This device measures the time gap between two signals read by a sensor on a revolving or linear movement. When the time gap becomes greater then the pre-set value, the device itself activates and signals a drop in velocity or full stop of the mechanism’s movement. Lower values compared to pre-set value do not activate the device. This device is ideal for control of slipping transport belts, chain breakage, power interruption or overloads etc... in applications such as belt transport, chain elevators, mills, grinders, pumps, kneading mixers and in other situations where movement control of revolving or linear mechanisms is necessary