Brakes – Wheel – Axially movable brake element or housing therefor
Reexamination Certificate
1999-12-21
2001-11-20
Graham, Matthew C. (Department: 3613)
Brakes
Wheel
Axially movable brake element or housing therefor
C188S073320
Reexamination Certificate
active
06318514
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to disc brake systems and, more particularly, relates to a disc brake system having a brake pad retained in place within the system using a spring clip-type pad holder.
2. Discussion of the Related Art
Disc brake systems are used in a wide variety of applications such as bicycles, snowmobiles, golf carts, and automobiles. The typical disc brake system includes 1) a power source, such as a hydraulic master cylinder, and 2) a mechanical disc brake assembly that is actuated by the power source to apply the brake. The disc brake assembly includes a disc that rotates with the wheel, one or more brake pads, and one or more calipers each of which includes at least one piston that is selectively forced towards the disc by the power source to press the brake pad into frictional contact with the disc, thereby applying the brake.
The brake pads of a disc brake assembly are installed in the assembly using pad holders formed from any of a variety of structures such as retainer clips, bolts, and/or fastening lugs. Pad holders of these types are disclosed, for example, in U.S. Pat. No. 5,529,150, GB Patent No. 2,017,236, and GB Patent No. 2,056,601. These pad holders are typically of a relatively complex design, making them rather expensive to fabricate. They also tend to be relatively difficult to remove and install, usually requiring special tools and often requiring partial or complete removal of the caliper and/or disc from the assembly before the pad can be removed from the remainder of the assembly. Many are less than fully effective at holding the pad tight against the associated piston, thereby giving rise to drag and rattling problems.
One example of an application in which disc brake assemblies are the type of which the inventive pad holder is usable in bicycle brakes. However, many conventional disc brake assembly designs are not well suited for use on bicycles, particularly since bicycles are operated by both children and adults, are flipped upside down and laid on their sides, and are made to be of extremely light weight. Prior attempts at adapting motorcycle and automotive hydraulic disc brake technology to bicycles have fallen short due to this markets particular needs.
SUMMARY OF THE PRESENT INVENTION
The brake system described herein innovates a bleedable fluid reservoir with a bladder system that allows the atmospheric pressure reservoir to be drawn upon allowing the brake caliper piston to self adjust for pad wear without the potential of air ingestion and with room to expand the full volume in a high brake temperature condition. This system adapts a thermally compliant brake disk concept to an extremely lightweight embodiment for the bicycle industry yielding high torque carrying ability along with unparalleled thermal durability in a one piece design.
The system uses a ball joint piston design as shown in U.S. patent applications Ser. No. 08/638,526, entitled “Ball Joint Piston,” and Ser. No. 09/044,276, entitled “Heavy Duty Brake Disc,” to allow the smallest packaging for low weight and good wheel spoke clearance as well as eliminating the possibility of brake drag. This system demonstrates a user friendly lever adjustment to allow hand sizes from those of children to adults for comfort and safety. This lever adjustment avoids rattles and vibration effects with a rod backstop that reduces critical tolerances and whose piston and boot grip the mating push rod.
A unique post and piston assembly is coupled to a friction pad backing plate that uses a wire formed spring to secure the friction pad which both maximizes the disk to friction material clearance (eliminating any brake drag) while allowing an extremely easy pad change. This pad retention system also prevents the pads from falling out while transporting the bicycle with the wheel (and therefore the brake disk) out of the front fork. This system also prevents rattling noise by holding the friction pad backing plate tightly to the face of the brake piston.
In accordance with another aspect of the invention, an improved pad holder is provided for holding the brake pad in the brake assembly. The pad holder takes the form of a simple spring clip, preferably a wire form, that holds the rear surface of the pad tightly against the front surface of the piston or pistons of the caliper to prevent brake drag and brake rattle. The clip is simple and inexpensive to manufacture and can be easily installed without removing the disc or the caliper from the brake assembly. Indeed, the pad/pad holder subassembly can be removed from the brake assembly, without using any special tools, simply by imposing sufficient upward vertical retraction forces on the pad/pad holder subassembly to deflect the spring clip and to remove the pad holder from the pistons to which it is attached.
Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description and the appended claims.
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Buckley James A.
Gohr Jeffrey S.
Hinkens George H.
Pfeil Lee
Boyle Fredrickson Newholm Stein & Gratz S.C.
Graham Matthew C.
Hayes Brake, Inc.
Sy Mariano
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