The NZR RM class 88-seaters were a class of railcar used in New Zealand. New Zealand Government Railways (NZR) classified them as RM (Rail Motor), the notation used for all railcars, numbering the 35 sets from RM100 to RM134. They were the most numerous railcars in NZR service. Their purchase and introduction saw the demise of steam-hauled provincial passenger trains and mixed trains, and was part of a deliberate effort to modernise NZR passenger services at a time of increasing competition from private motor vehicles. Being diesel powered and lighter the railcars were less expensive to operate and able to maintain quicker timetables, although became plagued with mechanical and electrical problems, with a number of the class eventually being turned into depowered locomotive-hauled carriages and reclassified as the AC class "Grassgrubs".
Background
In the early 1950s, NZR was in the process of replacing steam traction with diesel and modernising the railways to cope with vastly increased traffic, the after-effects of wartime stringency, and increasing competition from motor vehicles and aeroplanes. As part of this modernisation process, it was decided to upgrade provincial passenger services, which were provided by a combination of steam-hauled passenger trains that operated several times a week, and "mixed" trains that carried both freight and passengers. NZR had experimented with several different classes of railcars, but it was not until after the second World War that railcars began to replace provincial passenger services en masse.
Following the success of the Vulcan railcars introduced in the 1940s, NZR began investigating the replacement of the older Wairarapa class railcars in the mid-1940s with larger diesel-electric railcars. A tender for 25 replacement railcars was approved by Cabinet in 1944, but the second World War delayed responses being completed until 1947. In 1948, NZR decided not to proceed with this tender as the prices received were considered too high. In 1949, Cabinet approved a new tender to replace the Wairarapa railcars and other steam-hauled services, which were to have 88 seats and have braking equipment for the centre rail on the Rimutaka Incline. A total of 35 railcars were now specified. It was decided that engines for the railcars should be mounted underfloor for increased passenger capacity and for a parcels and baggage compartment, with trussed-chassis to support the braking equipment.
Tenders were received from English Electric and the Drewry Car Company. Drewry's tender presented a design for an articulated railcar with seating for 88 passengers, with either Hercules or Fiat engines. An order was placed with Drewry in the United Kingdom in March 1950 for the railcars with the Fiat engines. Drewry had supplied some smaller diesel shunting locomotives (DSA class and DSB class locomotives) to NZR previously. Due to the progress of the Rimutaka Tunnel (which opened in November 1955), and the impending closure of the Rimutaka Incline, it was decided by NZR to remove the requirement for centre-rail braking and the trussed-chassis required to hold the braking equipment.
Introduction
The railcars were constructed under subcontract by the Birmingham Railway Carriage and Wagon Company from Drewry. There were significant delays in delivering the railcars, with one (RM 120) damaged in transit, and used as a spare parts source for the other railcars. The first railcar was delivered in November 1954 and the last in May 1958.
The arrival of the first railcars was greeted with enthusiasm by local newspapers, and were described as a "new-dawn for long-distance rail travel" in New Zealand. A number of "ministerial special" promotional services were run in March 1955, and the first service operated by an 88-seater railcar was the Wellington-Gisborne daily service on 6 April 1955.
Following their introduction, the railcars suffered overheating from ballast dust and engine failure, which led to railcars running 20 to 30 minutes late every two to three days. This was despite two Fiat fitters being in New Zealand as the railcars went into service.