PURPOSE: The collision of a cocoon whose thread is being reeled to the thread- guiding tube is sensed, thereby the reeling frame is stopped to ensure the prevention of thread break caused by the impact of the collision of a concoon being reeled, husk or cocoon shell.

CONSTITUTION: When a concoon, whose thread is being reeled, collides with the thread end connector 14, the concoon pushes up the sensing part 12 and the pushing up is converted through the sensing arm 20 into the vibration of the holding lever 18 and the connecting rod 21 sends the vibration to the frame-stopping mechanism 4, which stops the revolution of the frame 3. Thus, the thread breakage caused by the impact of cocoon collision is prevented.