The air separation market for large air compressor trains is continuously growing, driven by future oriented applications like gas-to-liquid or coal-to-chemicals. We have recently introduced the AIRMAX train for large air separation units (ASU). As main air compressor it features our proven and now further developed axial/radial main air compressor type AR, now called AR-MAX1. In its new blading, AR-MAX1 combines for the first time the advantages of both heavy-duty as well as aircraft engine compressors. This makes AR-MAX1 uniquely compact, as well as robust and efficient.