Romanian Railway series 040 DH

The 040 DH was a series of four-axle diesel locomotives produced in large numbers by the “August 23^rd” works (FAUR) in Bucharest. Designated LDH 125 by their manufacturer, the original design came from Sulzer of Switzerland and used hydraulic transmissions which were also manufactured under license in Romania. Their main task was to replace the last steam locomotives on secondary lines and in heavy shunting service.

Power comes from a six-cylinder Sulzer diesel that produces 1,250 hp, hence the “125” in the manufacturer's designation. The hydraulic transmission has one step for shunting service with a top speed of 60 km/h and a second step for line service up to 100 km/h. Some locomotives were built with a steam heating boiler, which later became class 80 of the CFR. The variant without steam heating became class 81.

Between 1968 and 1976, a total of 944 was built for domestic and foreign customers. Of 633 built for Romania, 475 came to operators in the industry and only 158 to the CFR. 263 more were built for the Bulgarian BDŽ, where they were designated class 55. Additionally, 42 came to industrial operators in Czechoslovakia, three into Iraq, two to China and one to the Soviet union. Derived from the original LDH 125, there were variants with lower power, for broad gauge or with electric transmission.

Some locomotives in service with the CFR were later rebuilt to electric train heating and designated class 89. Two different variants of rebuilds by Alstom and Remarul included a more modern engine, while retaining the same transmission. Locomotives which got Caterpillar engines became class 82 and others with a MTU engine became class 83. After 2005, more received a more comprehensive overhaul by Remarul which became class 84.