Early in 1950 Abetong designed its first concrete sleeper. The sleeper was based on a new specification issued by the Swedish State Railways (SJ), resulting in what was known as the twin block sleeper. Ten years later the twin block sleeper was replaced by the first monoblock sleeper, which had a number of technical and production-related advantages. Since then Abetong's focus has been totally directed towards monoblock sleeper designs.
Over the years the company has developed extensive expertise in designing concrete sleepers. Abetong was the first company in the world to begin series production of concrete turnout sleepers. The turnout sleepers are individually designed and produced in accordance with the company’s patented system. Special emphasis is placed on guaranteeing the lowest possible tolerances for positioning of the fastenings. The result is superb track geometry and exceptional reliability for users.
The Abetong Long Line Method
All sleepers under licence from Abetong are manufactured according to the Abetong Long Line Method, a proven technology that has been used to produce more than 50 million sleepers all over the world. The Abetong Method has a number of special production advantages that ensure the highest quality sleepers available today. Some of the major features of this technology are
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Beds of at least 100 m in length, ensuring very accurate prestressing force in each of the prestressing tendons.
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All tendons for each line of sleepers are stressed by means of one jack, ensuring the accuracy of the total prestressing force in each sleeper.
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Modern machines with poker vibrators, vibrating beam and roller vibrator for the distribution and automatic compaction of the concrete.
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The use of small diameter prestressing tendons with good bonding characteristics, allowing for a relatively low concrete compression strength at the time of release of the prestress.
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Curing in the moulds, guaranteeing very close tolerances of the track geometry and a very good surface finish.
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All sleepers in each bed are cast in a continuous length, then demoulded, destressed and separated with a diamond cutting disc. This results in very smooth ends without any protruding prestressing tendons.