NZR AB class

The NZR AB class was a class of 4-6-2 Pacific tender steam locomotives that operated on the national railway system of New Zealand Railways, originally an improvement on the 1906 A class. A total of 141 were built between 1915 and 1927 by NZR's Addington Workshops, A and G Price of Thames, New Zealand, and the North British Locomotive Company, making the AB class the largest class of steam locomotives ever to run in New Zealand. The prototype, AB 608 of 1915, had a new cab and boiler fitted with a superheater and the Vanderbilt tender that became a hallmark of the class, and it was named Passchendaele in 1918 to commemorate NZR staff killed in the First World War. Two North British locomotives were lost in the wreck of the SS Wiltshire in May 1922. Known as the maids for all work, the class was used on almost every section of the network for passenger and freight trains, and could pull an express at 100 km/h or a 700-tonne goods train on easy grades. Most were withdrawn in the 1960s as diesel traction replaced steam, and seven have been preserved.