Parking brake, especially for an automotive gearbox

A parking brake for a drive, the parking brake comprising:

• a blocking apparatus for receiving actuating signals from a regulating device for control of the drive, the blocking apparatus, upon activation of a spring accumulator (10), is brought into a blocking position from which, by one of hydraulic and pneumatic pressure, the blocking apparatus is released while simultaneously prestressing the spring accumulator (10);
• a mechanical acting locking apparatus (40) for holding of the blocking apparatus in an unblocked condition;
• and
• an energizable electromagnet (30) for holding of a locking apparatus (40) in a locking condition, the locking apparatus (40) is mechanically activated by the blocking apparatus upon release of the blocking position and the locking apparatus (40) is retained in the locked position by the energized electromagnet (30);
• the locking apparatus (40) comprises a spreader cone (41), which is linearly movable between an actuation spring (46), which abuts axially against a hydraulically or pneumatically controlled piston (20), which said piston is designed to release the parking brake and a repositioning spring (47) which axially abuts on an immovable part (11) of the spring accumulator (10),
• the spreader cone (41) comprises a first cylindrical surface (42) bordering a second conical surface (43) and further demarked by a third, at least approximately cylindrical surface (44) which third surface has a greater diameter than the first surface (42),
• the spreader cone (41) is securely bound to an armature (36) of the electromagnet (30),
• the locking apparatus (40) has at least one radially movable detent means for the holding of the blocking apparatus in the unblocked condition,
• the piston (20), upon release of the brake apparatus from a braked condition, pushes the spreader cone (41) mechanically toward a holding magnet (35) of the electromagnet (30), whereby the spreader cone (41), via the three surfaces (42, 43, 44) causes the detent (45) to move radially outward into a piston recess (22) into a locking position, in such a manner that a shape-fit is created between the piston (20) and an immovable part (11) of the spring accumulator (10).