GB2170566A

GB2170566A - Improvements relating to brake pad retaining plate assemblies for use in brake shoe assemblies

Info

Publication number: GB2170566A
Application number: GB08502953A
Authority: GB
Inventors: Kenneth Riding; John Adamson
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1985-02-06
Filing date: 1985-02-06
Publication date: 1986-08-06
Also published as: GB8502953D0; US4682905A; FR2576990B1; DE3603776A1; FR2576990A1; GB2170566B

Description

1 GB2170566A 1 SPECIFICATION to fall slightly and prevent the retaining

plate from returning to its proper position under the Improvements relating to brake pad retain- influence of the return springs. In this condi ing plate assemblies for use in brake shoe tion subsequent braking forces can move the assemblies 70 brake pad out from the dovetail recess in the brake shoe. The eventual outcome of pad loss The present invention relates to a brake pad from such an occurance is damage to the retaining plate assembly for use in a brake brake shoe by braking contact with the brake shoo assembly. disc.

In particular the present invention relates to 75 The above described pad retaining plate as- 6 brake pad retaining plate assembly for use sembly is available in component parts which in a broke shoe assembly for a railway vehicle are assembled on the shoe plate. Thus if re disc brake. Such a shoe assembly basically placement of worn parts is required, this has comprises a metal plate to which a pad of to be done on site, and involves the handling friction material is secured. The metal plate is 80 of several individual component parts, and the usually generally rectangular with a number of need to ensure that all parts are properly re bearing housings formed on one face, for fitted. This, it will be appreciated, can be a pivotally supporting the brake shoe assembly. difficult and time consuming operation, and The other face of said plate is generally planar parts can be lost.

with a dovetail recess extending along the ma- 85 A further disadvantage with the above de jor part of the length of the plate. The pad of scribed pad retaining plate assembly, is that friction- material is formed with a complimen- after a long period of service the springs can tary dovetail shape on one face, this shaped and do fill with'dirt, and products of corrosion portion being encased in metal. The pad can making operation difficult, if not impossible.

thus be secured to the plate by sliding the 90 Cleaning the springs is tedious and often re dovetail shaped portion of the pad into the quires disassembly of the pad retaining plate complimentary dovetail recess of the -plate. To assembly.

secure the friction pad in the dovetail recess The aim of the present invention is to pro of the plate, a brake pad retaining plate as- vide a brake pad retaiing plate assembly which sembly is provided, this latter assembly having 95 is easy to install and maintain, and which can a spring loaded plate member which extends not be operated to release brake pad(s) inad through a slot in said metal plate, into the ventently, yet requires a minimum of tools for dovetail recess, the plate member blocking off its proper use.

the open end of the dovetail recess. According to the present invention there is The brake pad retaining plate is generally L- 100 provided a pad retaining plate assembly for shaped and has a rectangular aperture formed use in a shoe brake assembly, said pad retain in the section of the L-shape which extends ing plate assembly comprising a retaining plate through the slot in said metal plate; the other which has a pair of bolts screwed into parallel section of the L-shape extending generally parbores in one end face of said plate, the shafts allel to the plane of the plate. A cylindrical 105 of said bolts extending through aligned bores member engages in said aperture and is a in first and second plate member, and a close fit with complimentary surfaces provided spring engaged over the shaft of each bolt, in the walls of the slot in said metal plate. engaging against said retaining plate and bi Thus the cylindrical member serves to guide assing said plate members towards the heads the brake pad retaining plate in said slot. A 110 of the bolts, the plate member nearest the spring retaining member is bolted to a raised retaining plate, being adapted to be secured part of said one face of the metal plate, and to a shoe plate of the shoe brake assembly.

comprises a pair of springs which are engaged In a preferred embodiment of the present in blind bores in the brake pad_ retaining plate. invention, the retaining plate is a rectangular Thus, to release a friction pad, the brake pad 115 block of metal with a pair of bolts screwed retaining plate member is lifted against its into parallel blind bores in one end face of spring loading, by use of a suitable too[ or said block. The springs are engaged over the manually, to thus allow the friction pad to be shafts of the bolts and press planar first and slid out of the dovetail recess. second plate members against each other and Whilst the above design was made to a 120 against the heads of the respective bolts. The user specification requiring manual operation, it plate member which directly engages the has been found that in use, in untutored heads of the bolts is a rectangular strip of hands it is possible to use the conventioanily metal having planar surfaces, and the other locate manual releasing part of the brake pad plate member which is nearest the retaining retaining plate to apply lateral movement to 125 plate, is a larger metal plate having planar sur the brake shoe to confirm, from the slackness faces, this larger metal plate extending felt, that the brake is in the released condition laterially with respect to said bolts, well clear before commencing-a journey. Under some of the retaining plate, and having two bores circumstances this may, by retracting the by means of which it can be bolted to a brake pad retaining plate, allow the brake pad 130 raised portion of said one face of a shoe 2 GB2170566A 2 plate, adjacent said slot. The facing planar and press the two plate members (19, 21) surfaces of the plate members thus engage against each other, and against the heads (23) together, and a groove is provided in one or of the bolts (13); the springs (17) being other, or both facing planar surfaces, to allow always compressed to a certain extent. The a screw-driver or similar tool to be inserted, 70 plate member (19) adjacent to the bolt heads to force the plate members apart against said (23) is a rectangular strip of metal whereas springs, and thus move the retaining plate to the plate member (21) nearest the springs a released position when mounted on a shoe (17) is larger and extends laterally beyond the plate. To prevent the screw-driver from slip- block (12). This lateral extension of plate ping a recess or hole is preferably provided in 75 member (21) has two apertures by means of said larger plate member, the tip of the which the retaining plate assembly can be screw-driver being located in the recess or bolted by bolts (25), as a preconstructed sub hole after it has been passed along said assembly, on a raised portion (27) of the shoe groove or grooves. plate (1), with the retaining plate (12) extend- The above pad retaining plate, springs, bolts 80ing through a slot (29) in the shoe plate (1), and plate members, thus form a sub-assembly across the end of dovetail recess (5)-see which can be manufactured in a factory and Fig. 3.

simply bolted to a show plate in situ, on for The plate member (19) has a groove (3) cut example, a railway vehicle. This sub-assembly in the planar surface (33) which engages with thus simplifies replacement. Further, solely a - 85 the other plate member (21), and the other screw-driver is required to force the said plate plate member (2 1) has a bore or recess (not members apart to release the pad retaining shown) located in line with the groove (31).

plate and allow a friction pad to be replaced; During maintenance a screwdriver can be en manual operation, and its problems if effected gaged in the groove (3 1) to enable the plate accidentally, being prevented. 90 members to be forced apart against the The present invention will now be further springs (17), to thus lift the retaining plate described, by way of example, with reference (12) and allow a friction pad to be replaced in to the accompanying drawings, in which:- the dovetail recess (5). To prevent the screw Figure 1 is a front view of a shoe plate - driver from slipping, the tip of the screw assembly incorporating a pad retaining plate 95 driver can be engaged over the lip of the bore assembly constructed according to the present or recess (not shown) located in line with the invention; groove (3 1).

Figure 2 is a plan view of the shoe plate As the plate member (19) nearer to the bolt assembly of Fig. 1; and - heads (23) is the smaller plate member, a tool Figure 3 is an end elevation of the shoe 100 e.g. screw-driver, has to be used to lift the plate assembly shown in Figs. 1 and 2. retaining plate (12) and thus accidental manual The show plate assembly shown in the ac- operation of the pad retaining plate assembly companying drawings comprises a generally (11) is' prevented.

rectangular shoe plate (1) wh - ich has a number Further, as the pad retaining plate. assembly of bearing housings (3) formed on one face 105 (11) is an integral sub- assembly which is pre thereof, for pivotally supporting the shoe plate viously manufactured, it can be simply re assembly on a brake, and an elongate dove- placed in situ as and when required, unlike the tail-shaped recess (5) formed in the other face prior art arrangements where the pad retaining (7)-see Fig. 3. In use, a dovetail-shaped por- plate assembly has to be assembled on site tion of a friction pad (not shown), is engaged 110 from its component parts.

in the complimentary dovetail-shaped recess A further added advantage arises from the (5) of the shoe plate (1); a pad retaining plate fact that the bolts (13) pass through, and 12 of pad retaining plate assembly (11) hold- therefore block, the centres of the springs ing the friction pad in the recess (5). (17). In the prior art, the centres of the

The pad retaining plate assembly (11) com- 115 springs can and do become blocked with dirt prises a retaining plate in the form of a rec- and the products of corrosion, making it diffi tangular block of metal (12), with a pair of cult to operate the pad retaining plate as bolts (13) screwed into parallel blind bores sembly. Such open springs are also difficult to (not shown) in one end face (15) of the block clean in situ. However with the present inven (12). Mounted on the shaft of each bolt (13) - 120 tion, the springs (17) are effectively filled with is a spring (17) together with two plate mem- the shafts of the bolts (13) and it is a rela bers (19,-21). Each-plate member has oppo- tively simple matter to clean the spaces be sitely facing planar surfaces (20, 22) and a tween adjacent coils, with, for example, the pair of bores extending therebetween, corretip of a screw-driver.

sponding bores in each plate member being 125 The present invention thus provides a pad coaxial with each other, and the bores in each retaining plate assembly which is simple in plate being so spaced apart from each other construction and which overcomes a number that the shafts of the bolts (13) can be of problems inherent in equivalent prior art as passed therethrough. The springs (17) engage semblies.

against said one end face (15) of the block (5) 3 GB2170566A 3

Claims

1. A pad retaining plate assembly for use in a shoe brake assembly, said pad retaining plate assembly comprising a retaining plate which has a pair of bolts screwed into parallel bores in one end face of said plate, the shafts of said bolts extending through aligned bores in first and second plate members, and a spring engaged over the shaft of each bolt, engaging against said retaining plate and biassing said plate members towards the heads of the bolts, the plate member nearest the retaining plate, being-adapted to be secured to a shoe plate of the shoe brake assembly.

2. An assembly as claimed in claim 1, in which the retaining plate is a rectangular block of metal with the bolts screwed into parallel blind bores in one end face of the block.

3. An assembly as claimed in claim 1 or 2, in which said springs press said plate members against each other with one plate member being engaged against the heads of the bolts.

4. An assembly as claimed in claim j, in which the other plate member nearest to the retaining plate is larger than said one plate member and extends laterally beyond said one plate member in a direction normal to the plane in which the axes of said bolts lie.

5. An assembly as claimed in any one of the preceding claims, in which said plate members are planar with a groove provided in one of the facing surfaces of the plate mem- bers.

6. An assembly-as claimed in claim 5, in - which a bore or recess is provided in one of said facing surfaces, aligned with said groove.

7. An assembly as claimed in any one of the preceding claims when mounted on a shoe brake assembly.

8. An assembly as claimed in claim 7 when dependent upon claim 4, in which said other plate member is bolted to one face of a shoe plate adjacent to a slot in the shoe plate, so that said rectangular plate extends through said slot.

9. A pad retaining plate assembly for use in a shoe brake assembly, constructed and arranged substantially as hereinbefore described. with reference to and as illustrated in the accompanying drawings.

Printed in the United Kingdom for Her Majestys Stationery Office, Dd 8818935, 1986, 4235. Published at The Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.