Funicular

Funicular drive train

Petřín funicular wheelset with Abt rack and pinion brake

In most modern funiculars, neither of the two carriages is equipped with an engine of its own. Instead, the propulsion is provided by an electric motor in the engine room (typically at the upper end of the track); the motor is linked via a speed-reducing gearbox to a large pulley – a drive bullwheel – which then controls the movement of the haul rope using friction. Some early funiculars were powered in the same way, but using steam engines or other types of motor. The bullwheel has two grooves: after the first half turn around it the cable returns via an auxiliary pulley. This arrangement has the advantage of having twice the contact area between the cable and the groove, and returning the downward-moving cable in the same plane as the upward-moving one. Modern installations also use high friction liners to enhance the friction between the bullwheel grooves and the cable.[6][9][10]

For emergency and service purposes two sets of brakes are used at the engine room: the emergency brake directly grips the bullwheel, and the service brake is mounted at the high speed shaft of the gear. In case of an emergency the cars are also equipped with spring-applied, hydraulically opened rail brakes.[10]

The first funicular caliper brakes which clamp each side of the crown of the rail were invented by the Swiss entrepreneurs Franz Josef Bucher and Josef Durrer and implemented at the Stanserhorn funicular, opened in 1893.[11][12] The Abt rack and pinion system was also used on some funiculars for speed control or emergency braking.[2][6]

The wastewater-powered Fribourg funicular featuring an Abt switch

Many early funiculars were built using water tanks under the floor of each car, which were filled or emptied until just sufficient imbalance was achieved to allow movement, and a few such funiculars still exist and operate in the same way. The car at the top of the hill is loaded with water until it is heavier than the car at the bottom, causing it to descend the hill and pull up the other car. The water is drained at the bottom, and the process repeats with the cars exchanging roles. The movement is controlled by a brakeman using the brake handle of the rack and pinion system engaged with the rack mounted between the rails.[2][6]

The Bom Jesus funicular built in 1882 near Braga, Portugal is one of the extant systems of this type. Another example, the Fribourg funicular in Fribourg, Switzerland built in 1899,[13] is of particular interest as it utilizes waste water, coming from a sewage plant at the upper part of the city.[14]

Some funiculars of this type were later converted to electrical power. For example, the Giessbachbahn in the Swiss canton of Berne, opened in 1879, was originally powered by water ballast. In 1912 its energy provision was replaced by a hydraulic engine powered by a Pelton turbine. In 1948 this in turn was replaced by an electric motor.[2]

Track layouts used in funiculars

East Hill Cliff Railway in Hastings, UK – a four-rail funicular

Angels Flight in Los Angeles, California – a three-rail funicular

Nazaré Funicular in Nazaré, Portugal – a two-rail funicular

There are three main rail layouts used on funiculars; depending on the system, the track bed can consist of four, three, or two rails.

• Early funiculars were built to the four-rail layout, with two separate parallel tracks and separate station platforms at both ends for each vehicle. The two tracks are laid with sufficient space between them for the two carriages to pass at the midpoint. While this layout requires the most land area, it is also the only layout that allows both tracks to be perfectly straight, requiring no sheaves on the tracks to keep the cable in place. Examples of four-rail funiculars are the Duquesne Incline in Pittsburgh, Pennsylvania, and most cliff railways in the United Kingdom.
• In three-rail layouts, the middle rail is shared by both carriages, while each car runs on a different outer rail. To allow the two cars to pass at the halfway point, the middle rail must briefly split into two, forming a passing loop. Such systems are narrower and require less rail to construct than four-rail systems; however, they still require separate station platforms for each vehicle.[2]
• In a two-rail layout, both cars share the entire track except at the passing loop in the middle. This layout is the narrowest of all and needs only a single platform at each station (though sometimes two platforms are built: one for boarding, one for alighting). However, the required passing loop is more complex and costly to build, since special turnout systems must be in place to ensure that each car always enters the correct track at the loop. Furthermore, if a rack for braking is used, that rack can be mounted higher in three-rail and four-rail layouts, making it less sensitive to choking in snowy conditions compared to the two-rail layout.[7]

Some funicular systems use a mix of different track layouts. An example of this arrangement is the lower half of the Great Orme Tramway, where the section "above" the passing loop has a three-rail layout (with each pair of adjacent rails having its own conduit which the cable runs through), while the section "below" the passing loop has a two-rail layout (with a single conduit shared by both cars).

Some four-rail funiculars have their tracks interlaced above and below a now required passing loop; this allows the system to be nearly as narrow as a two-rail system, with a single platform at each station, while also eliminating the need for the costly junctions either side of the passing loop. The Hill Train at the Legoland Windsor Resort is an example of this configuration.

In the case of two-rail funiculars, various solutions exist for ensuring that a carriage always enters the same track at the passing loop.

One such solution involves installing switches at each end of the passing loop. These switches are moved into their desired position by the carriage's wheels during trailing movements (i.e. away from the passing loop); this procedure also sets the route for the next trip in the opposite direction. The Great Orme Tramway is an example of a funicular that utilizes this system.

Abt switch

Another turnout system, known as the Abt switch, involves no moving parts on the track at all. Instead, the carriages are built with an unconventional wheelset design: the outboard wheels have flanges on both sides, whereas the inboard wheels are unflanged (and usually wider to allow them to roll over the turnouts more easily). The double-flanged wheels keep the carriages bound to one specific rail at all times. One car has the flanged wheels on the left-hand side, so it follows the leftmost rail, forcing it to run via the left branch of the passing loop; similarly, the other car has them on the right-hand side, meaning it follows the rightmost rail and runs on the right branch of the loop. This system was invented by Carl Roman Abt and first implemented on the Lugano Città–Stazione funicular in Switzerland in 1886;[2] since then, the Abt turnout has gained popularity, becoming a standard for modern funiculars.[9] The lack of moving parts on the track makes this system cost-effective and reliable compared to other systems.

• 
  The two cars on the upper half of the Great Orme Tramway passing each other at a switch-controlled passing loop
• 
  Wheelset of a two-rail funicular with the Abt switch turnout system

The two cars of the Petřín funicular—one of them is about to call at Nebozízek station (seen in the foreground), while the other will stop and wait for it to exchange passengers.

The majority of funiculars have two stations, one at each end of the track. However, some systems have been built with additional intermediate stations. Because of the nature of a funicular system, intermediate stations are usually built symmetrically about the mid-point; this allows both cars to call simultaneously at a station. Examples of funiculars with more than two stations include the Wellington Cable Car in New Zealand (five stations, including one at the passing loop)[15] and the Carmelit in Haifa, Israel (six stations, three on each side of the passing loop).[16]

A few funiculars with asymmetrically placed stations also exist. For example, the Petřín funicular in Prague has three stations: one at each end, and a third (Nebozízek) a short way up from the passing loop.[17] Because of this arrangement, carriages are forced to make a technical stop a short distance down from the passing loop as well, for the sole purpose of allowing the other car to call at Nebozízek.