US Patent 6918838 Longitudinal plunging unit with a hollow profiled journal

A longitudinal plunging unit (11) for torque transmitting purposes in a shaft assembly, comprising an outer profiled sleeve (21) having circumferentially distributed, inner, longitudinally extending first ball grooves (22) to be connected to a first attachment part, a profiled journal (31) positioned inside the outer profiled sleeve (21) and having circumferentially distributed, outer, longitudinally extending second ball grooves (32) to be connected to a second attachment part, groups of balls (41) arranged in pairs of first and second ball grooves (22, 32), and a sleeve-shaped ball cage (42) which is positioned in the annular space between the profiled sleeve (21) and the profiled journal (31) and which fixes the groups of balls (41) in their respective positions relative to one another. The profiled journal (31) is a hollow journal comprising a material with a substantially uniform wall thickness with a maximum deviation of ±15%.