A watercraft and a marine engine assembly for pivotably mounting to a watercraft about a tilt-trim axis are disclosed. The marine engine assembly includes an engine unit including: an engine unit housing; an engine disposed in the housing; and an exhaust conduit disposed in the housing, an exhaust inlet defined by the exhaust conduit being fluidly connected to the engine, the exhaust conduit extending forward and upward from the exhaust inlet and then subsequently extending downward and rearward to an exhaust outlet. The marine engine assembly also has a driveshaft operatively connected to the engine and a propulsion device operatively connected to the driveshaft. A center of mass of the engine is disposed below the tilt-trim axis at least when the driveshaft is vertically oriented.

A watercraft and a marine engine assembly for pivotably mounting to a watercraft about a tilt-trim axis are disclosed. The marine engine assembly includes an engine unit including: an engine unit housing; an engine disposed in the housing; and an exhaust conduit disposed in the housing, an exhaust inlet defined by the exhaust conduit being fluidly connected to the engine, the exhaust conduit extending forward and upward from the exhaust inlet and then subsequently extending downward and rearward to an exhaust outlet. The marine engine assembly also has a driveshaft operatively connected to the engine and a propulsion device operatively connected to the driveshaft. A center of mass of the engine is disposed below the tilt-trim axis at least when the driveshaft is vertically oriented.

A motor comprising: (a) a stator having a plurality of ferrous cores surrounded by a plurality of windings; (b) a pair of rotors positioned on opposing sides of the stator, each rotor including a ring gear; and (c) a drive shaft extending through a cutout of the stator, the drive shaft having a pinion gear positioned near an end of the drive shaft in communication with the ring gears of the rotors; wherein the rotors rotate in opposing directions so that the ring gears translate a movement of the rotors to the drive shaft through the pinion gear to rotate the drive shaft in a direction substantially orthogonal to a direction of rotation of the rotors.

A motor comprising: (a) a stator having a plurality of ferrous cores surrounded by a plurality of windings; (b) a pair of rotors positioned on opposing sides of the stator, each rotor including a ring gear; and (c) a drive shaft extending through a cutout of the stator, the drive shaft having a pinion gear positioned near an end of the drive shaft in communication with the ring gears of the rotors; wherein the rotors rotate in opposing directions so that the ring gears translate a movement of the rotors to the drive shaft through the pinion gear to rotate the drive shaft in a direction substantially orthogonal to a direction of rotation of the rotors.

A drive train in a marine vessel includes a marine pod drive unit and an inboard engine operatively connected by a driveshaft. To protectively enclose the driveshaft, a guard sleeve having a tubular configuration is disposed around the driveshaft and extends between the marine pod drive unit and the inboard engine. The first sleeve end of the guard sleeve is coupled to a first coupling collar on the marine pod drive unit using a first annular packing and the second sleeve end is coupled to a second coupling collar on the inboard engine using a second annular packing. The first and second annular packings enable relative angular displacement between the guard sleeve and the marine pod drive unit or the inboard engine.

An embodiment of a device for marine surface propulsion of a watercraft is provided that facilitates high speed performance in combination with steering and/or trimming control. The propulsion device may include a support member supportably interconnectable to and pivotable about one or both of a reclined axis and upright axis relative to a watercraft transom. A propeller shaft may be supported by the support member for pivotable movement therewith, and may have a first end interconnectable to a watercraft engine output. A hub body and a plurality of propeller blades may be interconnected to a second end of the propeller shaft for co-rotation therewith, wherein the hub body and propeller blades are pivotable with the support member about the reclined and/or upright axes. A variable pitch actuator may be interconnected to the support member for pivotable co-movement therewith about the reclined and/or upright axis, wherein the variable pitch actuator is provided for adjustably controlling a pitch orientation of the propeller blades.

A torque fluctuation absorber includes a first outer helical spline, an intermediate member, an outer member, a first spring, and a second spring. The first outer helical spline is rotatable integrally with a torque transmission shaft. The intermediate member is able to move in a first axial direction and in a second axial direction. The intermediate member is linked with the torque transmission shaft through a first helical spline coupling including the first outer helical spline. Axial movement of the outer member with respect to the torque transmission shaft is regulated. The outer member is linked with the intermediate member through a second helical spline coupling. The first spring biases the intermediate member in the first axial direction. The second spring biases the intermediate member in the second axial direction.

A torque fluctuation absorber includes a first outer helical spline, an intermediate member, an outer member, a first spring, and a second spring. The first outer helical spline is rotatable integrally with a torque transmission shaft. The intermediate member is able to move in a first axial direction and in a second axial direction. The intermediate member is linked with the torque transmission shaft through a first helical spline coupling including the first outer helical spline. Axial movement of the outer member with respect to the torque transmission shaft is regulated. The outer member is linked with the intermediate member through a second helical spline coupling. The first spring biases the intermediate member in the first axial direction. The second spring biases the intermediate member in the second axial direction.

The inventive technology described herein generally relates to the field of power transmission, more particularly power transmission through a mechanical drive system. More specifically, in certain embodiments the inventive technology includes methods and apparatus for a variable coupler drive utilizing, in one embodiment a dynamic drive-ratio gearing system to transmit a drive input for application with a variety of output uses. In a preferred embodiment, such a variable coupler drive may be used to transmit a rotational drive input to a drive shaft to power, for example, a variety of commercial and industrial applications, and may be particularity suited to power rotational propeller based propulsion systems.

The inventive technology described herein generally relates to the field of power transmission, more particularly power transmission through a mechanical drive system. More specifically, in certain embodiments the inventive technology includes methods and apparatus for a variable coupler drive utilizing, in one embodiment a dynamic drive-ratio gearing system to transmit a drive input for application with a variety of output uses. In a preferred embodiment, such a variable coupler drive may be used to transmit a rotational drive input to a drive shaft to power, for example, a variety of commercial and industrial applications, and may be particularity suited to power rotational propeller based propulsion systems.