They have five or more interchangeable key rows with independent air tubes each one with its own retention valve.
Because if one or more air tube should accidentally lose air, the others remain inflated and the job can be finished in any case.
Because the repair can be postponed to when the machine is stopped for other reasons. The faulty key row is easily identified being it the only one deflated. The repair does not take more than a few seconds by simply replacing the faulty key row with a spare new one.
Because they allow the cut of very narrow slits.
Because they don’t present the pumping effect common to shafts with one or more dependent air tubes. In fact the air cannot be pushed from one air tube to another by the weight of the reel while the shaft is rotating and even the heaviest reel remains perfectly centered even at very high speeds.
Because they grip the core along the entire width. The short keys rise uniformly providing continuous shaft to core contact even in the case of irregular cores.
Because they are extremely light. An aluminium shaft with body length 1,6 mt suitable for 6″ inside diameter cores weighs only 25 kg.
Despite this all the air tubes inflate and deflate at the same time with one simple operation like common pneumatic shafts.
Fitted with Nylon keys (black) suitable for cardboard cores or PVC keys (red) suitable for plastic or steel cores.
Suitable for entire rolls or very narrow slits.
Inflated to 6 bar, these shafts are able to transmit a torque of 190 daNm per linear meter of 3” cardboard core.
Minimum maintenance, spare key rows ready for replacement, steel end-blocks, air tube, protective steel and nylon strip, keys, springs and air valves are already included in a spare interchangeable key row. It can be changed easily in a few seconds, by unscrewing and rescrewing 2 cup screws, without stopping production.
Expanding air shafts with interchangeable key rows are also available in “hybrid” version, that is with expanding gripping keys for locking core and parallel mechanical system with precentering balls.