Track work machine

A track work machine adapted for mobility on a track supported on ballast and extending in a longitudinal direction, comprising

• a machine frame extending in the longitudinal direction and having a front end and a rear end with regard to an operating direction of the machine;
• an excavating device mounted on the machine frame at the rear end and having a ballast pick-up unit arranged underneath the track and a discharging end positioned rearwardly with regard to the operating direction;
• a conveyor belt associated with the discharging end and provided for receiving and transporting excavated ballast;
• and
• a front undercarriage and a rear undercarriage supporting the machine frame on the track, the rear undercarriage being mounted on the machine frame for displacement in the longitudinal direction relative to the machine frame from a transit travel position, in which the rear undercarriage is situated between the discharging end and the ballast pick-up unit of the excavating device, in the direction towards the front undercarriage.