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 comm ...

Thomas Transmission railcar was an experimental electro-mechanical

railcar A railcar (not to be confused with a 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 coach (carriage, car), with a drive ...

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 New Zealand's railway infrastructure and operating the railway ...

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

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

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. Although common in the early days of railways, by the 20th century they were largely confined to branch lines with little traffic. Typically, servic ...

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 Ap ...

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 We ...

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 Zeala ...

; 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 country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

. They also supplied the underframe and

bogies A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...

, 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 sized and found application in buses, lifeboats and First World War military vehi ...

London London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...

provided the railcar's V8

petrol engine A petrol engine (gasoline engine in American 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 (such as ''E ...

. Power from the engine was transmitted to the leading bogie mechanically and to the rear bogie electrically by current produced by a

generator Generator may refer to: * Signal generator, electronic devices that generate repeating or non-repeating electronic signals * Electric generator, a device that converts mechanical energy to electrical energy. * Generator (circuit theory), an eleme ...

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 engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

es and

gear A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic pr ...

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: * Grade (education), a measurement of a student's performance * Grade, the number of the year a student has reached in a given educational stage * Grade (slope), the steepness of a slope Grade or grading may also ref ...

. 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 Upper Hutt railway station is a suburban railway station serving central Upper Hutt, New Zealand. The station is on the Wairarapa Line, north of Wellington, and is served by Transdev Wellington on behalf of the Greater Wellington Regional C ...

and Mangaroa Railway Station, and on the level it could haul two

bogie A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...

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

Wellington Wellington ( mi, Te Whanganui-a-Tara or ) 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 second-largest city in New Zealand by me ...

to Johnsonville along what was then the

North Island Main Trunk Railway The North Island Main Trunk (NIMT) is the main railway line in the North Island of New Zealand, connecting the capital city Wellington with the country's largest city, Auckland. The line is long, built to the New Zealand rail gauge of and ser ...

and has, since the 1937 opening of the Tawa Flat deviation, 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 Wellington ...

. 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 (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

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