PURPOSE: To obtain a pressure energy translating device with a simple structure, useful in a pump or a fuel system by providing a pressure contained vane unit assembly comprising a pair of support plates, a cam ring, a rotor having a plurality of vanes, and flexible plates.

CONSTITUTION: A pressure contained vane unit assembly 20 in a fluid case is provided. The assembly 20 comprises a pair of support plates 30, 31, a cam ring 32 interposed between the support plates 30, 31, a rotor 60, and flexible plates 33, 34. The rotor 60 is rotatably mounted in the cam ring 32 and has a plurality of circumferentially extending vanes 61 adapted to engage the contour of the cam ring 32. The flexible plates 33, 34 are interposed between the cam ring 32 and each of the support plates 30, 31. The support plates 30, 31 include a hub portion spaced from its respective flexible plates 33, 34. Thus, the device has a simple structure and is useful in a pump or a fuel system.