WO2007116200A1

WO2007116200A1 - Brake block assembly

Info

Publication number: WO2007116200A1
Application number: PCT/GB2007/000852
Authority: WO
Inventors: Brian David Henry; Nanoobhai Kiakabhai Patel
Original assignee: Federal-Mogul Friction Products Limited
Priority date: 2006-04-07
Filing date: 2007-03-13
Publication date: 2007-10-18
Also published as: GB2436859A; GB0607013D0

Abstract

A brake block assembly (10; 50; 60) comprises a support (20; 56) and a plurality of pads (12). Each pad comprises a wheel engaging portion (14) formed from friction material and a mounting portion (15) fixed relative to the wheel engaging portion. Said support (20; 56) defines a plurality of re-entrant grooves (24; 54) arranged so that they extend parallel to one another in a direction which is parallel to the rotational axis of the wheel. Said mounting portions (15) are arranged so that each is a sliding fit in one of said grooves into which it is introduced to mount the pad on the support. The assembly also comprises locating means (16c; 15d) operative to locate each pad in its operative position relative to its groove, and fixing means (34) operative to fix said pad in its operative position.

Description

BRAKE BLOCK ASSEMBLY

This invention is concerned with a brake block assembly suitable for use in braking a wheel. In particular, assemblies according to the invention are suitable for use in railway vehicles in which they are mounted so that they can engage a generally cylindrical surface of a wheel and apply frictional braking force thereto. The generally cylindrical surface may be a rim of the wheel or the surface of a flange of the wheel.

Conventional brake block assemblies used in railway vehicles as aforementioned comprise a support and a block of friction material mounted on the support. The support is mounted on a holder which is pivotally mounted on the vehicle, the support having an arcuate concave surface which faces a generally cylindrical surface of the wheel. The friction material, (which is usually sintered metal but alternatives are possible such as resin bonded or cast iron friction material) is secured to the concave surface of the support so that a concave arcuate surface of the friction material faces and can be moved into engagement with said surface of the wheel. The friction material is normally sintered in situ on the support.

When the friction material of a conventional brake block assembly as described above has worn beyond an acceptable level, the assembly is detached from the holder and discarded and a new assembly is mounted on the holder. This is a difficult process requiring access to the under side of the vehicle and is wasteful.

There are brake block assemblies known in which the discarding of the support when the friction material has worn is avoided. In such assemblies, the friction material is removably mounted on the support and fresh friction material can be mounted on the support. For example, EP 0278376 describes an assembly in which the support is formed with a circumferentially-extending arcuate groove. The groove is re-entrant and is arranged to receive a plurality of pads each of which comprises a wheel engaging portion formed from friction material and a mounting portion which is a sliding fit in the groove. The groove has an entrance in an end edge of the support and the pads are mounted on the support by being introduced into the groove one after the other so that they form a circumferentially-extending row with all the pads in a single groove. The friction material of all the pads can then engage the wheel. However, although this assembly avoids the problem of discarding the support, it is difficult to replace the friction material and requires access to the underside of the vehicle.

It is an object of the present invention to provide a brake block assembly which enables easy replacement of friction material on the support of the assembly. In particular, said replacement can be achieved without access being required to the underside of the vehicle.

The invention provides a brake block assembly suitable for mounting on a vehicle to be moved into engagement with a wheel to brake rotation of the wheel about an axis thereof, the assembly comprising a support and a plurality of pads mounted on the support, each pad comprising a wheel engaging portion formed from friction material, each pad also comprising a mounting portion fixed relative to the wheel engaging portion thereof, the arrangement being such that, when said pads are mounted in operative positions thereof on said support and the support is mounted on a vehicle, engagement surfaces of said wheel engaging portions are positioned so that they can all engage said wheel, wherein said support defines a plurality of re-entrant grooves arranged so that they extend parallel to one another and each extends in a direction which is parallel to the direction of said rotational axis, and said mounting portions of said pads are arranged so that each is a sliding fit in one of said grooves into which it is introduced to mount the pad on the support, the assembly also comprising locating means operative to locate each pad in its operative position relative to its groove, and fixing means operative to fix said pad in its operation position.

In a brake block assembly according to the invention, the pads can be removed from their grooves individually. As the grooves run parallel to the rotational axis of the wheel, the pads are removed by sliding them transversely of the wheel and this can be achieved from the outboard side of the wheel without requiring access to the underside of the vehicle. If appropriate, it is possible to replace one or some of the pads without replacing or removing the remainder, since each pad is mounted in its own groove.

In an assembly according to the invention, the mounting portion of each pad may be provided by a mounting plate shaped to be a sliding fit in one of the grooves, the mounting plate being secured to the remainder of the pad, eg by fastening means such as rivets. Such a mounting plate may be made of steel. It is possible for the mounting plate to also have the friction material secured directly thereto or there may be a backing plate secured to the friction material and to the mounting plate. In another alternative, the pad is formed as an integral construction with a layer of friction material and a layer of strengthened material shaped to serve as the mounting portion.

The locating means of an assembly according to the invention may be in the form of a projection, which is arranged to engage a portion of the support, eg its side edge, when a pad has reached its operative position relative to its groove. Conveniently, such a projection also prevents the pad from moving further along the groove in one axial direction. The fixing means may be arranged to fix said projection relative to the support. For example, the fixing means may comprise one or more screws extending axially through said projection into said support. The fixing means is arranged to be operated from the outboard side of the wheel. The projection may project from a mounting plate of the pad, or may project from a backing plate thereof, or may be formed as part of the integral construction aforementioned.

Since the pads of an assembly according to the invention are independently mounted in separate grooves, it is possible to provide pads with friction material having different properties from one pad to the other. For example, leading and trailing end pads may be different in their properties from the other pads. In this case, it may be appropriate if the assembly also comprises interlocking means arranged to ensure that the pads are correctly inserted by arranging that only pads of a particular configuration can be mounted in each groove. Such interlocking means may, for example, comprise a pin or other projection projecting from the support into the groove and a matching slot formed in the pad, the slots being differently positioned transversely of the groove in pads of different configurations. Thus, when a pad of the correct configuration is inserted into a groove, the pin or other projection is received into said slot and the pad can be fully inserted. However, if an attempt is made to insert a pad of an incorrect configuration into a groove, said pin or other projection is not received into a slot and prevents the pad from being fully inserted.

In an assembly according to the invention, the support may be arranged to be mounted on a holder pivotally mounted on the vehicle in similar manner to the conventional assemblies described above. Alternatively, the support may be arranged to be pivotally mounted on a vehicle. Thus, the holder and support are combined as one component. This latter possibility enables larger depths of friction material to be used since the space occupied by a separate support can be utilised for this purpose.

There now follows a detailed description to be read with reference to the accompanying drawings of brake block assemblies which are illustrative of the invention.

In the drawings:

Figure 1 is a perspective view generally from the front of a first illustrative brake block assembly;

Figure 2 is a perspective view generally from the back of the first illustrative brake block assembly;

Figure 3 is a similar view to Figure 1 but showing part of the first illustrative brake block assembly in an exploded form;

Figure 4 is a cross-sectional view taken on the line IV-IV in Figure 1 ;

Figures 5 and 6 are views similar to Figure 4 but taken through variations of the first illustrative brake block assembly;

Figure 7 is a view similar to Figure 2 but of a second illustrative brake block assembly; and

Figure 8 is a plan view of a portion of a third illustrative brake block assembly.

The first illustrative brake block assembly 10 is shown in Figures 1 to 4. It is intended for use in braking a wheel (not shown) which is rotatable around an axis. The braking occurs by frictional engagement with a cylindrical edge surface of the wheel which is centred on said axis. The cylindrical edge may be a rim of the wheel or an edge of a flange on the wheel centred on the axis. In particular, the assembly 10 is suitable for use in a railway vehicle.

The assembly 10 comprises a plurality of pads 12. Specifically, there are four pads 12 but, in variations of the illustrative assembly 10, there may be a different number of pads provided that there are at least two. Each pad 12 comprises a wheel engaging portion formed from friction material in the form of a block 14. Each pad 12 also comprises a mounting portion in the form of a mounting plate 15 (see Figure 3) which is fixed relative to the wheel engaging portion of the pad 12. Each block of friction material 14 is secured to a backing plate 16 of the pad 12 which is in turn secured to the mounting plate 15.

Each block 14 has a rectangular wheel engaging upper surface 14a, a rectangular lower surface 14b, two side surfaces 14c and two end surfaces 14d. The side surfaces 14c extend upwardly parallel to one another from opposite edges of the lower surface 14b and normally to the surface 14b. The end surfaces 14d also extend upwardly from the other edges of the surface 14b but are tapered towards one another in the upward direction.

The backing plate 16 is made of steel and has an upper surface 16a which is rectangular and of the same size and shape as the lower surface 14b of the block 14. The block 14 is, in this case, made of sintered metal friction material of conventional type which is adhered to the upper surface 16a of the plate 16. Conveniently, the block 14 is sintered in situ against the upper surface 16a. The assembly 10 also comprises a support 20 on which the pads 12 are mounted in operative positions thereof in which their wheel engaging surfaces 14a can all engage said wheel. In their operative positions, the backing plates 16 of the four pads are arranged adjacent to one another along an arc. When the pads 12 are so mounted, the upper surfaces 14a of the blocks 14 are arranged along an arc (of smaller radius than the arc along which the plates 16 are arranged). The surfaces 14a are then adjacent to one another so that they co-operate to define an engagement surface which is generally arcuate and conforms to the shape of a portion of a cylindrical edge surface of the wheel. This is made possible by the tapering of the surfaces 14d of the blocks 14 as the taper accommodates the difference in radii. The support 20 generally has the form of a portion of a cylinder having an arcuate concave surface 20a and, co-axial therewith, an arcuate convex surface 20b. The surfaces 20a and 20b are connected by side edges 20c and end edges 2Od of the support 20, the end edges 2Od being considerably shorter than the side edges 20c. The support 20 is made as a one piece casting out of iron although other constructions are possible for example a pre-fabricated steel assembly.

The support 20 is intended to be mounted on a pivoted holder (not shown) of a railway vehicle and is provided, for this purpose, with a mounting bracket 22 which is welded to the convex surface 20b. In conventional manner, the bracket 22 is designed to fit in a recess in the holder and be retained therein by a bolt. The pads 12 are mounted, in a manner to be described, on the concave surface 20a along an arc which extends from one end edge 2Od to the other.

The concave surface 20a of the support 20 has formed therein four parallel reentrant grooves 24. Each groove 24 is of a dovetail form and extends throughout the width of the support 20 between end openings of the groove 24 formed in the side edges 20c. These grooves 24, when the assembly 10 is mounted in a vehicle extend parallel to one another in a direction parallel to the axis of the wheel, ie transversely of the support 20. Below the opening of each of the grooves 24 in one of the side edges 20c of the support 20, two tapped holes 26 are formed in the support 20, ie there is a total of eight holes 26, two associated with each of the four grooves 24. The side edge 20c in which the holes 26 are formed is intended to be positioned on the outboard side of the wheel when the assembly 10 is mounted on a vehicle so that the holes 26 are accessible.

In order to mount the pads 12 on the support 20, each pad 12 comprises the aforementioned mounting plate 15 which is a sliding fit in one of the grooves 24. Specifically, each mounting plate 15 has an upper surface 15a which engages the backing plate 16 and two side surfaces 15b which taper to conform to the taper of the sides of the groove 24. In order to secure the plate 15 to the remainder of the pad 12, the backing plate 16 of the pad is formed with six holes 16b which are arranged to correspond with six holes 15c formed in the mounting plate 15. Six rivets 32 are passed through the holes 16b and 15c and set to secure the plates 16 and 15 together.

The backing plate 16 is also provided with a downwardly extending plate-like projection 16c which extends past and beyond the plate 30. The projection 16c is provided with two holes 16d which are positioned to correspond with the positions of the holes 26 formed in the side edge 20c of the support 20.

In order to mount a pad 12 on the support 20, the end of the mounting plate 15 which is at the opposite end to the projection 16c is introduced into the opening of one of the grooves 24 which is formed in the side edge 20c in which the holes 26 are formed. The mounting plate 15 and thus the entire pad 12 are moved along the groove 24 transversely of the support 20 until the projection 16c abuts the side edge 20c and then two screws 34 are used to secure the pad 12 in position by inserting them through the holes 16d into the holes 26. Thus, the projection 16c provides locating means of the assembly 10 operative to locate each pad 12 relative to its groove 24 transversely of the support 20. The projection 16c also provides stop means operative to prevent the pad 12 from leaving the groove 24 in one transverse direction relative to the support 20, since further movement in the inboard direction is prevented. Furthermore, the screws.34 provide fixing means operable to prevent said pad 12 from leaving the groove 24 in the opposite transverse direction, outboard of the wheel.

As is best seen in Figure 4, the upper surface 14a of each block 14 is inclined in the transverse direction of the support 20, with the block 14 being thickest at the outboard edge 20c thereof and thinnest at the inboard edge. This inclination of the surface 14a is not essential but is appropriate if the surface of the wheel to be engaged tapers. Otherwise the surface 14a is flat. The arrangement is such that the centres of the upper surfaces 14a together define an arcuate surface corresponding in curvature to that of the wheel, the surfaces 14a being intended to wear in service to correspond precisely to the surface of the wheel.

Figure 5 shows a variation of the assembly 10 in which the projection 16c is omitted but is replaced by a similar projection 15d projecting downwardly from the mounting plate 15. The projection 15d acts in the same manner as the projection 16c being equipped with holes to receive the screws 34.

Figure 6 shows a further variation of the assembly 10 in which the backing plate 16 is omitted and the block 14 is secured directly to the mounting plate 15 which retains the projection 15d of the Figure 5 variation.

Figure 7 illustrates the second illustrative assembly 50 which is similar except as described below to the first assembly 10 and like parts are given the same reference numbers in Figure 7 as in Figures 1 to 4 without repeating the description thereof. The assembly 50 differs from the assembly 10 in that the support 20 is omitted and, instead of being received in grooves 24, the mounting plates 15 are received in grooves 54 which are similar to the grooves 24 but are formed in a support 56 which is pivotly attached to the vehicle in similar manner to the holder (not shown) on which the support 20 is mounted. There is one other difference in that the blocks 14 of the assembly 50 are thicker than those of the assembly 10, this being made possible by the absence of the support 20.

Figure 8 illustrates a portion of the third illustrative assembly 60 which is similar, except as described below, to the first assembly 10 and like parts are given the same reference numbers without further description thereof. The assembly 60 differs from the assembly 10 in that it comprises interlocking means arranged to ensure that only pads 12 of a particular configuration can be mounted in each groove 24. The interlocking means comprises a pin 62 positioned in each groove 24, the pin 62 in each groove being at a different relative position transversely of the groove 24 (longitudinally of the support 20). A slot 64 is provided in each mounting plate 15, the slot 64 in each plate 15 being positioned to correspond, when the plate 15 is received in a particular one of the grooves 24, to the position of the pin 62. If an attempt is made to insert the plate 15 into a different one of the grooves 24, the pin 62 is not received in the slot 64 and the pin 62 prevents the plate 15 from fully entering the groove 24. Thus, as the slots 64 in each plate 15 are positioned so that each plate can only be inserted fully into one of the grooves 24, it is not possible to secure the wrong pad 12 in any of the grooves 24.

Claims

A brake block assembly suitable for mounting on a vehicle to be moved into engagement with a wheel to brake rotation of the wheel about an axis thereof, the assembly comprising a support and a plurality of pads mounted on the support, each pad comprising a wheel engaging portion formed from friction material, each pad also comprising a mounting portion fixed relative to the wheel engaging portion thereof, the arrangement being such that, when said pads are mounted in operative positions thereof on said support and the support is mounted on a vehicle, engagement surfaces of said wheel engaging portions are positioned so that they can all engage said wheel, wherein said support defines a plurality of re-entrant grooves arranged so that they extend parallel to one another and each extends in a direction which is parallel to the direction of said rotational axis, and said mounting portions of said pads are arranged so that each is a sliding fit in one of said grooves into which it is introduced to mount the pad on the support, the assembly also comprising locating means operative to locate each pad in its operative position relative to its groove, and fixing means operative to fix said pad in its operation position.

An assembly according to claim 1 , wherein the mounting portion of each pad is provided by a mounting plate shaped to be a sliding fit in one of the grooves, the mounting plate being secured to the remainder of the pad.

An assembly according to claim 1 , wherein each pad is formed as an integral construction.

An assembly according to claim 3, wherein said integral construction comprises a layer of friction material and a layer of strengthened material shaped to serve as the mounting portion.

An assembly according to any one of claims 1 to 4, wherein said locating means is in the form of a projection which is arranged to engage a portion of the support when a pad has reached its operative position relative to its groove.

An assembly according to claim 5, wherein said fixing means is arranged to fix said projection relative to the support.

An assembly according to any one of claims 1 to 6, wherein the assembly comprises pads with friction material having different properties.

An assembly according to any one of claims 1 to 7, wherein the assembly also comprises interlocking means arranged to ensure that the pads are correctly inserted by arranging that only pads of a particular configuration can be mounted in each groove.

An assembly according to claim 8, wherein said interlocking means comprises at least one projection projecting from the support into the groove and at least one matching slot formed in the pad, the slots being differently positioned transversely of the groove in different pads.

An assembly according to any one of claims 1 to 9, wherein said support is arranged to be mounted on a holder pivotally mounted on a vehicle.

An assembly according to any one of claims 1 to 9, wherein said support is arranged to be pivotally mounted on a vehicle.

As assembly substantially as hereinbefore described with reference to and as shown in Figures 1 to 4, Figure 5, Figure 6, Figure 7 or Figure 8 of the accompanying drawings.