Abstract: A dry pump for gases comprises a first rotor (1) comprising a first lobe portion (1A) and a first screw (1B), as well as a second rotor (2) comprising a second lobe portion (2A) and a second screw (2B). A casing delimits an internal volume in which are located together the first and second screws (1B, 2B) and the first and second lobe portions (1A, 2A). Each of the first and second screws (1B, 2B) comprises a threading invariable along its length. The first and second rotors (1, 2) turn in opposite directions and are located in successive configurations. In a first configuration of the rotors, the first and second lobe portions (1A, 2A), a portion of the first screw (1B), a portion of the second screw (2B) and the casing together delimit a chamber (30) which is closed. In a second configuration of the rotors, the chamber (30) has a smaller capacity than in the first configuration.

Abstract: A ring gauge includes an entry zone followed by a measuring zone defined by a guide cylinder in which is installed an air jet measuring system. The entry zone includes a first region exhibiting an opening substantially larger than the opening of the guide cylinder then a second region including a spring support guide structure which defines a circle the diameter of which is equal to the diameter of the guide cylinder opening, and finally a third tapered region having an entry diameter substantially greater than that of the guide cylinder opening and an exit diameter equal to that of the guide cylinder opening. The gauge is employed for checking the outer diameter of cylindrical parts which may penetrate therein without jamming.