Static Compression Measurements of Equations of State

A rotary sliding vane pump or motor has pressure loaded cheek plates on each side of the revolving rotor and vanes. The cam ring has alternate major and minor diameter circular arcs connected by rising and falling ramps along which fluid displacement occurs. End covers and cheek plates of similar configuration enclose the end faces of the cam ring, rotor and vanes. The cheek plates have pressure loading cavities of circular form opposite each ramp. All of the cavities on each end are connected with a terminal in the adjacent end cover and alternate cavities are perforated to provide fluid passages into the working chambers of the device. The intermediate cavities on each cheek plate are blind. The cheek plates are so located that a perforated cavity on one end lies opposite a blind cavity on the other end of the device and the areas of the cavities are chosen to slightly overbalance the pressure forces existing at the interface between the rotor and cheek plates.