An assembly device, especially a retractable assembly, for a measuring probe for measuring process variables in a process, comprising: an assembly housing with a connection system for connecting the assembly device to a process container; a tubular holder for a measuring probe, wherein the tubular holder is guided in the assembly housing axially displaceably between a measuring position in the process container and a maintenance position outside of the process container; and a damping system to damp axial shifting of the tubular holder. The damping system comprises a fluid filled, damping cylinder within the assembly housing, and a damping piston unit guided within the damping cylinder (15) in operative connection with the tubular holder.