Temperature and speed sensor used for fluid torque Coupling The controler of temperature and speed monitors the required operating condition of the fluid coupling contactlessly and requires no maintenance. Spraying and loss of operating fluid if the coupling overheats and the pollution of the environment associated with it can be avoided. In thecase of internal-gear drives the output speed (minimum value), in addition to the temperature, can be monitored. In this case the controler of temperature and speed cuts out immediately the output speed falls below its required value or the drive stops even before the coupling overheats. The controler of temperature and speed can be used on coupling and upward at peripheral speeds > 15 m/s. The transmitter is fitted to the coupling in place of the screw plug . While the coupling is rotating and below the response temperature of 125°C, each time the pick-up is passed the transmitter emits an impulse signal which is transmitted to the evaluating instrument. The pulse number is compared in the evaluating instrument with the required value set on the front plate and, when the pulse number is fallen below, causes the output relay to cut out. If as a result of an operating fault the response temperature (oil temperature) exceeds the actuating temperature of 125°C, the transmitter stops emitting pulses and the output relay of the evaluating instrument drops out. The output relay can trigger a fault signal or trip the drive cut-out. The evaluating instrument has a time delay which prevents a fault signal during the drive starting phase. If the monitoring system has cut out, the operating fault must first be rectified. The transmitter must not be exchanged. After it has cooled down to below the actuating temperature, the coupling is once more ready to operate. Depending on the starting heating to be expected (moment of inertia of the drive unit), however, the drive should be switched on only at coupling temperatures under 90°C.