Abstract: A vessel propulsion apparatus includes a dog clutch that selectively engages either a front gear or a rear gear, an intermediate shaft rotatably supported by the front gear and by the rear gear and that rotates together with the dog clutch, a propeller shaft to which rotation of the intermediate shaft is transmitted, a lower case containing a drive gear and other elements, and a thrust transmitting member that receives a forward-direction thrust from the propeller shaft and that transmits the thrust to the lower case without transmitting the thrust to the intermediate shaft.

Abstract: A vessel propulsion apparatus includes a drive shaft that is rotationally driven by a prime mover, a drive gear connected to the drive shaft, a front gear that engages the drive gear, a rear gear that engages the drive gear and that is disposed behind the front gear, a dog clutch that selectively engages one of the front gear and the rear gear, and an oil passage that passes through the inside of the front gear and that guides oil from a forward space in front of the front gear to a rearward space behind the front gear.

Abstract: A vessel propulsion apparatus includes a drive shaft that is rotationally driven by a prime mover, a drive gear connected to the drive shaft, a front gear that engages the drive gear, a rear gear that engages the drive gear and that is disposed behind the front gear, a dog clutch that selectively engages one of the front gear and the rear gear, and an oil passage that passes through the inside of the front gear and that guides oil from a forward space in front of the front gear to a rearward space behind the front gear.

Abstract: A vessel propulsion apparatus includes a dog clutch that selectively engages either a front gear or a rear gear, an intermediate shaft rotatably supported by the front gear and by the rear gear and that rotates together with the dog clutch, a propeller shaft to which rotation of the intermediate shaft is transmitted, a lower case containing a drive gear and other elements, and a thrust transmitting member that receives a forward-direction thrust from the propeller shaft and that transmits the thrust to the lower case without transmitting the thrust to the intermediate shaft.

Abstract: A vessel propulsion apparatus includes a prime mover, a propeller shaft, a planetary gear train, a lower case, a cylindrical housing, and a fixing member. The planetary gear train is disposed on a propeller axis. The propeller shaft and the planetary gear train are housed in the lower case. The housing surrounds the propeller shaft about the propeller axis inside the lower case. The housing supports a sun gear such that the sun gear is not rotatable with respect to the housing. The fixing member is fixed to both the lower case and the housing.

Abstract: A vessel propulsion apparatus includes a prime mover, a drive shaft, a pinion, a rear gear, a propeller shaft, a front bearing, a cylindrical front housing, and a cylindrical rear housing. The front housing surrounds the front bearing about a propeller axis and supports the rear gear via the front bearing in a manner rotatable about the propeller axis. The rear housing is disposed behind the front housing. The front housing surrounds the propeller shaft about the propeller axis and supports the propeller shaft at a position more rearward than the rear gear in a manner rotatable about the propeller axis.

Abstract: A vessel propulsion apparatus includes a prime mover, a drive shaft, a pinion, a rear gear, a propeller shaft, a front bearing, a cylindrical front housing, and a cylindrical rear housing. The front housing surrounds the front bearing about a propeller axis and supports the rear gear via the front bearing in a manner rotatable about the propeller axis. The rear housing is disposed behind the front housing. The front housing surrounds the propeller shaft about the propeller axis and supports the propeller shaft at a position more rearward than the rear gear in a manner rotatable about the propeller axis.

Abstract: A vessel propulsion apparatus includes a prime mover, a propeller shaft, a planetary gear train, a lower case, a cylindrical housing, and a fixing member. The planetary gear train is disposed on a propeller axis. The propeller shaft and the planetary gear train are housed in the lower case. The housing surrounds the propeller shaft about the propeller axis inside the lower case. The housing supports a sun gear such that the sun gear is not rotatable with respect to the housing. The fixing member is fixed to both the lower case and the housing.

Abstract: An outboard motor that facilitates replacement of an impeller of a water pump includes a water pump arranged to pump coolant and a pump driving mechanism arranged to distribute power from a drive shaft to the water pump. At least a portion of the water pump in which an impeller is housed can be detached and attached from the outside of an upper case. The pump driving mechanism distributes power in a direction generally perpendicular to the axial direction of the drive shaft and transmits the power to the water pump.

Abstract: An outboard motor includes a propeller, an engine, a transmission, a casing, an engine cooling mechanism, a cooling jacket, a water intake opening, and a transmission coolant flow channel. The casing is arranged to house the transmission. The engine cooling mechanism is arranged to cool the engine by supplying the water taken into the casing from the water intake opening to the engine via an engine coolant flow channel. The cooling jacket is arranged adjacent to the transmission inside the casing. The water intake opening is provided at a predetermined position of the casing to which a dynamic pressure is applied by water flow when a marine vessel travels. The transmission coolant flow channel is arranged to connect the water intake opening and the cooling jacket. The transmission coolant flow channel is provided independently of the engine coolant flow channel.

Abstract: A boat propulsion unit minimizes a shock upon switching of an engagement state of a clutch mechanism. The boat propulsion unit includes an upper clutch mechanism that is arranged on an axis of a lower drive shaft and that can be switched between an engagement state (first engagement state) in which driving force of an engine is transmitted to a downstream side, and a half clutch state in which the driving force of the engine is reduced and then is transmitted; and an advance-reverse drive that is disposed on an axis of a front propeller drive shaft and a rear propeller drive shaft and that can be switched between a forward travel engagement state and a reverse travel engagement state (second disengagement state) in which the driving force of the engine is transmitted to a front propeller and a rear propeller in order to propel a boat, and a disengagement state (second disengagement state) in which the driving force of the engine is disengaged.

Abstract: A cooling system includes a coolant distributing device arranged to distribute coolant discharged from a water pump to both an engine and a transmission device. The coolant distributing device includes a coolant relay section, an inlet conduit member, an outlet conduit member, and a transmission cooling conduit member, and supplies a portion of the coolant discharged from the water pump to a highest portion of a water jacket of the transmission device, and discharges the water from a lowest portion of the water jacket. The cooling system effectively cools the transmission device with a simple construction facilitating assembly and maintenance.

Abstract: An oil supply device includes an axial oil passage and an intersecting oil passage provided in a propeller shaft, an axial oil passage and an intersecting oil passage provided in a drive shaft, and an oil guide passage. The intersecting oil passages allow oil inside the axial oil passages to be spouted radially of the shaft by centrifugal force generated as the shafts rotate. The oil is then supplied via the oil guide passage to an intermediate speed reduction device. As a result, it is possible to sufficiently lubricate an intermediate speed reduction device mounted on a drive shaft through a simple and compact arrangement.

Abstract: A boat propulsion unit has a construction that prevents a structure near a drive shaft from becoming complicated and increased in size. The boat propulsion unit preferably in the form of an outboard motor includes a front propeller that is rotated together with a front propeller drive shaft during both forward travel and reverse travel of the boat, a rear propeller that is rotated together with a rear propeller drive shaft in an opposite direction of the front propeller during both of the forward travel and the reverse travel of the boat, and a forward-reverse drive that is arranged on an axis of the front propeller drive shaft and the rear propeller drive shaft, and that can be switched between a direction in which the front propeller drive shaft and the rear propeller drive shaft are rotated during the forward travel of the boat and a direction in which the front propeller drive shaft and the rear propeller drive shaft are rotated during the reverse travel of the boat.

Abstract: In an outboard motor, a lower casing is located below an upper casing, and an engine with a vertically-arranged crankshaft is mounted above the upper casing. The rotation of the crankshaft is transmitted to a drive shaft pivotally supported in the upper casing, has its speed changed by a transmission mounted on the drive shaft, and is transmitted to a propeller shaft pivotally supported in the lower casing. The upper casing includes an upper-side casing and a lower-side casing, and mating surface portions of the upper-side casing and the lower-side casing are laterally wider than an upper section and a lower section of the upper casing.

Abstract: A motor including an intake-side conduit member disposed outside a casing that makes a connection between a cooling water intake section of a water pump and an intake hole, and a cooling water relay section provided outside the casing. The cooling water relay section communicates with a cooling water supply passage in the casing. A discharge-side conduit member that is disposed outside the casing connects the cooling water relay section to a cooling water discharge section of the water pump. Additionally, the other end of a transmission cooling conduit member that is branched from the cooling water relay section is connected to a water jacket of the transmission. The conduit members are preferably flexible hose members, for example. Accordingly, this unique construction improves a cooling water piping layout around a water pump, a discharge performance of the water pump, and an assembly workability of a motor.

Abstract: An outboard motor includes a water pump arranged to draw in cooling water, a pump drive mechanism that decelerates rotation of a drive shaft and transmits the rotation to the water pump, and an oil supply device (a main oil passage, oil ejection passages, a hollow portion, and an oil ejection hole) arranged to supply oil to lubricate a transmission to the pump drive mechanism. The outboard motor is able to prevent occurrence of cavitation in a water pump of a vane-type pump and to increase a discharge amount of the pump while an engine is running at high speed.

Abstract: An outboard motor includes a variable speed mechanism portion arranged to transmit a driving force to propellers such that the driving force is changed in its speed by a low reduction ratio and a high reduction ratio, an upper housing that houses the variable speed mechanism portion, oil tanks provided on the outside of the upper housing and arranged to retain oil to be supplied to the upper housing, and an oil lubrication route arranged to supply oil in the oil tanks to the upper housing and to collect the oil supplied in the upper housing in the oil tanks. The above arrangement provides a boat propulsion unit capable of allowing both a performance of acceleration and a maximum speed to approach a level desired by a user and to prevent the occurrence of a loss of the driving energy of an engine.

Abstract: A power transmission system for a marine propulsion unit includes a case arranged to be supported on a hull; a propeller supported at the lower end portion of the case for rotation about an axis extending in a fore-and-aft direction; a transmission housed in the case and having an axis with planetary gear trains extending vertically to receive an output from an engine, and change the speed of the output prior to transmission thereof; and an interlocking device arranged to receive the output from the transmission and transmit the output to the propeller. A speed reduction device is arranged such that it is interposed between the transmission and the interlocking device, receives the output from the transmission, and decelerates the output to transmit it to the interlocking device. This arrangement reduces the weight of a transmission unit in a power transmission system of a marine propulsion unit and decreases an external size of the transmission unit.

Abstract: An outboard motor includes a propeller, an engine, a transmission, a casing, an engine cooling mechanism, a cooling jacket, a water intake opening, and a transmission coolant flow channel. The casing is arranged to house the transmission. The engine cooling mechanism is arranged to cool the engine by supplying the water taken into the casing from the water intake opening to the engine via an engine coolant flow channel. The cooling jacket is arranged adjacent to the transmission inside the casing. The water intake opening is provided at a predetermined position of the casing to which a dynamic pressure is applied by water flow when a marine vessel travels. The transmission coolant flow channel is arranged to connect the water intake opening and the cooling jacket. The transmission coolant flow channel is provided independently of the engine coolant flow channel.