An apparatus for compressing or pumping fluid includes a housing having an interior chamber. A rotating cam is rotatably mounted within an interior chamber and includes a reversible cam body configured to enable fluid to flow in a foreword direction and a reverse direction. The reversible cam body has a first sloped annular channel formed therein. The first end of the reversible cam body includes a ramp up portion, a ramp down portion, and inner and outer circumferential sidewalls that circumscribe the ramp to define the first sloped annular channel. The apparatus may include a circumferential cam gear located on the outer circumferential sidewall and a secondary drive shaft with a pinion gear to rotate the circumferential cam gear.