Patent ID: 8366384

Claim:
A pump assembly comprising a cutting wheel mounted on a drive shaft in coaxial and co-rotational relation with a pump wheel, and a cutting plate stationary mountable in a pump housing between the cutting wheel and the pump wheel, the cutting plate having perforations forming passages there through for a liquid to be transported by the pump wheel in rotation, the cutting wheel and cutting plate in co-operation providing a shearing interface effective for cutting solid matter which may be entrained in the liquid, wherein the cutting wheel has an internal thread engaging an external thread on the drive shaft, the pump assembly further comprises an adjusting element, which is arranged to establish an axial clearance at the shearing interface between the cutting wheel and the cutting plate by applying a separating axial force on the cutting wheel and on the drive shaft and thereby eliminating an axial play in the threaded engagement between the cutting wheel and the drive shaft.