Drum brake for a motor vehicle

Abstract

The invention relates to a drum brake comprising a disk-shaped plate having an inner face to which a wheel cylinder and a bearing element, which bearing element is referred to as a fixed point bearing element, are attached at diametrically opposite positions, a first and a second segment, the drum brake having a second actuator comprising a parking brake lever (21) for immobilising the vehicle, which lever (21) is carried by the core of a segment and has one end that is rotatably linked to a first end of the core and another free end (23) to which an end of a brake cable (5) is attached, which brake cable, when under tension, pulls the free end of the lever (21) causing the lever to rotate (21) in order to separate the segments, the brake (1) having means for blindly installing the brake cable (5), the means comprising a through-opening formed in the plate, means for guiding the brake cable (5) made up of a sheath such as a coil spring (26) extending between the opening in the plate and the free end of the lever (21), and means for supporting the guide means. The invention is characterised in that the support means are made up of a U-shaped support element (27), the coil spring (26) being carried in the space defined between the arms of the U.

Description

Description Title of the invention: Motor vehicle drum brake

[0001] The invention relates to a drum brake comprising a disc-shaped plate having an inner face to which are fixed a wheel cylinder and a support member called the fixed point, at diametrically opposed positions, a first and a second segment respectively comprising a web on the outer edge of which is fixed a sole usually called a rim made of cylindrically curved sheet metal which carries a brake lining, each web having one end bearing on a piston of the wheel cylinder and another end bearing on the fixed point, the drum brake comprising a second actuator comprising a parking brake lever which allows the vehicle to be immobilized, this lever being carried by the web of a segment, and having one end rotationally fixed to a first end of the web, and another free end to which is fixed one end of a brake cable, which, when under tension, pulls the free end of the lever,causing a rotation of the lever in order to separate the segments, the brake comprising means allowing blind mounting of said brake cable, said means comprising a through hole made in the plate, guiding means for said brake cable consisting of a sheath such as a helical spring extending between the hole in the plate and the free end of the lever, as well as supporting means for said guiding means.

[0002] The invention also relates to a method of manufacturing a drum brake as well as a method of blindly assembling a brake cable onto an actuation lever of a drum brake according to the invention.

[0003] The field of the invention is the automotive field and more particularly a drum brake for motor vehicles.

[0004] STATE OF THE ART

[0005] A drum brake is a braking device fitted to a vehicle to slow down or even stop the wheel's rotation through friction. Therefore, this type of drum brake can be used as a service brake to slow down or stop the vehicle, and also as a parking brake to secure the vehicle when parked.

[0006] Such a drum brake comprises a fixed plate having an inner face to which are A wheel cylinder and a support element, called the fixed point, are fixed in diametrically opposite positions. This plate carries a first and a second segment, the ends of which are held in place by two springs that clamp them against the wheel cylinder and the fixed point. The first segment has a sheet metal web shaped like a portion of a crown, to the outer edge of which is welded or crimped a rim, usually called a cylindrical sheet metal rim, which carries a brake lining. This web has one end bearing against a piston of the wheel cylinder and the other end bearing against the fixed point. The second segment has the same general structure.

[0007] These segments move radially to be pressed against the inner face of a rotating wheel drum, generating braking torque. The wheel cylinder contains a chamber closed by two pistons that, upon increase in hydraulic pressure, spread the ends of the segments apart. Additionally, a wear-compensating linkage runs along the wheel cylinder, with one end bearing against a lever on the first segment and the other end bearing against the web of the second segment when the brake is at rest. This linkage incorporates a mechanism that extends as the linings wear, ensuring that the brake lever travel remains constant throughout the brake's lifespan.

[0008] A lever carried by the brake shoe web is actuated by a second actuator that controls the parking brake. This lever has one end that is rotationally connected to the brake shoe web, and another free end to which a brake cable head is attached. This lever rests near the connection on the end of the connecting rod. When the cable is tensioned, it pulls the free end of the lever away from the rim, pressing on the connecting rod to separate the brake shoes and press them against the drum.

[0009] After installing this type of brake on a vehicle, the cable is connected to the lever blindly, with the pressure plate in place within the drum. This connection is achieved by first inserting the front end of the cable, fitted with a ferrule, through an outer face of the pressure plate into a hole provided for this purpose in the plate, located approximately opposite the second segment. This cable end is then guided to the end of the lever and secured using guide rails. Continuing along this path, the cable end is secured to the end of the lever through a passage hole in the lever end.

[0010] Although such an arrangement facilitates blind mounting of the brake cable, it still has drawbacks. Indeed, the guiding means can consist of a helical spring through which the cable is inserted to reach the lever, as described in US-A-4753325.

[0011] However, using a helical spring as a guide presents problems related to its attachment in the tray's opening and the quality of the guidance in the area between the tray's opening and the lever's end. The relative "flex" of the spring between the engagement hole and the lever can cause difficulties because the cable end can hit the spring and deform it, hindering proper and rapid guidance.

[0012] Therefore, in FR-A-2772704, we proposed guidance means comprising a conduit fixed relative to the plate, one end of which is housed in the orifice of the plate, and the other end of which is linked to one end of a second conduit consisting of a helical spring, the other end of which is linked to the lever.

[0013] Similarly, in FR-A-2841619, brake cable guidance means were described comprising a helical spring extending between the plate opening and the lever end, and a cylindrical element consisting of two gutter-shaped parts which, when joined, form a passage to retain the spring.

[0014] Such guiding methods make it possible to solve the problems related to the flexibility and the risk of jamming of the helical spring, but require for this purpose the use and placement on the plate and the lever of elements such as a conduit, which complicates the manufacture of the brake, in particular the mounting of the spring in said conduit, and therefore increases the manufacturing cost.

[0015] DESCRIPTION OF THE INVENTION

[0016] The present invention therefore aims to provide a drum brake that overcomes these drawbacks. In particular, the invention relates to a drum brake in which the risks of the front end of the cable jamming in the helical spring are limited, while also being simpler to manufacture and implement.

[0017] To this end, the invention relates to a drum brake comprising a disc-shaped plate having an inner face to which are fixed, at diametrically opposed positions, a wheel cylinder and a support member called a fixed point, a first and a second segment comprising respectively a core on the outer edge of which is fixed a sole usually called a rim made of cylindrically curved sheet metal which carries a brake lining, each core having one end bearing on a piston of the wheel cylinder and another end bearing on the fixed point, the drum brake comprising a second actuator comprising a parking brake lever which allows the vehicle to be immobilized, this lever being carried by the core of a segment, and having one end rotationally linked to a first end of the core, and another free end to which is fixed one end of a brake cable, which, when under tension, pulls the free end of the lever, causing a rotation of the lever in order to spread the segments apart, the brake comprising means allowing the blind mounting of said brake cable, said means comprising a through hole made in the plate,means for guiding said brake cable consisting of a sheath such as a helical spring extending between the plate opening and the free end of the lever, and means for supporting said guiding means, characterized in that the support means consist of a U-shaped support element, one of whose arms extends substantially parallel to the inner face of the plate and the web extends substantially perpendicular to said inner face of the plate, the open face of said retaining element being oriented towards the center of the plate, the helical spring being carried in the space defined between the arms of the U.

[0018] Advantageously, during the manufacture of the brake according to the invention, the helical spring as a guiding means can be fixed with its ends on one side in the orifice of the plate and then at the lever and can then simply be slid into the support element between the arms of said U-shaped support element. The mounting of the helical spring is thus much simpler to implement than when the spring is engaged through a conduit or under a retaining cover.

[0019] Furthermore, according to a preferred embodiment, the U-shaped support element has a core and a U-shaped arm consisting respectively of a wall and the other arm of the U being defined by at least one tongue, preferably two, extending from the core of the U-shaped element opposite the other arm.

[0020] Advantageously, the branch made up of tabs allows flexibility in holding the helical spring, which facilitates the guidance of the cable during blind assembly and also allows the movement of the helical spring when the parking brake control lever is operated.

[0021] The support element is fixed to the plate, preferably on the support member, by example by screwing. For this purpose, the support element has a fixing tab, fixed on the support member.

[0022] Thus, during the blind installation of the brake cable, these support means allow the helical spring to be held along a precise trajectory, preventing deformation of the spring as the cable passes through the angled section of the path exiting the plate opening. This gives the spring, thus constrained and held in position, a certain "rigidity" so that, when guiding the end of the parking brake cable through the spring, it cannot deform despite its elastic nature, even when the cable end comes against the spring. This prevents the end of the brake cable from getting stuck and facilitates its smooth passage through the helical spring.

[0023] The guidance of the cable from the plate opening to the lever is thus facilitated and promoted, with the help of these support means which makes it easier to mount blindly on a drum brake actuation lever of a motor vehicle, of a brake cable without the need for overly rigid or bulky guide parts to be mounted on the plate.

[0024] Preferably, the coil spring has a fitting at one end for inserting into the chainring hole, and its opposite end is fixed to the end of the lever at the brake cable head attachment points. The resulting path for the coil spring has a substantially angled section as it exits the chainring hole, causing the coil spring to extend along the face of the chainring to the end of the lever.

[0025] To facilitate the retention of the angled section in a preferred shape, the U-shaped support element extends asymmetrically from its attachment point on the support member, which is located approximately centrally between the plate opening and the lever end. Thus, the support element's retaining tab extends at one end of the support element, and the element itself extends primarily towards the plate opening. This provides better support for the angled section, facilitating the guidance of the brake cable head within it. In particular, it prevents the risk of deformation of the coil spring as the brake cable head passes through the angled section.

[0026] Thus, advantageously, when the brake cable end or head is engaged in the front end, at the entry of the helical spring at the level of the plate opening, it can pass the angled portion of said spring without deforming it too much, which promotes good guidance.

[0027] These support means thus formed are fixed to the platform by screwing, welding or any other appropriate means.

[0028] In a preferred embodiment, the actuating lever of a drum brake is formed by an oblong plate of thickness "e" and longitudinal axis X, designed to extend, once mounted in the drum brake, in a transverse vertical plane. One end of the actuating lever is rotationally fixed by a connection at its first end, and its other free end is attached to the front end or head of a parking brake control cable. Securing means for the end of the brake control cable are arranged at the operating end of the actuating lever; the tension exerted on the brake cable causes the actuating lever to pivot at its opposite end, thereby actuating the parking brake.The means for securing the end of the brake cable arranged at the free end of the lever may consist of a U-shaped retaining channel, for securing the end of the parking brake control cable.

[0029] According to a first embodiment of the invention, the retaining channel is made in one piece with the actuating lever. Thus, the end of the lever is preferably cut so as to present a tab extending axially, which is folded in such a way as to define on one face of this lever, the one facing the plate, a retaining channel with a U-shaped cross-section, the first free arm of which is parallel to a second arm formed by the lever.

[0030] According to a second embodiment, it is possible to provide a piece with a U-shaped cross-section attached to the end of the lever and fixed to it by any appropriate means such as riveting to form said channel.

[0031] Preferably, the retaining channel has an internal transverse dimension equal to or greater than that of the cable and less than the external diameter of the cable head.

[0032] Advantageously, the free arm of the retaining channel formed by the end of the tongue, for example, is defined so as to form a ramp to guide the head of the brake cable during the assembly of the brake cable.

[0033] To facilitate proper seating of the brake cable head in the U-shaped recess or retaining channel of the lever, a means for retaining the brake cable head in the channel can also be provided on the lever. This retaining means is movably mounted between a first position that blocks the passage of the brake cable head and a second position in which the brake cable head can pass. Elastic return means bring the retaining means back from the open position to the blocked position, so that the retaining means exerts a force against the head. of the brake cable, which, once the rear end, exiting the retaining channel, is held against the rear of said channel.

[0034] Preferably, this retaining device consists of a leaf spring having at least one leaf portion extending substantially parallel to and above the retaining channel, connected by an angled portion to a leaf portion extending across the retaining channel at its end, thus blocking the passage beyond said channel. The leaf spring is mounted on the lever by a mounting plate.

[0035] The invention also proposes a method of manufacturing said brake according to the invention, characterized in that the helical spring is fixed with its ends on the one hand in the orifice of the plate then at the level of the lever and is then slid into the support element between the arms of said U-shaped support element.

[0036] As previously mentioned, after installing this type of brake on a vehicle, the parking brake control cable is attached to the lever blindly, with the plate in place inside the drum. The invention also relates to a method for blindly assembling a brake cable onto a drum brake according to the invention, characterized in that the end of the brake cable is inserted, from the outer face of the plate, into an opening in the plate. This brake cable head is then guided by guiding means, such as a helical spring, carried on the inner face of the plate, towards the free end of the lever to be attached there. The cable head then engages in the retaining groove arranged at the end of the lever until it is lodged after the rear end of said groove, the head being held against said rear end of said groove.

[0037] BRIEF DESCRIPTION OF THE FIGURES

[0038] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for which reference should be made to the attached drawings which represent:

[0039] [Fig. 1] a plan view of a drum brake according to the invention, intended to be mounted on a wheel of a motor vehicle;

[0040] [Fig. 2] a perspective view of the guiding means of a blind mounting arrangement;

[0041] [Fig. 3] a perspective view of the parking brake lever and the brake cable fixing means according to the invention;

[0042] [Fig. 4] A perspective view of the end of the lever in Figure 3

[0043] [Fig. 5A] a cross-sectional view of the end of the lever in Figure 4 according to a first step in mounting a brake cable;

[0044] [Fig. 5B] a cross-sectional view of the end of the lever in Figure 4 according to a second step in mounting a brake cable;

[0045] [Fig. 5C] a cross-sectional view of the end of the lever in Figure 4 according to a third step in mounting a brake cable.

[0046] A drum brake 1 according to the invention is shown in Figure 1. Such a drum brake 1 comprises a fixed plate 2 having an inner face to which are fixed a wheel cylinder 6 and a support member called a fixed point 7, at diametrically opposed positions. This plate 2 carries a first and a second segment 3 and 4, the ends of which are held in contact with the wheel cylinder 6 and the fixed point 7 by two springs 8 and 9 to clamp them together. The first segment 3 has a sheet metal web 12 shaped like a portion of a crown, to the outer edge of which is welded or crimped a flange, usually called a rim 13, made of cylindrically curved sheet metal, which carries a brake lining 14. This web 12 has one end 15 bearing against a piston of the wheel cylinder 6, and another end 16 bearing against the fixed point 7. The second segment 4 has the same general structure.

[0047] These segments 3 and 4 are radially movable to be pressed against an inner face of a rotating wheel drum in order to generate braking torque. The wheel cylinder 6 includes a chamber closed by two pistons that move apart upon increase in hydraulic pressure, thus separating the ends of segments 3 and 4. Additionally, a wear-compensating link 17 runs along the wheel cylinder 6, with one end 18 bearing against a lever 21 carried by the first segment and the other end 19 bearing against the web of the second segment when the brake is at rest. This link 17 incorporates a mechanism that increases its length as the linings wear, so that the brake control stroke remains unchanged throughout the brake's service life.

[0048] A lever 21 carried by the web 12 of segment 3 is actuated by a second actuator that controls the parking brake. This lever 21 has one end rotationally connected by a linkage 22 to a first end of the web 12, and another free end 23 to which a brake cable head (not visible in Figure 1) is attached. This lever 21 bears against the end 18 of the connecting rod 17 near the linkage 22. When the cable is under tension, it pulls the free end 23 of the lever 21, which then moves away from the rim 13, to press on the connecting rod 17 in order to spread segments 3 and 4 apart so as to press them against the drum.

[0049] After fitting a brake of this type to a vehicle, the cable is coupled to the lever 21 blindly, with the plate 2 in place in the drum. This assembly is achieved by first inserting the front end of the cable 5, fitted with a fitting 51, through an outer face of the plate 2, into a through hole 24 in the plate located approximately opposite the second segment 4. This end of cable 5 is then routed to the end 23 of the lever to be secured there by means of guide means 26. Continuing along this path, the end of cable 5 is secured to the end 23 of the lever 21 through a through hole arranged on said end.

[0050] In particular, the means for actuation of the drum brake for parking according to the invention are shown in Figure 2. There can be seen the actuation lever 21 having at its stress end 23, means for fixing the end of a brake cable such as a U-folded tab to form a retaining channel 20 for the end of a parking brake control cable 5.

[0051] As previously mentioned, after fitting this type of brake to a vehicle, the parking brake control cable is connected to the lever 21 blindly, with the plate 2 in place in the drum. This connection is achieved by first inserting the front end of the cable 5, fitted with a head or end 51, through an outer face of the plate 2, into a hole 24 provided for this purpose, which is located approximately opposite the second segment 4. This end of the cable 5 is then guided by guiding means, such as a helical spring 26, carried by the plate 2 on its inner face, towards the end 23 of the lever 21 to be secured there.

[0052] Thus, in the example shown, the actuating lever 21 of a drum brake according to the invention is formed by an oblong plate of thickness "e" and longitudinal axis X, intended to extend, once mounted in the drum brake, in a transverse vertical plane as can be seen in figure 1. One end of the actuating lever 21 is mounted rotationally connected by a link to a first end and its other free end 23 is secured to a front end or head 51 of a parking brake control cable 5.

[0053] This free end 23 is cut to present a tab 231 extending axially, which is folded so as to define on one face of this lever 21 a retaining channel 20 with a U-shaped cross-section. The retaining channel 20 is formed by the tab 231 folded into a U-shape to form a first free arm parallel to a second branch formed by lever 21.

[0054] It is possible to provide a U-shaped cross-section piece attached to the end of the lever 21 and fixed to it by any appropriate means such as riveting to form said retaining channel 20.

[0055] The free arm of the retaining channel 20 formed by the end of the tongue 231 is defined so as to form a ramp 232. The retaining channel 20 has an internal transverse dimension equal to or greater than that of the cable 5 and less than the external diameter of the head 51 of the cable 5.

[0056] The parking brake control cable 5, introduced on the face of the plate 2 through the orifice 24, is guided through the helical spring 26 to the free end 23 of the lever 21.

[0057] This arrangement therefore includes, as means for guiding the brake cable 5, a helical spring 26, preferably with non-contiguous coils, which extends between the orifice 24 of the plate 2 and the excitation end 23 of the lever 21 and more precisely at the level of the retaining channel 20.

[0058] Thus, the helical spring 26 has one end 261 mounted in a ring 262 which is fixable in the orifice 24 and whose other end 263 is fixed to the actuating end 23 of the lever 21 so that said end 263 of the helical spring 26 emerges substantially at the level of the retaining channel 20. However, since the internal transverse dimension of the retaining channel 20 is less than the external diameter of the head 51 of the brake cable 5, the guiding means are provided to allow the head 51 to engage above the retaining channel 20, guided by the ramp 232 until said head 51 reaches the opposite end of the retaining channel 20, where, once the ramp 232 has been passed, the head 51, no longer retained by the ramp 232, comes to rest behind the end of the retaining channel. 20 thus blocking the cable 5 in the retaining channel and on the lever 21.

[0059] To facilitate the guidance of the head 51 of the parking brake control cable on the ramp 232, a cover 10 is provided, fixed to the free end, referred to as the engagement end 23, of the lever 21. This cover 10 covers the open portion of the retaining channel 20 and has at one end an annular piece 101 to which the end 263 of the helical spring 26 is attached. The cover 10 is thus mounted on the lever 21 so that the annular piece 101, equipped with the helical spring 26, is positioned at the so-called entry end 201 of the retaining channel 20, allowing the guided engagement of the head 51 of the parking brake control cable. parking 5.

[0060] Advantageously, the parking brake control cable head 51, which is larger than the retaining channel 20, slides on the ramp 232, therefore above the retaining channel 20, but held by the hood 10, until the ramp 232 ends, the brake cable head 51 is lodged after the rear end 202 of the channel 20, butted against it, while the cable 5 is lodged at the bottom of the retaining channel 20.

[0061] Thus, the head 51 of the brake cable 5 is engaged through the orifice 24 through the ring 261, is guided through the helical spring 26 to its opposite end where it is then engaged at the level of the retaining channel 20 until it comes to rest at the rear of said retaining channel 20. It is then possible to exert a pull on the cable 5 to drive the lever 21 into rotation to actuate the parking brake.

[0062] In order to facilitate this engagement of the brake cable head 51 and in particular its sliding along the ramp 232 for the purpose of fixing on the retaining channel 20, the cover 10 is positioned so that the annular piece 101 on which the helical spring 26 is fixed allows it to open substantially in relation to the retaining channel 20.

[0063] The blind mounting arrangement also includes support means for said helical spring 26 allowing simple installation of the spring and flexible retention of said spring 26 at least over a portion of the path between the orifice 24 of the plate 2 and the excitation end 23 of the lever 21, so as to aid and promote the guidance of the brake cable 5 in the helical spring 26 during blind mounting while promoting the actuation of the parking brake lever 21.

[0064] These support means consist of a support element 27 having substantially a U-shape, one arm of the U 272 and the web 271 being respectively constituted by a wall and the other arm of the U being defined by at least one tongue 273, preferably two, 273, 274 extending from the web 271 of the U-shaped element 27 opposite the other arm 272. This support element 27 is positioned between the orifice 24 of the plate 2 and the load end 23 of the lever 21, so that the solid arm 272 of the support element 27 extends substantially parallel to the face of the plate 2, the web 271 of said support element 27 extending substantially perpendicular to said face of the plate 2.In this way, during the assembly of the brake, the helical spring 26 is fixed with its ends on one side in the orifice 24 of the plate and then at the lever 21 and can then be slid into the support element 27 between the arms 272; 273, 274 of said U-shaped support element 27. The. mounting the spring is therefore much simpler to implement than when the spring is engaged through a conduit or under a retaining cover.

[0065] The support element 27 is fixed to the plate 2, preferably to the support member 7, for example by screwing. For this purpose, the support element 27 has a fixing tab 275.

[0066] As previously mentioned, the helical spring 26 has a substantially angled portion at the exit of the plate's opening 26, causing the spring 26 to extend along the face of the plate 2 to the end 23 of the lever 21, and more precisely opposite the retaining groove 20 of said lever 21. To facilitate the retention of this angled portion in a preferred shape, the U-shaped element 27 extends asymmetrically with respect to its attachment point on the support member 7, which is located substantially centrally between the opening of the plate 24 and the end 23 of the lever. Thus, the support element is more active on the side of the plate 24's opening, better holding the angled portion to facilitate the guidance of the brake cable head within this angled portion. In particular, the risks of deformation of the spring 26 during the passage of the angled portion by the head 51 of brake cable 5 are avoided.

[0067] In order to promote the proper placement of the brake cable head 51 in the U-shaped fold or retaining channel 20 of the lever 20, a retaining means 28 for the brake cable head 51 at the level of the retaining channel 20 can also be provided on the lever 21, said retaining means 28 being mounted movably between a first position of closing the passage of the brake cable head 51 and a second position of retraction in which the brake cable head 51 can pass, elastic return means bringing said retaining means 28 back from the retraction position to the closing position, so that said retaining means 28 exerts a thrust against the brake cable head, which, once the rear end 202 of the retaining channel 2 is reached, is held against the rear of said retaining channel 20.

[0068] Preferably, this retaining means 11 consists of a leaf spring 28 having at least one leaf portion 281 extending substantially parallel to and above the retaining channel 20, connected by an angled portion 282 to a leaf portion 283 extending across the retaining channel 20 at its rear end 202, thus blocking the passage beyond said retaining channel 20. The brake cable head 51, engaged at the level of the retaining channel 20 against the ramp 232, abuts against the blocking portion 283 of the leaf spring 28 (see Fig. 5A) and pushes it aside, allowing said head 51 to pass (see Fig. 5B). A leaf end portion 284 is provided following the portion sealing part 283 after an angled portion 285. Similarly, the sealing part 283 has a projection 286 preventing transverse slippage of the head 51. The head 51, protruding beyond the end 202 of the retaining channel 20, is pushed back by the restoring force F of the leaf spring 28, which simultaneously holds the head 51 against the rear end 202 of the retaining channel 20 and houses the brake cable 5 in the retaining channel 20, see Fig. 5C.

[0069] The leaf spring 28 is carried by a fixing plate 111 on the lever 21. Thus, the leaf spring 28 has a portion 287 extending parallel to the retaining channel 20 and then a bent part 288 in the shape of a hairpin to form the portion 281.

[0070] Thus, not only is the drum brake according to the invention simple to manufacture, but it also offers a blind mounting that is easy to implement with simple means.

[0071] Nomenclature 1 drum brake 2 fixed shelves 3 first segment 4 second segment 5 brake cable 51 brake cable head 6-cylinder wheel 7. Supporting element called fixed point 8-9 springs 10 hood 11 means of maintenance 111 mounting plate 12 souls 13 sole 14 brake lining 15,16 extremities of the soul 17 wear compensation link 18,19 ends of the connecting rod 20 retaining chute 201 front end of the retaining chute 202 rear end of the retaining chute 21 Parking brake actuation lever 22. Lever end connection 23 free end of the lever 231 free end tab of the lever 232 ramp 24 hole in the platform 25 means of support 26 helical spring 27 support element 271 core of the supporting element 272 branch of the supporting element 273, 274 retaining tabs for the support element 275 support element fixing tab 28 leaf spring 281, 282, 283, 284, 285, 287, 288 blade portions 286 tongue

Claims

Demands

1. Drum brake (1) comprising a disc-shaped plate (2) having an inner face to which a wheel cylinder (6) and a support member (7) called a fixed point are fixed at diametrically opposite positions, a first and a second segment (3, 4) respectively comprising a web (12) to the outer edge of which is fixed a flange (13) usually called a rim made of cylindrically curved sheet metal which carries a brake lining (14), each web (12) having one end bearing on a piston of the wheel cylinder (6) and another end bearing on the fixed point (7), the drum brake comprising a second actuator comprising a parking brake lever (21) which allows the vehicle to be immobilized, this lever (21) being carried by the web (12) of a segment (3, 4), and having one end rotationally connected to a first end of the web (12),and another free end (23) to which is attached a front end or head of a brake cable (5), which, when under tension, pulls the free end of the lever (21), causing a rotation of the lever (21) in order to separate the segments (3, 4), the brake (1) comprising means allowing the blind mounting of said brake cable (5), said means comprising a through hole (24) made in the plate (2), means for guiding said brake cable (5) consisting of a sheath such as a helical spring (26) extending between the hole (24) in the plate and the free end (23) of the lever (21) as well as means for supporting said guiding means, characterized in that the support means consist of a U-shaped support element (27) one of whose arms (272) extends substantially parallel to the inner face of the plate (2) and the core (271) extends substantially perpendicular to said inner face of the plate (2),with the open face of said retaining element (27) oriented towards the center of the plate (2), the sheath (26) being carried in the space defined between the arms of the U.

2. Brake (1) according to claim 1, characterized in that the U-shaped support element (27) has a core (271) and a U-shaped arm (272) consisting respectively of a wall and the other arm of the U being defined by at least one tongue (273), preferably two, extending from the core (271) of the U-shaped element opposite the other arm (272).

3. Brake (1) according to claim 1 or 2, characterized in that the support element (27) has a fixing tab (275) fixed to the plate (2), preferably on the support member (7).

4. Brake (1) according to any one of claims 1 to 3, characterized in that sheath (26) has at one end a fixing tip (261) in the hole (24) of the plate (2) and its opposite end (262) is fixed on the end (23) of the lever (21) at the level of the fixing means of the brake cable (5), the trajectory thus defined for the sheath (26) having at the exit of the hole (24) of the plate (2) a substantially bent portion causing the sheath (26) to extend along the inner face of the plate (2) to the end (23) of the lever (21).

5. Brake (1) according to any one of claims 1 to 4, characterized in that the means for fixing the head of the brake cable (5) arranged at the free end (23) of the lever (21) consist of a U-shaped retaining channel (20) for fixing the head (51) of the brake cable (5).

6. Brake (1) according to claim 5, characterized in that the retaining chute (20) is made in one piece with the lever (21), the end of the lever (21) being cut so as to present a tab (231) extending axially, which is folded so as to define on one face of this lever (21), that opposite the plate (2), the retaining chute (20) of U cross-section whose first free arm is parallel to a second arm constituted by the lever (21).

7. Brake (1) according to claim 5, characterized in that the retaining chute (20) consists of a piece with a U-shaped cross-section attached to the end (23) of the lever (21) and fixed on it.

8. Brake (1) according to any one of claims 5 to 7, characterized in that the retaining chute (20) has an internal transverse dimension equal to or greater than that of the brake cable (5) and less than the external diameter of the head (51) of the cable (5).

9. Brake (1) according to any one of claims 5 to 8, characterized in that a retaining means (28) for the brake cable head (51) is provided at the level of the retaining channel (20), said retaining means (28) being movably mounted between a first position of closing the passage of the brake cable head (51) and a second position of retraction in which the brake cable head (51) can pass, elastic return means bringing said retaining means (28) back from the retraction position to the closing position, so that said retaining means (28) exerts a thrust against the brake cable head, which, once the rear end of the retaining channel (20) is reached, is held against the rear of said retaining channel (20).

10. Brake (1) according to claim 9, characterized in that this retaining means (28) consists of a leaf spring having at least one portion of a blade (281) extending substantially parallel to and above the retaining chute (20), connected by an angled portion (282) to a portion of a blade (283) extending across the retaining chute (20) at the rear end (202) thereof and thus blocking the passage after said retaining chute (20), the leaf spring being carried by a mounting plate (29) on the lever (21).

11. Brake (1) according to any one of claims 5 to 9, characterized in that a cover (10) is fixed on the free end (23) of the lever (21), this cover (10) covering the open part of the retaining channel (20) and having at one end an annular piece (101) on which the end (263) of the helical spring (26) is fixed so that the annular piece (101) provided with the helical spring (26) is positioned at the level of the brake cable fixing means (5).

12. Method of manufacturing a drum brake according to any one of claims 2 to 11, characterized in that the sheath (26) is fixed with its ends on the one hand in the orifice (24) of the plate and then at the level of the lever (21) and is then slid into the support element (27) between the arms (272; 273, 274) of said U-shaped support element (27).

13. A method for blindly assembling a brake cable on a drum brake according to any one of claims 5 to 11, characterized in that the head of the brake cable is engaged, from the outer face of the plate (2), in an orifice (24) of the plate (2) and then this head (51) of brake cable (5) is then guided by guiding means such as a helical spring carried by the plate (2) on the side of its inner face, towards the free end (23) of the lever (21) to be fixed there, the head (51) of cable (5) then engaging in the retaining channel (20) arranged at the end of the lever until it lodges after the rear end of said retaining channel (20), the head (51) being held against said rear end of said retaining channel (20).

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