Rotary leadthrough, especially for a torsional vibration damper in a drive train of a vehicle

A rotary lead-through includes a first rotary lead-through element having a first channel opening on a first boundary surface, and a second rotary lead-through element having a second channel opening on a second boundary surface which opposite from the first boundary surface and can rotate relative to the first boundary surface about an axis of rotation, the first and second channels being in fluid communication via a channel boundary space. A sealing arrangement acting between the first and second lead-through elements includes at least one sealing stage, each sealing stage including a first sealing element toward the boundary space and a second sealing element away from the boundary space, the first and second sealing elements enclosing a backpressure chamber surrounding the axis of rotation. Where successive sealing stages are provided, a pressure-limiting valve can be provided in parallel to the seal separating immediately successive backpressure spaces.