The turbocharger has a cast housing with separate chambers in the intake and exhaust systems, each housing has an impeller. The impellers are linked by a common shaft mounted in roller bearings. The turbine impeller on the exhaust side is driven by the flow of exhaust gasses, and in turn drives the compressor impeller on the intake side. The compressor impeller pressurizes the intake air up to a specified limit, controlled by a pressure relief mechanism called a wastegate.