Abstract: A rotary pump for pumping compressible fluid comprising an eccentrically mounted rotor 20 and a stator 10. The stator 10 comprises a stator inner liner 80 that is free to rotate, driven directly or in response to rotation of the rotor 20 such that the relative velocity between the outer surface of the rotor 20 and the inner surface of the stator 10 is reduced. The vanes 40 are held at each end by sockets 90, 95 in the rotor 20 and stator 10. The vane 40 and socket 90, 95 coupling provides fluid sealing without liquid lubricant. Opposing solid lubricant and hard surfaces are used on contact surfaces between the elements.