Abstract: A check valve of the type in which a pair of valve members are hingedly mounted to a transverse pin for pivoting movement between respective open positions and complementary closed positions in which the valve members together engage a valve seat. Torsional spring means are provided to bias the valve members to their closed positions. This means comprises a single length of wire formed into three windings which extend transversely within said passageway, two of which windings separately apply a biasing force to the respective valve members while the third, being between the other two, is wound on an axis offset from the axes of the other two, the arrangement being such as to substantially prevent dissipation of stored compressive energy from either of the respective co-axial windings to the other. Also disclosed is a bearing arrangement for valve pins which are of a material harder than the valve body.