An improved two part detachable shaft device is connected to a rotatable cutting and shredding member of a comminutor. When these detachable shaft devices are mechanically key connected to the rotatable member along the axis of the comminutor on opposite sides thereof, the shafts and rotatable member form an effective unitary rigidly mounted rotor along the axis of the comminutor and perpendicular to the flow of fluid through the comminutor. Each detachable shaft device provides a unique and convenient means whereby a comminutor cutting and shredding member or both or either shaft device may be readily and efficiently removed for repair or replacement. Each of the detachable shaft devices includes a unique bearing sealing arrangement into which each end of the shaft not connected to the rotatable member extends. One shaft is characterized as the blind side, which provides axial support and sealing of the rotor only, while the other shaft is characterized as the drive side, which provides axial support, fluid sealing and torsion drive through the shaft to the rotor within the comminutor.