Drum brake

Abstract

drum brake (1), in particular for a commercial vehicle, having - a brake drum (2) rotatably mounted about an axis of rotation (D), - several brake shoes (3) mounted in a receiving space (22) of the brake drum (2) with a respective friction lining carrier (32) and a friction lining (31) arranged on it, - wherein the brake shoes (3) are radial to an axis of rotation (A D ) of the brake drum (2) can be pressed against an inner surface (21) of the brake drum (2) designed as a friction surface, - a brake cylinder assembly (4) arranged in the receiving space (22) of the brake drum (2) on an anchor housing (8) in a rotationally fixed manner for actuating the brake shoes (3), - wherein the brake cylinder arrangement (4) comprises a housing (41) fixedly attached to the anchor housing (8) in the receiving space (22) of the brake drum (2) and a service brake piston (42) displaceable relative to the housing (41) parallel to the axis of rotation (D) of the brake drum (2), characterized in that - the brake cylinder assembly (4) comprises a parking brake piston (43) which is displaceable relative to the housing (41) parallel to the axis of rotation (D) of the brake drum (2) and is subjected to the spring force of a spring element (5), and several plungers (44) for transmitting a movement of the parking brake piston (43) to the service brake piston (42), - wherein respective compressed air supplies are provided into a service brake pressure chamber (45) between the housing (41) and the service brake piston (42) and a parking brake pressure chamber (46) between the housing (41) and the parking brake piston (43), and - on a side of the friction lining carrier (32) facing away from the friction lining (31) a respective pressure wedge (33) is arranged, which rests on a wedge ring (6) which is movable parallel to the axis of rotation (D) of the brake drum (2), - wherein the wedge ring (6) can be moved from a non-braking position to a braking position by moving the service brake piston (42) of the brake cylinder assembly (4) parallel to the axis of rotation (D) of the brake drum (2).

Description

[0001] The present invention relates to a drum brake, in particular for a commercial vehicle, according to the preamble of claim 1.

[0002] Drum brakes of this type feature a cylindrical rotor with friction surfaces arranged on the inside of the rotor, also known as the brake drum. Braking force is generated by brake shoes that are pressed against the inner friction surface of the brake drum.

[0003] The simplest and currently most commonly used type of drum brake is the so-called simplex drum brake. In this type, two brake shoes are pressed against the drum by a clamping device acting on one side of the brake shoes, either hydraulically or mechanically, for example using a cam, a spreader lock, a spreading wedge, or a spreading lever.

[0004] The two brake shoes are rotatably mounted on opposite sides of the clamping device. Due to the geometric arrangement, different forces are exerted on the two opposing brake shoes, depending on the direction of rotation of the brake drum.

[0005] While in the case of the so-called leading brake shoe, whose bearing is located behind a friction lining of the brake shoe in the direction of rotation of the brake drum, the contact force is increased by the leverage effect resulting from the position of the brake shoe bearing, the opposite effect occurs in the case of the so-called trailing brake shoe.

[0006] Accordingly, with this drum brake, the majority of the braking work is performed by the leading brake shoe.

[0007] This results in an uneven distribution of the contact force and the thermal load on the two brake shoes, which means that the wear of the friction lining of the two brake shoes is different.

[0008] One disadvantage of self-reinforcing brakes is that the so-called braking coefficient (C* value) increases disproportionately with the coefficient of friction of the brake pad. This can result in significantly different braking forces at the wheels and axles of the vehicle being braked.

[0009] On the other hand, such drum brakes have the advantage that the brake shoes are not directly exposed to the environment and are therefore considerably less affected by dirt, splash water and road salt on the function and condition of the brake shoes than, for example, disc brakes.

[0010] Therefore, drum brakes are better suited for off-road use than disc brakes, for example.

[0011] Another advantage of drum brakes is that there is practically no residual grinding torque with drum brakes, since in this type of brake the brake shoes are actively pulled back into a non-braking position by brake shoe return springs, thus preventing the grinding of the brake shoes, as occurs with brake shoes of disc brakes.

[0012] Another advantage of drum brakes is that they can collect the abrasion from the friction lining, thus relieving the surroundings and environment of such brake dust and, moreover, preventing the irreversible loss of valuable material elements bound in the friction lining of the brake shoes.

[0013] To reduce self-amplification, it is known, for example, from DE 10 2010 003 250 A1, to press two oppositely arranged brake shoes radially to the axis of rotation of the brake drum against the inner surface of the brake drum by means of an actuating element along a brake carrier.

[0014] Drum brakes are known from DE 666237 A and US 2527126 A, in which brake cylinders for actuating the brake shoes are installed in the interior of the drum brake.

[0015] US 2527126 A provides for two brake cylinders to actuate opposing brake shoes attached to armature housings. Each opposing end of the armature housing can be advanced by means of a plunger protruding from the pressure chamber of the respective brake cylinder, which is wedge-shaped at its end. This plunger presses the brake shoes against an inner wall of the brake drum between rollers located at the opposite ends of the armature housings, with the rollers pressing against plungers attached to the ends of the armature housings. Simultaneous actuation of both brake cylinders is crucial, as otherwise uneven wear of the brake shoes will occur.

[0016] The object of the present invention is to develop a drum brake with a more compact design and stable friction behavior.

[0017] This problem is solved by a drum brake having the features of claim 1.

[0018] The drum brake according to the invention has a brake drum rotatably mounted about an axis of rotation and several brake shoes mounted in a receiving space of the brake drum, each with a friction lining carrier and a friction lining arranged on it.

[0019] The brake shoes can be pressed radially towards a rotational axis of the brake drum against an inner surface of the brake drum designed as a friction surface.

[0020] Inside the drum brake, a brake cylinder assembly is provided, which is fixed to an armature housing and is designed to actuate the brake shoes.

[0021] On one side of the friction lining carrier facing away from the friction lining, a respective pressure wedge is arranged, which rests on a wedge ring that can be moved parallel to the axis of rotation of the brake drum.

[0022] The wedge ring can be moved from a non-braking position to a braking position by moving the service brake piston of the brake cylinder assembly parallel to the axis of rotation of the brake drum.

[0023] A drum brake designed in this way is characterized by its compact design.

[0024] In particular, the space for the brake cylinder, which is usually located outside the brake drum, can be saved, since it is now located inside the drum brake without having to significantly increase the volume of the drum brake.

[0025] The transfer of the movement of the wedge ring parallel to the axis of rotation of the brake drum into the radial movement of the brake shoe results in a multitude of further advantages.

[0026] Thus, the radial movement of the brake shoes and the short circumferential length of the brake shoes compared to those used in the prior art reduce the leverage effect that influences the brake shoes during the otherwise usual pivoting movement of the brake shoes.

[0027] Furthermore, the radial pressing of the brake shoes ensures stable friction behavior and even wear of the friction linings.

[0028] Unlike conventional drum brakes and disc brakes, the pad wear on the individual brake shoes is identical, since all brake shoes are actuated or actuated in the same way due to the principle.

[0029] Advantageous embodiments of the invention are the subject of the dependent claims.

[0030] According to an advantageous embodiment, the brake cylinder arrangement comprises a housing fixed in the receiving space of the brake drum on the anchor housing, a service brake piston displaceable relative to the housing parallel to the axis of rotation of the brake drum, a parking brake piston displaceable relative to the housing parallel to the axis of rotation of the brake drum and subjected to the spring force of a spring element, and a plunger for transmitting a movement of the parking brake piston to the service brake piston.

[0031] In a service brake pressure chamber between the housing and the service brake piston and in a parking brake pressure chamber between the housing and the parking brake piston, respective compressed air inlets are provided.

[0032] The spring element, in conjunction with the parking brake pressure chamber, enables a reliable parking brake function.

[0033] According to another design variant, the plunger is housed in a partition wall of the housing that separates the service brake pressure chamber from the parking brake pressure chamber.

[0034] In an alternative design variant, the plunger is housed in a partition wall of the housing that separates the service brake pressure chamber from the receiving chamber.

[0035] Both variants enable reliable brake actuation when the compressed air is released from the parking brake pressure chamber.

[0036] Depending on the installation situation, the two variants allow the spring element, preferably designed as a disc spring, to be fixed at a radially outer or a radially inner edge of the spring element.

[0037] According to a preferred embodiment of the drum brake according to the invention,

[0038] According to another preferred embodiment, the wedge ring is adjustable via an adjusting device.

[0039] In a preferred embodiment, a thread is arranged, in particular molded, on a surface of the wedge ring facing away from the pressure wedge, which meshes with a threaded sleeve of the adjusting device.

[0040] The threaded sleeve, together with the wedge ring, can be moved parallel to the axis of rotation of the brake drum by shifting the service brake piston of the brake cylinder assembly.

[0041] This allows, firstly, the threaded sleeve to be carried along during a braking process when it is moved parallel to the axis of rotation of the brake drum.

[0042] Secondly, rotation of the threaded sleeve allows for adjustment of the wedge ring relative to the threaded sleeve, which, depending on the wear condition of the friction lining of the brake shoes, adjusts the wedge ring so that the clearance of the drum brake can always be kept constant.

[0043] According to a preferred embodiment, the threaded sleeve is coupled to an adjusting drive via a toothed ring of the threaded sleeve.

[0044] According to another preferred embodiment, a slide with several rolling elements is arranged between the pressure wedge and the wedge ring, which enables the reduction of frictional resistance between the pressure wedge and the pressure surface of the wedge ring.

[0045] Preferred embodiments are explained in more detail below with reference to the accompanying drawings. They show: Fig. 1 an isometric representation of an embodiment of a drum brake according to the invention Fig. 2 an isometric representation of the drum brake according to Fig. 1 with brake drum hidden to show the arrangement of the brake shoes, Fig. 3 a schematic sectional view along the axis of rotation of the drum brake with a wheel rim overlapping the drum brake, Fig. 4 an isometric sectional view of the in Fig. 1 drum brake shown, Fig. 5 a sectional view of a section enlargement of the in Fig. 4 drum brakes shown, Fig. 6 an isometric sectional view of the representation of the drum brake according to Fig. 2 with hidden brake drum, Fig. 7 an isometric sectional view of the representation of the drum brake according to Fig. 1 in another section plane, Fig. 8 an isometric representation of the ring-shaped brake shoes arranged on the wedge ring resting on the threaded sleeve, Fig. 9 one opposite the Fig. 7 rotated isometric sectional view of the in Fig. 7 arrangement shown, Fig. 10a - 10d Sectional views of a section of the drum brake analogous to Fig. 5 in different functional positions and Fig. 11a - 11d the Fig. 10a - 10d corresponding illustrations of the drum brake in an alternative design variant.

[0046] In the following figure descriptions, terms such as top, bottom, left, right, front, rear, etc., refer exclusively to the exemplary representation and position of the drum brake, brake drum, brake shoe, brake cylinder, wedge ring, threaded sleeve, and the like as chosen in the respective figures. These terms are not to be understood as restrictive; that is, these references may change due to different working positions, mirror-symmetrical design, or similar factors.

[0047] In Fig. Reference numeral 1 designates a variant embodiment of a drum brake according to the invention. The drum brake 1 has a brake drum 2 rotatably mounted about an axis of rotation D, which, as shown in Fig. 3 is shown, connected in a rotationally fixed manner to a hub 13 and a rim 14 radially enclosing the brake drum 2.

[0048] In a space radially inside the brake drum 2, several brake shoes 3 are arranged, each with a friction lining carrier 32 and a friction lining 31 arranged on it, and are mounted in a receiving space 22 of the brake drum 2.

[0049] The brake shoes 3 can be pressed radially to the axis of rotation D of the brake drum 2 against an inner surface 21 of the brake drum 2 designed as a friction surface in order to carry out a braking process.

[0050] To carry out this radial pressing movement of the brake shoes 3 against the inner surface 21 of the brake drum 2, a brake cylinder arrangement 4 is arranged in the receiving space 22 of the brake drum 2 on an anchor housing 8 in a rotationally fixed manner.

[0051] As in the Fig. As shown in detail in Figures 3 to 6, the brake cylinder arrangement 4 preferably has a housing 41 which is fixedly attached to the anchor housing 8 in the receiving space 22 of the brake drum 2.

[0052] Relative to this housing 41, a service brake piston 42 is arranged to be displaceable parallel to the axis of rotation D of the brake drum 2.

[0053] Furthermore, the brake cylinder arrangement 4 has a parking brake piston 43 which is displaceable relative to the housing 41 parallel to the axis of rotation D of the brake drum 2 and can be acted upon by the spring force of a spring element 5.

[0054] The spring element 5 is preferably designed as a disc spring fixed in the housing 41, as is also exemplified in Fig. 2 is shown.

[0055] The brake cylinder assembly 4 further comprises several plungers 44, which serve to transmit a movement of the parking brake piston 43 to the service brake piston 42.

[0056] Furthermore, compressed air inlets are provided, which lead firstly into a service brake pressure chamber 45 between the housing 41 and the service brake piston 42 and secondly into a parking brake pressure chamber 46 between the housing 41 and the parking brake piston 43.

[0057] In Fig. Figure 1 shows a first pressure fluid inlet 81 and a second pressure fluid inlet 82 for the supply / exhaustion of compressed air into the service brake pressure chamber 45 and the parking brake pressure chamber 46, respectively.

[0058] The movement of the service brake piston 42 is always important for the actuation of the brake shoes 3; this movement is effected by supplying compressed air to the service brake pressure chamber 45 in the event of an intended reduction in the speed of the commercial vehicle, a so-called service braking process.

[0059] In the event of the intended locking of the brake, which serves to prevent the commercial vehicle from unintentionally rolling away in a parked situation, compressed air present in the parking brake pressure chamber 46 during driving operation is released from the parking brake pressure chamber 46, resulting in a displacement of the parking brake piston 43 towards the service brake piston 42. This displacement is caused by the force exerted by the spring element 5 on the rear side of the parking brake piston 43 facing away from the service brake piston 42.

[0060] To transmit the movement of the service brake piston 42 to the brake shoes 3, a respective pressure wedge 33 is arranged on a side of the friction lining carrier 32 facing away from the friction lining 31 as part of a respective brake shoe 3.

[0061] This pressure wedge 33 rests on a wedge ring 6 which is movable parallel to the axis of rotation D of the brake drum 2.

[0062] The wedge ring 6 can be moved from a non-braking position to a braking position by moving the service brake piston 42 of the brake cylinder arrangement 4 parallel to the axis of rotation D of the brake drum 2.

[0063] As in the Fig. As illustrated in Figures 3 to 6, the wedge ring 6 has an end face 63 which always rests against a surface of the service brake piston 42 facing away from the parking brake piston 43. The wedge ring 6 is held in place by a spring element 10, as shown in the figures. Fig. 5 and Fig. 6, always pressed in the direction of the service brake piston 42.

[0064] As in the Fig. As can be seen from 4 to 6 further on, the wedge ring 6 is adjustable via an adjusting device 7.

[0065] In the preferred embodiment shown here, a thread 62 is arranged, in particular formed, on a surface of the wedge ring 6 facing away from the pressure wedge 33, which meshes with a threaded sleeve 71 of the adjusting device 7.

[0066] The threaded sleeve 71, together with the wedge ring 6, can be displaced by moving the service brake piston 42 of the brake cylinder arrangement 4 parallel to the axis of rotation D of the brake drum 2.

[0067] The movement of the brake shoes 3 back from the braking position to the non-braking position is ensured, as mentioned above, by the spring element 10, which, as in the Fig. 5 and Fig. 6 can be seen, it is supported on a section of the anchor housing 8 and presses against a shoulder of the threaded sleeve 71.

[0068] To maintain a constant clearance between the friction linings 31 of the brake shoes 3 and the inner surface 21 of the brake drum 2, an adjusting drive 75 is preferably used.

[0069] The adjusting drive 75 is preferably coupled to a toothed ring 73 of the threaded sleeve 71. In the embodiment shown here, the toothed ring 73 extends radially in a region between the end face 63 of the wedge ring 6 and the wedge-shaped base body 64 of the wedge ring 6, on one side of which the thread 62 is formed, which meshes with the thread 72 of the threaded sleeve 71, and whose other obliquely oriented pressure surface 61 faces the pressure wedge 33 of the brake shoes 3.

[0070] The radially external toothing 74 of the gear ring 73 meshes with a Fig. 7 shown, gear wheel 77 of the adjuster drive 75 arranged on an adjuster shaft 76.

[0071] To reduce friction between the brake shoes 3 and the wedge ring 6, in the embodiment shown here a slide with several rolling elements 92 is arranged between the pressure surface 61 of the wedge ring 6 and the pressure wedge 33 of the respective brake shoes 3.

[0072] The Fig. 8 and Fig. Figure 9 shows as a separate illustration the arrangement of the brake shoes 3 on the wedge ring 6 and the arrangement of the wedge ring 6 on the threaded sleeve 71 of the adjusting device 7.

[0073] The spring element 5, preferably designed as a disc spring, can be fixed radially inside or radially outside the housing 41 of the brake cylinder 4, depending on the design of the brake cylinder 4.

[0074] Thus, spring element 5 is located in the Fig. The embodiment shown in 2 to 6 and 10a to 10d has a radially inner end region 51 radially inside (relative to the axis of rotation D of the brake drum 2), preferably fixed via screw bolts 53 and a clamping ring 52.

[0075] During the Fig. In the embodiment shown in 11a to 11d, the spring element 5, designed as a disc spring, is fixed radially outside on the housing 41 of the brake cylinder 4 with a radially outer end region 51.

[0076] The Fig. Figures 10a to 10d show the operation of the drum brake 1 with radially internally mounted spring element 5.

[0077] This shows Fig. 10a a functional position of the drum brake 1 in which the brake shoes 3 are in a non-braking position and in which the friction linings 31 are unworn or almost unworn.

[0078] In this non-braking position, the parking brake pressure chamber 46 of the brake cylinder assembly 4 is filled with compressed air. The service brake pressure chamber 45, on the other hand, is empty, so that the service brake piston 42 rests against a first partition 48 between the service brake pressure chamber 45 and the parking brake pressure chamber 46. The compressed air present in the parking brake pressure chamber 46 pre-tensions the spring element 5.

[0079] At the in Fig. In the illustration shown in 10b, the components of the brake cylinder assembly 4 are identical to those of the Fig. 10a arranged. The friction lining 31 of the brake shoes 3 is partially worn here.

[0080] Accordingly, the wedge ring 6 is relative to the in Fig. In the illustration shown in 9a, the adjusting device 7 is axially displaced a short distance away from the spring element 5 relative to the threaded sleeve 71, which causes a slight radial displacement of the brake shoes 3 outwards and thus compensates for the clearance between the friction lining 31 and the inner surface 21 of the brake drum 2.

[0081] The Fig. Figure 10c shows the service brake position of drum brake 1. Relative to the in Fig. In the position shown in Figure 10a, compressed air was introduced into the service brake pressure chamber 45 to trigger the service brake. This moved the service brake piston 42 towards the wedge ring 6. This shifted the wedge ring 6 and thus pressed the brake shoes 3 radially outwards against the inner surfaces 21 of the brake drum 2.

[0082] The Fig. Figure 10d finally shows the state of a parking brake application. In such a so-called parking brake application, instead of supplying compressed air to the service brake pressure chamber 45, the compressed air present in the parking brake pressure chamber 46 is released from the parking brake pressure chamber 46. This causes the spring element 5 to push the parking brake piston 43 towards the service brake piston 42.

[0083] The plunger 44, arranged on the inner side of the parking brake piston 43 facing the service brake piston 42, which in this embodiment is received in a first partition 48 of the housing 41 separating the service brake pressure chamber 45 from the parking brake pressure chamber 46, thereby pushes the service brake piston 42 axially towards the wedge ring 6 and thus pushes the wedge ring 6 away from the first partition 48 of the housing 41 so far that the brake shoes 3 are pushed radially outwards into the parking brake position.

[0084] During the Fig. In the embodiment shown in Figures 11a to 11d, the plunger 44 is received in a second partition 49 of the housing 41, which separates the service brake pressure chamber 45 from the receiving chamber 22. Furthermore, in this embodiment, the spring element 5 is fixed radially outside the housing 41 of the brake cylinder assembly 4.

[0085] The initial position of the brake cylinder assembly 4, as shown in Fig. As shown in 11a, this corresponds to the one shown on the basis of Fig. The position described in section 10a applies. The same applies to the partial wear position of Fig. 11b, the description of which is shown accordingly on Fig. 10b is referred to.

[0086] The service braking also works analogously to the one based on... Fig. as described in 10c.

[0087] The parking brake position of the Fig. 11d differs from the parking brake position of the Fig. 10d, that the plunger 44 is now arranged radially further inwards in the illustrated embodiment.

[0088] The parking brake piston 43 has a radially inner ring 431 projecting axially towards the spring element 5, which, by releasing the compressed air from the parking brake pressure chamber 46, enables the radially inner part of the spring element 5 to press the plunger 44 arranged in this area against the service brake piston 42 and thus press the brake shoes 3 against the brake drum 2 by moving the wedge ring 6.

[0089] Furthermore, in Fig. 1 can still be seen that a dust outlet 11 is arranged on a wall of an anchor housing 8, through which it is possible to extract brake dust generated during braking operations from an interior of the drum brake 1.

[0090] The enclosed design of the drum brake 1 shown here reliably prevents brake dust from being released into the environment during a braking process. Reference symbol list 1 drum brake 2 brake drums 21 Inner surface area of ​​the mantle 22 Recording room 3 brake shoes 31 friction lining 32 friction lining carriers 33 Pressure wedge 34 Sliding element 35 Support roller 4 brake cylinder arrangement 41 cases 42 service brake pistons 43 Parking brake pistons 44 pestles 45 Service brake pressure chamber 46 Parking brake pressure chamber 47 Sealing ring 48 first partition wall 49 second partition wall 5 spring element 51 first end 52 clamping ring 6 wedge ring 61 pressure surface 62 threads 63 Front surface 7 Adjustment device 71 Threaded sleeve 72 threads 73 Sprocket 74 gear teeth 75 Adjuster drive 76 Adjuster shaft 77 Gear wheel 8 anchor housings 81 First pressure fluid inlet 82 Second pressure fluid inlet 9 sleds 91 Rolling element mounting 92 rolling elements 10 Return spring 11 Dust outlet 12-axis 13 Hub 14 rim 15 screw bolts D axis of rotation x direction y direction z direction

Claims

[1] Drum brake (1), in particular for a commercial vehicle, comprising - a brake drum (2) rotatably mounted about an axis of rotation (D), - several brake shoes (3) mounted in a receiving space (22) of the brake drum (2) with a respective friction lining carrier (32) and a friction lining (31) arranged on it, - wherein the brake shoes (3) are radial to an axis of rotation (A D ) of the brake drum (2) can be pressed against an inner surface (21) of the brake drum (2) designed as a friction surface, - a brake cylinder assembly (4) arranged in the receiving space (22) of the brake drum (2) on an anchor housing (8) in a rotationally fixed manner for actuating the brake shoes (3), - wherein the brake cylinder arrangement (4) comprises a housing (41) fixed in the receiving space (22) of the brake drum (2) on the anchor housing (8) and a service brake piston (42) which is displaceable relative to the housing (41) parallel to the axis of rotation (D) of the brake drum (2),characterized by , that - the brake cylinder assembly (4) comprises a parking brake piston (43) which is displaceable relative to the housing (41) parallel to the axis of rotation (D) of the brake drum (2) and is subjected to the spring force of a spring element (5), and several plungers (44) for transmitting a movement of the parking brake piston (43) to the service brake piston (42), - wherein respective compressed air supplies are provided into a service brake pressure chamber (45) between the housing (41) and the service brake piston (42) and a parking brake pressure chamber (46) between the housing (41) and the parking brake piston (43), and - on a side of the friction lining carrier (32) facing away from the friction lining (31) a respective pressure wedge (33) is arranged, which rests on a wedge ring (6) which is movable parallel to the axis of rotation (D) of the brake drum (2), - wherein the wedge ring (6) can be moved from a non-braking position to a braking position by moving the service brake piston (42) of the brake cylinder assembly (4) parallel to the axis of rotation (D) of the brake drum (2). [2] Drum brake (1) according to claim 1, characterized by , that the plungers (44) are received in a first partition (48) of the housing (41) separating the service brake pressure chamber (45) from the parking brake pressure chamber (46). [3] Drum brake (1) according to claim 1, characterized by , that the plunger (44) is received in a second partition (49) of the housing (41) separating the service brake pressure chamber (45) from the receiving chamber (22). [4] Drum brake (1) according to any one of the preceding claims, characterized by , that the spring element (5) is designed as a disc spring fixed to the housing (41). [5] Drum brake (1) according to any one of the preceding claims, characterized by, that the wedge ring (6) is adjustable via an adjusting device (7). [6] Drum brake (1) according to claim 5, characterized by , that a thread (62) is arranged, in particular formed, on a surface of the wedge ring (6) facing away from the pressure wedge (33), which meshes with a threaded sleeve (71) of the adjusting device (7), wherein the threaded sleeve (71) together with the wedge ring (6) is displaceable by moving the service brake piston (42) of the brake cylinder arrangement (4) parallel to the axis of rotation (D) of the brake drum (2). [7] Drum brake (1) according to claim 6, characterized by , that the threaded sleeve (71) has a toothed ring (73) coupled to an adjusting drive (75). [8] Drum brake (1) according to any one of the preceding claims, characterized by , that a slide (9) with several rolling elements (92) is arranged between the pressure wedge (33) and the wedge ring (6).

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