Patent ID: 7905717

Claim:
A positive displacement pump comprising: a drive shaft passing through a gearbox and being detachably connected to a first rotor, the drive shaft being rotatively coupled to a driven shaft, the driven shaft being detachably connected to a second rotor, the first and second rotors being disposed in a pump casing, the pump casing being disposed between a head cover and the gearbox, the drive and driven shafts passing through first and second mechanical seals respectively that are sandwiched between the first and second rotors and the gear box respectively, the first and second rotors each comprise a central hub for accommodating the drive and driven shafts respectively, each central hub comprising a distal end directed towards the head cover and a proximal end directed towards the gear box, the proximal ends of the central hubs of the first and second rotors each being connected to an annular section that connects its respective proximal end to at least one radially outwardly directed wing, the first and second rotors each comprise an annular slot between their respective central hubs and its respective wing, the head cover comprising first and second cup-shaped structures with first and second cylindrical walls, and the annular slots of the first and second rotors receiving the first and second cylindrical walls of the head cover respectively, wherein removal of the head cover and the first and second rotors from the drive and driven shafts respectively provides access to the first and second mechanical seals.