The

NZR RM class The RM class was the classification used by the New Zealand Railways Department (NZR) and its successors gave to most railcars and railbuses that have operated on New Zealand's national rail network. "RM" stands for Rail Motor which was the co ...

Thomas Transmission railcar was an experimental electro-mechanical

railcar A railcar (not to be confused with the generic term railroad car or railway car) is a self-propelled railway vehicle designed to transport passengers. The term "railcar" is usually used in reference to a train consisting of a single coa ...

operated by the

New Zealand Railways Department The New Zealand Railways Department, NZR or NZGR (New Zealand Government Railways) and often known as the "Railways", was a government department charged with owning and maintaining Rail transport in New Zealand, New Zealand's railway infrastruc ...

(NZR). It was introduced to service in 1916 and therefore was one of the earliest railcars to operate in

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

Development

In the early 20th century, NZR sought a means of providing economic services on lowly trafficked services including some suburban routes and to provide a faster alternative to

mixed train A mixed train or mixed consist is a train that contains both passenger and freight cars or wagons. In some countries, the term refers to a freight train carrying various different types of freight rather a single commodity. Although common in the ...

s on rural lines. It aimed to develop a light and self-contained vehicle that could operate economically even with low passenger levels. The first true railcar, the MacEwan Pratt petrol railcar of 1912, did not pass its tests and never entered revenue service. It was followed by the Westinghouse railcar in 1914, which did enter revenue service but proved unreliable. Accordingly, in 1916, NZR developed its third railcar, the

Thomas Thomas may refer to: People * List of people with given name Thomas * Thomas (name) * Thomas (surname) * Saint Thomas (disambiguation) * Thomas Aquinas (1225–1274) Italian Dominican friar, philosopher, and Doctor of the Church * Thomas the A ...

Transmission railcar. It was classified as RM 2; the Westinghouse railcar had previously re-used the MacEwan-Pratt railcar's classification of RM 1.Jones, ''Where Railcars Roamed'', p. 6.

Technical specifications

The body of the railcar was built at

Petone Workshops The Petone Workshops were a government-owned railways maintenance and repair facility located in Petone, in Lower Hutt in the Wellington region of New Zealand's North Island. It took over construction and maintenance of rolling stock in the Wel ...

in the

Hutt Valley The Hutt Valley (or 'The Hutt') is the large area of fairly flat land in the Hutt River valley in the Wellington Region of New Zealand. Like the river that flows through it, it takes its name from Sir William Hutt, a director of the New Zea ...

; driver's compartments were located at both ends and it could carry fifty passengers. The railcar employed the Thomas system of transmission, built by Thomas Transmission Ltd. of

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

. They also supplied the underframe and

bogies A bogie ( ) (or truck in North American English) comprises two or more wheelsets (two wheels on an axle), in a frame, attached under a vehicle by a pivot. Bogies take various forms in various modes of transport. A bogie may remain normally ...

, and

J. Tylor and Sons J. Tylor and Sons Limited of London was a company with a background in sanitation that moved into petrol engine manufacture in the 1900s. Its engines were of medium size and found application in buses, lifeboats and First World War military vehic ...

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

provided the railcar's V8

petrol engine A petrol engine (gasoline engine in American and Canadian English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends ...

. Power from the engine was transmitted to the leading bogie mechanically and to the rear bogie electrically by current produced by a generator within the engine. When engine revolutions passed a certain level, the electrical system was cut and used for battery charging while special

clutch A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does th ...

es and

gear A gear or gearwheel is a rotating machine part typically used to transmit rotational motion and/or torque by means of a series of teeth that engage with compatible teeth of another gear or other part. The teeth can be integral saliences or ...

s allowed the engine to mechanically drive both bogies. Unladen, the railcar weighed approximately and its length was .

Operation

The railcar was designed to reach speeds of on level track, and while hauling a carriage up a 1 in 40 (2.5%)

grade Grade most commonly refers to: * Grading in education, a measurement of a student's performance by educational assessment (e.g. A, pass, etc.) * A designation for students, classes and curricula indicating the number of the year a student has reach ...

. Trials were conducted to see if it could achieve these expectations, and in some ways it exceeded them. A trailer was hauled with ease along the 1 in 35 (2.86%) route between Upper Hutt Railway Station and Mangaroa Railway Station, and on the level it could haul two

bogie A bogie ( ) (or truck in North American English) comprises two or more Wheelset (rail transport), wheelsets (two Railroad wheel, wheels on an axle), in a frame, attached under a vehicle by a pivot. Bogies take various forms in various modes ...

passenger carriages and a brake van at . The railcar was subsequently introduced to service, operating the steep route out of

Wellington Wellington is the capital city of New Zealand. It is located at the south-western tip of the North Island, between Cook Strait and the Remutaka Range. Wellington is the third-largest city in New Zealand (second largest in the North Island ...

to Johnsonville along what was then the North Island Main Trunk Railway and has, since the 1937 opening of the

Tawa Flat deviation The Railway Magazine February 1934 pp. 100-105 Tawa Flat deviation is a double-track section of the Kapiti Line just north of Wellington Wellington is the capital city of New Zealand. It is located at the south-western tip of the North ...

, been the

Johnsonville Branch The Johnsonville Branch, also known as the Johnsonville Line, is a commuter branch line railway from the main Railway Station of Wellington, New Zealand to the northern suburb of Johnsonville via Ngaio and Khandallah. Transdev Wellingto ...

. This route was also operated by the Westinghouse railcar until 1917, when its repeated failures caused it to be permanently withdrawn from service. A similar but temporary fate befell the Thomas Transmission railcar; it gave good service for a few months but then had to be mothballed as a critical component of its transmission failed and

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

restricted the ability of NZR to source a replacement. In 1920, the railcar was finally returned to service. It suffered further reliability problems and did not operate for long. It was written off in 1925 and NZR sold its body to private interests for use as a dwelling.

References

External links

Alexander Turnbull Library 1916 photos -
Railcar

Driver's compartment

Engine at the Petone Railway Workshops

Frame
{{NZR Locomotives Railcars of New Zealand Rail transport in New Zealand Train-related introductions in 1916