Flexicoil suspension
Encyclopedia
Flexicoil suspension is a wear-resistant and maintenance-free suspension
system, used in railway vehicles. It is a secondary suspension, installed between the body and the bogie
of the locomotive
, passenger car or wagon so fitted.
This type of suspension is most commonly used in modern rail passenger cars when air suspension
is not required, since it is cheaper both to buy and to maintain than air suspension.
The word "Flexicoil" was coined by General Motors
' Electro Motive Division, to describe a suspension system fitted to some of the diesel locomotive
s in its range. As early as the 1930s, flexicoil suspensions were being used in locomotives in Spain
, the Soviet Union
and Africa
.
Flexicoil suspension technology in high speed electric locomotive
s was pioneered in Germany
in the 1950s and 1960s, in various DB
standard electric locomotives, and especially the DB Class 103
. Between 1969 and 1971, British Rail
conducted trials of a flexicoil suspension system in a British Rail Class 86
locomotive, no E 3173. These experiments were successful, and led initially to the rebuilding of 56 members of the class with flexicoil suspension, as class 86/2. Ultimately, all members of class 86 were fitted with flexicoil suspensions.
The springs
in a flexicoil suspension are made of steel. Protruding from above and below, and into, each spring is a spherical rubber dome that can absorb some of the horizontal forces. Several of these domes are connected firmly to the vehicle body (above) and the bogie frame (below). Under this arrangement, each flexicoil spring is twisted and moved from its vertical axis when the vehicle is cornering. This helps the two bogies to align themselves equally underneath the vehicle body. The vertical forces are absorbed entirely by the steel springs.
As the springs have relatively soft characteristics, hydraulic vertical dampers must also be installed for vibration damping at higher speeds than 160 km/h, along with longitudinal dampers. Lateral damping is not normally required.
In railway passenger cars fitted with flexicoil suspension, the springs are the only mechanical connection between the bogie and the car body. In heavier types of flexicoil suspension rolling stock, a bogie pivot fitted with rubber-metal bearings is used to hold a cross anchor yoke, which transfers the forces to the bogie frame via two cross anchor link pins.
Locomotive bogies are usually also provided with a weight transfer linkage, or with a different tension transmission.
This article is based upon a translation of the German language version as at August 2010. The original authors can be seen here.
Suspension (vehicle)
Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose — contributing to the car's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants...
system, used in railway vehicles. It is a secondary suspension, installed between the body and the bogie
Bogie
A bogie is a wheeled wagon or trolley. In mechanics terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage/car or locomotive, or sprung as in the suspension of a caterpillar...
of the locomotive
Locomotive
A locomotive is a railway vehicle that provides the motive power for a train. The word originates from the Latin loco – "from a place", ablative of locus, "place" + Medieval Latin motivus, "causing motion", and is a shortened form of the term locomotive engine, first used in the early 19th...
, passenger car or wagon so fitted.
This type of suspension is most commonly used in modern rail passenger cars when air suspension
Air suspension
Air suspension is a type of vehicle suspension powered by an engine driven or electric air pump or compressor. This pump pressurizes the air, using compressed air as a spring. Air suspension replaces conventional steel springs. If the engine is left off for an extended period, the car will settle...
is not required, since it is cheaper both to buy and to maintain than air suspension.
The word "Flexicoil" was coined by General Motors
General Motors
General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...
' Electro Motive Division, to describe a suspension system fitted to some of the diesel locomotive
Diesel locomotive
A diesel locomotive is a type of railroad locomotive in which the prime mover is a diesel engine, a reciprocating engine operating on the Diesel cycle as invented by Dr. Rudolf Diesel...
s in its range. As early as the 1930s, flexicoil suspensions were being used in locomotives in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
, the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
and Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
.
Flexicoil suspension technology in high speed electric locomotive
Electric locomotive
An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or an on-board energy storage device...
s was pioneered in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
in the 1950s and 1960s, in various DB
Deutsche Bundesbahn
The Deutsche Bundesbahn or DB was formed as the state railway of the newly established Federal Republic of Germany on September 7, 1949 as a successor of the Deutsche Reichsbahn-Gesellschaft '...
standard electric locomotives, and especially the DB Class 103
DB Class 103
The Baureihe 103 is a class of electric locomotives in Germany, originally operated by Deutsche Bundesbahn. For a long period, they were perceived as flagships of the DB rolling stock.- Development :...
. Between 1969 and 1971, British Rail
British Rail
British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...
conducted trials of a flexicoil suspension system in a British Rail Class 86
British Rail Class 86
The British Rail Class 86 was the standard electric locomotive built during the 1960s, developed as a result of testing with the earlier Classes 81, 82, 83, 84 and 85. One hundred of these locomotives were built from 1965-1966 by either English Electric at Vulcan Foundry, Newton-le-Willows, or...
locomotive, no E 3173. These experiments were successful, and led initially to the rebuilding of 56 members of the class with flexicoil suspension, as class 86/2. Ultimately, all members of class 86 were fitted with flexicoil suspensions.
The springs
Spring (device)
A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication...
in a flexicoil suspension are made of steel. Protruding from above and below, and into, each spring is a spherical rubber dome that can absorb some of the horizontal forces. Several of these domes are connected firmly to the vehicle body (above) and the bogie frame (below). Under this arrangement, each flexicoil spring is twisted and moved from its vertical axis when the vehicle is cornering. This helps the two bogies to align themselves equally underneath the vehicle body. The vertical forces are absorbed entirely by the steel springs.
As the springs have relatively soft characteristics, hydraulic vertical dampers must also be installed for vibration damping at higher speeds than 160 km/h, along with longitudinal dampers. Lateral damping is not normally required.
In railway passenger cars fitted with flexicoil suspension, the springs are the only mechanical connection between the bogie and the car body. In heavier types of flexicoil suspension rolling stock, a bogie pivot fitted with rubber-metal bearings is used to hold a cross anchor yoke, which transfers the forces to the bogie frame via two cross anchor link pins.
Locomotive bogies are usually also provided with a weight transfer linkage, or with a different tension transmission.
External links
- Saechsische Waggonfabrik Stollberg: Voith Maxima – Das Vorbild (page 3) - includes a diagram showing the general arrangement of a flexicoil spring, and how it works .
This article is based upon a translation of the German language version as at August 2010. The original authors can be seen here.