Adjustment device for a camshaft

An adjustment device for a camshaft, the adjustment device comprising a brake system and a superposition gear system which is connected on a drive output side to the camshaft and on a drive input side to a crankshaft, such that to adjust the camshaft, the superposition gear system dissipates a portion of energy from the drive input side into the brake system, the brake system being a frictional brake system in which a necessary braking force is produced by a friction lining (2) that operates permanently in a slipping condition and the brake system being an electromagnetically actuated frictional system, the brake system comprises an electrically actuated shift solenoid (1) having a friction surface (8), a friction lining (2) with a locking element (6) that co-operates with a drive-side element (5) of the superposition gear system (7), and a spring (3), the friction lining (2) being axially slidable and rotationally fixed on a spur gear (4) of the superposition gear system (7), such that when the shift solenoid (1) is not energized, the force of the spring (3) and via the friction lining (2) and the locking element (6), the spur gear (4) is positively engaged with the drive-side element (5) of the superposition gear system (7), and when the shift solenoid (1) is energized, a magnetic force on the friction lining (2), causes the spur gear (4) to contact with the friction surface (8) of the shift solenoid (1) such that a braking torque built up by the shift solenoid (1) is transmitted, via the spur gear (4), to the superposition gear system (7).