A rotary feed-through, which contains a hollow shaft, which is supported in a first housing part so that it can rotate, with a first sealing surface and a sealing bushing, which is arranged rotationally fixed within a second housing part and which is coaxial with the hollow shaft, with a second sealing surface for contact to the first sealing surface. In order to also enable lower leakage losses, in addition to less wear, with the supply of cooling lubricants and compressed air, the second housing part contains a first lateral supply channel, which can be attached to a coolant supply line or a compressed air supply line, for the supply of cooling lubricant or compressed air via at least one radial opening of the sealing bushing and a second supply channel, which is charged during the supply of cooling lubricant, for the supply of cooling lubricant to a pressure piston, which closes the rear end of the sealing bushing, to increase the contact pressure of the sealing surfaces.