GUIDE VANE PROTECTING DEVICE FOR HYDRAULIC MACHINERY

PURPOSE:To spread the function range of a protecting device by operating the first protecting device which does not cut a weak point pin in the range starting from the perfect opening of a guide vane to a certain opening degree and operating the second protecting device which cuts the weak point pin in the range over the above-described range. CONSTITUTION:An upper guide vane lever 6A and a lower guide vane lever 6B are connected by a weak point pin 4. When an obstacle nipped by a guide vane 8 is smaller than the shift-enable range L of a connecting pin 13, the connecting pin 13 is pushed back by the stability force of a spring 11, and the guide vane 8 returns to a synchronization position. When the obstacle is larger than the shift-enable range L, the connecting pin 13 shifts up to the contact with a suppressing block 12, and when the larger operation force is applied, the weak point pin 4 is cut, and the upper guide vane lever 6A is turned. Thus, the captioned protecting device can be operated over the whole range of the guide vane operation.