These locomotives were Irish Rail's principle locomotive for 40 years, the 001 class or A class locomotives as they were originally called were built between 1955 and 1956, with the last class member withdrawn in 1995.
They were mechanically similar to the British Rail Class 28. Meaning it had the same Crossley engine, and the same amount of unreliability.
They are closely related to the CIÉ 201(C) Class locomotives.
During the 1970s all of the locomotives were re-engined with EMD 12-645s to help with the hopeless reliability of their original Crossley engines.
They were originally fitted with Crossly HSTV8s of 1200 b.h.p, later they were fitted with an EMD 12-645E of 1325 horsepower.
Locomotive 055 has been gutted and put in a bar as decoration.
Locomotive 003 has been repainted and is currently in storage.
Locomotive 039 is in use at the Downpatrick & County Down heritage railway.
Locomotive 015 is rotting at Moyasta Junction.