A motor brake for an air-compressing internal combustion engine is provided. A hydraulic linkage system is disposed between a cam and an exhaust valve, and communicates via a connecting line with a high-speed solenoid valve and a linkage oil compensating system of an engine lubricating-oil circuit. A control valve is disposed in an exhaust manifold of the engine and upon actuation of the motor brake partially closes off the exhaust manifold along with activation of the solenoid valve. Via the interposition of a control unit, signals of at least one sensor are conveyed to a solenoid of the solenoid valve in such a way that, upon actuation of the motor brake during a specific time interval during lifting of a valve tappet via a projection of the cam in a compression phase, the solenoid valve is closed. The time interval is derived via processing of signals of the sensor formed from the cam position and camshaft speed. The cam is divided into six sectors having a first angular range for opening the exhaust valve in an exhaust phase, a second angular range for filling a cylinder space of the valve tappet, a third angular range for initiating closure of the solenoid valve, a fourth angular range for the cam projection, a fifth angular range for reopening the solenoid valve, and a sixth angular range for emptying the cylinder space.