DESCRIPTION OUTBOARD DRIVE WITH MOUNT UNIT

FIELD OF THE INVENTION

[0001] The present invention generally relates to an outboard drive with a mount unit, and πiore particularly relates to an outboard drive with a clamping bracket and a swivel bracket.

BACKGROUND OF THE INVENTION

[0002] Outboard drives such as, for example, outboard motors are mounted to an associated watercraft to propel the watercraft forward or backward. Typically, the outboard motors include a drive unit and a mount unit. The mount unit can be fixed to a transom board for mounting the drive unit on the associated watercraft. The drive unit typically includes an engine atop thereof as a prime mover. The engine includes a crankshaft generally extending vertically as an output shaft of the engine. A driveshaft is coupled with the crankshaft and extends downward from the crankshaft. The crankshaft drives the driveshaft. A propeller shaft is coupled with the driveshaft and can extend generally normal to the driveshaft. Typically, the propeller shaft carries a propulsion device such as, for example, a propeller for generating the thrust. Normally, a casing houses the driveshaft and the propeller shaft.

[0003] Typically, the mount unit includes a clamping bracket and a swivel bracket. The clamping bracket is fixed to the transom board, while the swivel bracket is coupled with the clamping bracket for pivotal movement about a tilt axis extending generally horizontally. The swivel bracket also carries the drive unit for pivotal movement about a steering axis extending generally vertically.

[0004] The clamping bracket and the swivel bracket are usually produced by die- casting or mold casting. For example, JP-A-Sho 55-119592 discloses such a clamping bracket and a swivel bracket. However, the brackets produced by casting are likely to be thick and heavy. It is thus attempted to make them thinner. Although such attempt is made, the brackets cannot be sufficiently thin as expected.

SUMMARY OF THE INVENTION

[0005] A need thus exists for an outboard drive having a clamping bracket and a swivel bracket that can be thinner and lighter than ever.

[0006] To address such needs, in accordance with one aspect of the present invention, an outboard drive includes a drive unit. A clamping bracket is adapted to be mounted to a

transom board of an associated watercraft. A swivel bracket is coupled with the clamping bracket for pivotal movement about a tilt axis extending generally horizontally. The swivel bracket carries the drive unit for pivotal movement about a steering axis extending generally vertically. The clamping bracket includes a first bracket arm and a second bracket arm transversely spaced apart from each other. At least one cross member extends between the first and second bracket arms. The swivel bracket has a first end and a second end. The first end of the swivel bracket is coupled with an end of the first bracket arm for the pivotal movement about the tilt axis. The second end of the swivel bracket is coupled with an end of the second bracket arm for pivotal movement about the tilt axis.

[0007] In accordance with another aspect of the present invention, an outboard drive includes a drive unit. A clamping bracket is adapted to be mounted to a transom board of an associated watercraft. A swivel bracket is coupled with the clamping bracket for pivotal movement about a tilt axis extending generally horizontally. The swivel bracket carries the drive unit for pivotal movement about a steering axis extending generally vertically. The clamping bracket includes a first bracket arm and a second bracket arm transversely spaced apart from each other. At least one cross member extends between the first and second bracket arms. The first and second bracket arms and at least a portion of the swivel bracket are made of sheet metal

BRIEF DESCRgTION OF THE DRAWINGS

[0008] These and other features, aspects and advantages of the present invention are now described with reference to the drawings of preferred embodiments, which are intended to illustrate and not to limit the present invention. The drawings include 16 figures in which:

[0009] FIGURE 1 is a side elevational view (the port side) of an outboard motor configured in accordance with certain features, aspects and advantages of a first embodiment of the present invention, an associated watercraft partially shown; [0010] FIGURE 2 is a top plan view of the outboard motor of FIGURE 1 ; [0011] FIGURE 3 is a rear view of an engine and a fuel tank of the outboard motor of FIGURE 1;

[0012] FIGURE 4 is a partial, side elevational view (the starboard side) of the outboard motor of FIGURE 1, showing a clamping bracket and a swivel bracket, a transom of an associated watercraft shown in phantom;

[0013] FIGURE 5 is a top plan view of the clamping and swivel brackets, the transom shown in phantom;

[0014] FIGURE 6 is a rear view of the clamping and swivel brackets;

[0015] FIGURE 7 is a side elevational view of another outboard motor modified in accordance with certain features, aspects and advantages of a second embodiment of the present invention, an associated watercraft shown in phantom;

[0016] FIGURE 8 is a partial, cross-sectional and side elevational view of the outboard motor of FIGURE 7, showing a steering shaft and a coupling of a crankshaft and a driveshaft with each other;

[0017] FIGURE 9 is a partial, cross-sectional and side elevational view of the outboard motor of FIGURE 7, showing a steering shaft thereof;

[0018] FIGURE 10 is a partial, cross-sectional and side elevational view of the outboard motor of FIGURE 7, showing a lower portion of a casing thereof;

[0019] FIGURE 11 is a cross-sectional view taken along the line 11-11 of FIG. 9;

[0020] FIGURE 12 is a cross-sectional view taken along the line 12-12 of FIG. 9;

[0021] FIGURE 13 is a top plan view of a lower casing, stud bolts shown in section, and some portions of an upper casing shown in phantom;

[0022] FIGURE 14 is an enlarged side elevational view of the outboard motor of

FIGURE 7, showing a clamping bracket and a steering bracket, the associated watercraft and a drive unit of the outboard motor shown in phantom;

[0023] FIGURE 15 is an enlarged top plan view of the outboard motor of FIGURE 7, showing the clamping and swivel brackets; and

[0024] FIGURE 16 is an enlarged rear view of the outboard motor of FIGURE 7, showing the clamping and swivel brackets, and bushings shown separately and in section.

DETAILED DESCRIPTION OF THE INVENTION

[0025] With reference to FIGURES 1-3, an overall structure of an outboard motor 30 which is a preferred embodiment of the present invention will be described below. [0026] The outboard motor 30 merely exemplifies one type of outboard drives. The present invention can apply to other outboard drives whether the drives are called outboard motors or not, such as, for example, stern drives. In other words, a prime mover which is a source of the thrust can be placed above a casing of the outboard drive, or can be placed in an associated watercraft.

[0027] The outboard motor 30 in this embodiment also has a mount unit 32 and a drive unit 34.

[0028] The mount unit 32 supports the drive unit 34 on a transom board 36 of an associated watercraft 38 and places a marine propulsion device such as, for example, a ■ propeller 40 in a submerged position with the watercraft 38 resting relative to a surface of the body of water. The drive unit 34 can be tilted up (raised) or tilted down (lowered) relative to the watercraft 38.

[0029] As used through this description, the terms "forward" and "front" mean at or to the side where the mount unit 32 is located, unless indicated otherwise or otherwise readily apparent from the context used. Also, the terms "rear," "rearward" and "backward" mean at or to the opposite side of the front side.

[0030] Also, as used in this description, the term "horizontally" means that the subject portions, members or components extend generally parallel to the water surface when the watercraft 38 is substantially stationary with respect to the water surface and when the drive unit 34 is not tilted and is generally placed in the position shown in FIGURE 1. The term "vertically" means that portions, members or components extend generally normal to those that extend horizontally.

[0031] Additionally, the arrow FWD of FIGURES 1, 2, 4,: 5, 7-10 and 12-15 indicates the forward direction of the associated watercraft 38.

[0032] The mount unit 32 preferably includes a clamping bracket 44, a swivel bracket 46 and tilt pins 47. The clamping bracket 44 is detachably fixed to the transom board 36 by a pair of clamp screw units 48. The swivel bracket 46 is coupled with the clamping bracket 44 by the tilt pins 47 for pivotal movement about axes of the tilt pins 47 extending generally horizontally.

[0033] The swivel bracket 46 carries the drive unit 34 for pivotal movement about an axis of a steering shaft or support tube 49 extending generally vertically. That is, the steering shaft 49 is a top portion of a casing 50 of the drive unit 34 in this embodiment. A driveshaft 52 extends generally vertically through the steering shaft 49. A bracket body 56 of the swivel bracket 46 through which the steering shaft 49 extends is preferably divided into upper and lower body sections 56a, 56b. Right and left wing sections 58R, 58L (FIGURE 5) extend from the bracket sections 56a, 56b. In the illustrated embodiment, semi-cylindrical portions 60 (FIGURE 5) of the respective upper and lower body sections

56a, 56b are unitarily formed with the wing sections 58R, 58L, as will be described in greater detail later.

[0034] The casing 50 includes an upper casing 62 and a lower casing 64. The upper casing 62 depends from the steering shaft 49 and extends downward. A top end of the upper casing 62 is preferably coupled with a bottom end of the steering shaft 49. The lower casing 64 depends from the upper casing 62 to further extend downward. A top end of the lower casing 64 is preferably coupled with a bottom end of the upper casing 62. The driveshaft 52 continuously extends vertically and entirely through the upper casing 62 and a bottom end thereof reaches the lower casing 64.

[0035] The lower casing 64 has a power transmission gear unit 66 and a propeller shaft 68. The propeller shaft 68 extends generally horizontally and normal to the driveshaft 52. A front end of the propeller shaft 68 is coupled with the bottom end of the driveshaft 52 through the power transmission gear unit 66. The transmission gear unit 66 is preferably formed with a drive bevel gear positioned at the bottom of the driveshaft 52 and a driven bevel gear positioned at the front end of the propeller shaft 68 and meshing with the drive bevel gear of the driveshaft 52. The propeller 40 is fixed to the propeller shaft 68. [0036] _. The drive unit 34 preferably includes a prime mover. In the illustrated embodiment, the prime mover is an internal combustion engine 72. Other prime movers such as, for example an electric motor can replace the engine 72.

[0037] The engine 72 is disposed above the steering shaft 49. That is, a unit housing 74 of a speed reduction unit 76 is fixed to a top end of the steering shaft 49, and the engine 72 is fixed to a top end of the unit housing 74. The speed reduction unit 76 in this embodiment is a planetary gearing mechanism.

[0038] The illustrated engine 72 is an air cooling, single cylinder and four stroke engine. The engine 72 has a crankshaft extending generally vertically. The crankshaft is connected to an input shaft of the speed reduction unit 76, and the input shaft is connected to the driveshaft 52. The rotational speed of the crankshaft is reduced by the speed reduction unit 76. The power of the engine 72 is transmitted to the propeller 40 through the crankshaft, the input shaft of the speed reduction unit 76, the power transmission gear unit 66 and the propeller shaft 68. The propeller 40 thus rotates to generate the thrust. The crankshaft, the speed reduction unit 76, the power transmission gear unit 66 and the propeller shaft 68 together form a power transmission mechanism 78 of the outboard motor 30.

[0039] The engine 72 has an engine body 80. The engine body 80 includes a cylinder unit 82. A combustion chamber of the cylinder unit 82 is preferably disposed at the rearmost end. An air intake pipe 84 is disposed above the cylinder unit 82. An air cleaner 86 is coupled with the intake pipe 84. The intake pipe 84 preferably has a carburetor 88 which can be operated by a throttle valve control mechanism 90. An exhaust pipe 92 is disposed below the cylinder unit 82. A muffler 94 is coupled with the exhaust pipe 92. Exhaust gases are discharged to the atmosphere through the exhaust pipe 92 and the muffler 94.

[0040] The throttle valve control mechanism 90 can move a throttle valve of the carburetor 88 between an open position and a closed position. The throttle valve control mechanism 90 preferably includes a throttle lever 98, a first throttle rod 100, a second throttle rod 102, a support link 104, an operational link 106 and an operational shaft 108. [0041] ₍ A plate 112 is fixed to the engine body 80 on the left side (port side) by bolts 114. The plate 112 supports the throttle lever 98 for pivotal movement about a pivot axis 116. One end of the first throttle rod 100 is connected to the throttle lever 98, while the other end of the first throttle rod 100 is connected to the support link 104. Also, one end of the second throttle rod 102 is connected to the support link 104, while the other end of the second throttle rod 102 is connected to the operational link 106; The operational link 106 is fixed to the operational shaft 108.

[0042] When the throttle lever 98 is pulled forward, through the first throttle rod 100, the support link 104, the second throttle rod 102 and the operational link 106, the operational shaft 108 pivots in a direction in which the throttle valve moves toward the open position. Meanwhile, when the throttle lever 98 is returned to its initial position, the operational shaft 108 pivots in a reverse direction in which the throttle valve moves toward the closed position.

[0043] The plate 112 preferably has a stopper 118 which limits a range of the pivotal movement of the throttle lever 98. That is, when a hooked portion 120 of the throttle lever 98 abuts the stopper 118, the throttle lever 98 is prevented from being further pulled. A support section 122 which is unitarily formed with the intake pipe 84 supports the support link 104 for rotation.

[0044] A fuel tank 126 is preferably disposed above the engine body 80. A rear portion of the fuel tank 126 is supported by the engine body 80 through a right and left pair of stays 128 which is fixed to lateral sides of the engine body 80. A front portion of the fuel tank

126 is supported by a flywheel magneto cover 130 of the engine body 80 through a front stay 134 fixed to the flywheel magneto cover 130. A certain space 138 is preferably defined between the fuel tank 126 and the engine body 80 including the flywheel magneto cover 130.

[0045] A starter handle grip 140 for a recoil starter 142 protrudes forward from a front surface of the flywheel magneto cover 130. The operator of the outboard motor 30 simply pulls the starter handle grip 140 to start the engine operation.

[0046] Each of the right and left stays 128 is generally shaped as the letter "L." A vertically extending portion 146 of each stay 128 is fixed to the lateral side wall of the engine body 80 by bolts 148. A rearward extending portion 150 of each stay 128 has a bracket 152 welded thereto. The fuel tank 126, on the other hand, has flanges 156 extending outward on both the right and left sides. Each flange 156 of the fuel tank 126 is fastened to the bracket 152 of the respective stay 128 by a bolt 158.

[0047] Preferably, the front stay 134 extends transversely in front of the fuel tank 126 and is welded to a top front portion of the flywheel magneto cover 130. The fuel tank 126 preferably has a pair of front flanges 160 spaced apart from each other, the front flanges

160 are fastened to the front stay 134 by bolts 162. .

[0048] The fuel tank 126 has a cap 166 atop thereof. The fuel tank can be filled with fuel by removing the cap 166.

[0049] As shown in FIGURES 2 and 3, a fuel cock 168 is disposed at a lower portion of the fuel tank 126 on the right side. When the fuel cock 168 is opened, the fuel in the fuel tank 126 is supplied to the carburetor 88 through a fuel supply pipe 170.

[0050] As shown in FIGURE 1, a handle bar bracket 174 is preferably positioned at a bottom portion of the engine body 80 on the left side. The handle bar bracket 174 is fastened thereto by bolts 176. A manually operable steering handle bar 178 is attached to the handle bar bracket 174 for pivotal movement about a pivot axis 180. A position of the steering handle bar 178 is adjustable between a fully extended position and a fully retracted position using an arcuately extending slot 182 and a bolt 184 both placed at a base section

186 of the steering handle bar 178. For example, the steering handle bar 178 is placed at the fully extended position by fastening the bolt 184 at the position indicated in FIGURE 1 when the operator steer the outboard motor 30. Meanwhile, the steering handle bar 178 is placed at the fully retracted position by fastening the bolt 184 at the opposite position in the slot 182 when the outboard motor 30 is not operated. When the operator moves the steering

handle bar 178 rightward or leftward, the steering shaft 49 pivots to direct the propeller 40 leftward or rightward.

[0051] In the illustrated embodiment, a front end 188 of the swivel bracket 46 abuts stoppers 190 fixed to the clamping bracket 44, and the swivel bracket 46 can be tilted up ^■ about the axis of the tilt pin 47 from the abutting position. FIGURE 1 shows the outboard motor 30 is in a forward mode. If the operator desires to change the outboard motor 30 to a reverse mode (backward moving mode), the operator rotates the drive unit 34 about the steering axis so as to bring the backside of the drive unit 34 directing forward. Preferably, the drive unit 34 has a hook 192 fixed to the steering shaft 49, while the clamping bracket 44 has a support member 194 fixed thereto. The hook 192 engages with the support member 194 to prevent the drive unit 34 from being raised up by the thrust of the propeller 40.

[0052] The illustrated outboard motor 30 has no cowling that can surround the engine 72 and the fuel tank 126. Thus, seawater or water can splash on them. The outboard motor 30, however, can be easily washed by fresh water. In addition, because the space 138 is defined between the engine 72 and the fuel tank 126, the top of the engine 72 and the bottom of the fuel tank 126 also can be easily washed.

[0053] As discussed above, the illustrated outboard motor 30 has the right and left stays 128. The operator thus can easily tilt the drive unit 34 about the axis of the tilt pin 47 by pulling the right and left stays 128 forward. This is quite advantageous because the propeller 40 needs to be almost out of the water body whenever the watercraft 38 moves in shallow water.

[0054] In the illustrated embodiment, the axis of the tilt pin 47 is positioned in the rear of the transom board 36 and is placed lower than a top end 196 of the transom board 36. Thus, the distance Ll between the axis of the tilt pin 47 and the center of gravity G of the outboard motor 30 is shortened. The load of the drive unit 34 under the tilt up condition can be greatly reduced. Therefore, the operator can easily pulls the engine 72 forward by hands to tilt up the drive unit 34.

[0055] With reference to FIGURES 1 and 4-6, the mount unit 32 of the outboard motor 30 will be described in greater detail below.

[0056] The clamping bracket 44 preferably includes a right bracket arm 198R and a left bracket arm 198L which are transversely spaced apart from each other. The right bracket arm 198R is positioned on the starboard side, while the left bracket 198L is positioned on

the port side. Preferably, each bracket arm 198R, 198L is made of iron sheet metal and is produced by pressing. In comparison with bracket arms made of aluminum alloy and produced by casting, the iron material is less expensive than the aluminum alloy material and pressing is easier than casting. The production costs thus can be reduced. [0057] As best shown in FIGURE 4, each bracket arm 198R, 198L is generally formed like the reversed letter "U" so as to straddle the transom board 36 of the associated watercraft 38. That is, each bracket arm 198R, 198L preferably includes a straddling section 200, a front section 202, a rear section 204 and an abutting section 206. [0058] The abutting section 206 protrudes outward from the rear section 204 and can abut a rear surface 207 of the transom board 36. As best shown in FIGURE 6, the illustrated abutting section 206 generally has a rectangular shape so as to form a certain abutting area.

[0059] Front and rear cross members 208, 210 connect the respective bracket members 198R, 198L to each other. The front and rear cross members 208, 210 are preferably made of sheet metal. The front cross member 208 extends between the front sections 202 of the respective bracket arms 198R, 198L. Lateral ends of the front cross member 208 are preferably welded to inner surfaces of the respective bracket arms 198R, 198L. As shown in FIGURES 4 and 6, in the illustrated embodiment, a bottom end portion of , the rear section 204 of each bracket arm 198R, 198L has an aperture 212.

[0060] The rear cross member 210 is preferably a relatively narrow plain plate extending transversely. The rear cross member 210 has projections 214 corresponding to the respective apertures 212. The projections 214 are inserted into the apertures 212 to temporarily connect the rear sections 204 to each other. The rear cross member 210 can be rigidly connected to the bracket arms 198R, 198L when the swivel bracket 46 is coupled with the respective bracket arms 198R, 198L as ¹ will be described in greater detail later. [0061] In the illustrated embodiment, the front and rear cross members 208, 210 are spaced apart in a fore to aft direction of the watercraft 38. Preferably, the front and rear cross members 208, 210 can interpose the transom board 36 of the watercraft 38 therebetween when the outboard motor 30 is mounted to the transom board 36. [0062] As discussed above, the respective bracket arms 198R, 198L, the front cross member 208 and the rear cross member 210 can form a framework in which the respective components 198R, 198L, 208, 210 are rigidly coupled with each other.

[0063] More specifically, the front cross member 208 is generally formed like the letter "U," and has a rear section 218, a top section 220 and a bottom section 222. The rear section 218 is preferably in contact with a front surface 224 of the transom board 36. [0064] The front cross member 208 preferably has the clamp screw units 48. The ^• clamp screw units 48 are transversely spaced apart from each other. Each clamp screw unit 48 preferably includes a clamp screw 228, a dish-like shaped press member 230 and a handle lever 232. A tip (rear end) 234 of the clamp screw.228 rotatably extends through the press member 230. A front end 236 of the clamp screw 228 has the handle lever 232. The handle lever 232 is pivotable about an axis of a holding pin 238 in a certain angular range. Each clamp screw 228 extends through an aperture 240 having an inner diameter which is slightly larger than an outer diameter of the clamp screw 228. A nut 244 is fixed to a rear surface 246 of the rear section 218 in contact with the front surface 224 of the transom board 36 in such a manner that a center axis of the nut 244 coincides with an axis of the aperture 240. Preferably, the nut 244 is welded to the front cross member 208. The clamp screw 228 is screwed into the nut 244.

[0065] In the illustrated embodiment, the clamping bracket 44 is mounted to the transom _. board 36 so that the straddling section 2OQ is put on the top end 196 of the transom board 36. Under this condition, the abutting section 206 is positioned in the rear of the transom board 36, while the clamp screws 228 are positioned in front of the transom board 36.

[0066] When the handle levers 232 of the respective clamp screws 228 are rotated in a fastening direction of each clamp screw 228 with the associated nut 244, the clamp screws 228 moves rearward and the press members 230 abut and press the front surface 224 of the transom board 36. Simultaneously, the abutting sections 206 also abut and press the rear surface 207 of the transom board 36 by the reaction force. The clamping bracket 44 thus is rigidly fixed to the transom board 36.,

[0067] Meanwhile, when the handle levers 232 are rotated in a loosening direction of each clamp screw 228 with the associated nut 244, the clamp screws 228 moves forward and the press members 230 leave the front surface 224 of the transom board 36. Simultaneously, the abutting sections 206 also leave the rear surface 207 of the transom board 36. The clamping bracket 44 thus is loosened and is removable from the transom board 36.

[0068] The abutting section 206 is preferably formed with a portion of the rear section 204 of each bracket arm 198R, 198L which originally extends in the same direction of the rest part of the rear section 204 and is bent normal to the rest part thereof so as to protrude outward. Because the illustrated abutting sections 206 protrude outward, a distance L2 between the respective lateral ends of the abutting sections 206 is long enough as shown in FIGURE 5. A load, i.e., reaction force, given to the clamping bracket 44 from the transom board 36 when the watercraft 38 turns rightward or leftward can be certainly received by the abutting sections 206.

[0069] Because of the arrangement discussed above, both of the clamp screw units 48 are positioned between the respective abutting sections 206. Thus, when the press members 230 press the transom board 36, the right and left bracket arms 198R, 198L can be certainly fixed to the transom board 36.

[0070] Because each abutting section 206 can abut the rear surface 207 with the relatively broad area in this embodiment, the sufficient contact pressure can be obtained without damaging the transom board 36. [0071] The clamp screw units 48 are constructed as described above. Because of such a structure of the clamp screw unit 48, no portions of the clamping bracket 44 need to have any complicated work or to be specifically changed in shape, the clamp screw units 48 in this embodiment can contribute to reducing production costs.

[0072] In addition, the fastening force of each clamp screw 228 can be received by the rear section 218 of the front cross member 208 via the nut 244 in this embodiment. No force thus can affect the joint of the nut 244 to the front cross member 208 (i.e., welded portion). Any deterioration of the reliability which may occur by lack of rigidity can be avoided.

[0073] A front surface 252 of the rear cross member 210 is in contact with the rear surface 207 of the transom board 36. As best shown in FIGURE 5, the support member 194 is attached to a center portion of the rear cross member 210 by bolts 254. More specifically, the support member 194 is preferably made of sheet metal and is produced by pressing to have an attaching portion 256 and a support portion 258. The attaching portion 256 and the support portion 258 together form the letter "L." The attaching portion 256 arcuately extends in the transverse direction. A center of the arc is positioned in the rear of the body of the support member 194. The attaching portion 256 is mounted to a top surface

260 of the rear cross member 210 and is fixed thereto by the bolts 254. Alternatively, the support member 194 can be unitarily formed with the rear cross member 210 by pressing. [0074] As noted above, the semi-cylindrical portions 60 of the respective upper and lower body sections 56a, 56b are unitarily formed with the wing sections 58R, 58L. In other words, the right and left wing sections 58R, 58L extend from lateral ends of the semi- cylindrical portions 60 of the respective upper and lower body sections 56a, 56b. That is, the right and left wing sections 58R, 58L and the semi-cylindrical portions 60 of the upper and lower body sections 56a, 56b generally form the letter "U," although a center thereof projects forward.

[0075] In order to complete a cylindrical shape of each body section 56a, 56b, upper and lower semi-cylindrical members 262a, 262b are coupled with upper and lower portions 264a, 264b of the wing sections 58R, 58L, respectively. More specifically, each semi- cylindrical member 262a, 262b has flanges 266 extending outward on both sides thereof. Bolts 268 fasten the flanges 266 to portions of the right and left wing sections 58R, 58L adjacent to the semi-cylindrical portions 60. [0076] Preferably, the components of the swivel bracket 46, i.e., the right and left wing sections 58R, 58L, the semi-cylindrical portions 60 of the upper and lower bracket body sections 56a, 56b unitarily formed with the wing sections 58R, 58L, and ,the upper and lower semi-cylindrical member 262a, 262b, are made of iron sheet metal and are produced by pressing. Similarly to the bracket arms 198R, 198L, the iron material is less expensive than an aluminum alloy material and the pressing is easier than casting. The production costs thus can be reduced.

[0077] As best shown in FIGURE 5, an upper and front end of each wing section 58R, 58L preferably has a pin support portion 272. Preferably, each pin support portion 272 has an aperture 274. A bushing 276 fits in the aperture 274. A rear end portion of the rear section 204 of each bracket arm 198R, 198L also has an aperture 278. Each rear end portion of the rear section 204 is set onto the front end of the respective wing section 58R, 58L in such a manner that the apertures 274, 278 coincide with each other with the bushing 276 interposed therebetween. Each tilt pin 47 extends through the apertures 274, 278 and an aperture of the bushing 276. A nut 280 is screwed onto each tilt pin 47. The swivel bracket 46 thus is coupled with the clamping bracket 44 for pivotal movement about the axes of the respective tilt pins 47 extending horizontally.

[0078] As shown in FIGURE 6, each bracket arm 198R, 198L has the stopper 190. Each stopper 190 preferably has a threaded end extending through an aperture of the bracket 198R, 198L. A nut 284 is screwed onto the threaded end of each stopper 190 so that the stopper 190 is fixed to the bracket arm 198R, 198L. Front ends of the wing sections 58R, 58L of the swivel bracket 46 can abut the stoppers 190 under a normal operating condition of the outboard motor 30. The drive unit 34 thus can generally extend vertically. The stoppers 190 receive the thrust of the propeller 40 and the watercraft 38 can move forward because the thrust is transmitted to the transom board 36 through the clamping bracket 44.

[0079] The respective upper and lower body sections 56a, 56b of the bracket body 56 of the swivel bracket 46 contain a circular bushing 286. In the illustrated embodiment, the bushing 286 is divided into two pieces 286a, 286b. The respective bushings 286 positioned in the upper and lower body sections 56a, 56b support the steering shaft 49 for pivotal movement about the steering axis extending vertically.

[0080] Each semi-cylindrical member 262a, 262b preferably has a notch 288. Meanwhile, each bushing 286 has a recess 290. The notch 288 fits in the recess 290. The bushing 286 thus is prevented from rotating relative to the associated semi-cylindrical member 262a, 262b. Accordingly, the steering shaft 49 can certainly pivot, relative to the bushings 286, i.e., to the swivel bracket 46.

[0081] As discussed above, in the illustrated embodiment, the major part of the swivel bracket 46 is formed with the right and left wing sections 58R, 58L unitarily formed with each other through the upper and lower semi-cylindrical portions 60, the upper and lower semi-cylindrical members 262a, 262b, and the upper and lower bushings 286. That is, in general, relatively large stress affects the upper and lower portions of the swivel bracket 46. Because the body sections 56a, 56b are placed at the upper and lower portions to bear the stress and the rest portion interposed therebetween has nothing but a space, the outboard motor 30 can be lighter in weight and its production costs can be reduced. [0082] With reference to FIGURES 4 and 5, the upper casing 62 preferably has a flange 294 at a top end thereof. The hook 192 is fastened to the flange 294 by bolts 296. The hook 192 is made of, for example, iron sheet metal and is produced by pressing. The hook 192 preferably has an attaching portion 300 and a hook portion 302 turning generally at a right angle to the attaching portion 300. The attaching portion 300 is fixed to the flange

294 so that the hook portion 302 extends upward. The hook portion 302 is arcuately shaped in a top plan view.

[0083] When the outboard motor 30 is in a backward thrust mode, i.e., the drive unit 34 is turned 180 degrees from its initial position shown in FIGURES 1 and 4 relative to the mount unit 32, the hook portion 302 of the hook 192 engages with the support portion 258 of the support member 194. The drive unit 34 thus can be prevented from being raised up by the thrust of the propeller 40.

[0084] As shown in FIGURES 4-6, the outboard motor 30 preferably has a tilt lock unit 306 which can limit a tilt position of the drive unit 34. Preferably, the tilt lock unit 306 includes a tilt lock hook 308, a tilt lock lever 310 and a coil spring 312. [0085] The illustrated tilt lock hook 308 is preferably fixed to an upper portion of the right wing section 58R of the swivel bracket 46 by bolts 316 and nuts 318. A top end 320 of the tilt lock hook 308 turns rearward to form a hook end. The tilt lock hook 308, however, can be unitarily formed with the right wing section 58R of the swivel bracket 46. [0086] The tilt lock lever 310 preferably has a hoop 324 at an end positioned closer to the tilt lock hook 308 and a grip 326 at the other end. The tilt lock lever 310 also has a pivot shaft 328 at a center thereof and between the hoop 324 and the grip 326. The pivot shaft 328 is preferably welded to the lever 310. The pivot shaft 328 is inserted into a collar 330 which is fixed to the top section 200 of the right bracket arm 198R. A tip 333 of the pivot shaft 328 is threaded. A lock piece 332 is put on the tip. and a nut 334 is then screwed onto the threaded end to fasten the pivot shaft 328 carrying the lock piece 332. The coil spring 312 is wound around the collar 330. One end 338 of the coil spring 312 is inserted into a lock hole 340 of the lock piece 332, while the other end 342 of the coil spring 312 is inserted into a lock hole 344 of the tilt lock lever 310. Thus, the tilt lock lever 310 is attached to the clamping bracket 44 for pivotal movement about an axis of the pivot shaft 206. Normally, the coil spring 312 urges the tilt lock lever 310 to pivot counterclockwise in the view of FIGURE 4.

[0087] The tilt lock lever 310 can take a lock position and an unlock position. The coil spring 312 in this embodiment acts as a holding member that holds the tilt lock lever 310 in the lock position.

[0088] More specifically, the operator of the outboard motor 30 may want to hold the drive unit 34 in a tilted up position, for example, when the watercraft 38 moves in shallow water. While being tilted up, the drive unit 34 pivots clockwise about the axis of the tilt pin

47 in the view of FIGURE 4, the top end 320 of the tilt lock hook 308 touches the hoop 324 of the tilt lock lever 310. The top end 320 of the tilt lock hook 308 pushes the hoop 324 and the tilt lock lever 310 pivots clockwise about the axis of the pivot shaft 328 against the urging force of the coil spring 312. Then, the top end 320 of the tilt lock hook 308 enters . the hoop 324, and the coil spring 312 again urges the tilt lock lever 310 to pivot counterclockwise, i.e., holds the tilt lock lever 310 in the lock position. The tilt lock lever 310 thus keeps the drive unit 34 in the tilted position.

[0089] On the other hand, when the watercraft 38 emerges from the shallow water, the operator desires to tilt down the drive unit 34. The operator pushes the grip 326 downward to pivot the tilt lock lever 310 clockwise. The top end 320 of the tilt lock hook 308 thus can slip off from the hoop 324 of the tilt lock lever 310. The tilt lock lever 310 releases the drive unit 34. Therefore, the drive unit 34 pivots counterclockwise to the initial position (i.e., tilted down position) by its own weight until the front ends 188 of the wing sections 58R, 58L abut the stoppers 190. The outboard motor 30 thus returns to the normal running condition.

[0090] With reference to FIGURES 7-17, another outboard motor 430 modified in accordance with a second embodiment of the present invention will be described below. [0091] The outboard motor 430 preferably has a mount unit 432 and a drive unit 434. [0092] The mount unit 432 supports the drive unit 434 on a horizontal board 436 extending rearward from a transom of an associated watercraft 438 and places a marine propulsion device such as, for example, a propeller 440 in a- submerged position with the watercraft 438 resting relative to a surface 442 of the body of water. The drive unit 434 can be tilted up (raised) or tilted down (lowered) relative to the watercraft 438. [0093] The mount unit 432 preferably includes a clamping bracket 444, a swivel bracket 446 and a tilt pin 447. The clamping bracket 444 is detachably fixed to the horizontal board 436 by bolts (fasteners 600). The swivel bracket 446 is coupled with the clamping bracket 444 by the tilt pin 447 for pivotal movement about an axis of the tilt pin 447 extending generally horizontally. Additionally, the tilt pin 447 acts as a cross member in this embodiment.

[0094] The swivel bracket 446 carries the drive unit 434 for pivotal movement about an axis of a steering shaft 448 extends generally vertically. That is, the steering shaft 448 is a top portion of a casing 450 of the drive unit 434 in this embodiment. The steering shaft 448 preferably has a cylindrical shape. A driveshaft 454 extends through the steering shaft 48.

[0095] The drive unit 34 preferably includes an internal combustion engine 452. The engine 452 in this embodiment is an air cooling, single cylinder and four stroke engine. Alternatively, the engine can be water cooling type and can have more cylinders and further . can be two stroke engine.

[0096] The drive unit 434 also includes an upper casing 456, a lower casing 458, a speed reduction unit 460 and the propeller 440. The engine 452 is disposed atop of the drive unit 434. The upper casing 456 depends from the steering shaft 448 and extends downward. A top end of the upper casing 456 is preferably coupled with a bottom end of the steering shaft 448. The lower casing 458 depends from the upper casing 456 to further extend downward. A top end of the lower casing 458 is preferably coupled with a bottom end of the upper casing 456.

[0097] As shown in FIGURE 8, the speed reduction unit 460 preferably has a planetary gearing mechanism 464 within a unit housing 466 thereof. The planetary gearing mechanism 464 can be a conventional one and thus is not described in detail. The unit housing 466 is fixed to a top end of the steering shaft 448. The planetary gearing mechanism 464 reduces an output speed of the engine 452 and transmits the reduced speed to the driveshaft 454.

[0098] As shown in FIGURE 8, the engine 452 has a crankshaft 468 extending generally vertically. The crankshaft 468 is the output shaft of the engine. In the illustrated embodiment, a bottom end of the crankshaft 468 is coupled with a top end of the driveshaft 454 through the planetary gearing mechanism 464; The crankshaft 468, an input shaft 470 of the planetary gearing mechanism 464 and the driveshaft 454 together have a common axis 472 about which they rotate.

[0099] As still shown in FIGURE 8, the engine 452 has an oil pan 476 positioned below a crankcase 478 thereof. The crankcase 478 journals the crankshaft 468. The oil pan 484 contains lubricant 477 which can lubricate portions of the engine 452. In the illustrated embodiment, the engine 452 employs a wet sump lubrication system. [00100] The engine 452 also has an air intake device (not shown) for introducing ambient air into a combustion chamber, a fuel supply device (not shown) for supplying fuel which burns with the air in the combustion chamber and generates the power of the engine 452. As shown in FIGURE 7, the engine 452 also has an exhaust device 480 for discharging exhaust gases from the combustion chamber. The illustrated exhaust device 480 generally extends downward from a rear portion of the engine 452. The exhaust device

480 includes a muffler 482 which has a discharge pipe 484 that opens downward. The exhaust gases are discharged to the atmosphere through the discharge pipe 484 as indicated by the arrow 486 of FIGURE 7.

[00101] As shown in FIGURE 10, a propeller shaft 488 preferably extends generally horizontally within the lower casing 458. That is, an axis 490 of the propeller shaft 488 in this embodiment extends normal to the driveshaft 454.

[00102] The propeller shaft 488 carries the propeller 440. The illustrated propeller 440 has a boss 492 and three blades 494 extending from an outer surface of the boss 492 generally in radial directions. The boss 492 is coupled with the propeller shaft 488 by a fastener such as, for example, a nut 495 which is coupled with a threaded rear end of the propeller shaft 488.

[00103] Preferably, a drive bevel gear 496 is attached to a bottom end of the driveshaft 454, while a driven bevel gear 498 is attached to a front end of the propeller shaft 488. The drive and driven bevel gears 496, 498 can mesh with each other. The rotation of the driveshaft 454 is transmitted to the propeller shaft 448 through the drive and driven bevel gears 496, 498 when the bevel gears mesh with each other. The propeller 440 rotates and generates the thrust, accordingly.

[00104] The drive and driven bevel gears 496, 498 in this embodiment function as power transmission members. Preferably, the drive bevel gear 496 and the driven bevel gear 498 have the same configuration and size as one another. This is advantageous because managements of those bevel gears such as, for example, a storage management can be easier.

[00105] In the illustrated embodiment, a bottom end of the driveshaft 454 has spline teeth 499. Also, the front end of the propeller shaft 448 has spline teeth 500. The drive bevel gear 496 and the driven bevel gear 498 thus are coupled with the driveshaft 454 and the propeller shaft 488 by spline connections, respectively.

[00106] The outboard motor 430 can have a steering bar or the like for pivoting the drive unit 434 about the axis 472, which is also a steering axis in this embodiment, to make a right or left turn of the watercraft 438, although the steering bar is not shown. The illustrated outboard motor 430, however, has no advance direction change mechanism. If the operator of the outboard motor 430 desires to move the watercraft 438 backward, the operator simply pivots the drive unit 434 to place the propeller 440 in front of the axis 472.

[00107] With reference to FIGURES 7-13, the outboard motor 430 will be described in greater detail below.

[00108] As shown in FIGURE 8, the crankcase 478 supports the bottom end of the crankshaft 468 for rotation via a bearing 502. In the illustrated embodiment, the crankshaft 468 is coupled with the input shaft 470 of the planetary gearing mechanism 464 through a spline connection. Also, the driveshaft 454 is coupled with a component of the planetary gearing mechanism 464 through another spline connection. The steering shaft 448 and the upper casing 456 define an inner space 504. The driveshaft 454 extends through the inner space 504.

[00109] The steering shaft 448 in this embodiment is also an upper coupling member which couples a top end of the upper casing 456 with a bottom end of the unit housing 466 of the planetary gearing mechanism 464. The upper casing 456 also has a lower coupling member 506 which couples a bottom end of the upper casing 456 with a top end of the lower casing 458.

[00110] As shown in FIGURE 11, the body of the steering shaft 448 has a circular shape in section. On the other hand, as shown in FIGURE 12, the upper casing 456 has an elliptic shape in section and the major axis thereof extends fore to aft.

[00111] Preferably, the steering shaft (the upper coupling member) 448, and the lower coupling member 506 are made of aluminum alloy and are produced by casting. On the other hand, the upper casing 456 is preferably made of aluminum alloy and is preferably produced by extruding. This is because the upper casing 456 in this embodiment is a simple tubular member. Respective axes of the steering shaft (upper coupling member) 448, the upper casing 456 and the lower coupling member 506 coincide with the axis 472 when they are coupled with each other.

[00112] As shown in FIGURES 8 and 9, the steering shaft 448 preferably has a top flange 508, a bottom flange 510 and a tubular bottom section 512. The top flange 508 is positioned atop of the body of the steering shaft 448, while the bottom flange 510 is positioned at a bottom of the body of the steering shaft 448. The tubular bottom section 512 extends downward from the bottom flange 510. The tubular bottom section 512 has an elliptic shape which is consistent with the elliptic shape of the upper casing 456. [00113] As shown in FIGURE 8, a bottom end of the housing 466 of the planetary gearing mechanism 464 also has a flange 514. The top flange 508 of the steering shaft 448 is coupled with this flange 514 by bolts 516 so that the steering shaft 448 is fixed to the unit

housing 466 of the planetary gearing mechanism 464. Meanwhile, the tubular bottom section 512 is inserted into the top end of the upper casing 456 until the bottom flange 510 abuts the top surface of the upper casing 456. Fasteners such as, for example, rivets 518 . then fasten the tubular bottom section 512 to the top end of the upper casing 456. Thereby, the upper casing 456 is coupled with the unit housing 466 of the planetary gearing mechanism 464. Under the condition, a bearing 522 positioned in the unit housing 466 of the planetary gearing mechanism 464 supports a top end of the driveshaft 454 for rotation together with the input shaft 470 of the planetary gearing mechanism 464. [00114] As shown in FIGURE 10, the lower coupling member 506 preferably has a top flange 524, two bottom flanges 526a, 526b each having a through-hole, a tubular top section 528 and a cylindrical bottom section 529. The tubular top section 528 is positioned atop of the body of the lower coupling member 506 and extends upward from the top flange 524. The top flange 524 preferably elliptically shaped. The illustrated bottom flanges 526a, 526b, however, are formed at front and rear portions of the body so as to extend forward and rearward, respectively. The cylindrical bottom section 529 extends downward below , the bottom flanges 526a.

[00115] The tubular top section 528 is inserted into the bottom end of the upper casing 456 until the top flange 524 abuts the bottom surface of the upper casing 456. Similarly to the steering shaft (upper coupling member) 48, fasteners such as, for example, rivets 530 fasten the tubular top section 528 to the bottom end of the upper casing 46. Under the condition, the cylindrical bottom section 526a embraces a bearing 532, and the bearing 532 supports a bottom end of the driveshaft 454 for rotation together with the drive bevel gear 496.

[00116] The lower casing 458 is generally shaped like a torpedo. As shown in FIGURE 10, the lower casing 458 in the illustrated embodiment includes a front section 534 and a rear section 536. Preferably, the front and rear sections 534, 536 are made of aluminum alloy and are produced by casting (preferably, by die-casting).

[00117] The front section 534 has an internal cavity 540 which has an upward opening 542 and a rearward opening 544. The upward opening 542 is directed upward and has a circular shape as shown in FIGURE 13.

[00118] The rear section 536 forms a propeller shaft housing and has a front portion inserted into the rearward opening 544 of the front section 534. The rear section 536 also has a flange 546 and is coupled with the front section 534 at the flange 546 by bolts 548.

The front portion embraces a bearing 550, and the bearing 550 supports the front end of the propeller shaft 488 for rotation together with the driven bevel gear 498. [00119] The boss 492 of the propeller 440 has a recess 552 directed forward. A rear portion of the rear section 536 which is located rearward of the flange 546 is inserted into the recess 552. An inner diameter of the recess 552 is much larger than an outer diameter of the rear portion of the rear section 536. The rear portion of the rear section 536 also embraces a bearing 554 supporting a mid portion of the propeller shaft 488 for rotation. In this embodiment, almost a half portion of the bearing 554 is placed in the recess 552 of the boss 492.

[00120] According to the structure, the propeller boss 492 can be placed at a forward position more than ever without shortening the propeller shaft 488. Thus, the outboard motor 430 can be compact enough. In addition, because the propeller shaft 488 does not need to be shortened, the propeller shaft 488 can sufficiently keep its strength. The propeller shaft 488, thus does not need to be thicker, and the weight of the propeller shaft 488 does not increase.

[00121] In one variation, the entire part of the bearing 554 can be placed in the recess 552 of the boss 492.

[00122] The illustrated bearing 554 receives the thrust of the propeller 440 via the propeller shaft 488 and transmits the thrust to the lower casing 458. More specifically, the propeller shaft 488 has a large diameter portion 558 having a surface 560 in contact with the bearing 554 in an axial direction of the propeller shaft 488. Also, the bearing 554 has a surface 562 in contact with an inner surface 564 of the lower casing 458 in the axial direction of the propeller shaft 488. This is because a portion 566 of the rear section (driveshaft housing) 536 has an inner diameter narrower than an inner diameter of the portion embracing the bearing 554. Thus, the portion 566 functions as a stopper that prevents the bearing 554 from moving forward. Also, the large diameter portion 558 of the propeller shaft 488 functions as a stopper that prevents the propeller shaft 488 from moving forward. In other words, the thrust of the propeller 440 is transmitted to the lower casing 458 through the propeller shaft 488 and the bearing 554.

[00123] Because of this structure, only the rear portion of the propeller shaft 488 including the large diameter portion 558 needs to receive the thrust of the propeller 440. In other words, the front portion of the propeller shaft 488 is almost released from the thrust of the propeller 440. Thus, even though the front portion of the propeller shaft 488 is

shortened, the propeller shaft 488 can keep the necessary strength. Thereby, the lower casing 458 can be more compact.

[00124] Circular seal members 568 preferably are interposed between the large diameter portion 558 of the propeller shaft 488 and an inner surface of the. lower casing 458 at the rearmost end thereof. The rearmost end defines the rear opening of the lower casing 458. The large diameter portion 558 is closer to the propeller 440 than the front end portion of the propeller shaft 488 that has the spline teeth 500. An inner diameter of each seal member 568 is larger than an outer diameter of the front end portion of the propeller shaft 488. [00125] In such a structure, when the propeller shaft 488 is placed in the lower casing 458, the propeller shaft 488 is inserted into the internal cavity 540 from the rear opening where the seal members 568 are positioned. However, because the inner diameter of each seal member 568 is larger than the outer diameter of the front end of the propeller shaft 488, the spline teeth 500 of the front end scarcely harm the seal members 568. [00126] The lower casing 458 preferably has two stud bolts 570a, 570b which are formed at front and rear portions in a circular periphery around the upward opening 542. As shown in FIGURE 13, the stud bolts 570a, 570b thus are spaced apart from each other along the axis 490 of the propeller shaft 488. The stud bolts 570a, 570b also positioned corresponding to the through-holes of the bottom flanges 526a,- 526b of the lower coupling member 506 and extend upward along the axis 472 of the driveshaft 454. [00127] The upper casing 456 is sub-assembled with the lower coupling member 506 so as to support the bottom end of the driveshaft 454 together with the drive bevel gear 496 via the bearing 532 for rotation. ^■ That is, as noted above, the lower coupling member 506 is fixed to the bottom end of the upper casing 456 by the rivets 530. Thus, an upper casing unit 572 is completed.

[00128] On the other hand, the lower casing 458 is sub-assembled to support the front end of the propeller shaft 488 together with the driven bevel gear 498 via the bearing 532 and the bearing 554 for rotation. Preferably, the propeller 440 is also attached to the propeller shaft 488. A lower casing unit ,576 thus is completed.

[00129] Under the condition, the upper casing unit 572 is assembled with the lower casing unit 576. More specifically, first, the cylindrical bottom section 529 of the lower coupling member 448 is inserted into the upward opening 542 of the lower casing 458. When the cylindrical bottom section 529 moves downward, the stud bolts 570a, 570b fit in the through-holes 527 of the respective bottom flanges 510. After the cylindrical bottom

section 529 reaches the lower casing 458 and the bottom flanges 510 abuts the top surface of the circular periphery of the upward opening 542, nuts 580a, 580b are screwed onto the stud bolts 570a, 570b. In this state, the drive bevel gear 496 and the driven bevel gear 498 mesh with each other, and the upper casing unit 572 and the lower casing unit 576 are completely coupled with each other.

[00130] Thus, by only inserting the cylindrical bottom section 529 into the upper opening 542, the drive and driven bevel gears 496, 498 can autonomously and accurately mesh with each other. The assembling work thus can be easier because the complicated combining work of the bevel gears 496, 498 can be avoided.

[00131] The upper and lower casing units 572, 576 are detachable from each other whenever the nuts 580a, 580b are removed.

[00132] In the illustrated embodiment, as shown in FIGURE 10, the cylindrical bottom section ,529 of the lower coupling member 506 has a circular seal member (O-ring) 582 extending therearound. The seal member 582 is useful to couple the upper and lower casing units 572, 576 water-tightly.

[00133] Also, in the illustrated embodiment, a tubular cover member 466 is previously put around the bottom end of the upper casing 456 and the lower coupling member 506.

The cover member 584 is preferably made of a rubber material. Preferably, the cover member 584 extends from an upper location above the top tubular section 528 and to a lower location below the bottom flanges 526a, 526b. Thereby, the cover member 584 can entirely cover the rivets 530, the stud bolts 570a, 570b and the nuts 580a, 580b to protect them.

[00134] As thus constructed, the lower casing 458 in this embodiment has the internal cavity 540 opening upward and rearward. Therefore, no core is necessary to produce the lower casing 458 by casting. The casting work can be quite easily made, accordingly.

[00135] In the illustrated embodiment, first, the upper casing unit 572 and the lower casing unit 576 are sub-assembled, and then the upper and lower casing units 572, 576 are assembled with each other. Thus, no complicated assembling work in a relatively narrow space is necessary. Consequently, the assembling work can be easily made.

[00136] In addition, in the illustrated embodiment, the upper casing unit 572 and the lower casing unit 458 are coupled with each other by the stud bolts 570a, 570b positioned at the front and rear portions of the periphery of the upward opening 542 and are spaced apart from each other along the axis 490 of the propeller shaft 488. The coupling portions of the

upper and lower casing units 572, 576 thus do not extend broadly transversely. In other ^' words, the casing 450 can be slim enough. Thus, the resistance by the water body can be reduced when the outboard motor 430 moves forward or backward. [00137] With reference to FIGURES 7, 9 and 14-16, the mount unit 432 will be ^• described in greater detail below.

[00138] As shown in FIGURES 15 and 16, the clamping bracket 444 is formed with right and left bracket arms 444R, 444L transversely spaced apart from each other. The bracket arms 444R, 444L are preferably made of sheet metal and are detachably fixed to the horizontal board 436 by fasteners 600 such as, for example, bolts and nuts. Differently from the first embodiment, the tilt pin 447 is a single cylindrical member in this embodiment and has the tilt axis 602. The tilt pin 447 couples the bracket arms 444R, 444L with each other.

[00139] The swivel bracket 446 is coupled with the bracket arms 444R, 444L for the pivotal movement about the axis 602 so as to be tilted together with the drive unit 434. The swivel bracket 446 in this embodiment is formed with a fixed part 604 and a movable part 606.

[00140], The fixed part 604 preferably has a semi-cylindrical portion 608 and right and left wing sections 610R, 610L extending from the semi-cylindrical portion 608. The movable part 606 preferably has a semi-cylindrical portion 612 and flanges 614 extending from the semi-cylindrical portion 712. The semi-cylindrical portion 608 of the fixed part 604 and the semi-cylindrical portion 610 of the movable part 606 together form a body section of the swivel bracket 446 of this embodiment.

[00141] Thus, the swivel bracket 446 is almost similar to the swivel bracket 46 of the first embodiment. The body section of the swivel bracket 446, however, is not divided into upper and lower portions.

[00142] One of the most characteristic structures of the swivel bracket 446 in this embodiment is that the movable part 606 is hinged to the fixed part 604 for pivotal movement. More specifically, one of the flanges 614 is coupled with the wing section 610R by hinge units 618 and the other flange 614 can be detachably coupled with the other wing section 610L by thumbscrews 620.

[00143] The fixed part 604 has a semi-cylindrical recess 624, while the movable part 606 has another semi-cylindrical recess 626. When the movable part 606 is coupled with the fixed part 604, both of the semi-cylindrical recesses 624, 626 together define a

cylindrical cavity 628. The steering shaft 448, i.e., a portion of the drive unit 434, is positioned within the cylindrical cavity 628. In other words, the steering shaft 448 is interposed between the fixed part 604 and the movable part 606. Thus, the swivel bracket 446 supports the steering shaft 448 for pivotal movement about the steering axis 472. [00144] As shown in FIGURES 9 and 16, preferably, the respective lengths of the fixed and movable parts 604, 606 in the vertical direction are slightly shorter than the distance between the top flange 508 and the bottom flange 510 and are almost equal to the distance. The drive unit 434 does not totter relative to the swivel bracket 446, accordingly. [00145] As best shown in the enlarged and cross-sectional view separately provided in FIGURE 16, the body section of the swivel bracket 446 preferably has upper and lower rubber bushings 630 and upper and lower resin (plastic) bushings 632. The separate view of FIGURE 16 only shows the upper rubber busing 630 and the upper resin bushing 632. [00146J ₁ The upper and lower rubber bushings 630 are interposed between an inner surface of the cylindrical cavity 628 and an outer surface ^' of the steering shaft 448. The upper and lower resin bushings 632 are interposed between inner surfaces of the respective rubber bushings 630 and the outer surface of the steering shaft 448. Because the resin bushings 632 are positioned between the rubber bushings 630 and the steering shaft 448, the steering shaft 448 can pivot about the steering axis 472 in frictibnally contact with the resin bushings 632.

[00147] Each rubber bushing 632 preferably has a slit 636. The rubber bushing 632 thus can be detached from the body section of the swivel bracket 446 by unfolding respective surfaces of the slit 636 from each other. Reversely, the rubber bushing 632 can be attached to the body section of the swivel bracket 446 by folding respective surfaces of the slit 636 to each other. Each resin bushing 634 preferably has two slits 638. The two pieces of the resin bushing 634 separated by the slits 638 can be detached from the body section of the swivel bracket 446 when the respective pieces are pulled oppositely. Reversely, the respective pieces of the resin bushing 634 can be attached to the body section of the swivel bracket 446 when the pieces are mated together.

[00148] The operator can pivot the drive unit 434 about the steering axis 472 with the steering shaft 448 pivoting relative to the swivel bracket 446 via the rubber bushings 632 and the resin bushings 634. When the operator does not exert any force to the drive unit 434, the steering shaft 448 keeps its position because of the friction of the rubber and resin bushings 632, 634.

[00149] The clamping bracket 444 preferably has a stopper pin 640 extending between the respective bracket arms 444R, 444L parallel to the tilt pin 447. The stopper pin 640 receives the thrust of the propeller 440 and the watercraft 438 can move forward because the thrust is transmitted to the watercraft 438 through the clamping bracket 444.

[00150] In one variation, as indicated by the chain triple-dashed lines of FIGURE 14, the clamping bracket 444 can be mounted to a transom board 642 extending generally vertically instead of the horizontal board 436.

[00151] When the engine 452 of the outboard motor 430 operates, the rotational speed of the crankshaft 468 of the engine 452 is reduced by the speed reduction unit 460 and the power of the engine 452 is transmitted to the propeller 440 through the driveshaft 454, the drive bevel gear 496, the driven bevel gear 498 and the propeller shaft 488. Thus, the propeller 440 rotates to generate the thrust. The thrust of the propeller 440 is transmitted to the watercraft 438 through the stopper pin 640 and the clamping bracket 444 so that the watercraft 438 moves forward or backward.

[00152] If some obstacle such as, for example, a log collides with the lower portion of the casing 450, the drive unit 434 temporarily pivots rearward upward and returns to the initial position soon after the obstacle has gone. Any large shocks thus can be prevented from damaging the casing 450. ^' <

[00153] In addition, the drive unit 434 can be tilted up above the water surface 442 under the condition that the outboard motor 430 is not in use.

[00154] As thus discussed, in the illustrated embodiment, the movable part 606 of the swivel bracket 446 is hinged to the fixed part 604 thereof. When the thumbscrews 620 are removed, the drive unit 434 can be released and separated from the swivel bracket 446.

The operator or user of the outboard motor 430 thus can carry the drive unit 434 without the mount unit 432. Because the weight of the drive unit 434 is lighter than the whole weight of the outboard motor 430, the carry thereof can be easier.

[00155] In the illustrated embodiment, the movable part 606 is still coupled with the fixed part 604 even though the thumbscrews 620 are removed. Thus, the operator or user is not required to pay any attention to the loss of the moving part 606. The detachment of the drive unit 434 can be made more easily than, ever, accordingly.

[00156] Because such thumbscrews 620 are used in the illustrated embodiment, the operator or user does not need to use any tools to fasten or loosen the screws 620. As a

result, not only the removal or reinstallation of the drive unit 434 but also adjustment of the frictional force of the rubber and resin bushings 630, 632 can be made easily. [00157] Other one-touch type fasteners such as, for example, buckles can replace the thumbscrews 620.

[00158] Although this invention has been disclosed in the context of. certain preferred embodiments, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.