Modifications to Wb class coal bunker

The Wb class suffered from a lack of coal bunker space, a poorly 1¼ ton capacity as built. The Addington 2-6-2T Wa, by comparison, had 1¾ ton capacity. The lack of coal capacity was the principal reason for the follow-up order in 1901 being for a 2-6-4T design, incorporating a 2¾ ton capacity bunker.

NZR Drawing z6554 'Locos Class "WB" Alteration to Coal Bunker' dated 25.6.1917, gave directions to extend the bunker upwards by 9 inches. Details were not strictly followed, for example, the Westport locomotives had a flat plate extension provided, rather than curved sheet as per drawing.

Wb 299 stands outside Westport locomotive depot, c.1956. Note the extension to the bunker, and the reduced size of rear cab windows to allow for additional coal. PHOTO: M.W. Adams.