Hybrid locomotives overview of construction solutions

Nowadays, transportation becomes a significant source, apart from factories and power plants, of air pollution. Therefore, due to legal restrictions on the emission of noxious gases, other power sources for vehicles are necessary. Some of these power sources allow replacement of the internal combustion engine completely, whereas the other ones only support the engine operation. Hence, a hybrid powertrain – alternative to the drivetrain equipped with an internal combustion engine only – is increasingly being used. The hybrid powertrain was mostly applied in cars and buses but recently it has been also used in railway vehicles such as locomotives and multiple units. The paper presents a shortened and brief overview of construction solutions of selected hybrid locomotives. A list of the applied hybrid drive systems as well as the basic data and properties are provided. The most important variants of vehicles are compared. The presented material allows identification of the development trends in the considered area. The hybrid locomotive usually uses an onboard rechargeable energy storage system, placed between the power source and the traction transmission system connected to the wheelsets. Modification of a classic diesel-electric locomotives is a relatively simple procedure since they have all the components of a series hybrid transmission except the storage battery. Therefore, the existing and operated diesel-electric locomotives can be modified to increase their efficiency and reduce operating costs and emissions.