211/212 series locomotives are diesel-hydraulic locomotives constructed in Germany between 1958 and 1966, and intended for heavy shunting traction and traction of passenger and lighter freight trains.
The purpose of modernization was to extend the life cycle of locomotives for the next 25 to 30 years, providing efficient and reliable operation with low costs of exploitation and maintenance. With installation of new and modern equipment, the modernized locomotives have in terms of technical,
environmental, safety and economic indicators reached the level of new and modern shunting locomotives with significantly less financial investment.
As part of the general repair of the hydraulic transmission on 212 series locomotives, modernization of the change of operating mode and change of direction was perfomed, cooling of the transmission was improved and the locomotives were additionally equipped with a radio dispatching device and auto stop system.
On two 212 series locomotives, which are to be used for traction of passenger trains (212-215 and 212-307), there was installed a diesel generator for electric heating of passenger coaches.
After successfully performed locomotive testings and trial runs on the tracks of the Croatian Railways, the locomotives were equally successful in trial runs on the tracks of the Railways of the Federation of Bosnia and Herzegovina. Immediately thereafter the locomotives were put into operation on the public rail lines of the respective countries.