Abstract:
Method of assembling a drum brake device includes positioning a portion of a brake shoe ( 22 ) support structure ( 40, 42 ) near an opening of a brake actuating cylinder ( 80 ); manipulating the support structure ( 40, 42 ) so that a window ( 44 ) of the support structure ( 40, 42 ) is received over a portion of a shoe mount ( 50 ); moving the support structure ( 40, 42 ) relative to the shoe mount ( 50 ) so that the portion of the support structure ( 40, 42 ) is received into the brake actuating cylinder ( 80 ) and the support structure ( 40, 42 ) is engaged by the shoe mount ( 50 ) in a manner that the shoe mount ( 50 ) restricts movement of the brake shoe ( 22 ) in two dimensions and allows selective movement in a third dimension; and securing the brake shoe ( 22 ) in an installed position by placing the drum ( 26 ) over the brake shoe ( 22 ) with the braking surface facing the friction lining.

Description:
BACKGROUND 
       [0001]    Automotive vehicles include brakes associated with the wheels for controlling movement of the vehicle. For many years drum brakes have been used. Disc brakes are also well known. 
         [0002]    A typical configuration of a drum brake device includes two brake shoes that are forced outwardly against an inner surface of a drum. While drum brakes typically function reasonably well, they present challenges during assembly and service because of the relatively large number of springs, clips, linkages and adjusters that are used to hold the brake shoes in position. 
         [0003]    Three known types of drum brakes include the duo-servo brake, the two leading shoe brake (also known as the duplex brake) and the leading/trailing brake (also known as the simplex brake). The principle differences among these three drum brake types are the way in which the brake torque reaction is handled by the brake shoes. An anchor pin or abutment located at the leading edge of the shoe takes the torque reaction in the individual leading shoe arrangement. The trailing shoe arrangement, by contrast, has an anchor pin at the trailing end of the shoe. In a duo-servo brake, both shoes act in series on a single abutment at the leading end of one of the shoes. 
         [0004]    In all of the drum brake geometries described above, some level of self-excitation occurs. The brake application force may be amplified by the generation of tangential braking forces on the surface of the brake lining. While self-excitation was useful before power assisted brake systems were introduced, there may be disadvantages to a self-excited brake geometry. Greater sensitivity to changes in the coefficient of friction of the brake lining may be a disadvantage. Duo-servo brakes, in particular, have been known to experience brake fade associated with such changes. Also, a self-excited brake geometry tends to aggravate brake noise such as squeal. 
         [0005]    By contrast, disc brakes typically are configured to apply forces perpendicular to the braking surface and the reaction forces are parallel to the braking surface. Disc brakes typically do not experience an amplification effect and have less sensitivity to variations in the coefficient of friction. Disc brakes, however, generally require some form of power assist. While disc brake arrangements usually avoid the fade resistance characteristic of some drum brakes, disk brakes tend to be more expensive. 
       SUMMARY 
       [0006]    A drum brake assembly designed according to an embodiment of this invention includes brake shoes having assembly features that facilitate secure placement of the brake shoes in a quick, efficient and straight-forward manner. Embodiments of this invention eliminate the otherwise relatively complex components that have typically been associated with drum brake devices. 
         [0007]    An illustrative example method of assembling a drum brake device includes positioning a portion of a brake shoe support structure near an opening of a brake actuating cylinder; manipulating the support structure so that a window of the support structure is received over a portion of a shoe mount; moving the support structure relative to the shoe mount so that the portion of the support structure is received into the brake actuating cylinder and the support structure is engaged by the shoe mount in a manner that the shoe mount restricts movement of the brake shoe in two dimensions and allows selective movement in a third dimension; and securing the brake shoe in an installed position by placing the drum over the brake shoe with the braking surface facing the friction lining. 
         [0008]    In an example method having one or more features of the method of the previous paragraph, the support structure comprises a table and a web; the friction lining is secured to the table; the web is generally perpendicular to a surface of the friction lining that is configured to contact the braking surface of the drum; the window is on the web; and the portion of the support structure that is positioned adjacent the opening of the brake actuating cylinder is an end of the web. 
         [0009]    In an example method having one or more features of the method of any of the previous paragraphs, there are two brake actuating cylinders; there are two ends of the web that are positioned adjacent the opening on the cylinders, respectively; and the two ends of the web are inserted into the cylinders as the web is moved relative to the shoe mount in a direction that is generally perpendicular to the surface of the friction lining. 
         [0010]    In an example method having one or more features of the method of any of the preceding paragraphs, the cylinders include pistons configured to move for actuating the brake device; the ends of the web and the pistons include cooperating surfaces for holding the ends of the web inside the pistons; and the cooperating surfaces become engaged during the moving. 
         [0011]    In an example method having one or more features of the method of any of the preceding paragraphs, the cooperating surfaces comprise at least one spring clip and at least one groove. 
         [0012]    In an example method having one or more features of the method of any of the preceding paragraphs, the at least one spring clip is supported on the web near the end of the web and the at least one groove is on the piston. 
         [0013]    In an example method having one or more features of the method of any of the previous paragraphs, manipulating the support structure so that the window is received over a portion of the shoe mount comprises tipping the web toward the shoe mount; and moving the support structure relative to the shoe mount comprises sliding the web over the portion of the shoe mount in a direction that is parallel to a direction of movement of the web for brake application. 
         [0014]    In an example method having one or more features of the method of any of the previous paragraphs, the shoe mount comprises an abutment bar including notches; and sliding the web over the portion of the shoe mount comprises positioning portions of the web on opposite sides of the window within the notches. 
         [0015]    In an example method having one or more features of the method of any of the previous paragraphs, engagement between the abutment bar and the portions of the web within the notches resists rotational movement of the brake shoe about an axis of rotation of the drum and resists movement of the brake shoe along a direction parallel to the axis of rotation of the drum. 
         [0016]    In an example method having one or more features of the method of any of the previous paragraphs, the positioning, manipulating, moving and securing are all done by hand. 
         [0017]    In an example method having one or more features of the method of any of the previous paragraphs, the positioning, manipulating, moving and securing are all done without using any tools. 
         [0018]    An example method having one or more features of the method of any of the previous paragraphs includes pre-assembling a brake shoe assembly by performing the positioning, the manipulating and the moving; and subsequently installing the pre-assembled brake shoe assembly onto a vehicle suspension component. 
         [0019]    An illustrative example drum brake device includes a drum having an inner, braking surface; at least one brake shoe including a friction lining and a support structure for the friction lining, the support structure including a window having a first portion and a second portion, the first portion of the window being wider than the second portion; and a shoe mount that is configured to be received through the first portion of the window, the shoe mount engages the support structure adjacent the second portion of the window in a manner that resists movement of the brake shoe in two dimensions and allows selective movement of the brake shoe in a third dimension for allowing the friction lining to selectively engage the braking surface. 
         [0020]    In an example drum brake device having one or more features of the device of the previous paragraph, the shoe mount includes notches; the support structure adjacent each of two sides of the second portion of the window is received in the notches; engagement between the support structure and the notches prevents movement of the brake shoe in a rotational direction corresponding to rotation of the drum; movement in the rotational direction corresponds to movement in one of the two dimensions; engagement between the support structure and the notches prevents movement of the brake shoe in an axial direction parallel to an axis of rotation of the drum; movement in the axial direction corresponds to movement in the other of the two dimensions; and engagement between the support structure and the notches allows movement of the brake shoe in a brake applying direction that corresponds to movement in the third dimension. 
         [0021]    In an example drum brake device having one or more features of the device of any of the previous paragraphs, the drum comprises an inner portion and an outer rim; the inner portion has the inner, braking surface; the outer rim includes a plurality of openings that are configured to accommodate air flow through the openings to facilitate reducing a temperature of at least the drum. 
         [0022]    In an example drum brake device having one or more features of the device of any of the previous paragraphs, the inner portion comprises a stainless steel stamping; and the outer rim comprises aluminum. 
         [0023]    In an example drum brake device having one or more features of the device of any of the previous paragraphs, the drum includes an outer face that includes a plurality of vanes configured to direct air flow toward the openings of the outer rim during rotation of the drum. 
         [0024]    In an example drum brake device having one or more features of the device of any of the previous paragraphs, the brake shoe support structure comprises a table and a web; the table and the web comprise stainless steel; and the friction lining comprises a layer of ceramic alumina on the table. 
         [0025]    In an example drum brake device having one or more features of the device of any of the previous paragraphs, the layer of ceramic alumina is flame sprayed on to the table. 
         [0026]    In an example drum brake device having one or more features of the device of any of the previous paragraphs, the shoe mount comprises an abutment bar, a connector and a torque reaction bracket; the connector is configured to be secured to a suspension component; and the torque reaction bracket comprises four linear load path members that extend between the abutment bar and the connector. 
         [0027]    In an example drum brake device having one or more features of the device of any of the previous paragraphs, the shoe mount comprises a central support portion and load path members; the shoe mount comprises two metal stampings that are received against each other in the central support portion and spaced from each other along at least a portion of a length of the load path members. 
         [0028]    In an example drum brake device having one or more features of the device of any of the preceding paragraphs, the support structure comprises a table and a web; the friction lining is secured to the table; the web is generally perpendicular to a surface of the friction lining that is configured to contact the braking surface of the drum; and the window is on the web. 
         [0029]    In an example drum brake device having one or more features of the device of any of the preceding paragraphs, there are two brake actuating cylinders including pistons configured to move for actuating the brake device; ends of the web that are received into the cylinders, respectively; and the ends of the web and the pistons include cooperating surfaces for selectively holding the ends of the web inside the pistons. 
         [0030]    In an example drum brake device having one or more features of the device of any of the preceding paragraphs, the cooperating surfaces comprise at least one spring clip and at least one groove. 
         [0031]    In an example drum brake device having one or more features of the device of any of the preceding paragraphs, the at least one spring clip is supported on the web near the end of the web and the at least one groove is on the piston. 
         [0032]    An example drum brake device having one or more features of the device of any of the previous paragraphs includes a parking brake actuator that includes at least one lever having an end that urges the brake shoe in a brake application direction to cause engagement between the friction lining and the braking surface. 
         [0033]    In an example drum brake device having one or more features of the device of any of the previous paragraphs, the lever has a pivot point spaced inward from ends of the lever; one of the ends moves inward toward a center of the drum based on the lever pivoting about the pivot point during use of the parking brake actuator; and another one of the ends moves the brake shoe outward toward the braking surface based on the lever pivoting about the pivot point during use of the parking brake actuator. 
         [0034]    Embodiments of this invention make it possible to guide each brake shoe in a direction that is radial to the brake drum. When this is done, the brake torque is reacted in such a way that there is no amplification effect. This avoids the disadvantages of existing drum brakes in terms of brake fade and brake noise, and results in performance comparable to disk brakes. 
         [0035]    Various features and advantages of example embodiments will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIG. 1  is a perspective illustration of a drum brake assembly designed according to an embodiment of this invention, in which the drum has been partially cut away. 
           [0037]      FIG. 2  shows the embodiment of  FIG. 1  from another perspective. 
           [0038]      FIG. 3  is a partially exploded view showing selected features of the embodiment of  FIGS. 1 and 2 . 
           [0039]      FIG. 4  is a perspective illustration of an example brake shoe. 
           [0040]      FIG. 5  is a top view of an example shoe mount that supports a brake shoe. 
           [0041]      FIG. 6  is a perspective illustration of the shoe mount also shown in  FIG. 5 . 
           [0042]      FIG. 7A  is a cross-sectional illustration schematically showing how brake shoe webs are received in a cylinder from a first perspective. 
           [0043]      FIG. 7B  is a cross-sectional illustration schematically showing the brake shoe webs and cylinder from a second, different perspective. 
           [0044]      FIG. 8A  is a cross-sectional illustration schematically showing how brake shoe webs are received in another cylinder embodiment from a first perspective. 
           [0045]      FIG. 8B  is a cross-sectional illustration schematically showing the brake shoe webs and cylinder of  FIG. 8A  from a second, different perspective. 
           [0046]      FIG. 9  is a perspective illustration of a parking brake lever component. 
           [0047]      FIG. 10  is a perspective illustration of an example suspension component including integrated brake shoe mount features. 
           [0048]      FIG. 11A  is a perspective illustration of another example embodiment of a drum brake assembly. 
           [0049]      FIG. 11B  shows the embodiment of  FIG. 11A  from a second, different perspective. 
           [0050]      FIG. 12  shows selected features of the embodiment of  FIGS. 11A and 11B  from an inboard side. 
           [0051]      FIG. 13  shows selected features of the embodiment of  FIGS. 11A and 11B  from an outboard side. 
           [0052]      FIG. 14  is an illustration similar to  FIG. 12  including parking brake components. 
           [0053]      FIG. 15  is a perspective illustration of a parking brake lever component. 
       
    
    
     DETAILED DESCRIPTION 
       [0054]      FIGS. 1 through 3  illustrate various features of an example embodiment of a drum brake device  20 . Brake shoes  22  having pads or friction lining material  24  are situated to engage an inside surface on a brake drum  26 , which is only partially shown in  FIG. 1  to make the illustrated components inside the device  20  visible. The brake drum  26  is associated with a wheel (not illustrated) in a known manner. A plurality of bolts  28  facilitate mounting the brake drum  26  and wheel to a bearing flange  30 , which is associated with an axle  32  in a conventional manner. 
         [0055]    As can be appreciated from  FIGS. 1-4 , the brake shoes  22  include a lining or pad support structure, which in this example includes a web  40  and a table  42  that supports the brake lining material  24 . The web  40  includes a window or cut-out  44  situated centrally between opposite ends of the web  40 . In this example, the window  44  is centered on the web  40 . The window  44  has two sections of different dimension. A first section  46  is wider compared to a second section  48 . The wider section  46  is positioned more toward an axis of rotation of the wheel when the drum brake is assembled in an operative position. 
         [0056]    The windows  44  are configured to be received over a shoe mount  50 . In this example, the shoe mount  50  is referred to as an abutment bar. The example abutment bar  50  is supported to remain in a stationary position relative to the suspension  32 .  FIG. 5  illustrates one example configuration of an abutment bar  50 . Notches  52  are provided between a distal or end portion  54  and a more central portion  56  of the abutment bar  50 . The width of the notches  52  is designed to correspond to a thickness of the web  40 . The size of the opening in the first portion  46  of the window  44  corresponds to a width W of the end portion  54  so that the end portion  54  may be received through the first portion  46  of the window  44 . The width of the second portion  48  of the window  44  corresponds to a distance D between the notches  52 . In other words, the portion of the web  40  along the narrower portion  48  of the window  44  is received within the notches  52  when assembled. 
         [0057]    With the web  40  situated relative to the abutment bar  50  in that manner, the brake shoe  22  may move in a radial direction to selectively apply a braking force to the inside surface of the drum  26 . In this example, the shoe mount  50  restrains motion of the shoe  22  in two out of three dimensions while allowing movement in a third so that the brake can be applied as needed. The cooperation between the surfaces on the abutment bar  50  and the web  40  restrains rotational and axial movement of the brake shoe  22  while allowing radial movement to apply or release the brake. 
         [0058]    Once the drum  26  is situated in place on the bearing flange  30 , disassembling the brake shoes  22  off of the abutment bars  50  is not possible. Disassembly only becomes possible when the drum  26  has been removed. 
         [0059]    As can be appreciated from  FIGS. 3 and 6 , the abutment bars  50  are supported by a structure  58 , which may be referred to as an anchor bracket or a torque reaction bracket. In this example, the supporting structure  58  comprises four linear load path members  59  that extend between the abutment bars  50  and connectors  60 . The connectors  60  are secured to an axle flange  90  using threaded members  92  (e.g., bolts), for example. 
         [0060]    The connection between the support structure  58  and the abutment bars  50  is strategically situated to be as close to the outboard end of the abutment bars  50  as possible without interfering with the brake shoes  22 . In the illustrated example, the outboard surface on the load path members  59  is situated as close as possible to the inboard side of the corresponding brake shoe  22  (when the shoe is in an operative position within the assembly as shown in  FIGS. 1 and 2 ). 
         [0061]    As can be appreciated from  FIGS. 4, 7A and 7B , the webs  40  include end portions  70  with contoured ends  72 . The end portions  70  are at least partially received within wheel cylinder assemblies  80  that are supported to remain stationary relative to the suspension  32 . As shown in  FIGS. 2 and 7B , the example wheel cylinder assemblies  80  are each supported at the end of a plate  87  that is secured to a connector  60  using threaded members  88  (e.g., bolts). 
         [0062]    Each wheel cylinder assembly  80  includes two pistons  82  that are activated during a brake application. The pistons  82  and the end portions  70  of the webs  40  have cooperating surfaces for holding the ends  72  within the corresponding pistons  82  in a selectively releasable manner. In this example, the end portions  70  include spring clips  74  that are resilient so that they can be moved toward or away from the surface of the end portion  70 . Each of the pistons  82  includes a groove  84  near an open end of the structure of the piston  82 . The groove  84  is configured to receive a portion of a clip spring  74  so that the end portions  70  of the webs  40  may be held in place as the springs  74  are effectively snapped into place within the wheel cylinder assemblies  80 .  FIG. 7B , is a cross-sectional view near an edge of the clip springs  74  in one embodiment in which the clip springs  74  are generally straight in a direction parallel to the web  40  of the brake shoe  22 . In such an embodiment, the springs  72  engage the corresponding grooves  84  near the edges of the springs. In other embodiments, the springs  74  may have a rounded contour or a bowed, outwardly facing surface that engages a groove  84  along a substantial portion of the length of that outwardly facing surface. 
         [0063]      FIG. 7B  also shows seal members  86  for retaining the brake fluid within the wheel cylinders  80 . The seals also serve the function of retraction of the brake shoe in a manner well known in disk brakes. 
         [0064]      FIGS. 8A and 8B  show another embodiment of the wheel cylinder assemblies  80 . In this example, the pistons have rounded inner ends compared to the more squared-off edges in the embodiment shown in  FIGS. 7A and 7B . The seals  86  are situated further into the wheel cylinder assembly and a scraper  87  is provided near the edge of the cylinder housing at the interface with the piston  82 . The scrapers  87  prevent contaminants from entering the assembly. In one embodiment, the scrapers  87  comprise plastic rings fit into a groove on the cylinder  80  and is received against the outer surface on the piston  82 , which comprises stainless steel in one example. 
         [0065]    While the examples illustrated in  FIGS. 7A-8B  include a spring clip  74  on the web portions  40 , other examples include other combinations of cooperating surfaces on the ends  72  and the pistons  82  to hold the ends of the brake shoes within the pistons  82  to facilitate assembling the brake drum device and to facilitate brake operation so that the brake shoes move based on movement of the pistons  82  within the cylinders  80 . 
         [0066]    As best appreciated from  FIGS. 1-3, 6 and 9 , the example embodiment provides a parking brake feature. An activator  100 , such as a push-pull cable, is associated with a parking brake applier (e.g., pedal or handle) that is accessible to a driver. The activator  100  has an associated snap-in mounting feature  102  that connects with an end on a mounting bracket  104 . The end of the cable in this example includes swaged cylindrical lugs  106  that are received against opposite sides on a lever  110 . Geometrically similar lugs are permanently attached to the end of mounting bracket  104  and engage the other lever  110  in the same manner. Other embodiments may include a plug, ball, eye or other terminal member that is configured to cooperate with the lever  110  so that the end of the activator  100  remains in a desired position relative to the lever  110  and movement of the activator  100  cable results in movement of the lever  110 . A tension force in the cable also results in an equal and opposite force in the cable housing which is transmitted through the mounting bracket  104  to the other lever  110  thus drawing the ends of the two levers towards each other. 
         [0067]    The lever  110  includes a pivot surface  120  ( FIG. 9 ) that is received in a fulcrum surface  114  ( FIG. 6 ) on the anchor bracket  58 . In this example, the fulcrum surface  114  is established on the abutment bar  50 . The lever  110  also includes a positioner  116  that is received in an opening  118  near the fulcrum surface  114 . 
         [0068]    An application surface  112  ( FIG. 3 ) on the lever  110  is configured to engage the inside of the table  42  of a corresponding brake shoe  22  to apply the parking brake based on a driver engaging the brake through manipulation of the activator  100 . The illustrated example includes one lever  110  for each brake shoe. 
         [0069]    The parking brake components (i.e., the activator  100  with its snap-in mounting feature  102 , mounting bracket  104 , and the levers  110 ) may be included in a pre-assembled drum brake assembly when the modular pre-assembly approach described above is desired. Once the drum  26  is in place over the shoes  22 , the parking brake components will be held in the desired, assembled condition, such as that shown in  FIG. 2 . 
         [0070]      FIG. 10  shows an example suspension component  130 , such as a knuckle casting. In this example, the abutment bars  50  are integrated into the suspension component  130 . A separate anchor bracket  58  is not needed in such an embodiment. Other embodiments include integrating one or more features of the drum brake assembly into an axle or suspension component, such as a twist beam axle. 
         [0071]      FIGS. 11-15  illustrate selected features of another embodiment.  FIGS. 11A and 11B  show this example from an outboard and inboard perspective, respectively. As shown in  FIGS. 11A and 11B , the drum brake device  20 ′ includes an outer rim  200  on the drum  26 ′. In one example embodiment, the outer rim  200  is made of aluminum and acts as a heat sink for absorbing and dissipating the friction generated heat resulting from aggressive brake use. Such a heat sink is particularly well-suited for high speed or high performance vehicles that may be driven at higher speeds and in a manner that requires braking often resulting in higher brake temperatures. 
         [0072]    The outer rim  200  includes a plurality of air channels  202  to enhance the ability to transfer heat to the ambient air. The mass of the outer rim  200  is sufficient to quickly absorb heat and thus reduce the magnitude of heat spikes. The outer rim also stiffens the drum  26  in this embodiment. 
         [0073]    As shown in  FIG. 11A  an outer end face  204  of the drum  26 ′ includes a plurality of vane members that establish air flow passages  206 . Openings  208  near radially inner ends operate as inlets to the flow passages  206 . Openings  210  near radially outer ends of the passages  206  operate as outlets. During rotation of an associated vehicle wheel, the air flow passages  206  operate as a centrifugal fan and direct air toward the outer rim  200  and through the openings  202  to provide more effective cooling of the drum brake device  20 ′. 
         [0074]    The outer face  204  may have a variety of appearances to provide a desired aesthetic effect when a particular wheel is mounted in place over the brake device. Many contemporary alloy wheel designs include openings through which brake components may be visible and the example outer face  204  allows for achieving a variety of looks. The outer face  204  may also serve as a splash guard to reduce the amount of liquid or contaminants that reach the interior of the drum  26 ′. 
         [0075]    As can be appreciated from  FIG. 11B , this example embodiment includes an inner cover plate  214  that serves to shield the interior of the drum brake device from exposure to water or contaminants that may be on a road surface. The inner cover plate  214  includes openings  216  to facilitate air flow within the drum  26 ′ to assist in cooling the brake components. The inner cover plate  214  may be secured to the anchor bracket or otherwise securely situated relative to the steering knuckle  218  and the rest of the brake device  20 ′ in the illustrated position. 
         [0076]      FIG. 12  shows the brake device  20 ′ with the inner cover plate  214  removed.  FIG. 13  shows the components of  FIG. 12  from the opposite side with the drum  26 ′ and the cover  204  removed. 
         [0077]    One feature of this embodiment visible in  FIGS. 12 and 13  is that the webs  40  of the brake shoes include openings  220  that reduce the weight of the brake shoes and allow for increased airflow within the drum brake assembly. 
         [0078]    The way in which the outer rim  200  is secured to the drum  26 ′ is visible in  FIG. 12 . In this example, the drum includes an annular braking surface  222  and a flange  224  that is generally perpendicularly oriented relative to the braking surface  222 . The outer rim  200  is received against and secured to the flange  224  by fasteners  226 . As the outer rim  200  strengthens and stiffens the drum  26 ′, the inner member of the drum that includes the braking surface  222  and the flange  224  may be made of a stainless steel stamping. Keeping the stamping thin facilitates heat transfer to the outer rim  200 . One example includes a Nitronic® 30 stainless steel material that has advantageous abrasive wear resistance. With such a drum configuration, it becomes possible to realize cost savings compared to the cost of a conventional disc brake rotor. 
         [0079]    The supporting structure  58  of this embodiment differs from that discussed above in several respects. The supporting structure has a central support portion  230  and load path members  59  arranged to distribute loads as described above. The supporting structure  58  in this example includes two steel stampings  232  and  234  that are received against each other in the central support portion  230  but spaced from each other along at least a portion of the length of the load path members  59 . 
         [0080]    The central support portion  230  includes mounting edges  238  that provide mounting locations for wheel cylinders  239  that include a hydraulic fitting  240  which serves as an inlet port for hydraulic pressure from the vehicle brake system. Hydraulic fittings  242  and pressure tube  244  serve to interconnect the two wheel cylinders. A bleed valve  246  in the upper wheel cylinder assists in evacuating any trapped air in the two wheel cylinders. 
         [0081]      FIGS. 14 and 15  show a parking brake feature of this embodiment that differs in some respects from the parking brake described above. In this example, the activator  100  operates to cause movement of levers  250  in a manner that applies the parking brake by urging the shoes into engagement with the drum. In particular, the activator  100  urges ends  252  of the levers  250  to move about a pivot established by a post or boss  254  on the lever  250 . As the ends  252  move inward (or toward each other in  FIG. 14 ), opposite ends  256  press against the inner edges of the webs to force the brake shoes outward into engagement with the braking surface  222 . The end  252  of lever  250  includes a spring retainer  270  which may be flexed to engage or release the cylindrical lug  272  attached to the end of the cable  274 , and the geometrically similar lug  276  in the end of mounting bracket  104 . 
         [0082]    The brake lining  24  in either embodiment may comprise a conventional brake friction material or a flame sprayed layer of ceramic alumina applied to the table  42 . Flame spraying such a layer on a stainless steel table provides a brake shoe lining that yields a higher and more stable coefficient of friction compared to most automobile brake friction materials when interacting with the stainless steel braking surface  222 . A conventional brake shoe friction material may have an associated coefficient of friction on the order of 0.4 while a ceramic alumina lining may have an associated coefficient of friction on the order of 0.6. The ceramic alumina lining is also capable of withstanding higher temperatures than convention friction materials without degradation, and the ceramic alumina lining  24  is virtually wear-free which results in much less frequent brake service procedures than otherwise might be needed if conventional friction materials were utilized. 
         [0083]    Assembling the drum brakes in the illustrated embodiments may be accomplished in the following manner. One or both of the brake shoes  22  is manipulated by hand (or automated machinery) into a position where the end portions  70  of the web  40  are situated just outside of or slightly interior of the wheel cylinder assemblies  80 . The larger portion  46  of the window  44  is received over the end portion  54  of the abutment bar  50  and the web  40  is manipulated until the body of the web  40  is lined up with the notches  52  on the abutment bar  50 . In that position, the brake shoe  22  may be manipulated in a radial direction toward the axis of rotation (of the wheel that will be eventually associated with the brake assembly) or slid inwardly toward the axis so that the end portions  70  move deeper into the wheel cylinders  80 . More particularly, the contoured ends  70  are moved into the pistons  82  until the clip springs  74  engage the grooves  84 . The clip springs  74  are effectively snapped into place within the pistons  82  to hold the webs  40  inside the pistons  82  so that the ends of the webs  40  are not going to move relative to the pistons  82  unless the clips springs  74  are manipulated (e.g., compressed inward toward the web  40 ). At the same time the portions of the web  40  on opposite sides of the window  44  are received into the notches  52 . At that point, the brake shoe (or both shoes) is securely situated so that the drum  26  may be manipulated into position over the brake shoes  22  and secured in position (e.g., as shown in  FIGS. 1 and 2 ). 
         [0084]    Those skilled in the art will recognize that the assembly process provided by the example embodiments is significantly simpler and more fool-proof compared to that associated with a conventional drum brake arrangement. The various springs, clips, linkages and adjusters otherwise associated with assembling a conventional drum brake device have been eliminated. Additionally, the conventional backing plate typically included in a drum brake for structural support is no longer required, providing additional material cost savings and opportunities to realize a reduced weight. 
         [0085]    The illustrated example embodiments allow for the drum brake assembly to be assembled in place on the end of an axle or suspension component in a piece-by-piece manner or by using a modular assembly approach. One example modular assembly approach includes pre-assembling at least the brake shoes  22 , the wheel cylinders  80 , and the anchor bracket  58 . Some pre-assemblies include the parking brake levers  110 . With this modular assembly approach, the pre-assembled drum brake assembly may be ready for installation onto an axle or suspension component on a vehicle assembly line (or axle or suspension sub-assembly line). This allows for reduced time and complexity along such an assembly line. 
         [0086]    The anchor bracket  58  of the embodiment illustrated in  FIGS. 1-6 , for example, has a wide enough opening between the connectors  60  and inside of the linear load path members  59  to fit over a bearing flange  30  on the end of an axle  32  so that the connector  60  may be manipulated into position against an axle flange  90  where the connectors  60  can be secured in position using the threaded members  92  (e.g., bolts). Taking this approach allows for readily positioning the drum brake assembly in an operative position on the axle or suspension. 
         [0087]    The assembly approaches useful with the disclosed embodiments are significantly less complex and time-consuming than the technique required to install a traditional drum brake assembly, which included mounting the backing plate in position and then arranging and connecting the various springs and other components required for the traditional assembly. Additionally, with the illustrated embodiment, no tools are required for assembly other than to tighten the threaded members  88  and  92 . The remainder of the assembly may be done by hand. Of course, automated machinery may be used for any or all of the assembly process if desired. 
         [0088]    Whether a modular, pre-assembly approach is utilized or the illustrated embodiments are assembled in place on an axle or suspension, the example embodiments present significant cost savings in terms of time and additional cost savings in materials and inventory because of the reduced number of components compared to a traditional drum brake assembly. 
         [0089]    Disassembling the drum brake device  20  of either illustrated embodiment occurs in an opposite manner from the assembly process described above. After removing the drum  26 , the ends of the clip springs  74  may be compressed manually or using an automated device and the brake shoe  22  may be slid radially outward until the abutment bar  50  is situated within the wider portion  46  of the window  44 . At that point, the brake shoe can be tilted or otherwise moved away from the abutment bar  50  and the shoe  22  is easily removed and separated from the remainder of the assembly. 
         [0090]    The illustrated embodiments demonstrate how a drum brake assembly designed according to an embodiment of this invention provides significant improvements over traditional drum brake assemblies. While different features or components are associated with the example embodiments, respectively, those features or components are not limited to that particular embodiment. One or more aspects or components of either embodiment may be used in a combination with components of the other embodiment. Any combination of the disclosed features is possible to realize other embodiments of a drum brake device designed according to this invention. 
         [0091]    The preceding description is illustrative rather than limiting. Variations and modifications to the disclosed embodiments may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection over this invention can only be determined by studying the following claims.