NZR RM class

The RM class is the classification used by the New Zealand Railways Department (NZR) and its successors given to most railcars and railbuses that have operated on New Zealand's national rail network. 'RM' stands for Rail Motor. As the NZR operated many diverse types of railcars, names were given to each railcar type to differentiate them from others.

In the early 20th century, NZR began investigating railcar technology to provide profitable and efficient passenger services on regional routes and rural branch lines where carriage trains were not economic and "mixed" trains (passenger carriage/s attached to freight trains) were undesirably slow. However, due to New Zealand's rugged terrain and the 3 ft 6 in (1,067 mm) narrow gauge of the railway network, overseas technology could not simply be directly introduced. A number of experimental railcars and railbuses were developed.

The most successful of the experimental and early railcars was the Edison battery-electric railcar, which provided a popular twice-daily service on the Little River Branch line in Canterbury. It may have been expanded into a full fleet of railcars had the economic difficulties of the Great Depression not intervened, and it was destroyed by a depot fire in 1934 and not replaced.

The first truly successful railcar classes to enter revenue service in New Zealand were the two that began operating in 1936, following the building of the Red Terror (an 8-seat inspection railcar) for the General Manager, Garnet Mackley, in 1934. More classes followed over the years, primarily to operate regional services. The various classes were:

The Silver Ferns were the only railcars to survive into the privatisation era of Tranz Rail and Toll Rail, and later re-nationalisation as KiwiRail. They were introduced to provide a premier service on the North Island Main Trunk between Wellington and Auckland, and after they were replaced by the Overlander locomotive hauled carriage train in 1991, they were redeployed to operate the Geyserland Express between Auckland and Rotorua, Kaimai Express between Auckland and Tauranga, and Waikato Connection between Hamilton and Auckland. When those services were cancelled in 2001, the Silver Ferns were transferred to Auckland and operated suburban services for the Auckland Regional Transport Authority between Britomart and Pukekohe station. The Silver Ferns are now only used for special charter services as they are no longer needed for Auckland suburban services.

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