MXPA98009452A - Automatic cable latching device for drum brake levers - Google Patents

Abstract

A parking brake assembly which includes a lever (15) for operation of a brake shoe (11, 12) to provide a parking function. The lever (15) has an automatic latching device (21, 22, 23) for automatically latching to the lever (15) an end fitting (20) on an operating cable (19). The automatic latching device (21, 22, 23) comprises a flap (22) mounted on the lever (15) which is deflected aside by the end fitting (20) as the cable (19) is fed in a first direction towards the lever (15) and which latches behind an abutment (20a) on the end fitting (20) to latch the cable (19) to the lever (15) so that subsequent movement of the cable (19) in a second direction opposite to the first direction moves the lever (15) to operate the parking function.

Description

- i - ATJTOM DEVICE &TTGM CABT.E ENGAGEMENT FOR DRUM BRAKE LEVERS DESCRIPTION OF THE INVENTION This invention relates to drum brakes and in particular to parking braking or immobilisation assemblies for use in drum brakes and which includes an automatic latching device for engaging and operating a cable to an operating lever of a parking brake. • parking lot . An object of the present invention is to provide a parking brake assembly with an improved latching device. Therefore, in accordance with the present invention, a parking brake assembly is provided which includes a lever for operation of a brake shoe to provide a parking function, the lever carries an automatic latching device to automatically engage the lever and an end adapter in an operating cable, the assembly is characterized in that the automatic coupling device comprises a flap mounted in the lever which is flexed to one side by the end adapter as the cable is fed in a first direction towards the lever and which is hooked beyond a stop on the end adapter to hook the cable to the lever in a manner that the subsequent movement of the cable in a second direction opposite to the first direction moves the lever to operate the parking or immobilization function. Preferably the fin engages the cable against a lever edge. The flap can be deflected by spring or diverted by gravity towards the lever. In a preferred arrangement, one end of the lever has a U-shaped cross section to form a channel and the fin is located adjacent one end of the channel with the cable that has been supplied along the channel and engaged between the fin and the adjacent end edge of the channel. The cable can be supplied to the lever through an opening in a rear mounting plate via a guiding means. The guide means may comprise a compression spring through which the cable is supplied, one end of the spring is attached to the back plate and the other end to the lever.

Alternatively, the guide means may comprise a rigid tube. A compression spring may extend between one end of the tube adjacent to the lever and the lever itself. The invention also provides a drum brake which includes a parking brake assembly as described above. The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a drum brake which includes a parking brake assembly according to the present invention; Figure 2 is a view in the direction of the arrow A of Figure 1 of the details of the attachment flap of the assembly; Figures 3A, 3B and 3C are perspective views showing three stages in the engagement sequence of the hooking flap of Figure 2; Figure 4 shows the details of the coupling flap of Figure 1 on a larger scale, and; Figures 5, 6 and 7 show side, end and sectional views in part of a brake assembly of alternative parking with a rigid tubular cable guide, And Figures 8 and 9 show side and perspective views, respectively, of a further form of the hook flap, according to the inventions. With reference to figures 1 to 4, these show a drum brake 10 in which two brake shoes 11 and 12 are mounted on a rear plate 13 for service application by a hydraulic cylinder 14 in a known manner. A parking brake function is provided in which the rotation of the parking lever 15 from the fully aligned position in FIG. 1 to the position 15 'in dashed lines applies both brake shoes to the brake drum by means of a pole 16. The post 16, which is retained against the shoe 12 at all times by the spring 16a which extends between the brake shoes and, in addition to operating the parking brake, also limits the retraction of the shoes under the action of the tension spring 16b. The effective length of the post 16 is adjusted by a handbrake adjustment mechanism, part of which is visible with the number 17 and which is more fully described in the United Kingdom patent application 2272261.

The lower end of the parking brake lever 15 has a U-shaped cross section to form a channel 18 (see Fig. 2) for receiving the end of a cable 19 that operates a handbrake which has an adapter 20 end. Pivotally mounted on the lever 15, adjacent to an edge 21 thereof is a latching device in the form of a fin 22 which is deflected by a helical spring 23 within the full line position shown in detail in FIG. 4. The rear plate 13 is provided with an opening 24 through which a drive cable 19 and a guide means in the form of a compression spring 25 is provided which extends between the opening 24 and the end of the channel 18 in the lever 15. The end 25a of the spring 25 is received as a direct flexure clamp in the U-shaped channel 18 while the end 25b is connected to a short rigid tubular guide 26 which is supported in the opening 24. The spring 25 of compression also loads the lever 15 which tends to return the lever to its non-operative full line position shown in Figure 1 with a tongue 29 which contacts the edge of the shoe 12 when the fun is released. handbrake The connection of the cable 19 to the lever 15 is best seen from FIGS. 1 and 3A to 3C. The cable 19 with its adapter End 20 is supplied through the opening 24 in the rear plate 13 and down the center of the guide spring 25 towards the inside of the end of the channel 18 in the lever 15.

Then, the end adapter makes contact with the latch 22 and moves the fin counterclockwise about its pivot 27 as shown by broken line detail 22 'in FIGS. 1 and 4. After the end adapter 20 has completely passed • the flap 22, the flap 22 closes rearwardly, by the rear part of the flange 20a of the end adapter 20 for hooking the cable between the lower edge of the flap 22 and the edge 21 of the lever 15, as shown in Figure 3C. Although the flange 20a, the edge 21 and the cooperating face 22a of the flap 22 are all shown as planar surfaces, these may be of a cooperating curved configuration, as shown in broken line detail 28 in Figure 4. flap 22 does not necessarily need to be spring loaded to its latching position, but can chronically be supported by gravity to reset the flap to this position after deflection by end fitting 20.

Figures 5, 6 and 7 show an alternative drum brake arrangement in which the guide spring 25 is replaced by a tubular guide 30 which extends from a position adjacent to the opening 24 to a position adjacent to the position 15"Operation of the lever 15. As best seen in Figure 6, the tubular guide 30 is formed of a metal foil member and has a support bracket 31 which is mounted on the stop 32 which reacts with the footing of the foot. brake and a rolled tubular portion 33 through which the parking brake and its associated end adapter 20 are supplied. The remaining features of Figures 5 to 6 are as previously described with reference to Figures 1 to 4. As a further alternative arrangement, a compression spring can be attached between the free end 34 of the tubular guide 30 and the U-shaped channel 18 of the lever 15, as shown by the broken-line detail with the number 35 in FIG. Figure 5. This spring not only provides more accurate guidance of the cable within the U-shaped channel 18, but also returns the lever 15 to its non-operating position.

Figures 8 and 9 show part of an alternative form of parking lever 15 in which the portion 18a of channel 18 is pressed to form a rung 18c against which the end 25a of the spring 25 is maintained by bending over the tongue 18b after the insertion of the spring 25. The wing 22 in figures 8 and 9 is biased against the edge of the channel 18 by a leaf spring 40 which is fastened at the number 40a on a projection 41 which is bent outwardly of the lever 15. The projection 41 of the leaf spring 40 assists in the friction of the end 20 of the cable 19 generally downwards as it emerges from the lower part of the cable. the flap 22 and therefore prevents the cable from entering between the lever 15 and the interior surface 12a (see figure 7) of the shoe 12. As will be appreciatedThe present invention provides a parking brake assembly which is of a relatively inexpensive construction and which provides a very positive locking of the hand brake cable end adapter to the lever 15 to prevent subsequent detachment of the cable.

Claims (16)

REIVTNNTFIATIONS

1. A parking brake assembly which includes a lever for operation of a brake shoe to provide a parking or immobilization function, the lever carries an automatic latching device for automatically hooking an end adapter onto a cable of the lever. operation, the assembly is characterized in that the automatic coupling device comprises a flap mounted on the lever which is bent to one side by the end adapter as the cable is supplied in a first direction towards the lever, and which is hooked behind from a stop on the end adapter to hook the cable to the lever so that subsequent movement of the cable in a second direction opposite to the first direction moves the lever to operate the parking function.

2. The assembly according to claim 1, characterized in that the fin engages the cable against an edge of the lever.

3. The assembly according to claim 1 or 2, characterized in that the fin is deflected by a spring towards the lever.

4. The assembly according to claim 3, characterized in that the spring is a helical spring that surrounds a bolt on which the fin rotates.

5. The assembly according to claim 3, characterized in that the spring is a leaf spring which bears against the wing.

6. The assembly according to claim 1 d, characterized in that the flap is deflected by gravity towards the lever.

7. The assembly according to any of claims 1 to 6, characterized in that one end of the lever has a U-shaped cross section to form a channel and the fin is located adjacent to one end of the channel with the cable that has been supplied. along the canal and hooked between the fin and an adjacent end edge of the channel.

8. The assembly according to any of claims 1 to 7, characterized in that the cable is supplied to the lever through an opening in a rear mounting plate via a guiding means.

9. The assembly according to claim 8, characterized in that the guide means comprises a spring of 'compression through which the cable is supplied, one end of the spring is attached to the back plate and the other end to the lever.

10. The assembly according to claim 8, characterized in that the guide means comprises a rigid tube.

11. The assembly according to claim 10, characterized in that the compression spring extends between one end of the guide tube adjacent to the lever and the lever itself.

12. The assembly according to claim 10 or 11, characterized in that the guide tube is formed by a rolling process.

13. The assembly according to any of claims 1 to 12, characterized in that the lever carries a stop which bends the end of the cable after it has passed below the flexed fin to prevent the end of the cable passing between the lever and the inside of the adjacent brake shoe.

14. The assembly according to any of claims 1 to 13, characterized in that the lever carries a stop for contact with the adjacent brake shoe to limit the retraction of the lever when the parking brake is released.

15. A drum brake, characterized by the inclusion of a parking brake assembly, according to any of claims 1 to 14.

16. A parking brake assembly, characterized in that it is constructed and positioned substantially as described in the foregoing with reference to, and as shown in Figures I to 4 d 5 to 7 or 8 to 9 of the accompanying drawings. REST7MEN FROM T.A INVENCIÓN A parking brake assembly which includes a lever (15) for operation of a brake shoe (11), 12) to provide a parking function. The lever (15) has an automatic coupling device (21, 22, 23) for automatically engaging the lever (15) an end adapter (20) on an operating cable (19). The automatic coupling device (21, 22, 23) comprises a wing (22) mounted on the lever (15) which is flexed to one side by the end adapter (20) as cable (19) is supplied in a first direction towards the lever (15) and which is hooked behind a stop (20a) on the end adapter (20) to hook the cable (19) to the lever (15) so that the subsequent movement of the cable (19) ) in a second direction opposite to the first direction moves the lever (15) to operate the parking function.