Abstract: Automatically controllable loading apparatus for a mass spectrometer or like equipment comprises a rotatable disc for holding a plurality of sample carriers for successive movement into a transfer position. A push rod transfers successive sample carriers from the transfer position to a loading position. Guide means guide the push rod during its transfer movement. The guide means include a shut-off valve adjacent the loading position. Sealing means define in a fixed position between the valve and the transfer position at least one vacuum chamber adapted to be exhausted for the purpose of equalizing the pressure at opposite sides of said valve.