The NZR UB class were a series of Ten Wheelers built by American manufacturers for New Zealand Railways (NZR) around the start of the twentieth century.

[1] The earlier batch of engines had slide valves and inside Stephenson motion, the later had piston valves and Walschaerts valve gear, as well as a higher boiler pressure.

Two additional locomotives were obtained in 1901 from ALCO, one each from Brooks and Richmond.

The locomotives were initially assigned to Dunedin to Christchurch expresses and were reassigned as newer power replaced them.

The last assignment for the class was on the West Coast Region.