The EW class was introduced in 1952 and were the most powerful locomotive on New Zealand Railways. They were also noteworthy for their articulated bodies and Bo-Bo-Bo wheel arrangement. They were used mainly in the North Island although one or two came south about 1980 to substitute for EA class locomotives which were being rebuilt after an accident.
After tunnel floor lowering between Wellington and Paekakariki in 1967 allowed DAs to work this section, the EWs saw less and less service although occasionally they banked diesel trains over the section. Eventually they were confined to hauling peak hour suburban passenger services around Wellington, until the new EM class units were delivered.
By mid 1983 only one loco was nominally in service as one had been withdrawn and the other five were in storage. In the mid 1980s two locos stored in the South Island were sent to Addington Workshops at Christchurch. The plan was to overhaul them to work on the Otira-Arthur's Pass section but this was considered uneconomic and the locos were written off. EW 1806 was delivered to the Ferrymead Railway for preservation in 1987.
