The rotor consists of a disc (1), two concentric shoulders (4 and 8) arranged on both sides of the disc and two fixed blades (3 and 7) arranged on diametrically opposing sides of the disc, each one against the face of the disc and joined at the edge of the shoulders, so as to obtain a unit that is balanced in rotation. The rotor, machined from a single part or executed from assembled components, is joined to a shaft supported by bearings and housed in a cylindrical chamber (2) arranged in a stator (item 9, figure 2).

The stops (5 and 6) are housed in the stator. They are mobile and actuated by mechanical, hydraulic, pneumatic or electric means, or by a combination of the said means arranged remotely from the cylindrical chamber so that the work volume is free from any form of lubrication and is able to operate dry and at high temperatures. This permits uninterrupted rotation of the rotor, the stops being positioned very close to the said shoulders during the work phase so as to generate volume variations between the blades and the stops, and retracted into the stator to allow the blades to pass from one side to the other of the stops.

In combination, the dimensions of the rotor faces associated with the stator faces, the dimensions of the stop faces associated with the rotor and stator faces, the clearance between the rotor faces and the associated stator faces, the clearance between the stop faces and the rotor faces and the associated stator faces, the arithmetic roughness of all the associated surfaces, are defined so that they generate turbulences in the said clearances in order to create a seal by controlled pressure losses and generate neither friction nor need for lubrication at these locations.