Shaft assembly for use in a dual clutch transmission system for improved lubrication and other improved parts of transmission systems

A shaft assembly for use in a dual clutch transmission system to be installed in a power train of a motor vehicle for selectively coupling three rotating transmission members, wherein the shaft assembly extends along a central axis and comprises:

• a transmission member comprising:
• a first axial end and a second axial end relative to the central axis, wherein the first axial end is configured to be rotatably connected to a shaft part;
• and
• a first bore extending along the central axis from the first axial end in a direction towards the second end, wherein the first bore is open at the first axial end and comprises a closed bore end opposite the first axial end,
• wherein the first bore comprises a stepped closed bore end section in which a diameter of the first bore decreases stepwise towards the closed bore end;
• the shaft part comprising a second bore extending along the central axis from a first axial end of the shaft part to a second axial end of the shaft part, wherein the second bore comprises a main section and an insert receiving section at the first axial end of the shaft part adjacent to the main section, wherein the shaft part is rotatably connected at the insert receiving section to the transmission member at the first axial end of the transmission member;
• and
• a hollow tube shaped insert placed in the bore at the insert receiving section, wherein a first channel extends along the central axis through the bore and an inside of the hollow tube shaped insert, wherein an outer diameter of the hollow tube shaped insert is smaller than an inner diameter of the bore at the insert receiving section such that a second channel is arranged between an outer side of the hollow tube shaped insert and an outer circumference of the second bore at the insert receiving section and concentrically relative to the first channel, wherein the first channel and the second channel are separated from each other.