The Córas Iompair Éireann 101 Class locomotives, numbered B101-B112, were built in 1956 by the Birmingham Railway Carriage and Wagon Company. They were fitted with Sulzer 6LDA28 engines of 960 hp (720 kW), with four Metropolitan-Vickers MV157 traction motors. They were of A1A-A1A wheel arrangement, weighed 75 tonnes and had a maximum speed of 120 km/h (75 mph).With their design, size and axle loading, they were intended for mixed traffic duties, hauling both freight and passenger trains.