Hydraulic bicycle brake system

A hydraulic bicycle brake system which comprises:

• means defining an actuating zone, said means being adapted to be attached to a bicycle;
• a first pressure plate located at one end of said actuating zone and axially movable within said zone;
• a second pressure plate fixedly attached to said first mentioned means at the opposite end of said zone;
• means adapted to move said first pressure plate axially in said actuating zone toward said second pressure plate;
• two independent hydraulic circuits, each circuit including only two expansible capsules, one being a compressor capsule and one an expansion capsule, said two capsules in each circuit being interconnected by tubing to provide communication therebetween, each of said circuits being sealed and charged with hydraulic fluid, the compression capsule of each circuit being positioned between said first and second pressure plates in juxtaposed relationship, each of said capsules having two generally parallel main walls, the external surfaces of said two main walls together constituting the major portion of the external surface of the capsule, the compressor capsule of each of said two hydraulic circuits being arranged with one of its said main wall external surfaces in close adjacent relationship with one of the main wall external surfaces of the other of said compressor capsules, thereby the compressor capsules between said plates are simultaneously compressed in an axial direction when said first pressure plate is moved axially toward said second pressure plate;
• a pair of elongated, spaced apart brake links adapted to be mounted adjacent each wheel of a bicycle, each of said links carrying a brake shoe at one end adapted to be positioned adjacent the rim of a bicycle wheel and being pivotally attached at its midportion to pivot means disposed transversely between said links;
• housing means located between the ends of each pair of said brake links opposite said one end thereof, the expansion capsule in each of said hydraulic circuits being positioned in said housing means;
• third and fourth pressure plates on opposite sides of said capsule within said housing means and adjacent said respective opposite ends of said links;
• means interposed between said housing and each of said latter pressure plates for resiliently biasing said pressure plates inwardly of said housing into engagement with the external surfaces of said two main walls of their associated expansion capsule;
• and means for pivotally attaching each of said latter pressure plates to its respective link, whereby compression of said capsules in said actuating zone causes simultaneous expansion of the capsules in said two housing means to pivot the brake shoes on said links into braking engagement with the rim of a bicycle wheel while each of said two housing means and members associated therewith freely follow the lateral movement of their respective bicycle wheel rim.