Rotor cap (turbo)

The rotor cap is a component on the compressor end of a turbocharger rotor that retains and protects the compressor wheel nut and the shaft end on the air-intake side. The turbocharger rotor is a single shaft carrying the turbine wheel at the hot exhaust end and the compressor wheel at the cool air end, spinning at 10,000 to 30,000 rpm on plain or rolling bearings. The cap, set in the inlet airflow, streamlines the nose and keeps the threaded fastening clear of the air path. It is a wear and inspection item checked at rotor overhaul, when the assembly is balanced before reuse.