Double direction thrust ball bearings consist of one shaft washer, two housing washers and two balls and cage thrust assemblies. The bearings are separable in which mounting is simple. The housing washers, balls and cage thrust assemblies are identical to single direction bearings. It accommodates axial loads acting in both directions and can thus serve to axially locate a shaft in both directions. The double direction thrust ball bearings supports bi-directional loads.
Double-door check valves are used to prevent water hammer from the backflow of a pressure tank when automatic controls shut down a fire pump. These are used for refineries, petro chemical plants and water pump stations.