Device for the sealing of a rotatable shaft

Claim 1

A sealing device affording a moderate leakage for the passage of a rotary shaft extending through the wall of a casing in which the internal fluid pressure differs from the external pressure, this device comprising in combination a tubular socket surrounding said rotary shaft, the inner surface of said socket having a small annular clearance with respect to the outer surface of said rotary shaft, so that these two surfaces provide therebetween an annular passage permitting a limited fluid flow between said casing and the surrounding atmosphere, a lining of a material having a low coefficient of friction on at least one of the two registering cylindrical surfaces, namely the inner surface of said socket and the outer surface of the corresponding portion of said shaft, a bellows-forming sleeve of flexible material connecting said socket to the wall of said casing through which said rotary shaft extends, and means for retaining said socket in the longitudinal direction, at least in the direction in which it tends to be moved as a consequence of the pressure differential between the internal fluid pressure in said casing and the surrounding external atmosphere, said retaining means being adapted to permit a certain free radial movement of said socket.