The NZR WE Class were rebuilt from earlier Addington built B class locomotives. In service, the first two were tried on the Rimutaka Incline, however, they lacked the required adhesion on the 1 in 15 (6.67%) grade. They were later transferred to Greymouth for use on the Rewanui Incline, where they were far more successful, on the line's 1 in 25 (4%) grade. It is not known if they ever operated on the Roa Incline.
The three We class locomotives lasted into the 1960s.