Low-power electric generators are widely used in solutions used in renewable, "clean" energy sources. Many watercourses are dammed and turbines are built to power electric generators. Depending on the height of the backwater and the size of the water stream, the first challenge is to choose the right type of turbine, so that the rotational speed of the active shaft drive is optimal and ensures a constant frequency of the electric current and that the power is generated with optimal efficiency. The efficiency of the system for converting mechanical energy into electricity is largely related to the design of the belt mechanical transmission. To obtain an average generator speed of about 1500 rpm, the speed of the turbine must be multiplied. In such cases, belt transmissions are used. They make it possible to increase the rotational speed several times while maintaining high efficiency. The operating parameters of the belt transmission are influenced by the appropriate selection of the mechanics of the drive system: the active shaft and the passive shaft, as a function of water flow velocity through the Kaplan turbine rotor.

The value of mass moments of inertia on the axis of the active shaft - the largest, and the smallest on the idle shaft, determine belt selection for the design of the driven mechanism. You can choose from a wide variety of drive belt types. In the case of medium power generators, this choice is limited. Belts are characterized by a number of material and construction parameters. A belt with "large" overall dimensions should be used in the transmission, which is resistant to typical rheological phenomena occurring in polymer belts. The design of the generator drive requires the use of a belt with a special load-bearing layer structure, made of steel or Kevlar cord. Its height should be minimal due to the work of internal friction when bending on the arc of contact.

Based on many years of professional experience in the design of belt drives and many studies on the mechanics of frictional coupling, the authors selected the appropriate type and dimensions of belts for the assumed mechanics and geometry of the drive. The work was implemented at a power plant on the Odra River. The gearbox has been in operation for 8 years without the need to correct the preload force and elongation symptoms. It is resistant to the effects of cyclically changing rheological phenomena, such as progressive and transverse creep, stress relaxation and the values ​​of elastic and inelastic strains.