The Córas Iompair Éireann 611 class locomotives were delivered from the manufacturers, Motorenfabrik Deutz at Cologne, Germany.

They were delivered between December 1961 and February 1962, entering revenue earning service in the following August after receiving the new tan / black paint job at Inchicore.

They went into traffic in various parts of the country, as shunting engines at smaller depots such as Dublin's North City Mills siding and branch line duties such as the Loughrea branch line between Attymon and Loughrea.

They briefly appeared on the Limerick - Foynes mixed train service for a few months until that line was closed in 1963.

Unlike the earlier 601 class, these locomotives were fitted with brake connections enabling them to work passenger trains.