Power transmitters are devices used to transmit energy from a prime mover to the machine designed to utilize it. This paper deals with a gearbox consisting of a pair of gear wheels with the prime gear being smaller than the target gear, which achieves an equivalent gear ratio higher than one (1) and makes it a single-stage speed reducer. A calculation of the described reducer according to set parameters was done in this paper. The calculation of the reducer consisted of the gear calculation, pinion shaft calculation and target gear bearing calculation. Based on the obtained results, the adequate design solutions were presented.