A rotary positive displacement pump for pumping a fluid product, the pump having a front side and a rear side and comprising: a main body providing rotational support to a pair of parallel, axially extending, shafts with gears in constant mesh condition, such that the pair of shafts are arranged to rotate in opposite directions, a rotor case body connected to a front side of the main body and having: - a stationary interior pumping cavity defined by an axial rear wall , a circumferential side wall , and a removable front cover , - a fluid product inlet opening , - a fluid product outlet opening , and - a pair of cylindrical rotor case hubs extending from the rear wall , wherein each cylindrical rotor case hub receives internally one of the pair of shafts , a pair of rotors , each having at least one rotor wing and a rotor drive element that is mounted torque proof on a rotor seat at an end region of one of the pair of shafts , wherein each of the pair of rotor seats has an axial abutment surface facing in an axial direction towards a front side of the pump and a mounting surface facing radially outwards, wherein the pump further comprises a pair of fasteners , each being engaged with a mating section at the end region of one of the pair of shafts , and each exerting an axial clamping force on one of the rotor drive elements against the axial abutment surface of one of the rotor seats , and characterized in that the axial abutment surface of each rotor seat is located axially outside, towards a front side , of the associated hub . a main body providing rotational support to a pair of parallel, axially extending, shafts with gears in constant mesh condition, such that the pair of shafts are arranged to rotate in opposite directions, a rotor case body connected to a front side of the main body and having: - a stationary interior pumping cavity defined by an axial rear wall , a circumferential side wall , and a removable front cover , - a fluid product inlet opening , - a fluid product outlet opening , and - a pair of cylindrical rotor case hubs extending from the rear wall , wherein each cylindrical rotor case hub receives internally one of the pair of shafts , - a stationary interior pumping cavity defined by an axial rear wall , a circumferential side wall , and a removable front cover , - a fluid product inlet opening , - a fluid product outlet opening , and - a pair of cylindrical rotor case hubs extending from the rear wall , wherein each cylindrical rotor case hub receives internally one of the pair of shafts , a pair of rotors , each having at least one rotor wing and a rotor drive element that is mounted torque proof on a rotor seat at an end region of one of the pair of shafts , wherein each of the pair of rotor seats has an axial abutment surface facing in an axial direction towards a front side of the pump and a mounting surface facing radially outwards, wherein the pump further comprises a pair of fasteners , each being engaged with a mating section at the end region of one of the pair of shafts , and each exerting an axial clamping force on one of the rotor drive elements against the axial abutment surface of one of the rotor seats , and characterized in that the axial abutment surface of each rotor seat is located axially outside, towards a front side , of the associated hub . <EOS>