The OR23 was a Soviet experimental locomotive built in 1949. Its cylinders were placed above the center driving axle, and had rods on both ends which transferred power to the wheels. The purpose was to balance the driving forces on the wheels, allowing the counterweights on the wheels to be smaller and reducing hammer blow on the track. The design was a failure and no further examples were built. The locomotive was never used beyond testing and was returned to its builder, the Voroshilovgrad Works, and scrapped sometime afterward.

• History of rail transport in Russia
• Russian Railway Museum, Saint Petersburg

• Rakov, V.A. (1995). Опытные грузовые паровозы со сцепной массой 112—117 т // Локомотивы отечественных железных дорог 1845-1955 [Experimental freight locomotives with a coupling weight of 112-117 tons // Locomotives of domestic railways 1845-1955] (in Russian) (2 ed.). Транспорт. ISBN 5-277-00821-7.
• Sologubov, V.N. (1952). Технический справочник железнодорожника [Technical Handbook of a Railwayman] (in Russian). Vol. 6. State Transport Railway Publishing House.^{[ISBN missing]}

• Russian Reforms - Describes this and other Russian locomotive types