Marine counter-rotating shaft drive mechanism

Abstract

A Counter-Rotating Shaft Drive Mechanism for a boat comprises an engine gearbox output shaft coupling ( 2 ); a differential arrangement which creates counter-rotating outputs in a dual output shaft arrangement and comprises a housing ( 1 ) and removable maintenance plates ( 4 ), means for arresting rotation of the differential housing and a coupling between the shaft arrangement and a twin propeller arrangement. A single drive gear ( 8 ) may be used to drive the output shaft arrangement which may comprise a pair of concentrically arranged shafts ( 5 ) and ( 9 ) which rotate in opposite directions. The inner and outer shafts may have rubbing pads arranged between them, while the shaft arrangement may operate as s self-lubricating sealed unit. The housing, maintenance plates, and shafts may be manufactured from a metallic material, a plastic polymer or a carbon composite. The Marine Counter-Rotating Shaft Drive Mechanism has been designed to be both retrofitable, and factory fit.

1 . A Counter-Rotating Shaft Drive Mechanism comprising: an engine gearbox output shaft coupling; differential arrangement creating counter-rotating outputs in the form of a housing and removable maintenance plates; a combined, dual, concentric shaft arrangement allowing for counter rotation; means for arresting rotation of the differential housing, and a coupling to a twin propeller arrangement sited at the propeller end of the dual shaft arrangement.  
   
   
       2 . A Counter-Rotating Shaft Drive Mechanism as claimed in  claim 1  wherein a single drive gear is used to rotate the two separate propeller shafts in opposing directions.  
   
   
       3 . A Counter-Rotating Shaft Drive Mechanism as claimed in  claim 2  wherein the single drive gear is provided as the input to the differential housing.  
   
   
       4 . A Counter-Rotating Shaft Drive Mechanism as claimed in  claim 1 ,  2  or  3  wherein the two concentric drive shafts operate on the same shaft line, but rotate in opposite directions.  
   
   
       5 . A Counter-Rotating Shaft Drive Mechanism as claimed in any preceding claim wherein the drive train is maintainable through the removable maintenance plates.  
   
   
       6 . A Counter-Rotating Shaft Drive Mechanism as claimed in any preceding claim wherein self-lubricating rubbing pads are used to support the inner shaft within the outer shaft.  
   
   
       7 . A Counter-Rotating Shaft Drive Mechanism as claimed in any preceding claim wherein the dual, concentric shaft arrangement is provided with a least one set of rubbing pads located on the inner drive shaft.  
   
   
       8 . A Counter-Rotating Shaft Drive Mechanism as claimed in  claim 6  wherein the, or each, rubbing pad set is spaced unevenly around the circumference of the inner shaft to provide smoother counter-rotating motion between the two shafts.  
   
   
       9 . A Counter-Rotating Shaft Drive Mechanism as claimed in any preceding claim wherein the dual shaft arrangement operates as a self-lubricating sealed unit.  
   
   
       10 . A Counter-Rotating Shaft Drive Mechanism as claimed in any preceding claim wherein the differential housing, maintenance plates, outer drive shaft and inner drive shaft are manufactured from either a metallic material, plastic polymer or carbon composite.  
   
   
       11 . A Counter-Rotating Shaft Drive Mechanism as claimed in any preceding claim wherein the dual, counter-rotating, drive shaft arrangement is designed for water and contaminant exclusion.  
   
   
       12 . A Counter-Rotating Shaft Drive Mechanism as claimed in any preceding claim wherein the differential housing is held between the gearbox output flange and the drive shafts.  
   
   
       13 . A Counter-Rotating Shaft Drive Mechanism substantially as described herein with reference to  FIGS. 1-3  of the accompanying drawing.