| 摘要 |
PURPOSE:To prevent any fracture from being produced due to overrunning of the captioned belt by giving an alarm when one of a pair of detection switches gets abnormal while securing the present track travelling of the belt by means of the other switch being normal. CONSTITUTION:When a sander belt is in the midst of turning to the right, and if a detection switch gets abnormal due to sticking of any dust thereto, then a circuit l2 is first switched off before the belt reaches the right end while biassed, whereby an alarm is given by circuits l17 and l18. In addition, since the circuit l12 is switched off and then a circuit l15 switched off whereby a solenoid SOL is energized, the belt still keeps on turning right. When the right end of the belt reaches a detection position, the detection switch is turned on. Therefore, the circuit l3 is switched off and then the circuit l15 switched off whereby the solenoid SOL is deenergized. As a result, a steering roller is inclined whereby the belt travels from the right end to the left while being biassed. Together with this, if a belt ear end gets out of the detection position, then the belt is biassed to the right owing to the steering roller but keeps on its travelling. |
