Patent ID: 7220157

Claim:
An arrangement for parallel alignment of propeller shafts ( 5 ) in a first and a second underwater housing ( 6 a , 6 b ) arranged on the hull of a vessel, which underwater housings can be rotated around an axis of rotation (a) which is angled in relation to the propeller shaft ( 61 ) arranged in each underwater housing ( 6 a , 6 b ), which arrangement comprises: a servo motor ( 26 ) arranged for each underwater housing ( 6 a , 6 b ), which servo motor is arranged to rotate said underwater housing ( 6 a , 6 b ); a position sensor ( 33 , 34 ) arranged for each servo motor ( 26 ), which position sensor is arranged to detect an angular position of the underwater housings ( 6 a , 6 b ); a memory ( 31 ′) in which reference positions of the underwater housings ( 6 a , 6 b ) are arranged to be stored during a calibration of the position of the underwater housing; and a means for calibration ( 38 , 42 ) of the position of the underwater housings by storing output signals from the position sensors ( 33 , 34 ) in said memory ( 31 ′) during a parallel alignment of propeller shafts ( 61 ) in two underwater housings ( 6 a , 6 b ) arranged on the hull of a vessel; and characterized in that said means for calibration ( 38 , 42 ) comprises a first calibrating device ( 37 ) which is attached in a first underwater housing ( 6 a ) and a second calibrating device ( 42 ) which is attached in the second underwater housing ( 6 b ), where the first calibrating device ( 37 ) comprises a light source ( 41 ) which emits rays of light within a plane (P) at right angles to the propeller shaft ( 61 ) in the first underwater housing ( 6 a ) and in a direction towards the propeller shaft ( 61 ) in the second underwater housing ( 6 b ), where the second calibrating device ( 42 ) comprises a reflecting surface ( 44 ) and where the first calibrating device ( 37 ) comprises a target area ( 45 ), where it can be ascertained that the propeller shafts ( 61 ) are parallel when a ray of light which is emitted from the light source ( 41 ) of the first calibrating device is reflected on the reflecting surface ( 44 ) of the second calibrating device and incides within said target area ( 45 ).