Patent ID: 8192240

Claim:
A contra-rotating propeller system installed between a rudder horn of a ship and shaft support at an engine-output side, the system comprising: a propeller shaft rotatably supported by the rudder horn and the shaft support, respectively; a front propeller fixed to the propeller shaft; a counter rotating gear set installed on the rudder horn and connected with the propeller shaft; and a rear propeller connected to the counter rotating gear set via the propeller shaft penetrating an axis of the rear propeller and disposed between the rudder horn and the front propeller, wherein each of the rudder horn, a hub of the rear propeller, and a hub of the front propeller is designed to have substantially ellipsoidal body in shape together, wherein the counter rotating gear set rotates the rear propeller in a reverse direction to a rotating direction of the front propeller, wherein the counter rotating gear set includes epicyclic gear set, in which the epicyclic gear set has: a gear housing mounted on the rudder horn; a sun gear fixed to the propeller shaft and rotatably disposed in a central portion inside the gear housing; a plurality of first planet gears arranged around the sun gear to be meshed with the sun gear, each planet gear having a pinion shaft at a center thereof; a planet gear carrier rotatably connected with each pinion shaft to maintain an engagement between the sun gear and the first planet gears; a plurality of second planet gears respectively fixed to end portions of the pinion shafts extending through the planet gear carrier; and a ring gear meshed with the second planet gears and mounted on one end portion of a hub of the rear propeller, wherein the planet gear carrier is fixed to the gear housing, and wherein a first sealing unit is provided on an inner circumference in the other side of the hub of the rear propeller.