US Patent 7438325 Rotating passage

A rotating passage feed system for admitting pressure means into two machine parts (hub part (2), shaft (3)) which rotate relative to one another about a common axis. Conduits (17) that convey the pressure means are located in the shaft (3) and are joined to pressure means connections (6) via tapped holes while a connecting part (5) in which ring channels (8) are provided is also joined thereto. A central sleeve (9) is joined to the connecting part (5) in a non-rotatable manner. The connecting part (5) and the central sleeve (9) are produced in an inexpensive manner as lightweight structure formed from sheet metal through a shaping process.