The multi-shaft integral gear unit “MULTICOM® gearbox GMX” are designed and constructed according to the latest findings and methods of gearbox technology. MULTICOM® gearboxes can propel up to 10 compressor stages at five different speeds and serve as the key component of an integral compressor system (such as those used for air separation, the supply of gas turbines, gas compression, in the chemical and petrochemical industries, the refining of raw materials, steelworks, and in the process industry). Equipped with HIRTH toothing or polygon hubs, the wheels are mounted directly on the shaft ends of the integral compressor pinions and rotate at up to 63,000 rpm. The gearbox housing becomes an integral component of the compressor system and absorbs the static as well as the dynamic forces of the worm housing and pipes. Special seals prevent process gases from penetrating into the gearbox housing. Integral compressor gearboxes can be propelled by gas turbines, steam turbines, synchronous or asynchronous electric engines, or by expanders (axial or radial turbines) as well. An energy recovery system can even be implemented in conjunction with a synchronous clutch coupling. In this case, a synchronous electric engine, for example, propels an integral compressor gearbox and an integral expander gearbox feeds process energy back into the system via the MS clutch.