Abstract: Rotary lobe pump and circumferential piston pump designs are disclosed where the drive and driven shafts are detachably connected to their respective rotors. The rotors are disposed in a pump or rotor casing, which is sandwiched between a head cover and a gearbox. The drive and driven shafts pass through mechanical seal assemblies, which are sandwiched between the first and second rotors and the gear box respectively. The seal assemblies can be serviced or replaced by simply removing the head cover and removing the rotors from the drive and driven shafts. The pump casing does not need to be removed to replace or service the seal assemblies. Further, the capacities of the disclosed rotary lobe and circumferential piston pumps can be modified without changing the gearboxes or shaft length. To modify a pump capacity, all that needs to be changed are the rotors, the pump or rotor casing and, in some designs, the head cover or cover plate.

Abstract: Rotary lobe pump and circumferential piston pump designs are disclosed where the drive and driven shafts are detachably connected to their respective rotors. The rotors are disposed in a pump or rotor casing, which is sandwiched between a head cover and a gearbox. The drive and driven shafts pass through mechanical seal assemblies, which are sandwiched between the first and second rotors and the gear box respectively. The seal assemblies can be serviced or replaced by simply removing the head cover and removing the rotors from the drive and driven shafts. The pump casing does not need to be removed to replace or service the seal assemblies. Further, the capacities of the disclosed rotary lobe and circumferential piston pumps can be modified without changing the gearboxes or shaft length. To modify a pump capacity, all that needs to be changed are the rotors, the pump or rotor casing and, in some designs, the head cover or cover plate.