Buffer (rail transport)

Buffers are equipment on rail vehicles, which absorb the impact energy in the event of a collision or impact, thereby preventing damage to the vehicle or its load to.

General

In railway operation regularly individual vehicles are pressed against each other with the front pages or encountered. This can occur both in mutually coupled vehicles, such as during braking of a train, as well as in the uncoupled vehicles ( during maneuvering ) as well as during start-up to a buffer. It exists because of the large forces occurring partly a need to run these operations with the least possible permanent damage. For this purpose, the buffer ( referred to as buffer rare or impact pads ) are provided.

Action principle

Technically, the buffer contains the up and extensions that carry the shock baffles ( buffer heads ) and also the built-in dampers ( shock absorber elements ). You are at the so-called buffer beam (→ buffer carrier ) mounted on the front sides that they acting in the longitudinal vehicle direction from the outside, operationally can accommodate unavoidable shock and pressure forces. There occur paired side buffer arrays or single central buffer arrays. In the latter case the connection couplings are mounted in pairs on both sides of the buffer means to the symmetrical distribution of the forces is often provided that the buffer means is not itself provided with a coupling device.

The first sprung buffers were invented by John Baillie 1846.

Designs

In the 1830s have been partially, as in the locomotive Adler, still used wood buffer. The first buffer rod had on a resistant against bending pipe rod the forward-facing buffer plate. The buffer rod was sitting backwards on a movable spiral volute, which was supported by a strong sheet metal sleeve. By compressing the spring, the shock was attenuated.

Since the relatively thin buffer rods often bent during operation, the buffer tube has been developed. Here, the buffer plate is located on a steel pipe with a larger diameter, which is more resistant to bending by dimensioned.

The first sleeve further used in the volute buffer system had the disadvantage of the fitment into the compression energy completely to release it again, so that the vehicles have been pushed apart again after the collision. This required that trains are evenly and especially not only slowed down at points, also to avoid vibrations in the train, which can lead, inter alia, to break the clutches. Buffer rod are only to be found in museum vehicles today. An improvement was achieved by the use of ring springs, as these are the energy introduced largely converted into frictional heat.

In many cases, the buffer at the respective end face located on the left was performed with a flat one, the right side with an arched plate, so getting a flat and a curved plates collide and thereby edge pressures are avoided.

The functions of buffers are usually transmitted in the central buffer couplings, the coupling elements which are built in a stable and interposed spring elements within the vehicle frame ( instead of a " buffer beam " ) are mounted.

Normalizations

In the early days of the railroad, each railroad company laid down the position and arrangement of the train and shock devices in its sole discretion. After a network began to develop from independently built trails, disabled the inter-vehicle gangways. Vehicles which should go into the network of other companies, had to be equipped with multiple buffers or clutch systems. In the train of the development of the Technical Unity of Railways to set out the usual in England and Northern Germany dimensions for buffer level and distance as regularity.

• For all built since 1st January 1939 vehicles, the distance was by RIV § 38 to 1750 mm / ​​- fixed 10 mm.
• The buffer middle European railway vehicles must 940-1065 mm above the top of rail.

One exception was for a long time Spain. Because of the introduction of force into the conditioned further outward through the broad gauge long carrier of the car onto a buffer distance of 1950 mm was established. Therefore transition Eligible cars were wider buffer plate. The adaptation to the international regularity was up in the nineties of the last century.

In the European railway companies standardized buffers are used:

• Freight cars: buffer with 75 mm stroke UIC 526-2 VE 1981-01
• Freight cars: buffer with 105 mm stroke UIC 526-1 VE 1998-07
• Freight cars: Buffer with 130/150 mm stroke UIC 526-3 V 1998-07
• Shock gear for coaches UIC 528 VE 1991-01

• According to the UIC regulations of 1961 now all vehicles in Europe are fitted with both sides domed buffer heads. The radius of curvature of the buffer is at passenger vehicles 1500 mm, with the built since 1994 freight car 2750 mm.

Commonly used are circular buffer plate with a diameter of 340, 370, 450 or 500 mm. Furthermore, there are buffer plates in different shapes and widths, the height between the upper and lower horizontal edge is 340-360 mm. According to the UIC 527-1 VE 2005-04 are the standard widths for freight wagons buffer 450 or 550 mm, for Spain 550 or 650 mm at a height of 340 mm each.

The remaining free space between the vehicles is known as Berne chamber.

Trivia

Railway fans are jokingly referred to as " buffer kisser " or " buffer smooch ".