Rack railway

The rack and pinion mechanism also provides more controlled braking and reduces the effects of snow or ice on the rails.

The first mountain rack railway in continental Europe was the Vitznau-Rigi-Bahn on Mount Rigi in Switzerland, which opened in 1871.

John Blenkinsop thought that the friction would be too low from metal wheels on metal rails even on level ground, so he built his steam locomotives for the Middleton Railway in 1812 with a 20-tooth, 3-foot (914 mm) diameter cog wheel (pinion) on the left side that engaged in rack teeth (two teeth per foot) on the outer side of the rail, the metal "fishbelly" edge rail with its side rack being cast all in one piece, in 3-foot (1 yd; 914 mm) lengths.

Blenkinsop's system remained in use for 25 years on the Middleton Railway, but it became a curiosity because simple friction was found to be sufficient for railroads operating on level ground.

[6] The first public trial of the Marsh rack on Mount Washington was made on August 29, 1866, when only one quarter of a mile (402 meters) of track had been completed.

Riggenbach was granted a French patent in 1863 based on a working model which he used to interest potential Swiss backers.

Eager to boost tourism in Switzerland, the government commissioned Riggenbach to build a rack railway up Mount Rigi.

It uses a ladder rack, formed of steel plates or channels connected by round or square rods at regular intervals.

Following the success of the Vitznau–Rigi railway, Riggenbach established the Maschinenfabrik der Internationalen Gesellschaft für Bergbahnen (IGB) – a company that produced rack locomotives to his design.

[8] The use of multiple bars with offset teeth ensures that the pinions on the locomotive driving wheels are constantly engaged with the rack.

[9] The Abt system is cheaper to build than the Riggenbach because it requires a lower weight of rack over a given length.

Its unique feature, however, was that the 'locomotive' was propelled by means of an endless cable driven from an engine house at the foot of the incline.

Horizontal pinions with flanges below the rack engage the centrally-mounted bar, both driving the locomotive and keeping it centered on the track.

The biggest shortcoming of the system is that the standard railway switch is not usable, and a transfer table or other complex device must be used where branching of the track is needed.

It uses a rolled flat-bottom rail with rack teeth machined into the head approximately 100 mm (3.9 inches) apart.

Safety jaws fitted to the locomotive engage with the underside of the head to prevent derailments and serve as a brake.

[17] In 1904, he patented a simplified but compatible rack, where the teeth on the engine pinions engaged square holes punched in a bar-shaped center rail.

[19][20] Curiously, Morgan recommended an off-center rack in order to allow clear passage for pedestrians and animals walking along the tracks.

[24] The Goodman Equipment Company began marketing the Morgan system for mine railways, and it saw widespread use, particularly where steep grades were encountered underground.

[21] Between 1903 and 1909, the McKell Coal and Coke company in Raleigh County, West Virginia, installed 35,000 feet (10,700 m) of Morgan rack/third-rail track in its mines.

[28] Between 1905 and 1906, the Mammoth Vein Coal Company installed 8,200 feet (2,500 m) of powered rack in two of its mines in Everist, Iowa, with a maximum grade of 16%.

The Dolderbahn switch works by bending all three rails, an operation that is performed every trip as the two trains pass in the middle.

Marsh's first rack patent shows such an arrangement,[5] and the original Mount Washington Cog Railway he built had no turnouts.

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.

The maximum speed of trains operating on a cog railway is very low, generally from 9 to 25 kilometres per hour (5.6 to 15.5 mph) depending on gradient and propulsion method.