A band brake actuator is for actuating a band brake on a planetary gearset. The band brake actuator comprises a actuator shaft; an output finger; and a linkage assembly. The linkage assembly connects the actuator shaft to the output finger such that rotation of the actuator shaft in a first rotation direction causes the output finger to engage the band brake on the planetary gearset, and such that rotation of the actuator shaft in an opposite, second rotation direction causes the output finger to disengage the band brake from the planetary gearset. Engagement of the band brake and the planetary gearset shifts the planetary gearset into one of a forward and a reverse gear and wherein disengagement of the band brake and the planetary gearset shifts the planetary gearset into a neutral gear.

A system for rotating inner and outer propeller shafts via a driveshaft. The system includes a stub shaft extending between forward and aft ends, the aft end having an engagement feature for engaging with the inner propeller shaft such that rotating the stub shaft rotates the inner propeller shaft. A reverse gear and a forward gear are each rotatably coupled to the stub shaft. The reverse gear and the forward gear mesh with the driveshaft and are engageable to become rotatably fixed to the stub shaft such that rotating the driveshaft rotates the stub shaft in reverse and forward directions, respectively. An outer driving gear is coupled to the inner propeller shaft to rotate therewith. An outer driven gear is coupled to the outer propeller shaft and a pinion rotatably coupling the outer driving gear to the outer driven gear such that rotation of the outer driving gear rotates the outer propeller shaft.

A coaxial contra-rotating circumferential thruster includes: an input end, a one-way commutator, a two-way deflector, a steering support and two output ends. The input end is connected to a power device. The one-way commutator converts one rotation into two rotations having the same rotation speed and opposite rotation directions. The two-way deflector respectively indirectly connects two shafts of a contra-rotating sleeve shaft to two output shafts thereof by means of two bevel gear pair. Two unidirectional deflecting torques respectively generated by the two bevel gear pairs have the same magnitude and opposite directions. By transferring by means of a bracket or an output sleeve shaft, the two unidirectional deflecting torques cancel each other. The two output ends are respectively connected to two propellers (or rotors). A turnaround control device controls the steering support to be turned around, the control torque required for co-rotating and contra-rotating is the same.

A system for adjusting the rotational timing between driveshafts rotated by an output shaft. The system includes a flange coupler configured to be coupled to a first of the driveshafts to prevent rotation therebetween. The flange coupler defines openings therein. A coupler input gear defines openings therein and is configured to rotatably mesh with a second input gear coupled to a second of the driveshafts. Fasteners are configured to the extend through the openings in the flange coupler and the openings in the coupler input gear to rotationally fix the flange coupler and the coupler input gear, which are fixable at multiple rotational orientations therebetween. The rotational timing between the driveshafts is adjustable by rotating the coupler input gear into different orientations of the multiple rotational orientations relative to the flange coupler prior to fixing the flange coupler to the coupler input gear.

A system for adjusting the rotational timing between driveshafts rotated by an output shaft. The system includes a flange coupler configured to be coupled to a first of the driveshafts to prevent rotation therebetween. The flange coupler defines openings therein. A coupler input gear defines openings therein and is configured to rotatably mesh with a second input gear coupled to a second of the driveshafts. Fasteners are configured to the extend through the openings in the flange coupler and the openings in the coupler input gear to rotationally fix the flange coupler and the coupler input gear, which are fixable at multiple rotational orientations therebetween. The rotational timing between the driveshafts is adjustable by rotating the coupler input gear into different orientations of the multiple rotational orientations relative to the flange coupler prior to fixing the flange coupler to the coupler input gear.

A propeller includes a propeller shaft, a plurality of first blades, and a plurality of second blades. The first blades are connected to the outer peripheral surface of the propeller shaft so as to be rotated synchronously with the propeller shaft. The second blades are connected to the outer peripheral surface of the propeller shaft, so that they are rotated in the same direction as the first blades. The second blades are located in front of the first blades and correspond to the first blades in a one-to-one manner. The size of the second blades is smaller than the size of the first blades, and the rotation direction of the second blades is the same as the rotation direction of the first blades. Thereby, the propeller of the present invention can improve the operation efficiency of the boat at high speed without increasing the size of the first blades.

A propeller includes a propeller shaft, a plurality of first blades, and a plurality of second blades. The first blades are connected to the outer peripheral surface of the propeller shaft so as to be rotated synchronously with the propeller shaft. The second blades are connected to the outer peripheral surface of the propeller shaft, so that they are rotated in the same direction as the first blades. The second blades are located in front of the first blades and correspond to the first blades in a one-to-one manner. The size of the second blades is smaller than the size of the first blades, and the rotation direction of the second blades is the same as the rotation direction of the first blades. Thereby, the propeller of the present invention can improve the operation efficiency of the boat at high speed without increasing the size of the first blades.

A propeller (20) for a marine vessel (10), the propeller (20) comprising a plurality of propeller blades (24, 26). The propeller blades comprise a leading edge (30), a trailing edge (32) and an outer edge (34) located between the leading edge and the trailing edge. A transition from the leading edge to the outer edge occurs at a first transition point (36) and a transition from the outer edge to the trailing edge occurs at a second transition point (38). A straight line from the first transition point to the second transition point coincides with the outer edge (34) or is located at least partially outside the propeller blade. A smallest distance (D.sub.2) from the second transition point to the axis of rotation (A) is smaller than a smallest distance (D.sub.\) from the first transition point to the axis of rotation.

A propeller (20) for a marine vessel (10), the propeller (20) comprising a plurality of propeller blades (24, 26). The propeller blades comprise a leading edge (30), a trailing edge (32) and an outer edge (34) located between the leading edge and the trailing edge. A transition from the leading edge to the outer edge occurs at a first transition point (36) and a transition from the outer edge to the trailing edge occurs at a second transition point (38). A straight line from the first transition point to the second transition point coincides with the outer edge (34) or is located at least partially outside the propeller blade. A smallest distance (D.sub.2) from the second transition point to the axis of rotation (A) is smaller than a smallest distance (D.sub.\) from the first transition point to the axis of rotation.

There is provided a ship propulsion machine including: a drive shaft; a drive gear fixed to the drive shaft; a front gear meshed with the drive gear; a rear gear meshed with the drive gear; a rear propeller provided on an inner propeller shaft; a front propeller provided on an outer propeller shaft; a casing having a gear chamber; a second bearing that supports a front end side of the outer propeller shaft at a rear portion of the casing; a third bearing that supports the inner propeller shaft and the outer propeller shaft in a manner rotatable with respect to each other. The third bearing is disposed on an inner peripheral side of a shaft portion of the rear gear, and the second bearing is disposed on an outer peripheral side of the shaft portion of the rear gear.