The air valve is a small but critical part of an air shaft, used to inflate and deflate the shaft quickly. It controls the flow of compressed air into the shaft, which expands the rubber bladder or lugs to grip the core from inside.
In day-to-day operation, the operator connects an air gun to the valve to inflate the shaft before mounting the roll. Once the job is done, releasing the air through the same valve allows the shaft to shrink back for easy core removal. A good-quality air valve ensures no air leakage, which is important to maintain proper gripping pressure during high-speed running.
It is commonly used in slitting, rewinding, and unwinding machines handling paper, film, foil, and packaging materials, where frequent roll changes are part of the process.
