Abstract:
An adjuster strut ( 10 ) for use in a drum brake assembly. The adjuster strut ( 10 ) has an adjustable elongate extent with first and second engagement means ( 17,37 ) disposed at opposite ends thereof for engaging opposed braking members ( 11,12,35 ) of a brake assembly. The first engagement means ( 17 ) is arranged for receipt and support within an inwardly opening slot ( 19,20 ) formed in one of the braking members ( 11,12,35 ) and includes an end face ( 18 ) for abutting engagement with the inner end wall ( 19   a, 20 a ) of the slot opening ( 19,20 ). The first engagement means ( 17 ) further includes a first channel ( 21 ) extending rearwardly from the face ( 18 ), for receiving therein an edge or wall portion (hereinafter an “edge portion”) defining the slot opening ( 19,20 ). The braking members can include opposed cross-sectionally T-shaped brake shoes and a parking brake lever disposed adjacent the inwardly extending web of one of the brake shoes.

Description:
RELATED APPLICATIONS 
     This application is a continuation under 35 U.S.C. 111(a) of International Application No. PCT/AU01/00101 filed Feb. 6, 2001 and published Aug. 16, 2001 as WO 01/59321 A1, which claimed priority to Australian Application No. PQ 5583 filed Feb. 11, 2000, which applications and publication are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an adjuster strut for use in a drum brake assembly and to a drum brake assembly that employs an adjuster strut. 
     BACKGROUND OF THE INVENTION 
     Adjuster struts are commonly employed in brake assemblies to facilitate compensation for wear over time in brake friction lining. The adjuster strut typically extends in engagement between opposed braking members, being opposed brake shoes, or a brake shoe and a parking brake lever, and is operative to automatically extend lengthwise upon wear of the friction lining, to maintain a substantially constant gap between the lining and the drum braking surface in a “brake off” or non-braking condition. 
     Most known adjuster struts generally have bifurcated or forked ends suitable to accept at one end thereof the leading edge of the inwardly depending web of a T-shaped brake shoe, and at the other end thereof, both the leading edge of the inwardly depending web of an opposed, T-shaped brake shoe and the similar edge portion of the parking brake lever positioned adjacent thereto. At least one portion of such a strut is normally formed from tubular metal and the bifurcated end of the strut is typically formed by pressing the end of the tubular portion together and removing a central portion therefrom to form a lengthwise slot. That slot is generally of a width approximately equal to, but slightly greater than the thickness of the sections or portions of the braking member or members which it is to accept. It is also normal for both the webs and the parking brake lever to be formed with slot openings at the desired strut engagement position to accept and support the ends of the strut. 
     One drawback of the above known strut arrangement is that the material removed from the pressed tubular end portion is wasted and the mechanism of removal, normally by grinding or stamping, requires a specific manufacturing step. Moreover, such struts can be awkward to install, given that the bifurcated ends are required to straddle the respective web and lever edges. 
     A further drawback of known adjuster struts is the manner in which the ends thereof are connected or supported in the brake assembly. In some prior art arrangements, the ends of the adjuster strut have a significant lengthwise bifurcation to such an extent to ensure that the adjuster strut remains engaged at either end with the braking members on radial expansion of the brake shoes, even if the strut malfunctions so as not to extend itself during that expansion. This arrangement prevents release of one or both ends of the adjuster strut from engagement with the relevant braking members, as such release is undesirable, by leaving the strut unsecured within the rotating wheel cavity and permitting the strut to possibly damage the components in that cavity or jam the brake assembly against operation, with obvious and potentially catastrophic consequences. 
     An alternative prior art arrangement adopted in this respect employs biasing springs to permanently secure the ends of the adjuster strut in engagement with the braking members. Such adjuster struts generally employ an adjuster mechanism that includes a nut threaded on a shaft and rotation of the nut by the adjuster mechanism permanently shifts the axial position of the shaft to lengthen the adjuster strut. The major length of the shaft is accommodated within an unthreaded tube so that the shaft can rotate freely within the tube and shift axially without obstruction. In the case of malfunction/seizure of the adjuster mechanism, expanding movement of the brake shoes can be accommodated as necessary through lengthwise expansion of the adjuster strut, by sliding movement of the shaft within the tube while the ends of the strut are secured to the braking members by the springs. This arrangement therefore secures the strut against release from the braking members, but requires additional spring components and can be awkward to fit. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an adjuster strut that overcomes or at least alleviates one or more of the above drawbacks. 
     According to the invention there is provided an adjuster strut for use in a drum brake assembly, said adjuster strut having an adjustable elongate extent with first and second engagement means (units) disposed at opposite ends thereof for engaging opposed braking members of a brake assembly, said first engagement means being arranged for receipt and support within an inwardly opening slot formed in one of said braking members and including an end face for abutting engagement with the inner end wall of said slot opening, said first engagement means further including a first channel extending rearwardly from said face, for receiving therein an edge or wall portion (hereinafter an “edge portion”) defined by said slot opening. 
     An adjuster strut of the above kind is distinguished from the prior art by the absence of the need for each end of the strut to be bifurcated. As such, there are reduced levels of wasted material in the strut construction. In particular, the strut can have reduced axial length, because at least one of the ends of the strut does not have to accept the radially inward extending edge of one or both of the braking members. Additionally, the channel formed in the adjuster strut of the invention can be formed as part of the pressing step normally already undertaken in the formation of one of the ends of known struts. Thus, an adjuster strut according to the invention can have less manufacturing steps compared to known struts. 
     An adjuster strut according to the present invention preferably includes a main portion which is formed from tubular metal section and the end portion for engagement within the slot opening of the braking member is preferably pressed to flatten the end and to form the channel between upstanding side regions to accept the edge portion of the slot opening. Receipt of the edge portion within the channel is such as to locate the respective end of the adjuster strut in at least one plane relative to the braking member to which it is engaged. A second channel may be formed on an opposite side of the channel described above so that the end has a cross-section which his generally dumb-bell shaped, and that second channel is provided to accept a second and oppositely disposed edge portion of the slot opening so that the adjuster strut is engaged by edges of the slot opening on opposite sides thereof. 
     A slot opening is provided in at least one of the braking members for receipt and support of one end of the adjuster strut, although in a preferred arrangement, each braking member includes a slot opening so that each end of the strut is received and supported in such a slot. In that arrangement, the end face of the or each strut end is preferably arranged for abutting engagement with the inner end of a slot opening at least in the brake off condition of the brake assembly, while the upper and/or the lower edge portions of that opening is/are received in a channel(s) extending rearwardly from the end face. 
     The invention further provides a drum brake assembly including a rotatable drum, a support, a pair of cross-sectionally T-shaped brake shoes defining a radially inwardly depending web mounted on said support in opposed relationship for substantially radial movement into and out of engagement with a braking surface of said rotatable drum, actuating means facilitating movement of said brake shoes, and an adjuster strut, said adjuster strut having an adjustable elongate extent with first and second engagement means disposed at opposite ends thereof for respectively engaging said brake shoes, said first engagement means being received and supported within an inwardly opening slot formed in the web of a first of said brake shoes and including an end face for abutting engagement at least in a radially contracted or brake off condition of said brake shoes with the inner end wall of said slot opening, said first engagement means further including a first channel extending rearwardly from said face and said slot being arranged so that an edge or wall portion (hereinafter an “edge portion”) of said slot opening extends into said channel. 
     The invention still further provides a drum brake assembly including a rotatable drum, a support, a pair of cross-sectionally T-shaped brake shoes defining a radially inwardly depending web mounted on said support in opposed relationship for substantially radial movement into and out of engagement with a braking surface of said rotatable drum, a parking brake lever disposed adjacent the web of one of said brake shoes, actuating means facilitating movement of said brake shoes, and an adjuster strut having an adjustable elongate extent with first and second engagement means disposed at opposite ends thereof, said first engagement means engaging said brake shoe and said adjacent parking brake lever, and said second engagement means engaging the other said brake shoe, said first engagement means being received and supported within adjacent inwardly opening slots formed in each of the web of the first of said brake shoes and said parking brake lever, and including an end face for abutting engagement at least in a radially contracted or brake off condition of said brake shoes with the inner end wall of at least one of said adjacent slots, said first engagement means further including a first channel extending rearwardly from said face and an edge or wall portion (hereinafter an “edge portion”) of at least one of said adjacent slots extending into said channel. 
     In a brake assembly in which a slot opening is formed in both the brake shoe web and the adjacent parking brake lever, the respective openings may be of different lengthwise extent, preferably with the slot opening of the brake shoe web having greater lengthwise extent than that of the parking brake lever. This arrangement is such that the relevant end face of the strut engages only the inner end of the slot opening in the parking brake lever during normal operation. This arrangement facilitates disassembly of the brake assembly to remove a drum that has developed a lip or step through wear in a manner which is described later. 
     The above arrangement secures the strut end against movement laterally to the plane of the shoe web or parking brake lever in which the slot opening is formed in both the brake on and brake off conditions. The arrangement also permits movement in the lengthwise direction of the strut, such that in the brakes on condition, when the brake shoes of the brake assembly and the parking brake lever shift radially outwardly, the or each end face of the strut and the inner end of the or each slot, can shift away from abutting engagement as required, but the channel engagement remains. Accordingly, despite any lengthwise movement of the strut, the ends of the strut remain engaged in the slots with the respective braking members. In accordance with its normal function, upon wear of the brake shoe friction lining, the adjuster strut extends lengthwise to compensate for that wear, although the mechanism by which the strut is extended can take any suitable form and is not restrictive on the present invention. 
     Preferably, the, or one of the end faces of the adjuster strut engages the inner end of a slot opening formed in a parking brake lever associated with a brake shoe. In such an arrangement, it is common for the body of the lever to be formed out of metal plate and to be positioned adjacent and generally in side-by-side sliding contact with the inwardly depending web of a T-shaped brake shoe with which it is associated. In that arrangement, given the close proximity of the lever to the shoe web, it is appropriate for both the parking brake lever and the brake shoe web to have slot openings for receipt of an end of the adjuster strut. In this arrangement, and as described earlier, the slots may have different elongate extents, such that the end face of the adjuster strut engages the inner end of the slot formed in the parking brake lever only. 
     During operation of the brake assembly to a brake on condition, the strut may undergo slight pivoting movement and therefore the slot openings in the braking members are preferably shaped to permit that pivoting movement. In one arrangement, the edges of the slot opening in the parking lever taper from the inner end to be wider at the mouth thereof, while the slot opening of the shoe web is shaped wide at the inner closed end thereof and converges toward the open mouth thereof. By this arrangement the adjuster strut may pivot as necessary without obstruction from either of the upper and lower edge portions of the slot opening in the brake shoe web, but the edge portions of the web slot opening can be arranged at the most convergent point to engage or be closely adjacent upper and lower surfaces of the respective strut end, to substantially eliminate vertical movement of that end, particularly if the end shifts in the lengthwise direction of the strut away from abutting engagement with the inner end wall of the parking brake lever to a position where the tapered edges of the slot in the parking lever are spaced further apart, so itself providing limited resistance to vertical movement. 
     In one preferred arrangement, the channel of the strut end portion has a width sufficient to accommodate only the edge portions of the slot opening of the parking brake lever. The side walls of the channel may extend closely adjacent the opposite sides of the edge portion to capture it in the channel against relative lateral or sideways movement. By this arrangement, the strut end section can conveniently be substantially restrained against undesirable movement both parallel and perpendicular to the plane of the shoe web. 
     In a second aspect of the invention, a biasing arrangement is employed for biasing the parking brake lever of a brake assembly toward the inwardly depending web of a T-shaped brake shoe. This aspect of the invention provides for engagement of an end of the adjuster strut in a slot opening of the parking brake lever and is characterised by the provision of biasing means extending between the adjuster strut and the brake shoe web which biases the parking brake lever and the brake shoe web towards each other and preferably together. 
     In one preferred arrangement of this second aspect of the invention, the biasing means includes a cantilever spring bias that has attachment means for attachment to the adjuster strut and that extends into engagement with a side surface of the brake shoe web to bias the web toward the parking brake lever. The attachment means may conveniently be a clip arrangement and in respect of an adjuster strut having a cylindrical body portion between respective opposite end portions, the clip arrangement may clip onto that cylindrical portion. The clip engagement may be sufficient to position the biasing means on the adjuster strut, although additional locating means such as to position the strut both angularly and longitudinally, may be provided for that purpose. 
     The attachment means may equally take other forms and the biasing means may for example, be attached to the adjuster strut by suitable fastening means, or such as by permanent welding attachment or riveting. 
     In the above arrangement the biasing means biases the brake shoe web toward and preferably into engagement with the parking brake lever in one direction only, being laterally to the elongate extent of the adjuster strut and to the plane of the web, and in that arrangement, a moment force will be generated tending to rotate the brake shoe relative to the strut. Thus, in an alternative arrangement, the biasing means imposes an equal and opposite biasing force so that no such moment force is created. In this arrangement, a pair of cantilever springs can extend into contact respectively with oppositely facing side surfaces of the brake shoe web or respective oppositely facing side surfaces of the brake shoe web and the parking brake lever. Both cantilever springs impose an equal and opposite force tending to bias the web and lever into engagement. 
     In a third aspect of the invention, an adjuster strut is provided with means to secure it to the braking member with which it is engaged to prevent release of the strut from its operative position. This third aspect of the present invention is characterised in that one end of the adjuster strut is formed to cooperate directly with one of the braking members so that that end of the strut is secured against release from the braking member in the assembled or operative position of the strut. In one preferred form of this aspect of the invention, the end of the adjuster strut includes abutment means suitable for engagement in the operative position of the strut to engage an abutment formed or provided on the braking member, whereby that cooperation secures the end of the adjuster strut against release from the braking member. 
     The abutment means can take any suitable form and in one form, it is formed by an elongate member which extends from the strut into engagement behind the braking member abutment in the operative condition of the strut. That member may for example, be of plate metal form which is fixed to the strut in any suitable manner and which has a distal end formed for positioning behind the abutment. An alternative form of this aspect of the invention includes a member that extends from the strut and engages in an opening provided in the braking member. In a preferred arrangement the opening is provided in the radially inwardly depending web of a T-shaped brake shoe and the strut member includes an abutment arranged to abut against a radially inward edge of the opening to resist release of the strut from its operative position as assembled between the braking members. The abutment may not engage the edge at all times and in a preferred arrangement, engagement only occurs when the brake assembly is in a brake on condition, or when the adjuster has failed and has stopped adjusting or extending. Thus, the opening preferably is shaped to allow movement of the abutment toward and away form the edge of the opening as the brake assembly shifts between brake on and brake off conditions. 
     In another form of this aspect of the invention, the end of the adjuster strut is formed to have a head and a neck portion and a substantially radial stepped surface extends at the junction between the head and the neck. In one form of this arrangement, both the head and the neck are generally cylindrical and the stepped surface is formed by an increase in the diameter from the neck to the head. The abutment formed by the braking member for cooperation with this form of strut end can be formed as part of the slot opening which is formed to receive the end of the adjuster strut. Conveniently, the abutment may be formed at the open end of the slot opening and may for example, depend downwardly from the upper edge thereof, forming a lip or catch. More than one abutment, of this kind or otherwise, may be provided. 
     The example forms of abutment means described above advantageously can be applied to opposite ends of the adjuster strut. Alternatively, they may be employed separately with other forms of strut ends applied to the opposite end of the strut. 
     The above arrangements are preferably such as to permit simple installation of the abutment means relative to the abutment to secure the adjuster strut in the place. However, in such an arrangements, it is preferable that means be provided to ensure the integrity of the arrangement during operation of the brake assembly, such as to prevent lateral disengagement of the abutment means from the shoe web abutment. Biasing means as described for the second aspect of the invention could, for example, be employed to prevent lateral disengagement of the stepped surface from the abutment, although in a preferred arrangement, the head may be bifurcated to engage opposite side surfaces of the braking member. In this arrangement, installation of the adjuster strut may be by angled insertion of the bifurcated head into the slot opening and onto the inner end thereof, followed by rotation of the strut into the general plane of the opposite brake member edge or web, whereby the abutment means, such as the stepped surface is brought into alignment behind the brake member abutment. 
     Each of the above described strut end forms can be employed in a single adjuster strut. That is, the strut end having an end face and a rearwardly depending channel of the first aspect of the invention can be employed in a strut in which the opposite end is formed according to the third aspect. Additionally, the method of angled insertion of the adjuster strut can be employed in a strut that has both described end forms. This is particularly the case in an adjuster strut that employs an end face of the first aspect, as that end face is not bifurcated and as such, is not required to straddle opposite sides of the braking member. As such, that end form does not have to be installed end on to the web or lever portion it is to engage, but can be rotated or swivelled into position. Moreover, biasing means as may be required, can be fitted subsequently. The third aspect of the invention is preferably applied between the end of the adjuster strut and the brake shoe web, although it could also be applied, but less preferably, to the parking brake lever. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The attached drawings show an example embodiment of the invention of the foregoing kind. The particularity of those drawings and the associated description does not supersede the generality of the preceding broad description of the invention. 
     FIG. 1 shows a partial view of a brake assembly according to one embodiment of the invention. 
     FIG. 1 a  is an enlarged, partial view of FIG.  1 . 
     FIG. 2 shows a partial end view of a prior art adjuster strut. 
     FIG. 3 shows a partial one end view of an adjuster strut according to one embodiment of the invention. 
     FIG. 4 is a cross-sectional view through section Y—Y of FIG.  1 . 
     FIG. 5 is a cross-sectional view through section Z—Z of FIG.  1 . 
     FIG. 6 shows a partial view of a further embodiment of the invention. 
     FIG. 7 is a cross-sectional view through section X—X of FIG.  6 . 
     FIG. 8 shows a partial view of a brake assembly according to a further embodiment of the invention. 
     FIG. 9 is a partial end view of the adjuster strut of the assembly shown in FIG.  8 . 
     FIG. 10 shows a method of installation of the adjuster strut of FIG.  8 . 
     FIG. 11 shows a partial view of a brake assembly according to still a further embodiment invention. 
     FIGS. 12,  13  and  14  respectively show a partial view of a brake assembly according to the invention during movement of the brake shoes. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows one end of an adjuster strut  10 , which embodies aspects of the present invention. As shown, the strut  10  is in operative engagement with a parking brake lever  11  and a brake shoe  12  with which the lever  11  is associated in side-by-side sliding engagement. Each of the lever  11  and the shoe  12  are shown only in partial view, but in general terms, the shape and operation of these components is in accordance with prior art arrangements. The brake shoe  12  for example, is of T-shaped cross-section and includes a radially inwardly depending web  12   a  and an abutment surface  13  against which a hydraulic piston actuator acts to radially shift the shoe  12  to apply a braking force to a drum braking surface. Additionally, the lever  11  and shoe  12  are coupled together by a projection  14  of the lever  11  extending through an opening  15  in the web  12   a,  while the lever  11  includes a projection  16  that engages the inner edge  12   b  of the web  12   a  to locate the lever  11  relative to the shoe  12  in a non-operative condition. 
     The strut  10  is of elongate form and is lengthwise adjustable by any suitable arrangement. The strut  10  as shown, cooperates with both the lever  11  and the shoe  12  in a unique manner which is considered to be superior when compared to the arrangements employed in the prior art struts. As an example of such prior art struts, FIG. 2 shows one end of a strut  100 , which has been formed by pressing a tubular section  101 . The end  102 , by the pressing operation, is generally flat and by a grinding or stamping operation, recess  103  is formed between the legs  104 . The end  102  is therefore forked or bifurcated. 
     The strut  10  does not require a bifurcated end  102  and therefore does not require removal of material as occurs from the pressed end  102 . Instead, the end  17  of the strut  10  is shown in FIG. 3 (in exaggerated form) and that figure shows a straight or flat end face  18 . Moreover, the strut  10  can be reduced length compared to the strut  100 , because the strut  10  does not require the legs  104 . 
     Each of the lever  11  and the shoe  12  include a slot opening  19  and  20  respectively. This arrangement is more clearly shown in FIG. 1 a.  The slot opening  20  has a greater lengthwise extent than the slot opening  19  such that the inner end  20   a  of the opening  20  is spaced from the inner end  19   a  of the opening  19  a distance D. As such, the strut end face  18  is in abutting engagement with the inner end  19   a  of the lever  11  in the brake off or home position shown in FIG.  1 . In this arrangement, the opposite end of the strut  10 , which is not shown in FIG. 1, is in abutting engagement with the inner end of a slot opening formed in the inwardly depending web of the opposite T-shaped brake shoe. 
     The dimension D is provided to facilitate inward movement of the shoe  12  when the lever  11  is pushed away from the web  12   a  to disengage the projection  16  from the inner edge  12   b.  By that disengagement, the brake shoe can be moved inwardly the distance D and that permits a “lipped” drum (a drum that has worn through contact with the friction lining to produce a lip on the braking surface) to be removed from the brake assembly. 
     The strut  10  is formed at least in part from a tubular section (see FIG.  1 ). The end  17  of the strut  10  is pressed together into a generally flattened form as shown in FIGS. 3 to  5 . As shown in these figures, the pressed end  17  is formed to have a pair of oppositely facing channels  21 ,  22  defined by side walls  23 ,  24 . As shown in FIGS. 4 and 5, the channels  21 ,  22  have a width sufficient to accommodate the upper and lower edge portions  25 ,  26  of the slot opening  19  of the lever  11  only. The channels  21 ,  22  do not accommodate the upper and lower edge portions  27 ,  28  of the slot opening  20  of the shoe  12 . Thus, the strut end  17  is trapped against movement laterally to the plane of the lever  11  by accommodation of the edge portions  25 ,  26  within the channels  21 ,  22 . It is preferred for ease of assembly that the channels  21 ,  22  only accommodate the wall portions  25 ,  26 , so that the strut end  17  only engages the lever  11  by way of engagement with the channels  21 ,  22  and not the shoe web  12   a.    
     The arrangement shown in FIGS. 1,  4  and  5  advantageously minimises movement of the strut end  17 , by the particular shape and arrangement of the slot openings  19  and  20  which engage the end at each of two separate and spaced positions. Section YY shown in FIG. 4 shows the edge portions  27 ,  28  of the web  12   a  respectively in engagement with the upper and lower faces of the side wall  23 , while the edge portions  25  and  26  of the lever  11  are respectively slightly spaced from the base of the channels  21  and  22 . The respective engagement between the edge portions  27 ,  28  and the side wall  23  resists movement of the strut end  17 , at least in the plane of the web  12   a.  To further ensure restriction of strut movement, section ZZ shows the edge portions  25 ,  26  respectively engaging the base of the channels  21 ,  22  while the edge portions  27 ,  28  are respectively slightly spaced from the upper and lower faces of the side wall  23 . Thus, by this arrangement, movement of the strut in the plane of the web  12   a  is restrained by engagement with the edge portions of each of the slot openings  19 ,  20  at separate locations, although that engagement permits some strut movement as may be required during brake actuation, such as limited pivoting movement. 
     The strut  10  can be installed at the end shown in FIG. 1 by positioning the end  17  in the slot opening  19  of the lever  11  before the lever  11  is moved into position adjacent the web  12  where projection  16  engages the inner edge  12   b.  The lever  11  may thereafter be brought into the operative position adjacent the web  12 . 
     The assembly shown in FIG. 1 further includes biasing means (unit) to bias the lever  11  and the shoe  12  together. The biasing means includes a spring  29 , which is more clearly shown in FIG.  6 . Referring to that figure, the spring  29  is of cantilever form and includes attachment means in the form of clip attachment arms  30 . The attachment arms  30  are resiliently flexible to fit about the outside of the strut  10  and to hold the spring  29  in position thereagainst. The spring  29  is held against rotation by engagement of the spring end  31  against the shoe web  12   a.    
     The assembly shown in FIG. 1 further includes anchoring means (unit) for anchoring the strut  10  to the lever  11 . The anchoring means could alternatively anchor the strut to the shoe web  12   a  and therefore it is not limited to the particular arrangement shown in FIG.  1 . The anchoring means includes a member  32  that extends from the spring  29 , preferably being formed integrally therewith, and the distal end of the member  32  is formed as a hook  33  for receipt within a recess  34 . Cooperation between the hook  33  and the recess  34  is such as to restrain the strut end  17  against movement in the lengthwise direction of the strut  10  relative to the lever  11  that would cause separation of the strut end  17  from the slot openings  19 ,  20 . Such separating movement can occur when the brake friction lining has worn a significant amount and the adjusting mechanism of the strut has failed providing no, or insufficient corresponding lengthwise extension of the strut  10 , such that upon radial expansion of the brake shoe, the strut end  17  would, without the provision of suitable anchoring means, be released from the slot openings and become loose within the brake assembly. This could also occur upon expansion of the brake drum due to high brake temperatures, such that the brake shoes have greater travel to engage the drum braking surface. 
     The arrangement of FIG. 1 advantageously permits the brake shoes to expand either by hydraulic actuation or by the parking brake lever without restriction from the anchoring means by providing the clearance C 1  and C 2  as shown. The clearance C 1  permits actuating movement of the parking brake lever  11 , while the clearance C 2  permits clockwise rotation of the lever  11  when the projection  16  is disengaged from the edge  12   b  of the shoe web  12 , for drum release as described earlier, or to disengage the strut end  17  from the lever  11 . Engagement of the hook  33  in the recess  34  may cause relative movement between the lever  11  and the shoe  12  during brake actuation, but that is acceptable and does not restrain the brake shoe from engaging the drum braking surface. 
     FIG. 7 is a cross-sectional view through section XX of FIG.  6 . This view shows each of the features of FIGS. 1 and 6. 
     FIG. 8 shows the opposite end of the strut  10  in an operative position in engagement with the web  35  of a T-shaped brake shoe  36  positioned opposite the brake shoe  12 . The strut end  37  is formed to have a head  38  and a neck  39 , with a stepped surface  40  extending therebetween. Both the head  38  and the neck  39  are generally cylindrical and the arrangement is such that head, or the head and neck could be formed as a separate component and be fixed, such as by threaded connection to the strut end  37 . 
     The head  38  is bifurcated to define a channel  41  (see also FIG. 9) for receipt of the inner end  42  of a slot opening  43  in the web  35 . Conveniently, the slot opening  43  is formed with a lip  44  that, in the operative position of the strut  10 , cooperates with the stepped surface  40  to prevent release of the head  38  from the slot opening  43 . By this arrangement and with reference to FIGS. 8 and 9, the strut end  37  is therefore restrained against axial and lateral movement relative to the axis of the strut  10 . The arrangement does however permit slight pivoting movement, which the head  38  may undergo during brake actuation. 
     An adjuster strut of the above form can conveniently be fitted in the brake assembly after the shoes have been fitted to the backing plate. FIG. 10 shows the method of fitting, which involves introducing the head  38  at an angle to the web  35  and thereafter swinging it in the direction A to the operative position. This angular introduction is necessary to permit the lip  44  to be located behind the head  38 . Angular insertion advantageously is facilitated by adoption of an opposite strut end of the kind shown in FIGS. 1 and 3 to  7 . Such a strut end is not bifurcated and therefore can be swung and slid into the operative position for engagement in the slot openings  19  and  20  as discussed earlier. However, it must nevertheless be appreciated that the FIGS. 8 to  10  arrangement can be employed separately from the FIGS. 1 and 3 to  7  arrangements in an alternative type of adjuster strut. 
     An alternative form of anchoring means (unit) is shown in FIGS. 11 to  14 . This anchoring means can be applied to an adjuster strut such as that shown in the preceding figures and therefore, the other aspects of the adjuster strut will not be described. Referring to FIG. 11, this shows anchoring means including a member  50  in partial view which includes an abutment  51 . A T-shaped brake shoe  52  is shown in cross section which includes an opening  53 . A parking lever  54  is also shown in cross section along with one end  55  of an adjuster strut. 
     As shown in FIG. 11, the abutment  51  is in engagement with a radially inward edge  56  of the opening  53 . The other end of the member  50  is attached to the strut body, such as in a like manner to that shown in FIG. 1, so that in the engaged condition of the abutment  51  with the inward edge  56 , the strut is prevented from shifting further away from the brake shoe  52 . The arrangement of FIG. 11 provides the same anchoring effect as the equivalent arrangement shown in FIG. 1, but the FIG. 11 arrangement operates in a plane disposed perpendicular to the FIG. 1 arrangement. 
     The elongate shape of the opening  53  permits the abutment  51  to shift away from the inward edge  56  as may be necessary during various stages of the operation of the brake assembly. FIGS. 12 to  14  partly illustrate a drum brake assembly of a similar kind to that shown in FIG. 1 notwithstanding that the assembly of FIGS. 12 to  14  is shown in the reverse to the assembly of FIG.  1 . In view of the similarity, like reference numerals have been used to designate like parts. FIGS. 12 to  14  show brake shoe movement as follows. 
     FIG. 12 shows the brake assembly in the brake off or “home” position. In that figure, the abutment  51  is positioned about midway along the opening  53 . It is to be noted in this figure that the projection  116  is in engagement with the inner edge  112   b.    
     FIG. 13 shows the brake assembly in the fully applied condition and in that figure, the abutment  51  is in abutting engagement with the inward edge of the opening  53 , as shown in FIG.  11 . The strut is therefore restrained by the abutting engagement against release from connection with the brake shoe  52 . 
     FIG. 14 shows the brake assembly fully retracted, and in this figure, it can be seen that the projection  116  has been disengaged from the inner edge  112   b  of the shoe web  112   a,  so that the brake shoe  112  can be shifted away from the braking surface of the drum. In FIG. 14, the abutment  51  has shifted to be positioned at or adjacent the end of the opening  53  opposite to the inward edge  56 . Thus, the abutment  51  provides no resistance to the shifting movement of the brake shoe. 
     The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.