In case of descending transport, the motors are run in regeneration mode, enabling the generation of electrical energy from the kinetic energy of the transported material. The motors, which are run in motor-driven and regeneration mode, are mostly adjustable. This permits an optimum load distribution over the drive units at different operating conditions. In certain loading conditions, the system is run in regeneration mode. The generated electric energy is fed to the mains by a regenerative feedback unit, enabling a reduction in operating costs of the complete system.