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.
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.
A number of different rack systems have been developed. Today, the majority of rack railways use the Abt system.
The Riggenbach rack system was invented by Niklaus Riggenbach working at about the same time as, but independently from Marsh. Riggenbach was granted a French patent in 1863 based on a working model which he used to interest potential Swiss backers. During this time, the Swiss Consul to the United States visited Marsh's Mount Washington Cog Railway and reported back with enthusiasm to the Swiss government. Eager to boost tourism in Switzerland, the government commissioned Riggenbach to build a rack railway up Rigi Mountain. Following the construction of a prototype locomotive and test track in a quarry near Berne, the Vitznau-Rigi-Bahn opened on 22 May 1871.
The Riggenbach system is similar in design to the Marsh system. It uses a ladder rack, formed of steel plates or channels connected by round or square rods at regular intervals. The Riggenbach system suffers from the problem that its fixed ladder rack is more complex and expensive to build than the other systems. Common structural shapes Following the success of the Vitznau-Rigi-Bahn, Riggenbach established the Maschinenfabrik der Internationalen Gersellschaft fur Bergbahnen (IGB) - a company that produced rack locomotives to his design.
The Strub rack system was invented by Emil Strub in 1896. It uses a rolled flat-bottom rail with rack teeth machined into the head approximately 100 mm apart. Safety jaws fitted to the locomotive engage with the underside of the head to prevent derailments.
The best-known use of the Strub system is on the Jungfraubahn in Switzerland. It is the simplest rack system to maintain and has become increasingly popular .
The Abt system was devised by Roman Abt, a Swiss locomotive engineer. Abt worked for Riggenbach at his works in Olten and later at his IGB rack locomotive company. In 1885 he founded his own civil engineering company.
During the early 1880s, Abt worked to devise an improved rack system that overcame the limitations of the Riggenbach system. In particular, the Riggenbach rack was expensive to manufacture and maintain and the switches were complex. In 1882 Abt designed a new rack using solid bars with vertical teeth machined into them. Two or three of these bars are mounted centrally between the rails, with the teeth offset. The use of multiple bars with offset teeth ensures that the pinions on the locomotive driving wheels are constantly engaged with the rack. The Abt system is cheaper to build than the Riggenbach because it requires a lower weight of rack over a given length. However the Riggenbach system exhibits greater wear resistance than the Abt.
The first use of the Abt system was on the Harzbahn in Germany which opened in 1885.
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.
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.
Locher set out to design a rack system that could be used on gradients as steep as 1 in 2 (50%). The Abt system - the most common rack system in Switzerland at the time - was limited to a maximum gradient of 1 in 4 (25%). Locher showed that on steeper grade, the Abt system was prone to the driving pinion over-riding the rack causing potentially catastrophic derailments, as predicted by Dr. Abt. To overcome this problem and allow a rack line up the steep sides of Mt. Pilatus, Locher developed a rack system where the rack is a flat bar with symmetrical, horizontal teeth. Horizontal pinion engage the centrally-mounted bar, both driving the locomotive and keeping it centered on the track.
Following tests, the Locher system was deployed on the Pilatus Railway which opened in 1889. No other public railway uses the Locher system, although some European coal mines use a similar system on steeply graded underground lines.
The Lamella system (also known as the Von Roll system) was developed by the Von Roll company after the rolled steel rails used in the Strub system became unavailable. It is formed from a single blade cut in a similar fashion to the Abt system but typically wider than a single Abt bar. The Lamella rack can be used by locomotives designed for use on the Riggenbach or the Strub systems and some railways use rack from multiple systems. The St. Gallen Gais Appenzell Railway in Switzerland has sections of Riggenbach, Strub and Lamella rack.
Most of the rack railways built from the late 20th century onwards have used the Lamella system.
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 .
See also list of mountain railways
Uses steam engines [WORLD HERITAGE CERTIFIED]
not a rack railway but similar technology
Fell system railway (not rack):
US Patent Issued to International Business Machines on Sept. 27 for "Tool-Less Rack Rail System Incorporating Clamping Mechanism" (Minnesota, Texas Inventors)
Oct 01, 2011; ALEXANDRIA, Va., Oct. 1 -- United States Patent no. 8,025,166, issued on Sept. 27, was assigned to International Business...
Patent No. 7,762,411 Issued on July 27, Assigned to IBM for Tool-Less Rack Rail System (Minnesota, Texas Inventors)
Jul 28, 2010; ALEXANDRIA, Va., July 30 -- Stephen Peter Mroz, Joseph Daniel Rico and Jeffrey Alan Verkerke, all from Rochester, Minn., and John...