Rotatable and extendable locking shaft apparatus

Abstract

An adjustable locking shaft apparatus is disclosed. A locking adjustment system, fully enclosed within the movable shaft segments enables rapid simultaneous angular and length adjustments to be made to the shaft. An eccentric cam configuration operated by simple twisting of the shaft segments provides the locking pressure for maintaining selected adjustments. The apparatus provides an infinite number of adjustment positions. A kayak paddle implementation of the invention is disclosed.

1 . An adjustable shaft apparatus, comprising: 
 (a) a first hollow shaft portion;    (b) a second hollow shaft configured for axial operative alignment with said first shaft portion; and    (c) a releasable locking assembly mounted within and connecting said first and second shaft portions in axial alignment, said locking assembly being arranged and configured to respond to relative twisting motion between said first and second shaft portions about said axis, to selectively fix the angular orientations of said first and second shaft portions relative to one another, to any desired angular positions.    
   
   
       2 . An adjustable shaft apparatus as recited in  claim 1 , wherein said releasable locking assembly contains no threaded operative parts.  
   
   
       3 . An adjustable shaft apparatus as recited in  claim 1 , wherein said releasable locking assembly is operable to fixedly lock the first and second shaft portions together when the shafts are relatively twisted in first angular directions about said axis, and is operable to release the locking condition and allow free angular relative motion between said first and second shaft portions when the shafts are relatively twisted in second angular directions, opposite to said first angular directions, about said axis.  
   
   
       4 . An adjustable shaft apparatus as recited in  claim 3 , wherein the amount of angular rotation of either said first or said second shaft portions about said axis in order to fixedly lock the shaft portions together when relatively twisted in said first angular directions, is less than about 180°.  
   
   
       5 . An adjustable shaft apparatus as recited in  claim 3 , wherein the amount of angular rotation of either said first or said second shaft portions about said axis in order to fixedly lock the shaft portions together when relatively twisted in said first angular directions, is less than about 90°.  
   
   
       6 . An adjustable shaft apparatus as recited in  claim 3 , wherein the amount of angular rotation of either said first or said second shaft portions about said axis in order to fixedly lock the shaft portions together when relatively twisted in said first angular directions, is less than about 45°.  
   
   
       7 . An adjustable shaft apparatus as recited in  claim 1 , wherein said releasable locking assembly further includes a shaft extension insert fixedly secured to the first shaft portion and longitudinally releasably securable to said second shaft portion; wherein said releasable locking assembly is operable to selectively change the distance between adjacent ends of said first and second shaft portions up to an operative length of said extension insert.  
   
   
       8 . An adjustable shaft apparatus as recited in  claim 7 , wherein said releasable locking assembly is operable to lock the longitudinal position of said shaft extension relative to said second shaft portion at any position along the operative length of said shaft extension.  
   
   
       9 . An adjustable shaft apparatus as recited in  claim 1 , wherein said first and second shaft portions are configured for cooperative longitudinal mating connection with one another so as to form an extendable composite shaft configuration; wherein said releasable locking assembly is fixedly secured to the first shaft portion and longitudinally releasably secured to said second shaft portion; wherein said releasable locking apparatus is operable to selectively lock the longitudinal positions of said shaft portions relative to one another.  
   
   
       10 . An adjustable kayak paddle, comprising: 
 (a) a shaft having first and second ends and being separable near its longitudinal center;    (b) paddle blades fixedly attachable to said first and second shaft ends; and    (c) a releasable locking assembly mounted within said shaft and bridging the separable portion thereof; said locking assembly being operable in response to relative twisting motion between the separable shaft segments about the shaft axis to fix the angular orientations of said shaft segments and attached paddle blades about said axis, at any desired angular positions.    
   
   
       11 . The adjustable kayak paddle of  claim 10 , wherein said releasable locking assembly is further operable in response to said relative twisting motion between the separable shaft segments to adjustably fix the length of said shaft at an infinite number of lengths within an adjustment range.  
   
   
       12 . A shaft adjustment locking apparatus of a type being sized and configured to be entirely operatively inserted within first and second joinable shaft segments to be controlled, and containing no operable threaded parts, comprising: 
 (a) a first portion configured for fixed mounting within the first shaft;    (b) a second portion configured for slidable movement within and relative to said second shaft, comprising: 
 (i) a cam member mounted for movement with said first portion; and  
 (ii) a cam follower rotatably mounted on said cam member and engageable with an inner surface of said second shaft, for selectively frictionally engaging said inner surface of said second shaft in response to rotation of said cam follower relative to said cam member.  
   
   
   
       13 . A shaft adjustment locking apparatus as recited in  claim 12 , wherein said cam member includes a cam surface eccentrically oriented with respect to a longitudinal axis of said first and second shafts.