Rack railway

A cog railway, rack-and-pinion railway or rack railway is a railway with a special toothed rack rail or rack mounted on the railroad ties (sleepers) between the running rails. The trains are fitted with one or more cog wheels or pinions that mesh with this rack rail. This allows the trains to operate on steeply inclined slopes.

Most rack railways are mountain railways, although a few are transit railways or tramways built to overcome a steep gradient in an urban environment.

The first cog railway in the world was the Mount Washington Cog Railway in the US state of New Hampshire, which carried its first fare-paying passengers in 1868 and reached the summit of Mount Washington in 1869. The first rack railway in Europe was the Vitznau-Rigi-Bahn on Mount Rigi in Switzerland, which opened in 1871. Both lines are still running today.

Rack systems

A number of different rack systems have been developed.

Riggenbach rack system

The Riggenbach rack system, invented by Niklaus Riggenbach, is the oldest form of rack railway and uses a ladder rack, formed of steel plates or channels connected by round or square rods at regular intervals. The Riggenbach system was the first system devised, and suffers from the problem that its fixed rack is much more complex and expensive to build than the other systems. This system is sometimes known as the Marsh rack system, because of simultaneous invention by an American inventor, Sylvester Marsh, builder of the Mount Washington Cog Railway.

Abt rack system

The Abt rack system was devised by Roman Abt, a Swiss locomotive engineer working for a Riggenbach-equipped line, as an improved rack system. The Abt rack features steel plates mounted vertically and in parallel to the rails, with rack teeth machined to a precise profile in them. These engage with the locomotive's pinion teeth much more smoothly than the Riggenbach system. Two or three parallel sets of Abt rack plates are used, with a corresponding number of driving pinions on the locomotive, to ensure that at least one pinion tooth is always engaged securely.

Today, the majority of rack railways use the Abt system.

Strub rack system

The Strub rack system, invented by Emil Strub, is similar to the Abt rack system but uses just one wide rack plate welded on top of a flat bottom T railway rail. It is the simplest rack system to maintain and has become increasingly popular.

Locher rack system

The Locher rack system, invented by Eduard Locher, involves gear teeth cut in the sides rather than the top of the rail, engaged by two cog wheels on the locomotive. This system allows use on steeper grades than the other systems, whose teeth could jump out of the rack. It is used on the Mount Pilatus Railway.

Von Roll rack system

The Von Roll rack system, by the von Roll company, is similar to the Abt system, except that the teeth in the single blade are cut to suit the gear geometry of either the Riggenbach system cog or the Strub system cog (or gear) wheels. Because of its simplicity, the Von Roll rack replaces the Riggenbach or Strub rack in new, or replacement, installations without the need to replace the cogs (or pinions) on the electric locomotives or EMU passenger cars.

Rack and adhesion systems / Pure rack systems

Some rail systems, known as 'rack-and-adhesion', use the cog drive only on the steepest sections and elsewhere operate like a regular railway. Others, the steeper ones, are rack-only. On the latter type, the locomotives' wheels are generally free-wheeling and despite appearances do not contribute to driving the train.

Cog locomotives

Originally, almost all cog railways were powered by steam locomotives. The steam locomotive needs to be extensively modified to work effectively in this environment. Unlike a diesel locomotive or electric locomotive, the steam locomotive only works when its powerplant (the boiler, in this case) is fairly level. The locomotive boiler requires water to cover the boiler tubes and firebox sheets at all times, particularly the crown sheet, the metal top of the firebox. If this is not covered with water, the heat of the fire will melt it until it softens enough to give way under the boiler pressure, leading to a catastrophic failure.

On rack systems with extreme gradients, the boiler, cab and general superstructure of the locomotive are tilted forward relative to the wheels, so that they are more or less horizontal when on the steeply graded track of the railway. These locomotives often cannot function on level track, and so the entire line, including maintenance shops, must be laid on a gradient. This is one of the reasons why rack railways were among the first to be electrified and most of today's rack railways are electrically powered.

On a rack-only railroad locomotives always push their passenger cars for safety reasons since the locomotive is fitted with powerful brakes, often including hooks or clamps that grip the rack rail solidly. Some locomotives are fitted with automatic brakes that apply if the speed gets too high, preventing runaways. Often there is no coupler between locomotive and train since gravity will always push the passenger car down against the locomotive. Electrically powered vehicles often have electromagnetic track brakes as well.

List of cog and rack railways

Argentina

Mendoza to Los Andes, Chile, see Chile below.

Australia

Mt Morgan - rack system existed until 1950s when deviated.
SkiTube - in Snowy Mountains.
West Coast Wilderness Railway in Tasmania, originally opened in 1896 to service the Mount Lyell copper mine and closed and completely removed in 1960s. Rebuilt and re-opened for tourists in 2003. Uses Abt system.

Austria

Brazil

Corcovado Rack Railway

Chile

Ferrocarill Arcica La Paz, Arica–La Paz
El Ferrocarril Trasandino Los Andes - Mendoza, Los Andes - Mendoza, El Ferrocarril Trasandino Los Andes - Mendoza, Museo Ferrocarril Transandino, seconstruye el tren Los Andes - Mendoza (all in Spanish only)

The rebuild will be adhesion only.

France

Germany

Greece

Diakofto Kalavrita Railway

Hungary

Fogaskerekű Vasút in Budapest, Hungary is a kind of cog-wheel tram in the hilly Buda part of the city.

India

Nilgiri Mountain Railway

Italy

Superga Rack Railway

Japan

Ikawa Line, Oigawa Railway
Usui Pass was the first rack and pinion line in Japan, on the Shin-Etsu Line of the then Japanese National Railway. It was replaced in 1963 by a new parallel pure adhesion line.

Lebanon

A rack railway used to exist on the climb from Beirut to Syria, gauge 1050 mm.

New Zealand

Rimutaka Incline, a Fell incline railway, closed in 1955, and the trackbed has been turned into the Rimutaka Rail Trail, north-east of Wellington

Spain

Switzerland

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