This gear concept is especially engineered to fully meet the tough requirements of vertical water turbines. For instance, the turbine shaft is bored hollow so that the rotor blades can be adjusted from above by way of the gear system. The bell is of massive design with suitable fins and is welded directly to the housing. As a result, the weight of the generator is accommodated securely and the risk of critical vibration is minimized. A special wear-free seal system on the input shaft side prevents any lubricant from escaping from the gear system.