Abstract: A sliding vane pump having an inside liner with a constant radius pump arc and a constant radius stop arc, connected together by cycloidal arcs. The liner has inlet slots arranged extending around a perimeter of a liner extending into the pump arc for maximum filling of the pumping volume. A herringbone-shaped slot arrangement is provided on a outlet side which increases vane life, increases sealing around the vanes on the outlet side, and decreases liner wear. A relief/fill porting arrangement is provided to pressurize the fluid in the pump chamber, or alternately to relieve pressure from the pump chamber. An improved thrust absorber is described particularly useful for truck mounting of the pump. An asymmetrical inside profile for the liner assists in pump operation by providing a fluid mathematical profile which approaches zero acceleration forces at the point of tangency.