Rack railway

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Rack railway track using Von Roll system rack.

Schneeberg cog railway steam locomotive, with tilted boiler, on level track.

functioning of the rack and pinion.

A cog railway, rack-and-pinion railway or rack railway is a railway with a toothed rack rail, usually 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 steep gradients.

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 was the Middleton Railway between Middleton and Leeds in West Yorkshire, England, UK, where the first commercial steam locomotive, The Salamanca, ran in 1812. This used a rack and pinion system designed and patented in 1811 by John Blenkinsop.

The first mountain cog railway 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.

Different rack systems: from the left, Riggenbach, Strub, Abt and Locher.

A number of different rack systems have been developed. Today, the majority of rack railways use the Abt system.

The 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 ladder rack is much more complex and expensive to build than the other systems. It was invented in 1863 and first used on the Vitznau-Rigi-Bahn in 1871.

The Marsh rack system was invented by the American inventor Sylvester Marsh at about the same time that Niklaus Riggenbach invented his Riggenbach system. It is used on the Mount Washington Cog Railway. The two systems resemble each other, and may be referred to by either name.

The 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 rail. It is the simplest rack system to maintain and has become increasingly popular.

Abt rack system

The Abt system was devised by Roman Abt, a Swiss locomotive engineer working for a Riggenbach-equipped line. The Abt rack has steel plates mounted vertically parallel to the rails, with rack teeth in them machined to a precise profile. 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.

The pinion wheels can be mounted on the same axle as the rail wheels (as in the picture at right), or driven separately. The steam locomotives on the Mount Lyell Mining and Railway Company had separate pistons driving the pinion wheel.

Locher rack system

Locher Rack system (seen from above)

The Locher rack system, invented by Eduard Locher, has 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 Pilatus Railway.

Joint between Riggenbach and Strub

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 wheels. Because of its simplicity, the Von Roll rack can replace Riggenbach or Strub rack without the need to replace the cogs. In some railways the (usually) older Riggenbach segments are freely mixed with the more recently mounted Strub sections.

Rack-and-adhesion systems use the cog drive only on the steepest sections and elsewhere operate as 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. In this case the racks continue also in the horizontal parts, if any.

The Fell mountain railway system is not a rack railway. This system uses a raised centre rail between the two running rails on steep lines. Trains are propelled by wheels or braked by shoes pressed horizontally onto the centre rail, as well as by means of the normal running wheels.

Pike's Peak cog steam locomotive on steeply graded track, showing the tilted boiler level.

Early electric cog locomotive and carriage

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 soften it 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. 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.

The maximum speed of trains operating on a cog railway is generally very low, about 25 km/h^{[citation needed]}.

See also list of mountain railways

This list is incomplete; you can help by expanding it.

Transandine Railway between Mendoza and Los Andes, Chile, see Chile below.

Mt Morgan Rack Railway on Mount Morgan - rack system existed until 1950s when the line was deviated.
Skitube Alpine Railway - 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 the Abt rack system.

Achenseebahn, Tyrol
Erzbergbahn, Styria
Gaisbergbahn, Gaisberg (1887 - 1928)
Kahlenbergbahn, Kahlenberg, Döbling, Vienna
Schafbergbahn, Upper Austria
Schneebergbahn, Lower Austria

Corcovado Rack Railway
The São Paulo Railway or the Serra do Mar line, originally part of Estrada de Ferro Santos a Jundiaí, part of Rede Ferroviária Federal Sociedade Anônima (RFFSA) 1957-1997, now owned by MRS Logística

Ferrocarill Arica La Paz, Arica–La Paz
The Transandine Railway, Los Andes - Mendoza, Argentina The rebuild will be adhesion only [1].

Cog railway Tanvald-Harrachov

Drachenfels Railway
Höllentalbahn (adhesion only since 1933)
Oberweißbacher Bergbahn
Schwarzatalbahn
Wendelstein Railway
Stuttgart Rack Railway, Stuttgart
Zugspitze Railway

Diakofto Kalavrita Railway

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

Aceh - no longer in operation but will be reconstructed.
Bedono - still in operation as a tourist line using steam locomotives.

Nilgiri Mountain Railway

Superga Rack Railway

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 adhesion line, themselve replaced by the Nagano Shinkansen line for the Nagano olympic games.

A rack railway used to exist on the climb from Beirut to Syria, gauge 1,150 mm (3 ft 5¹⁄₃ in) .

Large ships are guided through the Panama Canal Locks by electric locomotives known as mulas (mules), running on rack rails on the lock walls rather than proceeding under their own power. The new locks, approved in 2006, will use tugs.