Abstract:
A stern drive for a boat has inboard and outboard portions, the outboard portion having a propeller rotatably disposed thereon, and the inboard portion being adapted to receive rotational power about a motor output drive axis to rotationally drive the propeller. A mounting structure is operative to secure the inboard portion to the stern of a boat in a manner permitting the inboard and outboard portions to be rotated about the motor output drive axis for steering purposes. The outboard portion of the stern drive is rotatable relative to the inboard portion, about a second axis transverse to the motor output drive axis, in raising/lowering/trimming directions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/814,259 filed on Jul. 18, 2007 pursuant to 35 USC §371 as a national stage filing of PCT/ZA2006/000027 filed on Feb. 20, 2006, which claims priority from South African Patent Application No. 2005/01448 filed on Feb. 18, 2005 and South African Patent Application No. 2005/08874 filed on Nov. 2, 2005, such prior applications being hereby incorporated herein in their entireties by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to marine drives. 
       BACKGROUND OF THE INVENTION 
       [0003]    Marine drives can conveniently be classified into three categories. 
         [0004]    These are:
       a. Inboard motors;   b. Outboard motors;   c. Stern drives.       
 
         [0008]    Inboard motors and outboard motors are discussed in the preamble of U.S. Pat. No. 6,186,845 which discloses an embodiment of the type of drive known as a stern drive. In this type of drive the motor is mounted on or immediately inboard of the transom of the boat with its drive shaft passing through the transom and downwards within a fairing outside the boat&#39;s hull to the gear set and propeller shaft which are at the lower end of the fairing. 
         [0009]    A technical complexity which has to be dealt with in a stern drive results from two factors. Firstly, the fairing must be able rotate about a vertical, or substantially vertical, axis so as to direct the propeller&#39;s thrust at an angle to the front-to-rear line thereby to permit steering. Secondly, it must be possible to “trim” the fairing, which means tilting the fairing about a horizontal axis to change its pitch. This directs the propeller&#39;s thrust either horizontally or at a desired angle with respect to horizontal. This movement is also used for the purpose of raising the fairing so that the boat can be loaded on a trailer or run onto a shore. 
         [0010]    U.S. Pat. No. 6,186,845 discloses a stern drive which permits the steering motion of the fairing and also the tilting motion of the fairing which is needed to adjust the fairing&#39;s pitch and permit it to be raised to enable the boat to be placed on a trailer. 
         [0011]    PCT specification WO 2004/085245 discloses another form of stern drive. Without in any way attempting to provide an exhaustive list, other forms of stern drive are disclosed in U.S. Pat. Nos. 6,468,119, 5,601,464, 4,037,558, 3,847,108 and 3,166,040. 
         [0012]    Conventional stern drives are based on layouts in which the crank shaft of the engine drives an output shaft through a universal joint, or more usually two universal joints. Constant velocity joints have been proposed as substitutes for universal joints. The output shaft is horizontal, or substantially horizontal, and drives a gear set, the output shaft of which is vertical or substantially vertical. The vertical output shaft drives a lower gear set which in turn drives the propeller shaft. 
         [0013]    A gimbel is provided which carries the motor and which is mounted on a fixed part of the boat. The gimbel is usually mounted for motion about a vertical, or near vertical, axis. A steering arm is connected to the gimbel. By rotating the gimbel about its vertical mounting axis, the gimbel and the entire fairing are displaced about the vertical axis of the gimbel thereby directing the thrust of the propeller at an angle to the front-to-rear line of the boat and enabling it to be steered. 
         [0014]    The mounting of the fairing on the gimbel is about a generally horizontal axis. By tilting the fairing about this horizontal axis with respect to the gimbel using one or more rams, the fairing can be trimmed up or down and lifted for stowage. 
         [0015]    The universal or constant velocity joints provided between the crank shaft and the horizontal output shaft permit these shafts to move relative to one another as the fairing moves with the gimbel (about a vertical steering axis) and with respect to the gimbel (about a horizontal trim axis). 
         [0016]    A modification on this standard system has recently become available commercially. In this form the gimbel is mounted on the boat for movement, with the fairing, about a horizontal axis to enable the fairing to be trimmed. The fairing is mounted on the gimbel for movement with respect to the gimbel about a vertical axis. The steering arm displaces the fairing with respect to the gimbel about this vertical axis for steering purposes. 
         [0017]    The mounting structure of U.S. Pat. No. 6,186,845 avoids the use of universal joints but has the disadvantage that the entire motor and fairing moves during trimming motion. This means that a space, in addition to that occupied by the motor in its normal position, must be provided and into which space the motor can move when the fairing is raised for stowage purposes. 
         [0018]    The gear set of conventional stern drives as described above, can include a first bevel pinion driven from the crank shaft of the motor, first and second bevel gears meshing with the first bevel pinion and being rotated in opposite directions, a reversing clutch for connecting the first bevel gear or the second bevel gear to a first transverse shaft. The first transverse shaft will thus rotate in opposite directions, depending on whether the first or the second bevel gear are connected to it. The rotation of the first transverse shaft is transferred to the output shaft. 
         [0019]    The first and second bevel gears are coaxially carried on the first transverse shaft on opposite sides of the first bevel pinion and the clutch is thus used to connect either the first or the second bevel gear to the first transverse shaft in order to change the rotational direction of the output shaft between a forward and a reverse condition. Each of the first and second bevel gears can have a protruding part that defines a conical clutch face and the clutch can include a clutch element, connected to the first transverse shaft with helical splines, between the first and second bevel gears. The clutch element can be connected to either the first or the second bevel gear, by sliding axially on the first transverse shaft and engaging the conical clutch face of one of the bevel gears. 
         [0020]    The helical splines are oriented so that, if the clutch element is connected to one of the first or the second bevel gears and transfers torque from the bevel gear to the first transverse shaft, the clutch element is drawn into engagement with the particular bevel gear by the interaction between the clutch element and the splines. The result is that the clutch keeps itself in engagement, while torque is being transferred and little force is required to engage it. However, the force that is required to overcome the self engaging spline action and thus to disengage the clutch, can be quite high. The mechanism by which the clutch element is shifted on the first transverse shaft thus has to be capable of effecting substantial axial forces on the clutch element. 
         [0021]    In gear sets of this kind, the clutch is conventionally operated by sliding the clutch element on the first transverse shaft, with a fork-shaped selector, engaging the clutch element in a circumferential shifting groove. However, selectors of this type, that obviously have to be clear of the bevel gears, require space, which comes at a premium in these gear sets and the spacial requirements of these selectors inhibit the development of compact new types of stern drives. It should be borne in mind that the gearset is aft of the transom and the hydrodynamics of the marine drive can be severely affected by the size of the gear set, the gearbox casing, the cylindrical housing, etc. 
       SUMMARY OF THE INVENTION 
       [0022]    According to a first aspect of the present invention there is provided a stern drive which comprises an outer structure that is attachable to the stern of a boat; a housing supported in the outer structure; a gear set and reversing clutch inside the housing, said gear set including a pinion that is rotatable about a transverse axis; and an output shaft that extends downwardly within a fairing; wherein the housing is rotatable within the outer structure for steering purposes and the fairing and output shaft are rotatable about the transverse axis of said pinion thereby to permit raising, lowering and trimming of the fairing. The axis of rotation of the housing relative to the outer structure, may extend at an inclined angle. 
         [0023]    Said gear set and reversing clutch may comprise a first bevel pinion, connectable to a motor; first and second bevel gears that mesh with the bevel pinion on diametrically opposed sides of the bevel pinion and that are coaxial, each of the bevel gears defining a conical clutch face; a first transverse shaft passing coaxially through the bevel gears; a clutch element disposed on the transverse shaft between the bevel gears, said clutch element defining two conical surfaces, each of which is complemental to the clutch face one of the bevel gears; a helical pinion on said first transverse shaft; a helical gear meshing with said helical pinion and carried by a second transverse shaft; and a second bevel pinion carried by the second transverse shaft and meshing with a third bevel gear carried by said output shaft, said fairing rotating about the axis of the second transverse shaft. 
         [0024]    The fairing may be displaced by a ram the cylinder of which forms part of said housing and the rod of which may be connected to a structure which forms an extension of said fairing. 
         [0025]    Said output shaft may drive a pinion which meshes with a gear on a further output shaft that is parallel to the first mentioned output shaft, the output shafts driving co-axial propeller shafts and the arrangement being such that the output shafts rotate in opposite directions and the propeller shafts also contra-rotate. 
         [0026]    The stern drive may include a third output shaft, driven from the pinion. E.g. the third output shaft may have a gear that meshes with the pinion or with the gear of the second output shaft. 
         [0027]    Said fairing may comprise a pair of side sections which are attached together, and a top section which is attached to the side sections. 
         [0028]    The output shaft may be in an elongate casing which extends upwardly from said fairing and which may itself be extended by a pivot structure to which said rod is connected. The pivot structure may be mounted on said second transverse shaft and may rotate about it during lifting and lowering of the fairing and during trimming. 
         [0029]    The first transverse shaft may define helical splines with which the clutch element is in engagement and the transverse shaft may define a central passage that extends axially form at least one of its ends and defines at least one internal recess that extends in a radial direction. The stern drive may further include a selector rod, disposed coaxially within the central passage of the transverse shaft and being axially slidable within the central passage and at least one selector pin extending transversely form the selector rod, at least one slot being defined in the transverse shaft, extending from the central passage to the outside of the shaft and having an orientation that is generally aligned with the helical splines of the shaft, the selector pin extending from the selector rod, through the slot and into the internal recess defined in the clutch element. 
         [0030]    According to another aspect of the present invention there is provided a stern drive including a gear set and reversing clutch comprising a bevel pinion, connectable to an input shaft; first and second bevel gears that mesh with the bevel pinion on diametrically opposed sides of the bevel pinion and that are coaxial, each of the bevel gears defining a conical clutch face; a transverse shaft passing coaxially through the bevel gears, said transverse shaft defining helical splines and a central passage that extends axially form at least one of its ends; and a clutch element disposed on the transverse shaft between the bevel gears in engagement with the helical splines, said clutch element defining at least one internal recess, that extends in a radial direction, and said clutch element defining two conical surfaces, each of which is complemental to the clutch face one of the bevel gears; wherein the reversing clutch includes a selector rod, disposed coaxially within the central passage of the transverse shaft and being axially slidable within the central passage; and at least one selector pin, extending transversely form the selector rod; at least one slot being defined in the transverse shaft, extending from the central passage to the outside of the shaft and having an orientation that is generally aligned with the helical splines of the shaft, the selector pin extending from the selector rod, through the slot, into the internal recess defined in the clutch element. 
         [0031]    The reversing clutch may include two selector pins extending in diametrically opposing directions from the selector rod, each passing through a separate slot and into a separate internal recess of the clutch element. 
         [0032]    Each internal recess in the clutch element may extend to an outer circumference of the clutch element and each selector pin may be held captive within its internal recess, by a retaining element such as a circlip. 
         [0033]    The clutch may include a diaphragm, connected to a plunger which is configured to effect axial displacement of the selector rod and the diaphragm may be disposed adjacent the end of the transverse shaft from which the central passage extends. 
         [0034]    According to another aspect of the present invention a stern drive is provided which comprises a drivable propulsion structure having an inboard end portion and an outboard portion extending outwardly therefrom, the outboard portion having an outer end with a propeller structure rotatably disposed thereon, the inboard end portion being adapted to receive rotational power, initially input thereto about a motor output drive axis, to rotationally drive the propeller structure, and a mounting structure for securing the inboard end portion to the stern of a boat in a manner permitting the inboard end portion and the outboard portion of the drivable propulsion structure to be rotated relative to the boat, about the motor output drive axis, in steering directions, the outboard portion being pivotable relative to the inboard end portion, about a second axis transverse to the motor output drive axis, in raising/lowering/trimming directions 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]    For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of non-limiting example, to the accompanying drawings in which: 
           [0036]      FIG. 1  is a side elevation of a stern drive in accordance with the present invention in its normal running position; 
           [0037]      FIG. 2  is a pictorial view from the rear and to one side of the stern drive of  FIG. 1 ; 
           [0038]      FIG. 3  is a rear elevation of the stern drive of  FIGS. 1 and 2 ; 
           [0039]      FIG. 4  is a rear view similar to that of  FIG. 3  but showing the stern drive in the position it adopts during a port turn; 
           [0040]      FIG. 5  is a section through the stern drive of  FIGS. 1 to 4  in its normal running condition; 
           [0041]      FIG. 6  is a section similar to that of  FIG. 5  but showing the fairing of the stern drive raised to its stowed position; 
           [0042]      FIG. 7  is a section similar to that of  FIG. 5  but showing a drive with twin output shafts; 
           [0043]      FIG. 8  is a section through a gear set including a reversing clutch in accordance with the present invention; 
           [0044]      FIG. 9  illustrates the components of the fairing 
           [0045]      FIG. 10  is a detailed sectional view of the clutch of  FIG. 8  (with the first bevel pinion omitted); 
           [0046]      FIG. 11  is an elevation of a transverse shaft of the clutch of  FIG. 8 ; and 
           [0047]      FIG. 12  is an exploded view of the clutch of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0048]    The stern drive  10  shown in  FIGS. 1 to 6  of the drawings comprises a motor  12  which is mounted on the inclined transom  14  of the boat. The structure  16  which mounts the stern drive in an opening  18  provided therefor in the transom  14  is partly within the boat and partly outside the boat. 
         [0049]    A steering arm is shown at  20  and the steering cylinder which is connected to the arm is shown at  22 . 
         [0050]    The fairing of the stern drive is designated  24 . It is mounted for pivoting motion about a horizontal axis. It is also mounted for motion about a steering axis as will be described in more detail hereinafter. 
         [0051]    There is a bevel gear  26  in the lowermost part of the fairing  24  and a propeller shaft driven by the gear  26  is shown at  28 . The shaft  28  passes through a sleeve  30  within which bearings  32  for the shaft  28  are mounted. A further bearing is shown at  34 . The propeller is shown at  36  and is secured by a nut  38  to the shaft  28 . 
         [0052]    The structure  16  is hollow and constructed so that it can house two bearings and seals  40  and  42  which mount a gear set and clutch housing  44 . The steering arm  20  is connected to the housing  44  and oscillates the housing  44  for steering purposes as will be described hereinafter. 
         [0053]    A gear set and reversing clutch are shown at  46  in  FIGS. 5 and 6  and are illustrated in more detail in  FIG. 8 , with elements of the clutch shown in more detail in  FIGS. 10 to 12 . The gear set and reversing clutch  46  are inside the housing  44 . In  FIG. 8  the seal of the bearing and seal  42  is shown. The bearing is above the seal but has not been illustrated. 
         [0054]    An input shaft  48  has an array of splines (not shown) which enables it to be secured to the crank shaft (not shown) of the motor  12 . The shaft  48  rotates in bearings  52  and  54  which are mounted in a bearing sleeve  56  which is bolted to the housing  44 . A nut  58  secures the bearings  52 , 54  to the shaft  48  and a shaft seal is shown at  60 . The sleeve  56  is externally splined and the arm  20  is connected to this. 
         [0055]    The housing  44  comprises two outer shells  44 . 1 ,  44 . 2  of semi-cylindrical form and a centre part  44 . 3 . 
         [0056]    A first bevel pinion  62  is integral with the input shaft  48 . A first bevel gear  64  and a second bevel gear  66  are supported coaxially on a first transverse shaft  68 , with the first and second bevel gears  64 , 66  meshing with the first bevel pinion  62  on opposing sides. The first and second bevel gears  64 , 66  are supported on the first transverse shaft  68  on bearings  70  and it is to be understood that the first and second bevel gears will counter rotate, irrespective of the motion of the first transverse shaft. External bearings  72  are provided for mounting the first and second bevel gears  64 , 66  in the centre part  44 . 3  of the housing assembly  44 . 
         [0057]    The first transverse shaft  68  has helical splines  74  defined along its centre portion, the first transverse shaft passing through a sleeve-like clutch element  76 . The clutch element  76  has complemental internal helical splines. The clutch element  76  has external, conical clutch surfaces  78 , which co-operate with complemental internal conical clutch surfaces  80  defined in protuberances  82  of the first and second bevel gears  64 , 66 , respectively. 
         [0058]    The clutch element  76  can slide helically on the helical splines of the first transverse shaft  68 , so that one of its clutch surfaces  78  engages the corresponding clutch surface  80  of either the first bevel gear  64  or the second bevel gear  66 . Once engaged, the clutch element  76 , by virtue of the interaction between the helical splines, pulls itself into the engaged position. 
         [0059]    The clutch assembly is thus configured to connect the first bevel gear  64  to the first transverse shaft  68  via the clutch element  76  in a reverse condition, to connect the second bevel gear  66  to the first transverse shaft  68  in a forward condition and to connect neither the first nor the second bevel gear to the first transverse shaft, in a neutral condition, or vice versa. 
         [0060]    A helical pinion  84  is keyed onto the first transverse shaft  68  and rotates in bearings  86 . The pinion  84  meshes with a similarly mounted helical gear  88  which is keyed to a second transverse shaft  90 . A second bevel pinion  92  is secured to the second transverse shaft  90  and meshes with a third bevel gear  94  forming part of an output shaft  96 , which rotates in bearings  98  that are mounted in a bearing housing  100 . The bearing housing  100  is within a pivot structure that is designated  146 . A circlip  148  holds the housing  104  in the structure  146 . 
         [0061]    The output shaft  96  defines internal splines, which allows it to be connected to an externally splined inclined shaft  106  with a bevel pinion  110  at its lower end, that meshes with the gear  26  to drive the propeller  36 . 
         [0062]    It will be noted in  FIG. 8  that the left hand side of the housing  44  is configured to receive another set of a helical pinion and gear. For a boat with two stern drives, it is advantageous for one stern drive to have its gear set on the left of the housing  44  and for the other stern drive to have its gear set on the right of its housing  44 . 
         [0063]    Referring now to  FIGS. 10 to 12 , details of the clutch assembly  102 , forming part of the gear set and reversing clutch  46 , includes a selector rod  168  that is coaxially slidable within a central passage  170  that is defined inside the first transverse shaft  68 , from its end opposite from the end driving the pinion  84 , i.e. from the left hand side in the drawings. 
         [0064]    Two selector pins  172  extend transversely in diametrically opposing directions from the selector rod  168 , close to its right hand end. The selector pins  172  are in the form of hollow pins and each have a protuberance that is slidably received in a circumferential slot in the selector rod  168 . In this embodiment, the selector rod  168  can rotate relative to the selector pins  172 . 
         [0065]    In an alternative embodiment of the invention, instead of having a protuberance that slides in a slot defined in the selector rod  168 , the selector pins  172  could be in the form of a single pin that extends through a transverse aperture in the selector rod. In this embodiment, the selector rod  168  and selector pins  172  rotate together. 
         [0066]    Two diametrically opposed slots  174  are defined in the first transverse shaft  68  that extend from the central passage  170  to the outer surface of the shaft in the region of its helical splines  74 . Each slot  174  has a width generally equal to the diameter of the selector pins  172  and is generally aligned with the helical splines  74 . 
         [0067]    Two internal recesses in the form of radial apertures  176  are defined in the clutch element  76  and are diametrically opposed and coaxial. The diameter of each of the apertures  176  is generally equal to the outer diameter of the selector pins  172 . 
         [0068]    The selector pins  172  extend from the selector rod  168  through the slots  174  into the apertures  176 , where they fit snugly. Accordingly, if the selector rod  168  slides axially within the central passage, the selector pins  172  slide in the slots  174  and move the clutch element  76  axially. It would be clear to those skilled in the art that the movements of the selector pins  172  and clutch element  76  relative to the first transverse shaft, are not purely axial, but helical, since the selector pins slide in the slots  174  and the clutch element slides on the helical splines  74 . The helical movement of the clutch element  76  allows its clutch surfaces  78  to engage and disengage the clutch surfaces  80  as described above. 
         [0069]    The selector pins  172  are held captive in their positions by retaining elements (not shown) such as circlips in the outer ends of the apertures  176  or a retaining spring that extends around the circumference of the clutch element, in a circumferential groove  178 . 
         [0070]    The clutch  102  can be actuated in a number of ways, to impart axial movement to the selector rod  168 . However, in the illustrated, preferred embodiment of the invention, the clutch includes a diaphragm  180  housed in a chamber  182  in which it can be displaced to the left or the right by applying hydraulic pressure within the chamber on either side of the diaphragm. The diaphragm  180  is connected to the selector rod  168  in a transverse arrangement and it follows that displacement of the diaphragm causes axial displacement the selector rod and thus operates the clutch as described above. 
         [0071]    In an embodiment where the selector pins  172  extend through the selector rod  168  and the selector pins and selector rod thus rotate with the first transverse shaft  68 , the selector rod can be connected to the diaphragm  180  via bearings, to slide rotatably within this attachment. 
         [0072]    The use of hydraulic actuation and components extending from the diaphragm  180  to the clutch element  76  via the central passage  170  and the slots  174 , allows the clutch actuation mechanism to be very compact, which is essential, since it forms part of the gear set and clutch  46  that has to be housed inside the housing  44 , which in turn must be able to rotate as part of the steering action of the stern drive  10 . 
         [0073]    The stern drive of  FIG. 7  differs from that of  FIGS. 1 to 6  in that the shaft  96  drives a pinion  112  which is at the upper end of a first inclined output shaft  114 . The pinion  112  meshes with a gear  116  at the upper end of a second inclined shaft  118 . The shafts  114 ,  118  have bevel pinions  120 ,  122  at the lower ends thereof. These bevel pinions mesh with further bevel gears  124 ,  126  on two contra-rotating propeller shafts  128 ,  130 . 
         [0074]    The fairing  24  (see particularly  FIG. 9 ) comprises two side sections  132 ,  134  and an upper section  136 . The lower parts of the sections  132 ,  134  are generally semi-cylindrical and receive the propeller shaft  28  (or propeller shafts  128 ,  130 ). More specifically, the sleeve  30  is part of a tube  138  which is closed at its front end (see  FIGS. 5 ,  6  and  7 ) and houses the bearing  34 . The two semi-cylindrical parts of the sections  132 ,  134  house the tube  138 . 
         [0075]    The sections  132 ,  134  have horizontal webs  140  at their upper ends, these being secured to the section  136  during fabrication of the fairing. 
         [0076]    The inclined shaft  106  (or the inclined shafts  114 ,  118 ) are within an inclined elongate casing  142  which is clamped between the sections  132 ,  134  during fabrication. 
         [0077]    Referring to  FIGS. 1 to 8 , the structure  146  has two opposing cylindrical ends  150 , each of which extends around a cylindrical protuberance  152  of its corresponding part of the housing  44 . 2  and  44 . 3  with bearings  154  between the cylindrical ends and protuberances, all co-axial with the shaft  90 . Thus the pivot structure  146  can rotate about the axis of the shaft  90  carrying the housing  100  and shaft  96  with it. During such movement the gear  94  “rolls around” the pinion  92 . 
         [0078]    The casing  142  is secured by bolts (not shown) to the lower end of the structure  146 . A shell  144  which is purely aesthetic is provided to conceal the internal structure. 
         [0079]    An arm  158  forming part of the pivot structure  146  is connected by a link  160  to the rod  162  of a ram  164 . The cylinder  166  of the ram  164  is part of the housing  44 . 
         [0080]    There are two further rams (not shown) parallel to the ram  164 . These rams are of shorter stroke than the ram  164 . All three rams are used to displace the fairing  24  for trimming purposes, the force required being significant in view of the thrust exerted on the fairing by the propeller  36 . During lifting of the fairing  24  for stowage purposes, all three rams are operated. Two, however, reach the end of their travel before stowage is completed, and the ram  164  is effective to finalize such lifting. 
         [0081]    If reference is made to  FIG. 6  it will be noted that the link  160  is at right angles to the rod  162 . Thus no amount of downward force exerted on the fairing  24  can push the rod  162  back into the cylinder  166 . 
         [0082]    In  FIG. 5  the rod  162  is shown fully retracted into the cylinder  166  and the fairing  24  is thus in its lowered position. In  FIG. 6  the rod  162  is fully extended and the fairing  24  is thus raised. 
         [0083]    The fairing  24  thus moves between its raised and lowered positions by rotating about an axis which is the axis of the shaft  90 . 
         [0084]    For steering purposes the housing  44 , the entire gear set and reversing clutch  46  shown in  FIG. 8 , the structure  146 , the casing  142  bolted to the structure  146  and the fairing  24  all rotate about the axis of the input shaft  48 , which is aligned with the output drive axis of and receives rotational power from the motor  12 , when the steering arm pushes or pulls on the housing  44  via the sleeve  56 . In  FIG. 4  the fairing is shown displaced to the position it occupies during a turn to port.