The NZR H class locomotive was a unique class of locomotive used by the New Zealand Railways Department on the famous Rimutaka Incline, the 3-mile (4.8 km) section of 1 in 15 (6.67 %) gradient between Cross Creek and Summit, over the Rimutaka Ranges. The locomotives worked on the Fell mountain railway system and had four horizontal driving wheels between the frames, gripping a centre rail and providing the extra adhesion needed for the climb.