a radial flange at the outermost end. Elastomeric lips extend between the sleeve flange and a faceplate that terminates the outside end of the seal housing. The seal is packed with water-resistant grease and can, when installed in association with grease-packed bearings can create a permanently lubricated bearing/shaft assembly that requires no re-greasing. Resilient coatings both protect the sleeve and case and also improve leak resistance, especially when the seal is retrofitted onto shafts that have been damaged. The design provides a seal having performance that is comparable to that of dual cone face seals at a much lower cost and in a much smaller assembly. Seals made according to this design can easily be made in standard sizes that can serve as direct replacements for previously available seals.

Description:
RELATED APPLICATIONS 
     This application is a Continuation-in-part of Ser. No. 08/937,427 filing date Sep. 25, 1997 U.S. Pat. No. 6,186,507, issued on Feb. 13, 2001 to Michael R. Oldenburg, entitled Retrofittable Severe Duty Seal For A Shaft. 
    
    
     TECHNICAL FIELD 
     The present disclosure is related to the field of seals for sealing rotary shafts, generally. The methods and 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 rotary shaft and bearing 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. Even more particularly, 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. Most specifically, this seal can be used as a pin or roller seal for track driven vehicles. 
     BACKGROUND AND SUMMARY 
     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 shields have disadvantages that significantly restrict their use. The seal disclosed here overcomes the two major inherent disadvantages of dual cone face seals—large size and high cost. 
     Conventional unitized lip and sleeve seals are much smaller 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 because they are much larger than ordinary seals. They are simply too big to fit all of the machine locations where their superior performance could justify the significant added cost. 
     However, 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. Design possibilities made available by this new seal include increasing the size of wear surfaces without the necessity of increasing the overall size of the assembly to enhance the useful life of machines and their component parts. Another design possibility is to expand the utility of existing designs by making them better adapted for broader ranges of service. 
     The cost of making a seal according to the present disclosure is only a fraction of the cost of making a dual cone face seal. Cost savings can be substantial because the manufacturing cost for a dual cone face seal is currently between twenty and ninety times the cost of a conventional seal. A preferred embodiment of the present disclosure is expected to be two to three times the cost of a conventional seal. In some applications, such as crawler vehicles, a single machine will typically require 40 to 60 roller seals, each of which is subjected to extremes of heat, cold, moisture, dust, abrasives, acids and alkalis. In addition, the loads imposed on track vehicle components fluctuate extremely. For example, a roller may be subject to little load while the vehicle operates on a flat, level surface; but when tracks advance to a raised obstruction such as a rock, each roller that moves over the rock may be sequentially required to support almost the entire weight of the vehicle. The constantly fluctuating loads exacerbate the effects of any deviation from component design tolerances. 
     The most important benefit of the seal now 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. It is to be understood, however, that the present seal can be used to seal in either oil or grease and to exclude all environmental contaminants that do not attack the materials from which the seal is manufactured. 
     It is an object of the invention to accomplish the foregoing and to teach the structure of an externally flangeless retrofittable severe duty seal for a shaft. 
     It is a further object of this disclosure to show an embodiment useful for sealing bearings in shaft-mounted rotary rollers used in track-driven vehicles. 
     Another object is to provide an embodiment 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 rotary mechanical components. 
     Another object hereof is to disclose a seal that lasts longer than previously known low cost 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 at a much lower cost. 
     Yet another object hereof 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 an embodiment that can function 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 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 specific object is to provide a 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. 
     A further object is to provide a seal with sealing elements that include: a main sealing lip with a garter spring that biases the main sealing lip against the outside of the sleeve, at least one dust lip that contacts the sleeve, at least one dust lip that contacts the inner surface of the housing, at least one face dust lip that contacts the inner surface of the faceplate, and an elastomeric, shaft-contacting faceplate ring. 
     These and further objects of the apparatus taught in accordance with this specification, the claims, and the appended drawing figures are set forth below. 
     DISCLOSURE OF THE INVENTION 
     The present disclosure Shows an externally flangeless, unitized, retrofittable, radial lip seal for a paired shaft and bore assembly rotatable with respect to one another having a sleeve that may be disposed coaxially on the shaft. The term externally flangeless refers to seals in which the flanges are inside the seal, i.e., inside the seal case. Consequently, externally flangeless seals disclosed in the specification have sleeve and case flanges that are internal flanges, i.e., flanges that are inside the seal case. The sleeve has an inner end, (oil side) that would normally be in contact with the grease, oil, or other fluid to be contained within a housing, an outer end (dirt side) opposite, a bore that has an elastomeric coating, and a sleeve flange extending radially outward from the outer end of the sleeve and generally perpendicular to the sleeve axis. The sleeve flange is terminated with an outer edge. One or more circular elastomeric faceplate-contacting lips extend coaxially opposite the oil side from the sleeve flange outer face. 
     A circular elastomeric perimeter lip extends radially and outwardly from the outer edge of the sleeve flange to contact a generally cylindrical hollow 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. 
     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. 
     The inner surface of the case is smoothly finished in the region close to the outer end to properly adapt it for maintaining continuous operating contact with the perimeter lip of the sleeve flange. The case has an inner, fluid-contacting, end opposite the outer end; the inner end is sometimes referred to as the “oil side.” A case flange extends radially inward from, and generally perpendicular to, the outside end of the case. Various processes such as drawing, coining, or forging may be employed to make the case body and the case flange as a unit from a single piece of cylindrical tubular material. An equivalent case body and case flange assembly may also be formed by joining separate component parts. 
     Two case inner flanges are located between the outer end and the fluid end of the case. The case inner flanges extend radially inward from the case to support two axially spaced-apart seal elements, each of which may be fitted with a garter spring. 
     The case inner flanges extend radially inwardly from, and generally perpendicular to, the longitudinal axis of the inside of the case. When formed of two additional pieces of material, preferably coated with elastomer, the case has double thickness of material. The case reinforcement provided by the double layer of metal makes allows the use of a slightly thinner material to form the case body than would be necessary if the case material was a single thickness. Other methods of construction may be adopted, however, without departing from the scope of the invention disclosed. For example, one or more case inner flanges may be inserted into the case sequentially. 
     A sleeve-contacting secondary sealing lip may be formed on the radial flange of a first, or medial, insert. When the seal is assembled, grease such as Esso Beacon 325 or any other high quality, light, stable grease is applied to the surfaces of the sleeve and it is placed with the sleeve flange proximate the faceplate. The first, or medial insert is then greased and placed in the case with the seal lip, which may be fitted with a biasing garter spring, contacting the sleeve. Additional excluder, or dust, lips may extend from the radial flange of the insert to contact the sleeve and/or the sleeve flange. 
     A second, or oil side, insert may then be placed into the case with the oil side insert flange having a primary oil seal affixed to it and biased against the sleeve by a garter spring. One or more excluder lips may also be formed as part of the oil side insert to provide additional assurance that contaminants will not penetrate and contaminate the lubricant and bearing surfaces. It is desirable to fill the void spaces with grease during assembly. The grease reduces friction and wear, provides additional barriers to dust and other contaminants, and enhances seal performance by preserving the resiliency of elastomeric portions. 
     When the seal has been packed with grease and assembled, the inner end of the case may be crimped over the oil side insert inner end to secure the assembly and prevent dis-assembly during installation or use. 
     At least one sleeve-contacting, elastomeric, sealing lip extends from each case inner flange to operatively contact the outer surface of the sleeve at a region near the inner end of the sleeve. The main sealing lips may be fitted with a garter spring to enable the assembly to operate at higher pressures. Testing has confirmed that the seal disclosed herein can operate reliably at a pressure of one atmosphere (15 p.s.i.) with shaft speeds of 700 feet per minute. 
     The maximum pressure at which this seal, like seals in general, can reliably operate decreases with increasing shaft speed. Testing may show that operation is satisfactory at pressures of approximately 100 p.s.i. or that slight changes could allow the seal to operate in the range of 100 p.s.i. However, testing at higher pressures and rotational velocities had not been concluded before preparation of the present disclosure. 
     The primary and the secondary sealing lips extend inwardly, toward the inner end and medial region of the sleeve, coaxially with the sleeve. One or more dust lips are positioned to extend radially inwardly from the medial insert flange into coaxial contact with the sleeve outer surface. One of the inwardly oriented dust lips, the mid-sleeve dust lip, may be disposed generally between the case inner flange aperture and the sleeve outer surface. The optional second sleeve contacting dust lip, the forward sleeve dust lip, is disposed generally midway between sleeve flange and the medial insert flange. A third dust lip, the medial insert flange dust lip, extends axially outwardly from the medial insert flange. The three dust lips and the secondary sealing lip are molded at high temperatures in one piece using a single mold operation and bonded to the insert with suitable bonding agents. 
     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. It is possible to cover the oil side insert and form the primary seal element similarly. 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 relieves 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 parallel to the case skirt and the face of the sleeve flange. 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. 
     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. 
     The 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. 
     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 the perimeter lip-contacting medial insert inside cylindrical surface 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, fluroelastomers, 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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 shows a cross-sectional profile of a flangeless retrofittable severe duty seal for a shaft according to the present disclosure. 
     FIG. 2 shows a cross-sectional profile of an alternative embodiment of a flangeless retrofittable severe duty seal for a shaft which has only one insert and seal lip. 
     FIG. 3 shows a cross-sectional profile of the structure of an alternative embodiment of the seal of FIG. 1 that has an alternative configuration for the main sealing lip. 
     FIG. 4 shows a sample roller assembly into which the flangeless retrofittable severe duty seal for a shaft of FIG. 1 is installed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the various figures of the accompanying drawing, FIG. 1 depicts a cross-sectional profile of an embodiment of the externally flangeless retrofittable sever 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. 
     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 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  42  is disposed coaxially outside the sleeve  22 . The seal case  42  has a generally cylindrical case body  44  designed so that the case outside surface  45  can fit into and seal against a bore in a housing or flange through which the shaft  21  to be sealed extends. It is preferred to enclose the case outside surface  45  with an optional case elastomeric coating  46 . The seal  20  is less likely to leak when installed in a damaged bore if the optional case elastomeric coating  46  is provided. The case body  44  has a case inner surface  47  that may be smoothly finished in the region near the case outer end  48  if the perimeter lip  40  will contact it. 
     The case inner end  49  is axially opposite the case outer end  48 . An insert  50  (if there is more than one insert, a “first” or “medial” insert  50 ) may be introduced within the case  42  through the case inner end  49 . The medial insert  50  has an outer surface  51 , an insert inner end  52  and an outer end  53  that are securely disposed against the case inner surface  47  and the case outer end  48 . 
     A first insert flange  54  extends radially inwardly from the case body  44  toward the sleeve  22 . The first insert flange  54  has a circular central aperture through which the shaft  21  and sleeve  22  fit. Positioning the insert  50  within the case body  44  reinforces the structure with a double layer of the material from which the case body  44  is made. In addition, the insert flange  54  stiffens the case body  44 . 
     It may be desirable to coat the case  44  contacting insert  50  surface with an elastomer coating  55  opposite the first insert inside cylindrical surface  56 . The elastomer coating  55  may extend to the insert flange bore  57  and may also be used to integrally form the seal lip  58  and excluder lips. 
     The secondary sealing lip  58  (in configurations having multiple inserts, otherwise it is the primary sealing lip) attaches to the case medial, or first, insert flange  54  and extends both axially inwardly and radially inward from the first insert flange  54 . The sealing lip  58  may be biased radially inwardly by a garter spring  59 . 
     A optional second, or oil side, cylindrical insert  60  may also be fitted within the case body  44 . An oil side insert outer surface  61  can be disposed against the case body inner surface  47  with the second insert inner  62  end proximate the case inner end  49  and the second insert outer end  63  adjacent the first insert inner end  52 . An oil side flange  64  extends radially inwardly toward the sleeve  22  and has affixed to it the elastomer coating  65  that also coats the oil side flange bore  67 . One or more oil side excluder lips  69  and the primary seal  70  may be formed integrally from the elastomeric coating  65  applied to the insert  60 . 
     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  58  is optionally biased against the sleeve outer surface  72  by a garter spring  59 . 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  58 . These additional dust lips (also called excluder lips) may extend between the case body  44  or from the inserts  50   60  disposed within the case body  44  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  54  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  54  to contact the sleeve flange  32 . The case elastomeric coating  46 , 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  50  in a single injection molding operation. 
     On the inner end of the case body  44 , the case elastomeric coating  46  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  46 . 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  42 , 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; however, injection molding is believed preferable 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 inserts  50   60 . Second, the sleeve  22  is inserted into the seal case  42  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  47  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  50   60  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  42 , 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  22  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  42  may be fitted with a case inner end chamfer  96  to reduce damage to the case elastomeric coating  46  when the case is fitted with elastomeric coating and to prevent case distortion in embodiments without case elastomeric coating  46 . A case crimp  97  is used to prevent the inserts  50   60  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. 2 shows an embodiment wherein the seal  20  is fitted with a single insert  50  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. 3 shows an alternative embodiment of the seal  20  wherein a triple lip main seal  100  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.  1 . The triple lip seal  100  may allow a narrower profile, but will often require a seal configuration that has more radial space (i.e. increased height). 
     FIG. 4 shows a representative application in which the seal  20  may be installed, specifically, a roller assembly  110 . The roller  110  is retained on a stub shaft  112  secured with any known stub fastener assembly  113 , for example screw fasteners that retain a plate. The roller  110  may be comprised of an end cap  114 , opposite a seal cover  116  held in place by cover fasteners  118  such as cap screws that engage, either directly or indirectly, a roller load-contacting peripheral surface  120  situated between the end cap  114  and the seal cover  116 . By way of illustration only, and not by way of limitation, a stub shaft  112  may have a shoulder  122  and the end cap  114  may have a shoulder  123  also between which against which a distal roller bearing  124  may fit when affixed to the shaft  112 . Adjacent the roller bearing  124  and opposite the shaft shoulder  122 , a retainer  126  may be installed on the shaft  112  to prevent the roller  110  from detaching. 
     A coaxial spacer  128  can be fitted between the distal roller bearing  124  and a medial roller bearing  130 . A cover shoulder  132  urges the medial roller bearing  130  against the spacer  128 . The seal  20  is fitted into the cover bore  134  to prevent loss of lubricant and to exclude contaminants from the bearings  124   130 . 
     INDUSTRIAL APPLICABILITY 
     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 transmission 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. 
     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 appended claims. 
     
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 REFERENCES TO DRAWING NUMBERS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 20 
                 Flangeless Retrofittable Severe 
                 56 
                 (medial or first) insert 
               
               
                   
                 Duty Seal for a Shaft 
                   
                 side cylindrical surface 
               
               
                 21 
                 shaft (reduced scale) 
                 57 
                 (medial or first) insert 
               
               
                   
                   
                   
                 flange bore 
               
               
                 22 
                 sleeve 
                 58 
                 secondary seal lip 
               
               
                 24 
                 sleeve inner end (oil end) 
                 59 
                 secondary seal garter spring 
               
               
                 26 
                 sleeve outer end (air end) 
                 60 
                 oil side cylindrical insert 
               
               
                 28 
                 sleeve bore 
                 61 
                 oil side insert outer surface 
               
               
                 30 
                 sleeve bore elastomeric coating 
                 62 
                 oil side insert inner end 
               
               
                 32 
                 sleeve flange 
                 63 
                 oil side insert outer end 
               
               
                 34 
                 sleeve flange outer edge 
                 64 
                 oil side flange 
               
               
                 36 
                 face lips 
                 65 
                 oil side elastomer coating 
               
               
                 38 
                 sleeve flange outer face 
                 67 
                 oil side flange bore 
               
               
                 40 
                 perimeter lip 
                 69 
                 primary seal excluder lip 
               
               
                 42 
                 seal case 
                 70 
                 primary seal lip 
               
               
                 44 
                 case, body 
                 72 
                 sleeve outer surface 
               
               
                 45 
                 case outside surface 
                 74 
                 primary seal garter spring 
               
               
                 46 
                 case elastomeric coating 
                 75 
                 mid-sleeve dust lip 
               
               
                 47 
                 case body inner surface 
                 76 
                 forward sleeve dust lip 
               
               
                 48 
                 case outer end 
                 77 
                 sleeve flange dust lip 
               
               
                 49 
                 case inner end 
                 78 
                 case elastomeric coating 
               
               
                 50 
                 insert or medial (first) insert 
                   
                 chamfer 
               
               
                 51 
                 (medial or first) insert outer 
                 79 
                 case outside diameter 
               
               
                   
                 surface 
                   
                 optional relief channel 
               
               
                 52 
                 (medial or first) insert inner end 
                 80 
                 grease 
               
               
                 53 
                 (medial or first) insert outer end 
                 81 
                 faceplate 
               
               
                 54 
                 (medial or first) insert flange 
                 82 
                 faceplate inner side 
               
               
                 55 
                 (medial or first) insert elastomer 
                 84 
                 sleeve flange inner face 
               
               
                   
                 portion 
                 86 
                 elastomeric faceplate wiper 
               
               
                   
                   
                   
                 ring 
               
               
                 94 
                 sleeve inner end chamfer 
                 90 
                 sleeve radial channel 
               
               
                 96 
                 case inner end chamfer 
                 92 
                 sleeve outer end chamfer 
               
               
                 97 
                 case crimp 
               
               
                 98 
                 face lip undercut angle 
               
               
                 100 
                 alternative, triple lip, main seal 
               
               
                 110 
                 roller assembly 
               
               
                 112 
                 stub shaft 
               
               
                 113 
                 stub shaft fastener assy. 
               
               
                 114 
                 end cap 
               
               
                 116 
                 seal cover 
               
               
                 118 
                 cover fasteners 
               
               
                 120 
                 roller load-contacting peripheral 
               
               
                   
                 surface 
               
               
                 122 
                 shaft shoulder 
               
               
                 123 
                 end cap shoulder 
               
               
                 124 
                 distal roller bearing 
               
               
                 126 
                 retainer 
               
               
                 128 
                 spacer 
               
               
                 130 
                 medial roller bearing 
               
               
                 132 
                 cover shoulder 
               
               
                 134 
                 cover bore