Disc brake having a conversion cartridge provided with an anti-matting device

A disc brake comprising a floating calliper (100) which straddles the brake disc (2) which supports a fixed block (3) and forming a cylinder (110) which accommodates a piston (5) which supports a mobile block (4) in order to clamp the brake disc,

• the piston (5) being controlled by an hydraulic circuit and by a parking brake system by means of a movement conversion cartridge (200) which transforms the pivoting movement of the parking brake lever, which is supported by the calliper (100), into movement of translation in order to thrust the brake piston (5);
• the cylinder (110) having a front part which accommodates the brake piston (5) and a rear part which forms a receptacle (113) to receive the conversion cartridge (200) with a form of revolution which abuts the mobile block and the base of the cylinder;
• the conversion cartridge (200) is retained in the receptacle (113) by a clip (201) which passes in a sealed manner through an axial orifice in the base (114) of the cylinder, in order to connect its control shaft to the parking brake lever (120),
• which brake is characterized in that:
• A) the conversion cartridge (200) comprises:
• a rear part (210) which is supported against the base (114) of the receptacle (113) of the cylinder (110), and consists of:
• a bearing (211) in the form of a sleeve (212) provided with a collar (213) which is supported around an orifice (115) for passage of the base of the receptacle (113), through which the sleeve (212) partially passes, and
• a control shaft (220) which is connected to the pivoting lever (120) and supports a first plate (222);
• a front part (260) which is supported against the brake piston (5), and is mobile in translation relative to the cylinder (110) but blocked in rotation, and includes:
• a conversion piston (270) provided with a second plate (272) which is designed to co-operate with the first plate (222) of the control shaft (220), with interposition of mobile balls in ramps in the two plates (222, 272), in order to transform the relative movement of rotation between the two plates (222, 272) into movement of translation of the conversion piston (270), and
• a cage (290) for retention of the conversion piston (200) in the cylinder (110) by means of the clip (201),
• a return spring (280) being interposed between the cage (290) and the conversion piston (270) in order to act against the movement of translation generated by the plates (222, 272) and the balls;
• B) at the level of its front part which forms the receptacle (113) which receives the conversion cartridge (200), the cylinder (110) comprises at least one longitudinal groove (119), and the conversion piston (270) comprises on its periphery at least one longitudinal rib (274) with a cross section complementary to that of the longitudinal groove (119), in order to co-operate with the latter and block the rotation of the front part (260) of the cartridge (200), whilst leaving the conversion piston (270) free in translation;
• C) an anti-deformation device (300, 400), interposed between the longitudinal ribs (274) of the conversion piston (270) and the longitudinal grooves (119) of the receptacle (113) of the calliper (100), comprises a ring (310, 410) which supports lugs (320, 420) distributed according to the distribution of the longitudinal ribs (274) of the conversion piston, and having cylindrical tongues (322a, b;
• 422a, b), which are substantially curved according to the form of the cross section of the branches (274), in order to cover the branches (274) in the longitudinal grooves (119) of the receptacle (113) of the cylinder (110).