The air expansion shaft is suitable for the retraction and retraction reel of coating, slitting, printing, rewinding, papermaking, bag making, plastic and other related machinery, which can effectively improve the efficiency. The shaft body is made of high-quality steel pipe, the surface is chrome plated aluminum, and the convex key is flexible; Equipped with high-quality imported rubber liner and quick air filling and exhaust nozzle, the sealing effect is good, the service life is long, and the removable shaft head is easy to maintain.