A counter rotating gear case. The counter rotating gear case may include a forward gear assembly; an aft gear assembly; a pinion gear assembly; a spool adapter having a first portion and a second portion, wherein the forward gear assembly, the aft gear assembly, and pinion gear assembly may be supported on the second portion of the spool adapter; and wherein, the pinion gear assembly may be disposed between the forward gear assembly and the aft gear assembly, and wherein the pinion gear assembly may be operatively engaged with both the forward gear assembly and the aft gear assembly, such that rotation of one of the forward gear assembly or the aft gear assembly in one direction causes rotation of the other of the forward gear assembly or the aft gear assembly in a second direction opposite that of the first direction.

A marine propulsion device includes a first gear, a second gear, a third gear, a case, a partition wall, and a first flow path. The case includes an internal space in which the first gear, the second gear, and the third gear are located. The partition wall is located between the second gear and the third gear in the internal space. The partition wall partitions the internal space into a first space and a second space. The second gear is located in the first space. The third gear is located in the second space. The first flow path communicates the first space with the second space. The first flow path is located on a same side as the first gear with respect to a center line of the second gear and the third gear.

A multi-plate clutch transmission includes an arrangement for selectively engaging the clutch by moving the sleeve to cause one or more friction disks on a sleeve connected to a shaft to move into contact with one or more friction disks on a clutch basket connected to a gear driven by another gear and another shaft driven by a prime mover. An arrangement for selectively disengaging the clutch is provided that uses prime mover torque to move the one or more friction disks on the sleeve out of contact with the one or more.friction disks on the clutch basket.

A shift device for an outboard motor includes a forward gear and a reverse gear; a clutch gear; a shift actuator configured to move between a neutral reference position where the clutch gear is disengaged from the forward gear and the reverse gear and an engagement reference position where the clutch gear is engaged with the forward gear or the reverse gear; and a control device configured to control a movement of the shift actuator. The control device is configured to set an intermediate target position, and to set a speed at which the shift actuator moves from the intermediate target position to the engagement reference position slower than a speed at which the shift actuator moves from the neutral reference position to the intermediate target position.

An outboard motor includes an oil passage that through which an oil flows from the shift chamber to a gear chamber. A circular recessed portion is formed on an upper surface of the gear chamber. A rectangular recessed portion communicating with the circular recessed portion is formed on a portion of the upper surface adjacent to the circular recessed portion. The rectangular recessed portion includes a front surface facing a side surface of the circular recessed portion, a left surface located on a reverse side of a rotation direction of the drive gear with respect to the front surface, and a right surface located on a side of the rotation direction with respect to the front surface. An outlet of the oil passage is arranged on the front surface at a position closer to the left surface than to the right surface.

A reverse gear includes an input shaft, a forward clutch, a reverse clutch, an output shaft, a reduction mechanism, and a relay shaft. The input shaft receives rotational power of a main engine. The forward clutch transmits the rotational power of the input shaft as forward output. The reverse clutch transmits the rotational power of the input shaft as reverse output. The output shaft outputs the rotational power transmitted via the forward clutch and the reverse clutch. The reduction mechanism reduces the rotational power of the output shaft and transmits the reduced rotational power to the propeller shaft. The relay shaft intersects the input shaft and relays the rotational power from the forward clutch and the reverse clutch toward the output shaft. The relay shaft and the output shaft are coupled to each other via a pair of intersecting-shaft gears to be able to transmit power.

An gear case assembly for a watercraft propulsion system has a gear case housing, a driveshaft with a partially threaded bore defined in an end thereof, and a propeller shaft. The propeller shaft and the driveshaft are angled relative to each other. A bevel gear is mounted to the propeller shaft. A pinion mounted to the end of the driveshaft. The pinion meshes with the bevel gear. The pinion defines a central aperture. A fastener is disposed at least in part in the central aperture of the pinion. The fastener fastens the pinion to the end of the driveshaft. The fastener has a head and a shank. The shank is at least partially threaded. The shank extends into the bore of the driveshaft. An outboard motor having the gear case assembly is also disclosed.

A marine drive includes an output gear including a beveled gear and a hub. A propeller shaft extends through the hub. A first bearing and an adjacent second bearing are located on the hub and support rotation of the output gear. The first and second bearings have inner races and outer races. An inner spacer is located on the hub and sandwiched between the respective inner races of the first and second bearings. An outer spacer is sandwiched between the respective outer races of the first and second bearings. A bearing carrier surrounds the propeller shaft and holds the first and second bearings therein by way of a press fit. The inner and outer spacers and the bearing carrier are dimensionally sized to provide a dimensional preload on the first and second bearings to maintain the output gear in alignment with the propeller shaft during operation of the marine drive.

In an outboard motor, a feed passage, through which a lubricating oil that flows upward from a gear mechanism due to rotation of the gear mechanism, extends upward from a gear chamber and includes a first feed passage that extends from the gear chamber to a connection passage via a first upstream passage, a spiral passage, and an interior of an upper bearing, in that order. The feed passage further includes a second feed passage that extends from the gear chamber to the return passage while bypassing the spiral passage via a bypass passage. The bypass passage includes two ends spaced apart in a circumferential direction of the driveshaft and is disposed around the spiral passage.

The present invention discloses a mechanism that transfers an oscillating rotation into a unidirectional rotation. In one embodiment, the present invention discloses a spur gearing mechanism using spur gears. In another embodiment, the present invention discloses a bevel gearing mechanism using bevel gears, which reduces the total number of gears in comparison to the spur gearing mechanism.