A milking robot (1) for fully automatic milking of milking animals, comprising at least one movable component and a cylinder (4, 4') configured to support a movement of the component, which cylinder has a cylinder wall (11) with a ventilation opening (8) and a cylinder rod (5) which can move in and out of the cylinder, wherein the cylinder wall surrounds at least one variable volume part, which volume part is free from pressurized fluid connections for movement of the cylinder rod and is also configured, via said opening, to remain in virtual pressure equilibrium with an environment of the cylinder, wherein on the cylinder wall around said ventilation opening, a gas capture device (7) is connected which has a variable volume and which together with the variable volume part, forms an air-tight gas volume. Thus it is possible to keep the variable volume part at almost ambient pressure, so that on extension and retraction of the cylinder rod, no unnecessary counter-pressure occurs in the cylinder, making the function more reliable. Also less to no exchange of gas, dirt and similar with the environment can take place so the cylinder has a longer life and better reliability.La présente invention concerne un robot (1) de traite permettant la traite entièrement automatique d'animaux laitiers, comprenant au moins un composant mobile et un cylindre (4, 4') conçu pour supporter un mouvement du composant, lequel cylindre comprend une paroi cylindrique (11) dotée d'une ouverture de ventilation (8) et d'une tige de cylindre (5) permettant d'entrer et de sortir du cylindre, la paroi du cylindre entourant au moins une partie de volume variable, laquelle partie de volume est exempte de liaisons fluides sous pression pour le mouvement de la tige de cylindre et est également conçue, par l'intermédiaire de ladite ouverture, pour rester en équilibre de pression virtuelle avec un environnement du cylindre, un dispositif de capture de gaz (7) étant relié sur la paroi du cylindre autour d
