Sealing means for stirling engine crankcases

A sealing device for preventing leakage of gas through a crank casing wall along a rotatable crank shaft extending therethrough, said crank casing containing gas at a cyclically varying elevated pressure, characterised in that an oil-containing chamber is arranged on the outside of said crank casing wall and surrounding the said crank shaft, said crank casing has an oil sump within said wall, a conduit connects said oil sump of said crank casing with said chamber, a non-return valve being arranged in said conduit allowing flow of oil only in the direction from said sump to said chamber, a one way sealing member about said shaft and located between the shaft and said wall to permit flow of oil in the direction from said chamber into said crank casing, and rotation means being provided for causing rotation of the oil in said chamber in the direction of rotation of said crank shaft.