Mechanism including two cut-off devices in series

Claim 1

A tandem hydraulic valve assembly for use in high pressure and high flow environments such as a high-fall hydroelectric installation, the valve comprising: a main valve shell, including an upstream shell half and a downstream shell half symmetrically disposed on opposite sides of a transverse medial plane, the respective shell halves having radial flanges at the mutually presented juxtaposed ends thereof; bolts extending through said flanges and immovably securing the respective shell halves to each other; a rotatable valve member and an adjacent cooperating valve seat therefor positioned within said upstream shell half; a rotatable valve member and an adjacent cooperating valve seat therefor positioned within said downstream shell half; and a journal for each rotatable valve member, the respective journals being supported in their associated shell half for independent rotary movement, and a generally planar plate interposed between said mutually presented juxtaposed ends of the respective shell members and their associated flanges, said bolts extending through said plate and said flanges and immovably securing said plate and said shell halves to each other, and at least one of said adjacent valve seats carried by said plate and cooperating with an adjacent one of said valve members.