Patent ID: 6875067

Claim:
Jet propulsion unit ( 1 ) for propulsion of a waterborne craft comprising at least one impeller pump ( 3 ) with a pump housing ( 4 ) being an integrated part of the hull in which an impeller shaft ( 22 ) or a journal ( 21 ) connected to said impeller shaft ( 22 ) is rotatably journalled with respect to a bearing arrangement, and an impeller ( 7 ), having impeller blades ( 24 ), the impeller ( 7 ) being fixed to said impeller shaft ( 22 ) or journal ( 21 ) so as to follow the rotation of the impeller shaft ( 22 ), the impeller blades ( 24 ) being arranged at the impeller ( 7 ) with a play ( 25 ) between each impeller blade ( 24 ) and the inside ( 15 ) of the pump housing ( 4 ), characterized in that the jet propulsion unit ( 1 ) also comprises an axially adjustable thrust bearing ( 27 ) separate from the bearing arrangement and arranged to cooperate wit the impeller shaft ( 22 ) for adjusting said play ( 25 ), and that the thrust bearing ( 27 ) comprises a bearing housing ( 28 ) surrounding and encasing a bearing disc ( 29 ) connected to or cooperating with the impeller shaft ( 22 ), further characterized in that said bearing housing ( 28 ) is arranged to be axially movable by means of adjusting devices ( 43 ) a distance sufficient for the play ( 25 ) between the impeller blades ( 24 ) and the inside ( 15 ) of the pump housing ( 4 ) to stay within the limits of a maximally and minimally admissible play of the blades ( 25 ).