The present application claims the benefit of U. S. patent application No.

60/512,854 dated October 22,2003, which is hereby incorporated by reference.

This invention is concerned with a method of replacing brake pads of a full contact annular disk brake assembly from the exterior, meaning that the whole disk brake assembly does not need to be taken apart or removed from the axle around which it is mounted. It also relates to a newly designed full contact annular disk brake assembly in which the brake pads can be replaced from the exterior.

The concept of full annular disk brake is described and shown in U. S. Patents Nos. 5,205, 380 and 5,330, 034, which are hereby incorporated by refere, nce.

In all cases, brake pads must be replaced when they reach or are about to reach their maximum wear limit. This typically happens several times during the years a vehicle is in service. Replacing brake pads currently requires that the vehicle be removed from service for a large number of hours. It also requires relatively skilled mechanics to undertake the job because each disk brake assembly needs to be completely removed from the axle, which is usually a complex and time consuming task, partly because internal rotating parts are supported by sealed bearings filled with grease and oil. These bearings must be perfectly manipulated and re-assembled for the vehicle to operate correctly.

Considering this background, there was clearly a need to replace brake pads from the exterior of a full contact annular disk brake assembly.

In accordance with one aspect of the present invention, there is provided a full annular disk brake assembly for a vehicle, the disk brake assembly comprising a plurality of disk brake pads configured and disposed to engage a lateraily-movable rotor disk provided in a housing, the disk brake assembly

being characterized in that each disk brake pad is individually mounted on a corresponding support that is removably attached in a corresponding seat provided at the outer periphery of the housing, each disk brake pad and its corresponding support being removable from outside the disk brake assembly.

In accordance with another aspect of the present invention, there is provided The present invention will be better understood from the following detailed description and accompanying figures in which: FIG. 1A is an enlarged perspective side view of a full contact annular disk brake assembly in accordance with a preferred embodiment of the present invention; FIG. 1B is a partially exploded perspective view of the disk brake assembly shown in Fig. 1; FIG 2 is an elevation view of a set of brake pads and their respective support; FIG. 3 is an enlarged view of one brake pad, installed in its corresponding seat, shown in Fig. 2; \ FIG. 4 is a view similar to Fig. 3, showing the brake pad in a perspective view; FIG. 5 is an enlarged perspective view of a seat without its brake pad; FIG. 6 is a view similar to Fig. 5, showing the opposite side of the seat; FIG. 7 is a front elevational view of an external cover of the housing; FIG. 8 is a rear elevational view of the front cover of the housing; FIG. 9 is a perspective view of a support or a brake pad, without the brake pad itself.

FIGS. 1A and 1B shows a full annular disk brake assembly (10) in accordance with one possible embodiment of the present invention. It is designed with

individual brake pads that can be replaced from the exterior. It should be noted that the disk brake assembly (10) may comprise more than one rotor disk, thus more than two sets of brake pads, each usually comprising three or more brake pads.

The disk brake assembly (10) comprises a side flange (12) removably connected to a central hub (14) by means of a plurality of bolts (16). This side flange (12) supports a number of mounting bolts (18) provided to secure the corresponding wheel or wheels to the vehicle (not shown). Of course, before servicing the disk brake assembly (10), the corresponding wheel or wheels are removed. The hub (14) extents from the side of the disk brake assembly (10) and is journaled around the axle of the vehicle by bearings (not shown).

The disk brake assembly (10) also comprises an external cover (20). This external cover (20) is a fixed part that is secured to a housing (22) of the brake assembly (10) by means of plurality of bolts (24). A rotor disk (30), is slidably mounted around the hub (14) between the external cover (20) and the bottom of the housing (22). The rotor disk (30) is essentially a radial disk or, preferably, a pair of disks between which ventilation channels are provided.

Rotational engagement between the hub (14) and the rotor disk (30) is preferably made through a set of axial splines (14a) provided on the hub (14) and corresponding inner teeth (30a) provided on the interior of the rotor disk (30), as best shown in FIG. 1 B. Other arrangements are also possible.

The disk brake assembly (10) comprises rotating parts and fixed parts. The rotating parts are rotating with reference to the fixed parts. The fixed parts are the ones that are directly or indirectly rigidly attached to the axle of the vehicle. This includes the two sets of brake pads in the illustrated embodiment. The first set of brake pads (40) is attached to the external cover (20). The second set of brake pads (50) is attached to a slidable inner carrier (52) actuated by means of an annular air bellows (not shown) that is in fluid communication with the pneumatic braking system of the vehicle. In vehicles with a hydraulic braking system, a corresponding annular hydraulic actuator would be used. The braking action is achieve when a force is applied by the

actuator. This force urges the second set of braking pads (50) against the corresponding side surface of the rotor disk (30). The rotor disk (30) is then moved against the first set of braking pads (40). The mechanical energy of the rotation is transformed into heat due to the friction between both side surfaces of the rotor disk (30) and the brake pads (40,50).

As can be seen in the figures, the illustrated disk brake assembly (10) advantageously comprises optional heat sinks (60) behind each brake pad (40,50). The heat sinks (60) channel the heat from the brake pads (40,50) to the atmosphere. They can be mounted individually behind each brake pad (40,50). Alternatively, they can be mounted together on a one-piece ring.

These heat sinks (60) also work in conjunction with the ventilation system inside the rotor disk (30), if one is provided.

FIG. 2 shows a view from the interior side of the external cover (20). This view shows the first set of brake pads (40) and their respective support (42) to which they are rigidly attached. In the illustrated embodiment, five brake pads (40) with their corresponding supports (42) are used. These brake pads (40) are positioned and disposed so that they engage the corresponding surface of the rotor disk (30) when a braking force is applied. One can clearly see that each brake pad (40) is radially positioned in the disk brake assembly (10).

FIG. 3 is an enlarged view of one of the brake pads (40) shown in FIG. 2.

FIG. 4 shows an enlarged perspective view of the same area. The support (42) on which each brake pad (40) is attached rests in a receiving seat (70) provided in the external cover (20). On each side, a pair of V-shaped flanges (72) maintains adjacent supports (42) in place. A connection spring (74), which is best shown in FIGS. 5 and 6, is pivotally connected to the external cover (20). This spring (74) is preferably in the form of a bended wire. It maintains the support (42) of a corresponding brake pad (40) and prevents it from being ejected radially. It also prevents the brake pad (40) from moving towards the inside. This last function is achieved using small V-shaped sections (74a) in the spring (74). This creates a sufficient retention force that prevents the support (42) from moving inside.

FIG. 6 shows an enlarged view of the seat (70) for one of the braking pads (40) and its support (42). It shows that the back of the support (42) will rest against a set of four support pegs (76). Two of these pegs (76) are mounted on one side of a corresponding small flange (78) that is radially projecting from the external cover (20). The other side of each flange (78) is provided with a tab (78a) configured and disposed to retain the spring (74) once the braking pads (40) are in place, as shown in FIGS. 4 and 5.

FIGS. 7 and 8 show the external cover (20) alone.

FIG. 9 illustrates a support (42) in accordance with a preferred embodiment.

The illustrated support (42) is without the corresponding brake pad (40) that is normally attached to the visible side. This view shows that the support (42) comprises a pair of small flanges (42a) projecting from the upper side thereof.

It also shows that both lateral sides have a pleated portion (42b), each with a small beveled face (42c) at the top thereof. The top beveled faces (42c) are designed to be pressed by a respective small V-shaped section (74a) of the spring (74). A pair of notches (42d) are provided at the bottom of the support (42) to engage corresponding pegs (80) projecting from the external cover (22).

As can be appreciated, releasing the spring (74) from the tabs (78a), using for example a screwdriver or another elongated tool, allows to easily release each brake pad (40) and its support (42) from their seat (70). They can then be pulled radially from outside and easily replaced by new ones.

The same principle applies to the second set of brake pads (50).

Another interesting feature of the present invention is that the illustrated design of the external cover (20) also provides another important advantage.

As aforesaid, two of the pegs (76) are provided on small flanges (78) projecting from the external cover (20). The two other pegs (76) are projecting from the main portion of the external cover (20). When properly designed, it is possible to have a. different resiliency value between the outer and the inner pegs (76), thus depending on the radial position. This is an

important advantage in the context. A common problem with brake pads (40) is that over time, there is more intense wear at the outward radial positions than that at positions closer to the center of the radius. One of the reasons is that the tangential speed is higher at a larger radius and as a result, the outermost portion of the brake pads (40) is subjected to a more intense wear than that at a location closer to the center of radius. Using the structure with different resiliency values within the seat (70) is also possible without using pegs (76).

In view of the above, it was found that providing the outermost pegs (76) on a relatively more resilient structure than that of the innermost pegs (76) can counteract or at least diminish the usual unevenness in the wear of the brake pads (40).

Overall, this method of replacing the brake pads (40,50) of the disk brake assembly (10) can significantly reduce the time and costs associated with the task. Changing the brake pads (40,50) of the vehicle more quickly allow to reduce the down time. In a large vehicle fleet, for instance in the case of buses of a public transport agency, it can even reduce the number of standby vehicles needed to replace those under maintenance. The method also requires less skilled mechanics compared to a design where the complete disk brake assembly must be removed.

Although a preferred embodiment of the invention has been described in detail herein and illustrated in the accompanying figures, it is to be understood that the invention is not limited to this precise embodiment and that various changes and modifications may be effected therein without departing from the scope or spirit of the present invention defined by the appended claims. For instance, although the illustrated disk brake assembly (10) is designed to be used on a large truck or bus with a pneumatic braking system, slightly different versions can be designed for other kinds of vehicles, including vehicles with a hydraulic braking system. The disk brake pad assembly, or any sub-portion thereof, can be different from what is illustrated in the figures. The set of brake pads are not necessarily identical to each other. The support pegs in the seats can be omitted in some designs.