Abstract: This invention relates to a hydropneumatic valve actuator comprising an outer cylindrical casing and an inner cylindrical casing both having closure means at each end. The inner cylindrical casing is positioned in said outer casing and is transversely spaced therefrom to define an elongated annular gas chamber. A piston slidably mounted in said inner casing has a piston rod extending axially from one end thereof through an axial bore in one of said closure means. The gas chamber as well as the portion of the inner casing between the piston and the other closure means, are adapted to be charged with gas under pressure and the portion of the inner casing between the piston and the closure means through which the piston rod extends is adapted to be charged with liquid.The piston is provided with a pair of spaced annular seals and means are provided to prevent gas leakage past one of the seals into the portion of the inner casing charged with oil under pressure and to sense leakage of oil past the other seal.

Abstract: This invention relates to a hydropneumatic spring device comprising an outer cylindrical casing and an inner cylindrical casing both having closure means at each end. The inner cylindrical casing is positioned in said outer casing and is transversely spaced therefrom to define an elongated annular chamber. A piston slidably mounted in said inner casing has a piston rod extending axially from one end thereof through an axial bore in one of said closure means. A resilient sleeve encompassing the inner casing is positioned in the annular chamber extending substantially the length thereof. The ends of the sleeve are retained in fixed position so that a variable volume gas chamber is defined between the outer casing and the sleeve and a variable volume liquid chamber is defined between the inner casing and the sleeve. The gas chamber is adapted to be charged with gas under pressure and the portion of the inner casing between the piston and the other closure means is adapted to be charged with liquid.