Abstract:
A brake shoe assembly for a vehicle is provided. A brake shoe has at least one slot on its outer surface. A brake plate has a backing plate that includes at least one key. The brake plate is secured to the brake shoe via the key being received within the at least one slot in the brake shoe. is secured to the outer surface of the brake shoe. This provides a connection that resisting radial movement of the brake plate relative to the outer surface of the brake shoe. A plurality of additional fasteners is also provided for securing the brake plate to the brake shoe. A frictional brake lining is molded on the brake plate and includes cut out portions exposing corners of the brake plate. At least one of the corners of the brake plate defines a hole for receiving one of the fasteners.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. application Ser. No. 10/595,350 filed Apr. 12, 2006, which is a national phase of PCT/IB04/003329, filed Oct. 12, 2004, which is a continuation-in-part of U.S. Pat. No. 10/684,877, filed Oct. 13, 2003, now U.S. Pat. No. 6,983,831, and claims the benefit of U.S. provisional application Ser. No. 60/513,085 filed Oct. 21, 2003, the disclosures of which are hereby incorporated in their entirety by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to drum brake shoes and brake lining blocks for vehicles such as trucks or buses. 
       BACKGROUND 
       [0003]    Vehicle brakes are generally either disk brakes or drum brakes. Drum brakes are generally preferred for buses and commercial trucks because drum brakes may provide a greater surface area of friction material. The braking surface of the friction material is generally riveted to a backing plate of a brake block. Generally, 12 to i6 rivets are required to attach a brake block to a brake shoe due to the substantial shear forces that must be withstood during braking between the brake blocks and the brake shoe. 
         [0004]    Commercial and industrial vehicle brake linings that are riveted to steel brake shoes are generally rigid, non-asbestos friction material. If the outer diameter of the brake shoe surface that is to be retrofit with new brake linings is not completely fiat or within original design radius tolerances, the lining after securing to the shoe may crack or break off of the brake shoe. This may create problems relating to braking performance and durability. 
         [0005]    The paramount consideration for brake design is safety. Worn or damaged brakes can cause reduced braking performance that may result in longer stopping distances. If a brake lining becomes dislodged in whole or in part, the brake for a wheel can jam or lock-up and could result in a truck jack knifing. 
         [0006]    Rivet holes in friction material interrupt the smooth surface of the friction material and reduce the available braking surface. Reduction of the braking surface can increase temperature stress on the friction material. Corners of the friction material can be damaged during assembly or in use and heat stress at the corners can lead to fractures. 
         [0007]    The shear forces developed between the friction material and a backing plate or brake shoe must be withstood by the bond between the friction material and the surface to which it is secured. Shear forces between the surface of a backing plate and a brake shoe must be withstood by the fasteners that secure the brake plate that includes a backing plate to the brake shoe. If a brake plate or part of the friction lining material becomes detached from the brake shoe in an emergency, the brake assembly could lock-up or be otherwise seriously compromised. 
         [0008]    The friction material used on brake blocks is drilled and countersunk to receive rivets that are used to connect the brake block to the brake shoe. Holes are formed in the friction material by either a drilling or a punch operation. If the counter bore is not drilled deep enough, the brake block may crack when riveted to the brake shoe by a riveter. If the counter bore is drilled too deep, the brake block may be only loosely fastened. This condition can lead to cracking of the friction material or other problems. 
         [0009]    If the rivet tool misses a rivet location and contacts the friction material, it may harm the friction material. The friction material may be cracked, broken, or deformed if the rivet is misdirected, or improperly set-up for depth and rivet application force. Any cracking, breakage or deformation could adversely impact braking performance of the lined brake shoe when installed on a vehicle. 
         [0010]    Substantial labor costs are incurred to rivet brake blocks to a brake shoe. Additional expenses may be incurred if it is necessary to scrap a cracked brake block. 
         [0011]    The surface area of the friction material is reduced by each access hole in the friction material required for a rivet. Any reduction in surface area of the friction material may adversely affect stopping performance. Holes for rivets in the surface of the friction material may result in unwanted noise especially if dirt or other foreign material is permitted to collect in the rivet access holes. 
         [0012]    In the manufacture of brake blocks, problems may be encountered including blistering at the corners of the brake blocks. The corners of brake blocks may be broken or damaged especially if the corners are formed with right angle corners. 
         [0013]    There is a need for an improved brake shoe having brake blocks that maximize the friction material surface area while minimizing riveting operations. There is also a need to eliminate the potential for damage to friction material on brake blocks when they are assembled to a brake shoe. 
         [0014]    There is also a need in some applications to eliminate riveting operations in the assembly of brake blocks to brake shoes. Some repair facilities prefer to avoid such riveting operations and instead install brake blocks using only conventional threaded fastening tools. 
         [0015]    Conventional brake blocks for conventional drum brakes have a partial cylindrical backing plate that is mated to the partial cylindrical surface of the brake shoe. Rivets secure the brake blocks to the brake shoe and are the sole mechanism for resisting sheer forces between the brake blocks and the brake shoe when the brake engages the brake drum. Sheer forces develop as the brake shoe is pressed against the drum because brake drum rotation is slowed by contact with the friction material of the brake blocks. 
         [0016]    When a brake is used in reverse, the rotational forces applied to the brake blocks are reversed. If the brakes are frequently used in reverse or if the brakes are applied in an emergency stop while the vehicle is moving in reverse, the rivets may distort or stretch rivet holes in the friction material. If the rivets holes become enlarged the friction material may become loose. Any looseness of the rivets relative to the friction material may create unwanted noise or improper brake feel. 
         [0017]    With current drum brake shoes, when the lining is worn to a point beyond the recommended extent, as much as 95% of the steel shoe may contact the brake drum. When brake shoes are rebuilt and reinstalled in a vehicle, the first brake application may result in only 40% to 50% of the surface of the friction material actually contacting the brake drum. In a short period of time, of over 3 or 4 days or possibly 50 to 100 brake applications, the friction material may wear until 75%-80% of the friction material surface contacts the brake drum. Braking performance is improved as the proportion of friction material surface contacting the brake drum increases. 
         [0018]    There is a need for an improved brake shoe having brake blocks that have improved resistance to sheer forces, reduced manufacturing costs, reduced friction material waste, reduced break-in period, and that provide maximum friction material surface contact even when the friction material is worn to the maximum extent. There is also a need for brake shoes having brake blocks that are designed to minimize noise and vibration. 
         [0019]    The present disclosure is directed to solving the above problems as summarized below. 
       SUMMARY 
       [0020]    According to one aspect of the present disclosure, a brake shoe assembly is provided that includes a brake shoe and a brake plate. The brake shoe has an outer radial surface. The brake plate is secured to the outer radial surface of the brake shoe. A slot and an integrally formed key are provided between the brake shoe and brake plate. The slot and key prevent radial movement of the brake plate relative to the outer radial surface of the brake shoe. The slot and key also greatly increase resistance to shear forces when the brake is applied in comparison to conventional rivet secured brake linings. A plurality of fasteners, such as rivets or clinch bolts, may be provided for securing the brake plate to the brake shoe. 
         [0021]    According to another aspect of the present disclosure, a vehicle brake drum shoe assembly is provided that includes a cylindrical brake shoe and at least one brake plate that is secured to the outer radial surface of the brake shoe. A pair of keys may be integrally formed by a punching operation in each of the cylindrical brake shoes to extend outwardly from the outer radial surface of the brake shoe. The brake plate is secured to the outer surface of the brake shoe and includes a pair of slots for receiving the keys of the brake shoe. The keys of the brake shoe are received in the slots in the brake plate and function to prevent radial movement of the brake plate relative to the outer radial surface of the brake shoe. Alternatively, the keys may be formed in a backing plate of the brake shoe and the slots may be formed in the brake shoe. 
         [0022]    Other aspects of the disclosure relate to preassembling fasteners to the brake plate and providing a pair of alignment holes for receiving the preassembled fasteners that facilitate alignment of the brake shoe keys with brake plate slots. The preassembled fasteners may be longer than the height of the brake shoe key to align the brake shoe key with the brake plate slot. The preassembled fasteners, if rivets, may be secured to the brake shoe by a flaring tool. If the preassembled fasteners are, for example, clinch bolts they may be secured by a self-locking nut, or the like. The friction material of the brake lining is molded over and covers one end of the preassembled fasteners. One brake shoe may receive two brake blocks that each have two slots or key ways, wherein four keys are formed on each brake shoe. The keys are formed or pressed out from the inside of the outer surface of the brake shoe without breaking through the brake shoe. The elongated keys, or ribs, fit tightly within the elongated key ways formed in the backing plates. Alternatively, the keys may be formed on the brake plates and the slots may be provided in the brake shoe. 
         [0023]    Other aspects of the disclosure relates to the concept of forming four recesses at the four corners of the brake plate to expose a corner portion of the brake plate. Fasteners are inserted through the four exposed corner portions to join the brake plate and brake shoe after the preassembled fasteners align the brake shoe key with the brake plate slot. The brake plate may then be secured to the brake shoe to thereby provide metal-to-metal contact and eliminating the need to fasten through the friction material. The brake plate slot is axially elongated to receive the elongated brake shoe keys. The backing plates span the friction lining surface and provide additional strength for the brake linings as they are attached to the brake shoe. 
         [0024]    Another approach to eliminating fastening through the friction material is to assemble clinch bolts through a backing plate of a brake plate and then apply the friction material over the backing plate covering the clinch bolts. Keys may also be formed in the backing plates by partially severing and forming a key or tang to extend radially inward of the backing plate. The key or tang may then be received in a slot formed in the brake shoe. 
         [0025]    According to another aspect of the present disclosure, a method of manufacturing a brake assembly is provided. The method begins by providing a brake plate having a plurality of fastener apertures and an alignment slot. Four apertures may be provided at four corners of the brake plate with two intermediate apertures being provided at opposite sides of the brake plate. A set of preassembled fasteners are inserted into the two intermediate apertures of the brake plate. A frictional brake lining is then molded over the preassembled fasteners so that the frictional brake lining covers the preassembled fasteners. A brake shoe having a plurality of apertures that match the apertures in the brake plate also further includes a key that protrudes from the outer radial surface of the brake shoe. Each of the brake plate slots receives a brake shoe key when the brake plate is mated to the brake shoe. The preassembled fasteners are aligned with corresponding holes in the brake shoe to facilitate inserting the brake shoe key into the brake plate slot. Alternatively, the keys and slots could be on the brake plate and brake shoe, respectively. A set of fasteners is inserted in each of the fastener apertures in the corners of the brake plate. The fasteners extend through corresponding holes in both the brake plate and the brake shoe and are secured by a fastener tool in a fastening operation. The preassembled fasteners, if rivets, may be flared to secure the brake plate to the brake shoe. The brake shoe key when inserted in the brake plate slot limits, or prevents, movement of the brake plate relative to the outer radial surface of the brake shoe. 
         [0026]    According to other aspects of the disclosure as they relate to the method of manufacturing a brake assembly, the molding step may be performed without applying a brake lining over portions of the four corners of the brake plate. The open corners of the brake plate expose the four corner fastener apertures to facilitate fastening the brake plate to the brake shoe with metal-to-metal contact. This allows the fastening process to be used without drilling and counter boring the friction material for fastening access. The method may also comprise forming the brake slot as an axially elongated aperture and forming the brake shoe key as an axially elongated key, or rib, that fits within the axially elongated brake slot. The method may further comprise forming a pair of axially elongated slots in the brake plate and forming a corresponding pair of axially elongated keys in the brake shoe for each brake plate. The keys may be formed as integrally formed portions of the brake shoe in a punching or stamping operation. The location of the keys and slots may be reversed on the brake plate and brake shoe, as previously indicated. 
         [0027]    According to yet another aspect of the present disclosure, a brake shoe assembly is provided that includes a brake shoe and a brake plate. The brake shoe has an outer radial surface. The brake plate is secured to the outer radial surface of the brake shoe. At least one hole and an integrally formed cylindrical key are provided between the brake shoe and brake plate. The hole and cylindrical key prevent radial movement of the brake plate relative to the outer radial surface of the brake shoe. A plurality of fasteners are provided for securing the brake plate to the brake shoe. The fasteners may be rivets, clinch bolts or other fasteners. 
         [0028]    According to another embodiment of the disclosure a brake shoe having flat surfaces may be provided to which brake plates having flat backing plates may be attached with rivets or clinch bolts, or studs, that secure the backing plates to the brake shoe. The flat surfaces of the brake shoe resist movement of the brake plates when shear forces are applied to the friction material of the brake plates. In addition, one or more keys or key ways may be provided to secure the backing plates to a brake shoe to provide added resistance to shear forces. The key may be provided in a variety of shapes and types in either the brake shoes or the backing plates of the brake plates. Conversely, the key ways are of complimentary shapes and types and are provided in the facing part to the key supporting part. 
         [0029]    These and other aspects of the present disclosure will be better understood in view of the attached drawings and following detailed description of the illustrated embodiment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]      FIG. 1  is an exploded perspective view of a brake shoe with one brake plate secured to the brake shoe and a second brake plate shown as it is assembled to the brake shoe; 
           [0031]      FIG. 2  is an elevation view of a brake shoe and two brake plates; 
           [0032]      FIG. 3  is a cross-section taken along the line  3 - 3  in  FIG. 2 ; 
           [0033]      FIG. 4  is a cross-section taken along the line  4 - 4  in  FIG. 2 ; 
           [0034]      FIG. 4A  is a cross-section showing an alternative orientation for the slot and key shown in  FIG. 4 ; 
           [0035]      FIG. 5  is a cross-sectional view of a preassembled rivet in a brake plate inserted through a hole in the brake shoe; 
           [0036]      FIG. 6  is a cross-sectional view preassembled rivet flared to secure the brake plate to the brake shoe; 
           [0037]      FIG. 7  is an exploded perspective view of a brake shoe with one brake plate secured to the brake shoe and a second brake plate shown as it is assembled to the brake show; 
           [0038]      FIG. 8  is an elevation view of the brake shoe and the brake plate of  FIG. 7 ; 
           [0039]      FIG. 9  is a cross-section taken along the line  9 - 9  in  FIG. 8 ; 
           [0040]      FIG. 10  is a cross-section taken along the line  10 - 10  in  FIG. 8 ; 
           [0041]      FIG. 11  is an elevation view of a brake shoe and an alternative embodiment of a brake plate; 
           [0042]      FIG. 12  is a cross-section taken along line  12 - 12  in  FIG. 11 ; 
           [0043]      FIG. 13  is a side elevation view of a brake shoe having a plurality of flat sides to which brake blocks including friction material, a backing plate and rivets are secured; 
           [0044]      FIG. 14  is a side elevation view of a brake shoe having a plurality of flat sides and having a key to which brake blocks including friction material and a backing plate having a key way are secured with clinch bolts; and 
           [0045]      FIG. 15  is a side elevation view of a brake shoe having a plurality of flat sides and having a key way to which brake blocks including friction material and a backing plate having a key are secured with clinch bolts. 
       
    
    
     DETAILED DESCRIPTION 
       [0046]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
         [0047]    The brake plates  16  are attached, in part, by fasteners  22  that are secured to the backing plate  18  at open corners  24 . While the illustrated embodiment shows rivets  22 , other fasteners can be used instead of rivets and references to rivets should be construed to include other types of fasteners as well. The open corners  24  are areas where no friction material  20  is bonded to the backing plate  18 . Alternatively, the layer of friction material  20  could be applied over the entire backing plate  18  and then subsequently removed by cutting away or milling the friction material to create the open corners  24 . Holes  26  for receiving the fasteners  22  are formed in the brake shoe  10  at spaced locations corresponding to the spacing of the fasteners  22 . The brake plates  16  are secured by the fasteners  22  through holes  28  in the backing plate  18  directly to the outer surface  12  of the brake shoe  10  to create a metal-to-metal contact connection. 
         [0048]    Preassembled fasteners  30  extend from each of the backing plates  18 . The preassembled fasteners  30  are received in alignment pin holes  32  formed in the outer surface  12  of the brake shoe  10 . The preassembled fasteners  30  are secured to mounting holes  34 , the backing plates  18  and a layer of friction material  20  is molded onto the backing plate  18  covering one end of the preassembled fasteners  30 . The fasteners  22  and preassembled fasteners  30  are arranged in rows, as shown, on the inboard side  36  and outboard side  38  of the brake shoe  10 . The preassembled fasteners  30  are arcuately spaced from the fasteners  22  that are inserted through holes  28  in the open corners  24  of the brake plate  16 . 
         [0049]    Keys  40  are formed in the brake shoe  10  to extend outwardly from the cylindrical outer surface  12 . The keys  40  are preferably elongated in shape and extend lengthwise in an axial direction. Two keys  40  may be arranged, as shown, in axial alignment on the outer surface  12  of the brake shoe  10 . The keys  40  are received in slots  42  formed in the backing plate  18  of the brake plates  16 . The integrally formed keys  40  when received in the slots  42  provide a positive and effective part of the attachment system that can withstand substantial shear forces that are created when the brake shoe engages a brake drum (not shown) to stop a vehicle (not shown). 
         [0050]    Referring to  FIG. 2 , the construction of the brake plates is shown in greater detail. Each brake plate  16  has a backing plate  18  onto which a layer of friction material  20  is bonded. The open corners  24  of each brake plate  16  each reveal a part of the backing plate  18 . A layer of friction material  20  is molded over the preassembled fasteners  30  to provide a continuous layer of friction material  20  that is not interrupted by a plurality of fastening holes as was provided with conventional brake plates. The preassembled fasteners  30 , as illustrated, may be axially aligned with the keys  40  and slots  42 . 
         [0051]    Referring to  FIG. 3 , connection of the brake plates  16  to the brake shoe  10  by means of the fasteners  22  and preassembled fasteners  30  is shown. Fasteners  22  are flared in a riveting operation after insertion through the fastener receiving holes  26  and holes  28  formed in backing plates  18 . The preassembled fasteners  30  are assembled to the backing plate  18  before the layer of friction material  20  is applied to the backing plate  18 . After the brake plate  16  is assembled to the brake shoe  10 , a flaring tool is used to flare the end of the preassembled fasteners  30  forming a rivet-like connection between the brake plate  16  and brake shoe  10 . 
         [0052]    Referring to  FIG. 4 , a cross section of the connection between the key  40  of the brake shoe  10  and slot  42  in the backing plate  18  of the brake plate  16  is shown. The key  40  may be formed by a sheet metal forming process wherein a punch engages the brake shoe  10  to force the key  40  to extend outwardly from the outer surface  12  of the brake shoe  10  without separating the key  40  from the brake shoe  10 . 
         [0053]    Referring to  FIG. 4A , a cross-section of an alternative connection between key  41  and a slot  43  is illustrated that may be adapted to any of the disclosed embodiments or methods. This alternative design shows a cross-section of the key  41  formed in the backing plate  18  rather than in the brake shoe  10  and the slot  43  created in the brake shoe  10  rather than the backing plate  18 . This design allows the use of conventional brake plates because there is no protruding key on the brake shoe. 
         [0054]    Referring to  FIG. 5 , one of the preassembled fasteners  30  is shown inserted into one of the alignment pin holes  32 . The preassembled fasteners  30  orient the slots  42  relative to the keys  40  and also align the fastener receiving holes  26  on the brake shoe  10  with the holes  28  formed in the open corners  24  of the backing plate  18 . As shown in  FIG. 6 , the alignment pin  30  has been flared by a flaring tool to firmly secure the brake plate  16  to the brake shoe  10 . 
         [0055]    The method of manufacturing the brake shoe  10  having replaceable brake plates  16  is described below. While the embodiment illustrated in  FIGS. 1-6  shows rivets, it should be understood that specific references to fasteners and fastener holes include but are not limited to rivets and rivet holes. The method begins by providing a brake plate  16  having a plurality of apertures for receiving fasteners and at least one slot  42  for receiving a key  40 . Four fastener receiving apertures or holes are provided at the four corners of the backing plate  18  of the brake plate  16 . Two preassembled fasteners  30  are inserted into alignment pin holes  32  in the backing plate  18  between the fastener receiving holes  26 . A layer of friction material  20  is then molded over the preassembled fasteners  30  so that the friction brake lining  20  covers the outer ends of the preassembled fasteners  30 . The brake shoe  10  has fastener holes  26  that are provided to receive fasteners  22  and alignment pin holes  32  for receiving the preassembled fasteners  30 . The brake plates  16  have slots  42  for receiving a brake shoe key  40  when the brake plate  16  is mated to the brake shoe  10 . Preassembled fasteners  30  are used to align the brake plate  16  with the brake shoe  10  and facilitate insertion of the brake shoe key  40  into the slots  42 . Fasteners  22  are inserted into each of the fastener apertures in the four open corners  24  of the brake plate  16 . The fasteners  22  extend through corresponding holes  26  and  28  in the brake shoe  10  and brake plate  16 , respectively. The fasteners  22  are secured at the open corners  24  by a riveting tool. The preassembled fasteners  30  are flared to secure the brake plate  16  to the brake shoe  10  at a point generally axially aligned with keys  40  and slots  42 . If clinch bolts or studs are used they will be secured by nuts. The preassembled fasteners  30  could alternatively be offset from the keys  40  and slots  42 . The brake shoe key  40  is inserted in the slot  42  to prevent radial movement of the brake plate  16  relative to the outer radial surface  12  of the brake shoe  10 . 
         [0056]    The method of assembling brake plate  16  to a brake shoe  10  described above simplifies the manufacture of brake shoes by reducing the number of fasteners required to secure the brake plate  16  to the brake shoe  10 . It also eliminates boring and counter boring fastener holes in the friction material. Preassembled fasteners  30  align the keys  40  with the slots  42  while at the same time aligning the holes  28  in the backing plate  18  with the fastener receiving holes  26  in the brake shoe  10 . Metal-to-metal contact is provided for the fasteners  22  to secure the brake plate  16  to the brake shoe  10 . The open corners  24  provide clearance between the fastener locations and the friction material  20  so that the fastening operation will not crack the layer of friction material  20 . 
         [0057]    Referring to  FIG. 7 , a brake shoe  10  having a cylindrical outer surface  12  is illustrated with one brake plate  16  that is unattached to the brake shoe  10 . The brake plate  16  includes a backing plate  18  to which is bonded a layer of friction material  20 . While not illustrated, a plurality of apertures could be provided in the backing plate  18  into which friction material  20  is integrally molded to mechanically attach the friction material  20  to the backing plate  18 , like apertures  14  in the embodiment of  FIGS. 1-6 . 
         [0058]    Preassembled fasteners  30 , for example, clinch bolts or studs, extend from the backing plate  18 . The preassembled fasteners are received into alignment pin holes  32  formed in the outer surface  12  of the brake shoe  10 . The preassembled fasteners  30  are secured to alignment pin holes  32  by means of stud bolts  44 . A layer of friction material  20  is molded onto the backing plate  18  covering the preassembled fasteners  30 . The preassembled fasteners  30  are arranged in rows, as shown, on the inboard side  36  and outboard side  38  of the brake shoe  10 . 
         [0059]    Tabs  46 , or locking tangs, are formed in the backing plate  18  of the brake plate  16  and progressively extend inwardly from the cylindrical inner surface of the brake plate  16 . The tangs  46  are preferably elongated in shape and extend in an axial direction. The tangs  46  are received in slots  42  formed in the brake shoe  12 . The integrally formed tangs  46  when received in the slots  42  provide a positive and effective part of the attachment system that can withstand substantial shear forces that are created when the brake shoe engages a brake drum (not shown) to stop a vehicle (not shown). The recess created when the tab  46  is pressed out from the backing plate  18  may be filled with friction material  20 . The friction material  20  behind the tangs  46  aids in mechanically attaching the friction material to the backing plate  18 . 
         [0060]    Referring to  FIG. 8 , the construction of the brake plates is shown in greater detail. Each brake plate  16  has a backing plate  18  onto which a layer of friction material  20  is bonded. A layer of the friction material  20  is molded over the preassembled fasteners  30  to provide a continuous layer of friction material  20  that is not interrupted by a plurality of fastening holes as was provided with conventional brake plates. The preassembled fasteners  30 , as illustrated, may be axially aligned with the tangs  46  and slots  42 . 
         [0061]    Referring to  FIG. 9 , connection of the brake plate  16  to the brake shoe  10  by means of the preassembled fasteners  30  and tangs  46  is shown. Preassembled fasteners  30  are assembled to the backing plate  18  before the layer of friction material  20  is applied to the backing plate  18 . The preassembled fasteners  30  that are illustrated are clinch bolts that are clinched to the backing plate and have a threaded portion that extends inwardly from the backing plate  18 . After the brake plate  16  is assembled to the brake shoe  10 , the preassembled fasteners  30  are secured by self-locking nuts  44  to connect the brake plate  16  to the brake shoe  10 . 
         [0062]    Referring to  FIG. 10 , a cross-section of the connection between the tab  46  and the slot  42  is shown. Additionally,  FIG. 10  shows in greater detail the connection of the preassembled fasteners  30  to the stud bolts  44  which maintains the connection between the brake shoe  10  and the brake plate  16 . 
         [0063]    Referring to  FIG. 11 , the construction of another brake plate  16  is shown in detail. The brake plate  16  has a backing plate  18  onto which a layer of friction material  20  is bonded. The layer of friction material  20  is molded over the preassembled fasteners  30  to provide a continuous layer of friction material  20  that is not interrupted by a plurality of fastening holes as was provided with conventional brake plates. The preassembled fasteners  30 , as illustrated may be axially aligned with one or more cylindrical keys  48 . The cylindrical keys  48  are punched into the backing plate  18 . The cylindrical keys  48  are received in holes  50  in the brake shoe  10 . 
         [0064]    Referring to  FIG. 12 , a cross-section of the connection between the cylindrical keys  48  in the backing plate  18  and the holes  28  in the brake shoe  10  is illustrated.  FIG. 12  also shows in greater detail how the preassembled fasteners  30  are secured by nuts  44  to connect the brake plate  16  to the brake shoe  10 . 
         [0065]    Referring to  FIG. 13 , a brake shoe  60  is shown to include a wall  62  having a plurality of flat sections  64 . The brake shoe  60  also includes a pair of ribs  66  that are welded to one side of the wall  62 . Ribs  66  have straight sections  68  onto which the flat sections  64  of the wall  62  are welded. 
         [0066]    A plurality of brake blocks  70  are secured to the brake shoe  60 . The brake blocks  70  include a flat backing plate  72  and a block of friction material  74 . The block of friction material  74  has an arcuate braking surface  76  that is adapted to engage a brake drum (not shown). A pair of side surfaces  78  are provided on opposite sides of the block  74 . The side surfaces  78  are slightly canted or tapered to facilitate molding the block of friction material  74 . A backing plate bonding surface  80  is provided on the block of friction material  74 . A bonding agent may be applied to either the backing plate  72  or bonding surface  80  to facilitate bonding the block of friction material  74  to the backing plate  72 . 
         [0067]    Rivets  82  are attached to the brake blocks  70  and extend through the backing plates  72  and into holes  84  in the wall  62 . Rivets  32  are initially retained on the brake blocks  70  by the friction material  74  that is molded over or bonded to the backing plate  72 . 
         [0068]    Referring to  FIGS. 14 and 15 , other alternative embodiments are shown that feature brake shoes  90  having flats  92  to which brake plates  94  are secured. In  FIG. 14 , the brake shoe  90  has a key  96  that is received by a key way  98  formed in the backing plate  100  of the brake plate  94 . In  FIG. 15 , the brake shoe  102  has a key way  104  that receives a key  106  formed on the backing plate  108  of the brake plate  110 . In either embodiment, the keys  96 ,  106  and key ways  98 ,  104  are complimentary and may be of any of the types previously described with reference to  FIGS. 1-12 . The brake plates  94 ,  110  have clinch bolts  112  secured to the backing plates prior to application of the friction material  114 . The brake plates  94 ,  110  are assembled to the brake shoes  90 ,  102  and secured by self-locking nuts  116 . 
         [0069]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.