WO2009035348A1

WO2009035348A1 - Improvements relating to wheel brake assemblies

Info

Publication number: WO2009035348A1
Application number: PCT/NZ2008/000240
Authority: WO
Inventors: Bruce Archibald Short
Original assignee: Bas Manufacturing Limited
Priority date: 2007-09-14
Filing date: 2008-09-15
Publication date: 2009-03-19
Also published as: WO2009035348A9

Abstract

The wheel brake assembly of the invention comprises an axially movable brake disk, a brake calliper, and brake actuation means. The brake calliper is rigidly attachable to a wheel support and has two legs spaced apart. Each leg of the calliper is adapted to support brake pads. A first leg of the calliper is adapted to support one or more first brake pads and a second leg of the calliper is adapted to support one or more second brake pads in such a manner that the brake actuation means can move one or both of the first leg and second leg to clamp the brake disk between the first brake pad or pads and the second brake pad or pads. In the preferred form the brake disk is adapted to move axially relative to a wheel hub.

Description

Improvements Relating to Wheel Brake Assemblies

FIELD OF THE INVENTION

,This invention relates, to a> wheel brake assembly, and in particular, but not exclusively to a wheel brake assembly for trucks and trailers.

BACKGROUND

Wheel brake assemblies operate in relatively harsh environments, being exposed to moisture and dirt, and generating their own heat and additional contaminants. In addition, they are often subjected to considerable forces, and when used for extended periods some of the brake components can reach very high temperatures. These factors can affect the long term reliability of many brake assemblies.

Some disk brake assemblies have a calliper which extends to both sides of a rotatable disk. To account for brake pad wear, the calliper will either include a separate actuator on each side of the disk, or if only one actuator is used, the width of the calliper will be adjustable and will generally automatically adjust to account for brake wear. The adjustment is usually achieved by having one half of the calliper telescoping relative to the other half. In alternative arrangements the entire calliper is supported on a floating mount, allowing the calliper to align itself with the disk.

However, if the telescoping capability, or the floating mount, becomes stiff, uneven brake wear can result. Higher forces are applied to one side of the disk than to the other, resulting in higher wear in the. brake pads on, one side than on the other. This also leads to reduced braking efficiency.

If the telescoping capability, or the floating mount, of the calliper becomes stuck or jammed, braking efficiency can be reduced further, along with even greater unevenness in brake wear. Unbalanced forces that are applied to the disk can also cause damage. An _^alternative ₍ to an adjustable calliper unit is to have separate actuators on each side of the disk, for example a separate hydraulic cylinder and piston on each side. This increases the complexity of the brake unit, and also takes up additional space. The space within a typically wheel assembly is limited and therefore the overall size of brake units is often limited. Where significant levels of braking capability are required, for example on trucks and truck trailers, and where the brake assemblies need to be relatively large to cope with the loads they are subjected to, it is disadvantageous to use brakes that do not have a compact design.

OBJECT

It is therefore an object of the present invention to provide a wheel brake assembly which will at least go some way towards overcoming the above mentioned problems, or at least provide the public with a useful choice.

STATEMENTS OF THE INVENTION

Accordingly, in a first aspect, the invention consists in a wheel brake assembly comprising an axially movable brake disk, a brake calliper, and brake actuation means, the brake calliper being rigidly attachable to a wheel support and having two legs spaced apart, each leg of the calliper being adapted to support brake pads, a first leg of the calliper being adapted to support one or more first brake pads and a second leg of the calliper being adapted to support one or more second brake pads in such a manner that the brake actuation means can move one or both of the first leg and second leg to clamp the brake disk between the first brake pad or pads and the second brake pad or pads.

Preferably one calliper leg is substantially fixed within the wheel brake assembly and the brake actuation means moves the other calliper leg.

Preferably the brake disk is adapted to move axially relative to a wheel hub.

Preferably the brake disk is adapted to move axially on axially aligned guides on a wheel hub.

Preferably the axially aligned guides are pins, grooves or ridges which form part of the wheel hub. ^Optionally the_v wheel brake assembly further includes a wheel hub adapted to' support the brake^ disk and having axially aligned guides adapted to support the brake disk and to allow a degree of axial movement of the disk relative to the hub.

Preferably the brake actuation means can include a pneumatic actuator (vacuum or pressure), an electrical actuator, a spring brake actuator, or an air spring brake chamber actuator.

Preferably the brake actuation means includes one or more hydraulic actuators.

In a second aspect, the invention consists in a vehicle, a trailer or a carriage incorporating at least one wheel brake assembly substantially as specified herein.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

DESCRIPTION

Further aspects of the present invention will become apparent from the following description which is given by way of .example only and with reference to the accompanying drawings in which: '

FIGURE 1 is a perspective view of a wheel brake assembly shown fitted to one and of an axle,

FIGURE 2 is a second perspective view of the wheel brake assembly,

FIGURE 3 is a perspective view of a hub adapted for use with the wheel brake assembly,

FIGURE 4 is a cross sectional view showing the brake assembly fitted to an axle and situated within a wheel, and

FIGURE 5 is a cross sectional view showing a disk adapted for use with the wheel brake assembly and part of a calliper of the wheel brake assembly.

With reference to Figures, 1 to 5, a wheel brake assembly (10) is shown fitted onto the end of an axle (11). The wheel brake assembly (10) includes an axially movable brake disk (13). In this example the axle (11) comprises a main tube (15) and an axle stub (17).t .This overall arrangement is best seen in figure 4.

The wheel brake assembly (10) includes a calliper (19) and brake actuation means (21). The brake calliper (19) is rigidly attachable to a wheel support. In this example the brake calliper (19) is bolted to a flange (23) of the axle stub (17). The calliper (19) has two spaced apart legs, each leg of the calliper being adapted to support brake pads (25). A first leg (27) of the calliper is adapted to support one or more brake pads (25) in a generally fixed location within the calliper (19). And a second leg (29) of the calliper (19) is adapted to support one or more brake pads (25) in such a manner that each supported pad (25) can be moved by the brake actuation means (19). Alternatively each leg (27, 29) is able to move.

The pads (25) act on the brake disk (13) to provide braking for a wheel. The wheel brake assembly (10) can include the disk (13). The brake disk (13) is supported on a wheel hub (31), and is adapted to move axially relative to the hub (31). In this example, the axial movement of the brake disk (13) is allowed since the disk (13) is supported on a number of axially aligned guides or pins (33). The pins (33) form part of the wheel hub (31) and are arranged in a circular pattern about the hub (31), and the disk (13) is provided with a series of similarly configured holes (35). The diameter of the holes (35) is such that they allow the disk to freely slide axially along the pins (33). The pins (33) however substantially prevent rotational movement of the disk (13) with respect to the hub (31).

As the brake pads (25) wear, the disk (13) can reposition itself along the pins (33) to keep itself correctly aligned between the brake pads (25). The freedom of the disk (13) to float, or to move axially, eliminates the need for the calliper to either have separate actuators on each side of the disk, or to have a telescoping capability, as with prior art arrangements. This significantly simplifies the design and construction of the calliper and actuator assembly. The simplicity allows the overall size of the assembly to be minimised, and can help to improve brake reliability. However the axially movable disk (13) could be used in constructions where both callipers are moved so that the disk (13) would centre itself between the pads (25). Figure 4 shows the wheel brake assembly (10) fitted onto the axle stub (17) and situated within a wheel (37), in this example a truck or heavy trailer wheel. The wheel brake assemblyj (10) can further include the wheel- hub (31) "which is adapted' to support the brake disk (13) and to allow the disk to slide axially relative to the hub (31).

Vehicles, such as cars or trucks, and trailers or carriages can incorporate wheel brake assemblies (10) as described herein.

The, invention can be used in situation where the brake is normally on such as trailers, and where the brake is normally off such as in a car.

VARIATIONS

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.

The calliper (19) shown in the foregoing example is shown as a fabricated unit, however, it is envisaged that a production version can be manufactured as a one piece casting.

Also, the actuation means (21) is shown as a pair of hydraulic cylinders. However, in an alternative configuration the actuation means (21) can include a pneumatic actuator (vacuum or pressure), an electrical actuator, a spring brake actuator, or an air spring brake chamber actuator. Having said this, it is considered advantageous to use hydraulic actuators due to the compact overall size that can be achieved using hydraulics. In this example, two smaller side by side hydraulic actuators, rather than a single larger diameter hydraulic actuator. This configuration has been used to allow sufficient braking force to be achieved, but without exceeding the limited space, or dimension, between the hub (31) and the inside diameter of the wheel (37). If a single hydraulic actuator were used, the diameter of the cylinder would have exceeded this dimension.

In the foregoing example, the disk (13) is shown adapted to move axially along guides in the form of pins (33) which form part of the wheel hub (31). However, in an alternative configuration, the disk (13) could be adapted to move along guides in the form of axially aligned grooves or ridges of, or on, the wheel hub (31). In such a configuration the disk (13) can be provided with a castellated internal bore which is adapted to cooperate with the grooves or ridges. DEFINITIONS

Throughout this specification the word "comprise" and variations of that word, such as ■'comprises", and :"comprising",.are not intended to exclude other additives; components; integers or steps.

ADVANTAGES

Thus it can be seen that at least the preferred form of the invention provides a wheel disk brake assembly haying actuators which need only be provided on one side of the disk, and which does not have an adjustable width calliper, providing the possibility for improved brake pad wear and improved reliability.

In addition, the brake assembly only requires actuation means on one side of the calliper, which can help to minimise the overall size of the brake assembly for a particular braking capability.

The calliper can also_. be rigidly connected to the wheel support structure, simplifying the fastenirig method and eliminating another possible area of low reliability.

Claims

CLAIMS:

1. A wheel brake assembly comprising an axially movable brake disk, a brake calliper, and brake actuation means, the brake calliper being rigidly attachable to a wheel support, and ,

^: having two legs spaced apart, each leg of the calliper being adapted to support brake pads, a first leg of the calliper being adapted to support one or more first brake pads and a second, leg of the calliper being adapted to support one or more second brake pads in such a manner that the brake actuation means can move one or both of the first leg and second leg to clamp the brake disk between the first brake pad or pads and the second brake pad or pads. , • ._. , . _.. . - _. , . : ... -

2. A wheel brake assembly as claimed in claim 1 wherein one calliper leg is substantially fixed within the wheel brake assembly and the brake actuation means moves the other calliper leg.

3. A wheel brake assembly as claimed in either one of claim 1 and claim 2 wherein the brake disk is adapted to move axially relative to a wheel hub. . . _. . . ..

4. , A wheel brake assembly as claimed in claim 3 wherein the brake disk is adapted to move axially on axially aligned guides on a wheel hub.

5. A wheel brake assembly as claimed in claim 4 wherein the axially aligned guides are pins, grooves or ridges which form part of the wheel hub.

6. A wheel brake assembly as claimed in any one of the preceding claims the wheel brake assembly further includes a wheel hub adapted to support the brake disk and having axially aligned guides adapted to support the brake disk and to allow a degree of axial movement of the disk relative to the hub.

7. A wheel brake assembly as claimed in any one of the preceding claims wherein the brake actuation means can include a pneumatic actuator (vacuum or pressure), an electrical actuator, a spring brake actuator, or an air spring brake chamber actuator.

8. A wheel brake assembly as claimed in any one of claims 1 to 6 wherein the brake actuation means includes one or more hydraulic actuators.

9. , A wheel brake assembly substantially as herein described with reference to the accompanying drawings.

10. A vehicle, a trailer or a carriage incorporating at least one wheel brake assembly as claimed in any one of claims 1 to 9.