Working thoery of air shaft and safety chuck:
A. Air shaft: It is a special rewinding and unwinding shaft, its surface will be expanded out after injecting high pressure air source, and keys will shrinked quickly after exhausting air source. User only need to prepare air supply, and the air pressure within 6-8kg. When need to grip the paper tube, inputting air source into air nozzle is ok; press the air nozzle to release paper tube. All the winding and unwinding machine are both need this pneumatic expanding shaft.

Safety chuck: Safety chuck is used to hold and support air shaft for working together, safety chuck's reel holding mouth/insert jaw is made as air shaft's end size. Air shaft's two ends loaded into safety chuck's reel holding mouth, it is easy for putting and taking out. As usually, air shaft is made a position limited device for safety chuck.

In unwinding part, this air shaft and safety chuck are matched with pneumatic brake for braking or tension control; while in rewinding part, this pneumatic expanding shaft and safety chuck are matched with a pneumatic clutch for power transmission.