These railcars entered service in 1936 specially designed to be used on services between Wellington and the Wairarapa district. This route included a section which went over a mountain range which included the then famous Rimutaka Incline.
The railcars which were classified RM (Rail Motor) like all other New Zealand railcars were numbered from 4 to 9 inclusive and were single ended nccessitating turning at each end of their journey.
A distinctive feature of these railcars were the large wheels on the rear axle which were necessary for the final drive unit and the axle itself to clear the centre rail of the incline. In 1955, an eight kilometre tunnel was opened through the Rimutaka Ranges and this saw the end of services by these railcars.
They were gradually scrapped, however two were saved by Silverstream Railway, RM5 ran briefly on their tracks, RM5 is now the only survior.
Type: Diesel-Mechanical Railcar
Number in class: 6
Manufacturer: N.Z.R (Hutt Workshops)
Gauge: 3' 6"
Axles: B1 - A
Length: 49' over buffers
Width: 8'-11" over body
Weight: 13.35 tons
Engine: 6 cyl. Leyland
Transmission: Diesel mechanical through Torque Converter and 2-speed gearbox
Power: 120 hp
Max Speed: 60mph
As with the Standard Railcar's, the Wairarapa Railcars were given Maori names:
Rm 4 "Maahunui"
Rm 5 "Mahuhu"
Rm 6 "Mamari"
Rm 7 "Matahourua"
Rm 8 "Mataatua"
Rm 9 "Arai-Te-Uru"