Abstract: A fluid pressure energy translating device of the sliding vane type comprising a cam ring including an internal contour, a rotor having a plurality of vanes rotatable therewith and slidable relative thereto in slots in the rotor with one end of each vane engaging the internal contour. The rotor and internal contour cooperate to define one or more pumping chambers between the periphery of the rotor and the cam contour through which the vanes pass carrying fluid from an inlet port to an outlet port. At least one cheek plate is associated with the body and rotor. Two pressure chambers are formed for each vane and each vane has two surfaces, one in each chamber, both being effective under pressure in the respective chambers to urge the vanes into engagement with the cam. A generally annular internal feed passage is formed entirely within the rotor and communicates with one set of the pressure chambers.