Tamping unit for a track tamping machine

A tamping assembly for a track tamping machine, said tamping assembly comprising:

• a pair of tamping tools arranged on a carrier so as to be vertically adjustable in a tamping assembly frame,
• said tamping tools each comprising a respective rocker arm having a lower tamping pick end, said lower tamping pick ends being configured to plunge into a ballast bed, and being drivable in opposite directions using an oscillation drive,
• wherein said tamping pick ends can be fed hydraulically toward one another,
• wherein a respective hydraulic cylinder and a respective distance sensor determining a position of the respective hydraulic cylinder are associated with each of the tamping tools of the tamping tool pair, and
• wherein the hydraulic cylinders form a feed drive and also the oscillation drive of the tamping tools, and the hydraulic cylinders are each activated responsive to a respective signal from the respective distance sensor;
• and
• wherein the hydraulic cylinders are each actuated by respective hydraulic cylinder activation valves, which are each arranged directly on the respective hydraulic cylinder;
• wherein an oscillation is superimposed on a linear feed movement of the hydraulic cylinders;
• wherein a controller/regulator specifies the oscillation, including an oscillation amplitude and an oscillation frequency, based on a cylinder pressure, which is measured using a pressure sensor.