Reusing high-quality ballast

Save resources and reduce costs: The better the quality of the screened material, the less frequently the ballast bed will have to be cleaned and tamped. Therefore, the screening quality is crucial for the cost-efficiency of a ballast cleaning machine and the overall technology.

The screen size, mesh size, screen vibration and direction of vibration and angle of the screens are essential for optimising the quality and output of a ballast cleaning machine’s screening unit. When working on superelevated track, it should be possible to place the screen in horizontal position. Guide mechanisms at the base of the screens control the ballast flow. They make it possible to provide more ballast when there are differences in superelevation.

Many years of experience gained by Plasser & Theurer’s design engineers with machines in operation all over the world ensure cost-efficient machine operations.

Optimising the quality and output of the screening unit:

  • Screen size – depending on the size of the machine and the number of screens
  • Number of screen layers – usually three to separate over-sized stones and fine grain
  • Setting angle of the screen layer – affects the quality of the screened material
  • Vibration type and vibration frequency – determine the ideal screening time and ensure the high quality of the screened material


  • Spoil conveyor belts
  • High-pressure ballast washing plant including water treatment plant
  • Module for ballast reconditioning (pre-separation screen, metal separator, ballast crusher)
  • Finger screen, star screen


Plasser & Theurer’s ballast cleaning machines are fitted with triple-deck screening units. The most common mesh sizes are 80/50/40 mm. (Other sizes are available on request.)

  • Top screen deck – separates over-sized stones and sends them to the spoil conveyor belt
  • Middle screen deck – separates medium-sized stones
  • Lower screen deck – separates remaining grain and spoil and collects the fine grain
  • The unit transports fine particles and over-sized stones (spoil)

Our ballast cleaning machines produce excellent screening results. The figures of the recovered material are better than the figures of new ballast – depending on its quality. In addition, the recovered ballast has better frictional behaviour because it does not break at the edges like new ballast.

More screens for high capacity

Again and again, attempts have been made to raise the screening output of ballast cleaning machines using unsuitable measures such as steep, over-long screens or pre-separators. Ultimately, these measures minimise the cleaning quality. Plasser & Theurer is on the right track: We use a separate screening car with double-screening units or triple-screening units to increase the screening capacity. This ensures the high-quality stone separation.