Oil-free screw rotor apparatus

A rotary screw machine comprising:

• mutually co-acting screw rotors having planar end surfaces that are perpendicular to respective axes of the rotors;
• trunnions that project out from said planar end surfaces;
• a rotor housing that houses said rotors, said rotor housing comprising a barrel wall and two mutually opposing parallel side-walls in which bearing housings for the trunnions are provided, wherein a distance between said side-walls is greater than a length of the rotors and the rotors are able to move axially between said side-walls;
• a radial slide bearing provided in each bearing housing in spaced relationship with the respective rotor end surfaces;
• a channel that connects a pressurized lubricant source with an area of each radial slide bearing that lies proximal to the trunnions, said channel supplying each radial slide bearing with lubricant during working of the machine;
• and
• a rotor-housing inlet and outlet for gas under a first pressure and a second pressure respectively;
• wherein each radial slide bearing comprises a sleeve-like element that has at least one chamber which is open to the trunnions and which has axial limitations that define first and second constrictions on each side of said at least one chamber;
• wherein said at least one chamber of the sleeve-like element which comprises each radial slide bearing is in fluid connection with the lubricant source;
• and
• wherein the lubricant is an aqueous liquid.