GB2162602A

GB2162602A - Internal shoe brake

Info

Publication number: GB2162602A
Application number: GB08517082A
Authority: GB
Inventors: Rolf Weiler; Karl Dettmar
Original assignee: Alfred Teves GmbH
Current assignee: Continental Teves AG and Co oHG
Priority date: 1984-07-31
Filing date: 1985-07-05
Publication date: 1986-02-05
Also published as: DE3428135C2; ES288446Y; FR2568644A1; GB2162602B; SE8503598D0; IT8521702A0; GB8517082D0; ES288446U; FR2568644B1; BR8502582A; DE3428135A1; IT1185301B; SE8503598L

Abstract

In an internal shoe brake with brake shoes (3, 4) retained at an anchor plate (2) and with an expanding device (13) actuatable through a cable assembly (not shown), a stationary bracket (7) to support the ends of the brake shoes (3, 4) is provided which has an L-shaped cross-section and is secured, with its one stem (5), to the anchor plate (2) by means of rivets (9, 10), the heads (16, 17) of the rivets (9, 10) constituting abutments for cams (34-35) of the levers (11, 12) of the expanding device (13). The bracket (7) to support the brake shoes (3, 4) is cut from an L-shaped sectional material and is provided with bores for its fastening to the brake carrier. <IMAGE>

Description

SPECIFICATION Internal shoe brake The invention is related to an internal shoe brake with brake shoes retained at an anchor plate, an expanding lock actuatable through a cable assembly, a stationary bracket to support the ends of the brake shoes, and a device to detachably couple the cable assembly with the brake.

A drum brake is known (U.S. patent 4,337, 851) in which, instead of a circular disc-shaped anchor plate or supporting plate, a two-armed back element is provided which is stamped from a plate metal blank and is bolted to two supporting brackets drawn from metal plate and both jointly serving to support the ends of the two brake shoes.

The torque occurring during braking action is transmitted, through the pair of supporting brackets, to the two-armed back element which is, on its part, bolted to the steering knuckle. It is a disadvantage of this configuration of the brake that the back side of the brake is not protected against dust and dirt. In addition, the two-armed back element requires to be made of very thick-walled metal plate and this leads to an increase of the weight of the brake and of the cost of manufacture as well.

It is an object of the present invention to create an internal shoe brake, in particular a duo-servo parking brake, whose weight is remarkably reduced with respect to comparable prior-art versions. The cost of manufacture is to be lower than in conventional brakes of comparable efficiency owing to the use of thin-walled material. Moreover, mounting and unmounting of the internal shoe brake are to be particularly easy and to be allowed to be carried out mechanically. Forgings or castings are to be avoided and be largely substituted by commercial sectional materials. Finally, the parking brake according to the invention is to be fittable in the vehicle as a package assembly.

According to the present invention there is provided an internal shoe brake with brake shoes retained at an anchor plate, an expanding lock actuatable through a cable assembly, a stationary bracket to support the ends of the brake shoes, and a device to detachably couple the said cable assembly with the brake, characterised in that the said supporting bracket is provided with an Lshaped cross-section and is secured, with its one stem, to the said anchor plate by means of screws or rivets on whose heads facing the brake shoes, cams of levers of the said expanding lock slide, with the other stem of the said supporting bracket extending, in the region of the ends of lining car riers of the shoes positioned on the side of the said expanding lock, in a plane which is perpendic ular relative to the said anchor plate.For this pur pose, the supporting bracket is cut from standardised sectional material and thereupon al lows to be installed without any further tooling.

Preferably, the one stem of the supporting bracket which is abutted against the anchor plate is formed with arms or projections on either side which are bolted to the brake carries jointly with the anchor plate. Owing to such projections. or fastening eyes, the distance of the fixing screws between each other allows to be selected sufficiently large so as to ensure a particularly firm and safe support of the supporting bracket at the brake carrier.

Expendiently, the rivets to secure the supporting bracket to the anchor plate hold the flange of a socket which serves to accommodate a cable assembly with a jacket pipe, the cable assembly interacting with the levers of the expanding lock. The stationary arrangement of the socket at the anchor plate of the brake offers the advantage that suspension of the cable assembly, that is to say, its coupling to the expanding lock is substantially simplified. The socket, moreover, protects the expanding lock against the penetration of dust and moisture, so that an extended functioning of the expanding lock is safeguarded.

Advantageously, the heads of the screws or rivets interact, with their plane front faces facing the levers, with cams which are provided at the levers of the expanding lock which take support at the webs of the brake shoes. A durable and wear-resisting abutment for the levers of the expanding lock is created in this way, which is, beyond this, inexpensive in manufacture.

In order to tender possible a support of the brake shoes free of rattling noise and easing their motion, side faces of the other stem of the supporting bracket extending perpendicularly to the anchor plate are shaped in accordance with the front faces of the lining carriers, being, for example, rounded off. In a preferred embodiment, the side faces facing the lining carriers extend perpendicularly to the anchor plate of the brake, they being configured, in addition, in the shape of straight, plane surfaces.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is the partial view of a drum brake with expanding lock and supporting bracket; Figure 2 is a view of the drum brake in the direction of the arrow Z in Figure 1; Figure 3 is a cross-section along the line A-B through the drum brake according to Figure 1; Figure 4 is a part of a cable assembly with jacket pipe and coupling element for the drum brake according to Figure 1; Figure 5 is the side view, partly in cross-section, of the socket with coupling element and retaining clip for the drum brake according to Figures 1 to 4; Figure 6 is the cross-section along the line C-D through the socket according to Figure 5;; Figure 7 is an alternative embodiment of a retaining clip for the socket with coupling element, and Figure 8 is the cross-section along the line E-F through the socket according to Figure 7.

A drum brake is substantially comprised of two brake shoes 3, 4 with lining carriers 14, 15 and brake linings 38, 39 retained on an anchor plate 2, an expanding lock is in its entirety designated by reference numeral 13, a supporting bracket 7 riveted to the anchor plate 2 and to a flange 18 of a socket 19, a return spring 8, a jacket pipe 25 coupled to the socket 19 with the aid of a retaining clip 24 or 28, with coupling element 23 and cable assembly 20, and of a sealing collar 40 welded to the anchor plate 2. The part of the drum brake furnished with the adjusting device is not illustrated in detail, as it is without importance for the subject matter of the present invention.

The brake shoes 3, 4 are furnished with ribs or webs 41, 42 with which they are in abutment against the levers 11, 12 of the expanding (adjusting) lock 13 which are provided in pairs. The expanding lock 13 is actuated with the aid of a cable assembly 20, for which purpose the cable assembly 20 is articulated, with its nipple 43, to the free end of the lever 11 or, rather, pair of levers. The collar 22 of the coupling element 23 is abutted against the flanged rim 21 of the socket 19 and is unshiftably locked there by a retaining clip 24. The retaining clip 24 has a roughly omega-shaped configuration (see Figure 6), its two arms 26, 27 having a U-shaped cross-section (as is seen in Figure 5).The retaining clip 24 is pushed onto the flanged rim 21 of the socket 19 and onto the collar 22 of the jacket pipe 25 sideways like a clothes-peg, with the side wall 26', 27' of the arms 26, 27 being resiliently abutted with the flanged rim 21 and the side walls 26", 27" resiliently abutted with the collar 22 of the jacket body 25. In Figures 7 and 8, a retaining clip 28 is illustrated which can be used as an alternative, instead of the retaining clip 24 according to Figures 5 and 6. The retaining clip 28 is formed with two pairs of arms 29, 29' and 30, 30', the internal surfaces of each of them facing each other being furnished with bulges 32, 32' and 33, 33', respectively which are resiliently abutted against the members 21, 22 to be coupled to each other All arms 29, 29', 30, 30' are linked together by means of a leaf spring-shaped back portion.In addition, the arms 30, 30', 29, 29' are provided with arched cutouts 36, 36' and 37, 37', respectively, so that the edges of the arms 29, 29', 30, 30' facing each other are adapted to the contour of the socket 19 and of the coupling element 23, respectively.

The retaining clip 28 illustrated in Figures 7 and 8 offers the advantage that its arms 30, 30', 29, 29' result in its being extremely elastic in two planes because the back portion 31 as well as the four arms 29, 29', 30, 30' which are firmly coupled to the back portion 31 act in the manner of leaf springs. On actuation of the cable assembly 20 in the direction of the arrow A (Figure 3), the lever or, rather, the pair of levers 11 is pivoted around the pin 44, with the cam 34 sliding on the head 16 of the rivet 9 and the brake shoe 3 being moved, through the web 42, in the outward direction against the brake drum or against the cup-shaped portion of a brake disc 45 (shown in dash-dotted lines in Figure 3).Simultaneously, the lever or, rather, the pair of levers 12 moves in the opposite direction relative to the cam 34 (to the right in Figure 2) and urges the brake shoe 4, through the web 41, against the cup-shaped portion of the brake disc 45. During this motion of the pair of levers, the levers 12 slide, with their cams 35, on the head 17 of the rivet 10 taking support at it. The described swivelling and sliding motions of the levers (pairs of levers) 11 and 12 are accomplished against the force of the tension spring 8 which, moreover, retracts both brake shoes 3, 4 into their initial position (shown in Figure 1) again on the end of the braking action.

The supporting bracket 7 which is manufactured from an angle-shaped sectional material is fastened, with its one stem 5, to the anchor plate 2 with the aid of the two rivets 9, 10, together with the flange 18 of the socket 19. The stem 5 is formed with ear-shaped projections 5' , 5" which are furnished with bores. With the aid of the said projections 5', 5" , the supporting bracket 7 is firmly bolted to the brake carrier (not shown in detail in the drawingi. The stem 6 of the supporting bracket 7 extends at right angles to the stem 5 and serves as an abutment for the two brake shoes 3, 4 and their lining carriers 14, 15, respectively, the supporting bracket 7 being suitably dimensioned so as to be capable also of absorbing the circumferential forces occurring during actuation of the brake and to transmit them to the brake carrier.

The side faces 46, 47 (Figure 2) of the stem 6 extend at right angles to the anchor plate 2, so that the lining carriers 14, 15 can take support, with their straight front faces facing the supporting bracket 7, over their full width at the side faces 46, 47. Since all forces which are brought to bear on the supporting bracket 7 are transmitted by the latter directly to the brake carrier, the anchor plate 2 will allow to be made of comparatively very thinwalled metal sheet or plate.

Claims

1. An internal shoe brake with brake shoes (3, 4) retained at an anchor plate (2), an expanding lock (13) actuatable through a cable assembly (20), a stationary bracket (7) to support the ends of the brake shoes, and a device to detachably couple the said cable assembly (20) with the brake, characterised in that the said supporting bracket (7) is provided with an L-shaped cross-section and is secured, with its one stem (5), to the said anchor plate (2) by means of screws or rivets (9, 10) on whose heads (16, 17) facing the brake shoes (3, 4), cams (34, 35) of levers (11,12) of the said expanding lock (13) slide, with the other stem (6) of the said supporting bracket (7) extending, in the region of the ends of lining carriers (14, 15) of the shoes positioned on the side of the said expanding lock (13), in a plane which is perpendicular relative to the said anchor plate (2).

2. An internal shoe brake as claimed in claim 1, characterised in that the said one stem (5) of the said supporting bracket (7) which is abutted against the said anchor plate (2) is formed with arms or projections (5', 5" ) on either side which are bolted to a brake carrier jointly with the said anchor plate (2).

3. An internal shoe brake as claimed in claim 1, characterised in that the said screws or rivets (9, 10) to secure the said supporting bracket (7) to the said anchor plate (2) hold a flange (18) of a socket (19) which serves to accommodate said cable assembly (20) including a jacket pipe (25), which said cable assembly (20) interacts with the said levers (11, 12) of the said expanding lock (13).

4. An internal shoe brake as claimed in claim 1, characterised in that the said heads (16, 17) of the said screws or rivets (9, 10) interact, with their plane front faces facing the said levers (11, 12), with cams (34, 35) which are provided at the said levers (11, 12) of the said expanding lock (13) and which take support at webs (41, 42) of the said brake shoes (3, 4).

5. An internal shoe brake as claimed in claim 1, characterised in that side faces (46, 47) of the other stem (6) of the said supporting bracket (7) extending perpendicularly to the said anchor plate (2) are shaped in accordance with the front faces of the said lining carriers (14, 15), being, for example, rounded off.

6. An internal shoe brake as claimed in claim 1, characterised in that said side faces (46, 47) of the other stem (6) facing the said lining carriers (14, 15) extend perpendicularly to the said anchor plate (2) and are configured in the shape of straight plane surfaces.

7. An internal shoe brake substantially as herein described with reference to Figures 1 to 6, or Figures 1 to 4, 7 and 8, of the accompanying drawings.