Abstract:
A housing for an outdrive is installed with a replaceable tower support for a ball bearing race through which the drive shaft rotates. When the bearing race becomes worn, rather than replacing the entire housing and installing a new bearing race, only the tower support and worn bearing race is removed and replaced, which represents a considerable cost saving.

Description:
[0001]    This application is a continuation-in-part of U.S. Ser. No. 09/375,632, filed Aug. 17, 1999, entitled: “REPLACEMENT TOWER SUPPORT FOR A BEARING, RACE AND DRIVE SHAFT FOR A MARINE ENGINE”, Inventor: Leonard R. Payne. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to a new and improved replaceable tower support for a bearing and drive shaft, and having particular use for propeller drive shafts in the housing of motor boat outdrives.  
           [0003]    Usually, when the bearing support for a propeller drive shaft becomes worn, the entire housing for the drive shaft and worn bearing support must be replaced with a new housing and bearing race and the original drive shaft, and represents an expensive proposition. Typical publications concerning these types of motors are noted in U.S. Pat. Nos. 4,276,036; 4,767,225; 4,792,315; 4,917,639; 4,798,548; 4,925,414; 4,948,384; 4,986,775; 5,018,999; 5,094,639; 5,112,259; 5,171,177; 5,407,508; and, 5,411,423.  
           [0004]    However, none of these patents disclose or infer the capability for replacement of only a worn ball bearing race and/or support member from the housing of a marine outdrive without requiring replacement of the entire housing and its components. The capability of effecting such a replacement would represent a considerable saving since a marine outdrive housing has a wear lifetime significantly longer than either of the above two components, and is much more expensive.  
         THE INVENTION  
         [0005]    According to the invention, there is provided a marine outdrive housing and replaceable support tower for bearings and a race seated thereon, the bearings being suitable for engaging a drive shaft such as a propeller drive shaft positioned in the marine outdrive. The tower comprises a hollow, elongate structure whose lower end will usually rest on a machined portion of the housing floor, or the tower may be mounted within the interior portion of the marine outdrive. The upper end of the tower is circularly shaped, and typically will project into the propeller shaft cavity to enable direct engagement with drive gears.  
           [0006]    Mounting the tower structure into the housing may involve any one of the following steps: 1. heating the outdrive housing to about 350° F.-450° F. and chilling the bearing tower, for example to about freezing, e.g., 30° F.-32° F., followed by press fitting the tower into the housing as an interference fit; or, 2. threading the housing and tower, and screwing the tower into the housing; or, 3. securing the tower with a mechanical device such as a pin and bolt. However, since steps 2 and 3 require machining, they tend to be more expensive than press fitting.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is an external side elevation view, partly in cross section illustrating the tower support structure of this invention, which mount bearings and a race for vertical engagement with a drive for a propeller shaft;  
         [0008]    [0008]FIG. 2 is an exploded, external, perspective view of the tower support structure of this invention, and the bearings and race for rotational support of a propeller shaft and gear;  
         [0009]    [0009]FIG. 3 is a side elevation view in axial section showing an enlarged view of the support tower structure of this invention, shown in FIG. 1; and,  
         [0010]    [0010]FIG. 4 is a cut-away perspective, showing the tower support of this invention mounted within a housing of a marine engine for horizontal engagement with a marine drive shaft and gear. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0011]    One embodiment of the tower support  10  of this invention is shown in FIGS.  1 - 3 , mounted within a housing  11  of a marine outdrive  12 . An integrally formed, or machined extension or flange  13  is provided medially of the tower support  10 , the flange being secured within a ledge or groove (see FIG. 4) of the housing to stabilize the tower support against excessive movement such as vibration.  
         [0012]    The tower  10  provides a circular groove or support shoulder  15  machined around the flange base, an interior bore  10   a  having a lower machined cut-out shoulder  10   b , and a machined channel  10   c  terminated by a cut-out shoulder  10   d . A bearing race  16  is mounted on the support shoulder  15 , and bearings  17  are mounted circumferentially in channel  10   c , and supported on shoulder  10   d.    
         [0013]    A gear drive  19  with a centrally mounted shaft  19   a  and needle bearings  19   b  is seated on, and overrides the bearing race  16 , and is driven by an engine drive shaft  20 , through gear drives  21 ,  22 . In effect, drive shaft  20  and gear drives  19 ,  21  and  22  are supported by tower  10 . Bearings  17  rotatably center and stabilize shaft  19   a  which is spline connected to a vertical shaft  23  which connects through bevel gears to a propeller drive shaft  24  for rotation of a propeller  25 . Shaft  19   a  of gear drive  19  is mounted within interior bore  10   a  of the tower, and the end of shaft  19   a  is supported on lower shoulder  10   b.    
         [0014]    The replaceable tower support of this invention is preferably used in a marine engine known as the BRAVO, and is shown in FIG. 4. In this embodiment, the tower  30  is press fitted as an interference fit into the housing  27  of the outdrive and projects into the propeller drive cavity  28  for horizontal connection to a propeller drive and propeller (not shown).  
         [0015]    The tower defines a lower end  30   a , an upper end  30   b , and an interior channel  30   c . Similar to the tower  10 , the tower  30  is machined to form a flange  31  and a groove or shoulder  32  is shown supporting a bearing race  34  (however, the shoulder may be eliminated if not considered necessary); the interior channel  30   c  is configured to support bearings  35 . A circular groove  36  is machined into the housing  27  in which the flange  31  is seated, (see arrow) and a circumferential shoulder (or groove)  37  is machined along the inner wall of the housing to support the lower end  30   a  of the tower. The groove  36  and shoulder  37  support the flange and lower end of the tower respectively, and these two supports secure the tower in the housing  27 , to reduce vibration of the gear drive and engine.  
         [0016]    A gear assembly  40  is mounted on, and overrides the bearing race  34 , and the gear assembly horizontally engages and rotates a propeller drive and propeller (not shown), leading from the propeller drive cavity  28 . For purposes of illustration, the gear assembly  40  is shown only slightly larger relative to the support tower  30 , but the actual size of the gear assembly is considerably larger than the tower, itself.  
         [0017]    The gear assembly  40  includes needle bearings  40   a  which are seated on, and override bearing race  34 . The gear assembly also includes a centrally mounted shaft end  40   b  which rotates through, and is centered by the bearings  35  in the interior channel  30   c  of the tower  30 . The shaft end  40   b  of the gear assembly rests on, and is supported by the lower end  30   a  of the tower.  
         [0018]    The shaft end  40   b  is in turn spline connected to, and is supported by a centrally mounted idler shaft  45  which is mounted on bearings (not shown) that are set into a machined portion at the bottom of the BRAVO housing  27 . Hence, the upper portion of the gear assembly  40  is supported by the bearing race  34  and the tower  30 , and is supported on its lower shaft side by the tower and centrally by idler shaft  45 . In effect, an improved support is now provided for the central region of the BRAVO drive system. In the embodiments shown in FIGS. 1 and 4, the gear and drive system are essentially that of the BRAVO drive.  
         [0019]    The replaceable tower support itself may be constructed of a suitable corrosion resistant, load bearing steel such as a 304 stainless, a 4140 machine steel, etc. Typical dimensions of the tower support are approximately 2.5-11 inches in overall height and, about 3-5 inches in overall diameter; flange element  31  is about 1-5 inches wide and about 0.1-1 inch thick; if used, the shoulder  32  (or  15 ) or equivalent groove, is up to about 2.5 inches wide and preferably about 0.05-0.07 inches wide; and, the groove  36  in the housing  27  is about 0.15-1 inch in depth.  
         [0020]    These dimensions and materials of construction (supra) are sufficiently adequate to significantly improve present horsepower mounting characteristics, and an increase in tower dimensions will obviously impart even greater ruggedness, and further improve horsepower carrying capability, if desired.