The presented research is focused on proposing a suitable forced oil lubrication system for a commercially produced locomotive. The locomotive is designed for running speeds over 100 km/h. Therefore, a locomotive’s original wading lubrication system does not meet requirements for effective, efficient and reliable lubrication of components of the gearbox. Therefore, a forced oil lubrication gearbox system for the solved locomotive was proposed. The main objective of the research is to modify an existing lubrication system, which can supply oil to important gearbox components under operational conditions corresponding to running speeds over 100 km/h. The modified forced oil lubrication system includes an implementation of lubrication canals, an installation of a pump and filter systems, and the addition of lubrication nozzles. The result of these changes is a more efficient distribution of the lubricant between the gears and the minimisation of wear of gearbox components during operation at higher running speeds of the locomotive.