Clutch-Brake system is one of the most important element of mechanical press line. The main purpose of it is to transmit the torque from the electric motor and flywheel to gear and main shaft. It ensures slide motion, but also press safety. One of the parameter that needs to be measured periodically is overrun. This value directly shows what is the condition of clutch-brake unit. The longer overrun, the worse brake operation. Unfortunately this one does not show what is the root cause of that situation. From that reason it is necessary to perform deeper diagnosis of complete system. One may find out from this article how to check clutch-brake unit in details- how to correlate slide position and slide speed with hydraulic pressure and position of safety valve (PSV).