NZR RM class (Thomas Transmission)
Encyclopedia
The NZR RM class
Thomas Transmission railcar was an experimental electro-mechanical railcar
operated by the New Zealand Railways Department
(NZR). It was introduced to service in 1916 and therefore was one of the earliest railcars to operate in New Zealand
.
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 Transmission railcar. It was classified as RM 2; the Westinghouse railcar had previously re-used the MacEwan-Pratt railcar's classification of RM 1.
in the Hutt Valley; 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
. They also supplied the underframe and bogies, and J. Tylor and Sons of London
provided the railcar's 150 kW V8
petrol engine. 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 clutches and gears allowed the engine to mechanically drive both bogies. Unladen, the railcar weighed approximately 36 tonne
s and its length was 17.68 metres.
and Mangaroa Railway Station
, and on the level it could haul two bogie passenger carriages and a brake van at 58 km/h.
The railcar was subsequently introduced to service, operating the steep route out of Wellington
to Johnsonville
along what was then the North Island Main Trunk Railway and has, since the 1937 opening of the Tawa Flat deviation
, been the Johnsonville Branch. 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route was also operated by the Westinghouse railcar until 1917, when its repeated failures caused it to be permanently withdrawn from service.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
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.
NZR RM class
The RM class is the classification used by the New Zealand Railways Department and its successors given to most railcars and railbuses that have operated on New Zealand's national rail network. As NZR and its successors has operated many diverse types of railcars, alternate names have been given...
Thomas Transmission railcar was an experimental electro-mechanical railcar
Railcar
A railcar, in British English and Australian English, 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 , with a driver's cab at one or both ends. Some railways, e.g., the Great Western...
operated by the New Zealand Railways Department
New Zealand Railways Department
The New Zealand Railways Department, NZR or NZGR and often known as the "Railways", was a government department charged with owning and maintaining New Zealand's railway infrastructure and operating the railway system. The Department was created in 1880 and was reformed in 1981 into the New...
(NZR). It was introduced to service in 1916 and therefore was one of the earliest railcars to operate in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
.
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 trainMixed train
A mixed train is a train that hauls both passenger and freight cars or wagons. In the early days of railways they were quite common, but by the 20th century they were largely confined to branch lines with little traffic. As the trains provided passengers with very slow service, mixed trains have...
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
NZR RM class (MacEwan-Pratt)
The NZR RM class MacEwan-Pratt petrol railcar was the first railcar to run on New Zealand's national rail network, though it was never used in revenue service. It was built in 1912 at a time when the New Zealand Railways Department was seeking alternative methods of providing rural passenger...
of 1912, did not pass its tests and never entered revenue service. It was followed by the Westinghouse railcar
NZR RM class (Westinghouse)
The NZR RM class Westinghouse railcar was an experimental railcar built by the New Zealand Railways Department in 1914. Although not the first railcar to operate in New Zealand, it was the first to enter revenue service.- Development :...
in 1914, which did enter revenue service but proved unreliable. Accordingly, in 1916, NZR developed its third railcar, the Thomas Transmission railcar. It was classified as RM 2; the Westinghouse railcar had previously re-used the MacEwan-Pratt railcar's classification of RM 1.
Technical specifications
The body of the railcar was built at Petone WorkshopsPetone 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...
in the Hutt Valley; 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
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. They also supplied the underframe and bogies, and J. Tylor and Sons of London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
provided the railcar's 150 kW V8
V8 engine
A V8 engine is a V engine with eight cylinders mounted on the crankcase in two banks of four cylinders, in most cases set at a right angle to each other but sometimes at a narrower angle, with all eight pistons driving a common crankshaft....
petrol engine. 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 clutches and gears allowed the engine to mechanically drive both bogies. Unladen, the railcar weighed approximately 36 tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s and its length was 17.68 metres.
Operation
The railcar was designed to reach speeds of 65-70 km/h on level track, and 25 km/h while hauling a 25 tonne carriage up a 1 in 40 grade. Trials were conducted to see if it could achieve these expectations, and in some ways it exceeded them. A 13.25 tonne trailer was hauled with ease along the 1 in 35 route between Upper Hutt Railway StationUpper Hutt Railway Station
Upper Hutt railway station is a two-platform urban railway station serving the city of Upper Hutt in the Wellington region of New Zealand’s North Island. The station lies on the Wairarapa Line, and is on Station Crescent, off Fergusson Drive...
and Mangaroa Railway Station
Mangaroa Railway Station
Mangaroa railway station was a single-platform rural railway station on the Wairarapa Line between Upper Hutt and Featherston in the Wellington region of New Zealand’s North Island, on the section that was replaced by the Rimutaka Deviation in 1955...
, and on the level it could haul two bogie passenger carriages and a brake van at 58 km/h.
The railcar was subsequently introduced to service, operating the steep route out of Wellington
Wellington
Wellington is the capital city and third most populous urban area of New Zealand, although it is likely to have surpassed Christchurch due to the exodus following the Canterbury Earthquake. It is at the southwestern tip of the North Island, between Cook Strait and the Rimutaka Range...
to Johnsonville
Johnsonville, New Zealand
Johnsonville is a large suburb in northern Wellington, New Zealand. It is seven kilometres north of the city centre, at the top of the Ngauranga Gorge, on the main route to Porirua . The population of "J'ville" was about 6,500 at the 2001 census.- Public transport :Johnsonville is a reasonably...
along what was then the North Island Main Trunk Railway and has, since the 1937 opening of the Tawa Flat deviation
Tawa Flat deviation
The Tawa Flat deviation is a double-track section of the North Island Main Trunk Railway just north of Wellington, New Zealand. It includes two tunnels, Tawa No. 1 and Tawa No. 2 , separated by the Ngauranga Gorge. No. 2 tunnel passes under Newlands and comes out at Glenside, on the way to Tawa...
, been the Johnsonville Branch. 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
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
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.