Plasser & Theurer machines integrate several technologies for ballast reprocessing. These include the use of screens with star-shaped cleaning elements, high-pressure and wet cleaning technologies, crushing plants for sharpening the ballast stones and other technologies, all of which are mounted on additional vehicle components and coupled to the system. These technologies help to further improve the cleaning effect of the whole system. With washing screens, a water recycling unit is also integrated in the whole system.
Over the past years we have gathered a lot of experience in ballast reprocessing technology:
In many places, where complete excavation was required previously, the ballast can nowadays be reprocessed in a machine with a ballast washing plant. A high content of clay and/or silt in the subsoil in combination with the moisture content of the fines in the ballast (5–10% relative humidity) may reduce the cleaning effect considerably or require a complete excavation. However, if the moisture increases during cleaning due to rain, the cleaning effect will increase again. We have utilised this effect in our ballast washing plants.
Another argument in favour of ballast washing is the fact that fines are also present and allowed in new ballast, usually approx. 5 to 7 volume per cent per tonne. These fines will be removed when washing the ballast. Therefore, washed ballast is of higher quality than new ballast, resulting in a higher ballast bed quality.
