US Patent 7587981 Method for cleaning ballast of a track

A method for cleaning ballast of a track comprising rails extending in a longitudinal direction is executed by means of a ballast cleaning machine having a machine frame supported on on-track undercarriages. The machine includes a cleaning chain with a chain cross member extending perpendicularly to the longitudinal direction. At the start of the cleaning process, an on-track undercarriage situated immediately ahead of the cleaning chain, with regard to a working direction of the ballast cleaning machine, is lifted off the track. The rails are severed, and the track is lifted, after which the chain cross member of the cleaning chain is positioned underneath the track. Finally, the on-track undercarriage is set down upon the track again.