Adjustable length golf club

Abstract

A length adjustment mechanism useful on sports and other working implements allows the length of an implement to be easily adjusted. In the case of golf clubs, the length adjustment mechanism includes a handle with a set of interior threads that engage a set of exterior threads formed on an upper end of the golf club shaft. The handle can be screwed down over the threads on the upper end of the shaft to adjust the length of the club. The handle is then fixed with respect to the shaft, and a grip is formed over the handle. The handle can be selectively repositioned along the shaft to alter the length of the club by freeing the handle, screwing it to a new position, and re-fixing the handle in the new position.

What is claimed is:  
     
         1 . An adjustable length golf club, comprising: 
 a shaft having exterior threads formed at an upper end of the shaft;    a handle having an aperture configured to receive the upper end of the shaft, wherein interior threads that are configured to cooperate with the exterior threads on the shaft are formed on an inner surface of the aperture, and wherein the handle can be screwed down over the upper end of the shaft to adjust a combined length of the handle and shaft; and    a releasable fixation mechanism that releasably fixes the handle with respect to the shaft.    
     
     
         2 . The adjustable length golf club of  claim 1 , wherein the releasable fixation mechanism comprises a locking plug having exterior threads configured to cooperate with the interior threads of the handle, wherein the locking plug is screwed into the handle, wherein the locking plug can repositioned within the aperture of the handle by screwing the locking plug along the threads of the aperture, and wherein a lower face of the locking plug is configured to engage an upper end of the shaft to fix the handle with respect to the shaft.  
     
     
         3 . The adjustable length golf club of  claim 2 , wherein a shaped socket is formed in an upper face of the locking plug such that a driver with a shape corresponding to the socket can be used to reposition the locking plug.  
     
     
         4 . The adjustable length golf club of  claim 3 , wherein an access hole is formed in an upper end of the handle to allow a driver to extend through the access hole and into the shaped socket of the locking plug to engage and reposition the locking plug.  
     
     
         5 . The adjustable length golf club of  claim 3 , wherein the shaped socket in the upper face of locking plug comprises a hex socket, and further comprising an access hole formed in an upper end of the handle to allow a hex driver to extend through the access hole and into the hex socket to engage and reposition the locking plug.  
     
     
         6 . The adjustable length golf club of  claim 1 , wherein exterior threads are formed on an exterior surface of a lower end of the handle, and wherein the releasable fixation mechanism comprises a locking collar having interior threads configured to cooperate with the exterior threads on the lower end of the handle, and wherein screwing the locking collar onto the exterior threads on the lower end of the handle causes the handle to be compressed against the shaft to fix the handle with respect to the shaft.  
     
     
         7 . The adjustable length golf club of  claim 6 , wherein an exterior diameter of the handle increases from the lower end to an intermediate position, such that as the locking collar is screwed onto the exterior threads on the lower end of the handle, the handle will be compressed against the shaft to fix the handle with respect to the shaft.  
     
     
         8 . The adjustable length golf club of  claim 6 , wherein an inner diameter of the locking collar decreases from a upper end of the locking collar to a lower end of the locking collar such that as the locking collar is screwed onto the exterior threads on the lower end of the handle, the handle will be compressed against the shaft to fix the handle with respect to the shaft.  
     
     
         9 . The adjustable length golf club of  claim 1 , wherein the releasable fixation mechanism comprises: 
 a groove formed on an outer surface of the upper end of the shaft, wherein the groove extends along a longitudinal axis of the shaft; and    a fastener that passes through the handle and into the groove to fix the handle with respect to the shaft.    
     
     
         10 . The adjustable length golf club of  claim 9 , wherein the fastener comprises a threaded fastener having external threads that cooperate with internal threads on a fixation aperture that passes through the handle.  
     
     
         11 . The adjustable length golf club of  claim 9 , wherein a recess is formed in the handle, and wherein when the fastener is mounted on the golf club to fix the handle with respect to the shaft, the fastener is positioned in the recess.  
     
     
         12 . The adjustable length golf club of  claim 1 , further comprising an insert that is attached to and that forms the upper part of the shaft, wherein the exterior threads formed at an upper end of the shaft are formed on the insert.  
     
     
         13 . The adjustable length golf club of  claim 12 , wherein the shaft is formed of a synthetic or composite material, and wherein the insert is formed of a metallic material.  
     
     
         14 . The adjustable length golf club of  claim 1 , further comprising length indicating marks that are formed on the shaft.  
     
     
         15 . The adjustable length golf club of  claim 14 , wherein the handle and the shaft are configured such that when the handle is positioned to minimize the combined length of the handle and the shaft, the handle at least partially covers the length indicating marks, and wherein as the handle is re-positioned to increase the combined length of the handle and the shaft, the handle will expose more of the length indicating marks.  
     
     
         16 . The adjustable length golf club of  claim 1 , further comprising a grip that is attached to an exterior surface of the handle.  
     
     
         17 . An adjustable length golf club, comprising: 
 a shaft having exterior threads formed at an upper end of the shaft;    a handle having an aperture configured to receive the upper end of the shaft, wherein interior threads that are configured to cooperate with the exterior threads on the shaft are formed on an inner surface of the aperture, and wherein the handle can be screwed down over the upper end of the shaft such that rotation of the handle with respect to the shaft adjusts a combined length of the handle and shaft; and    means for releasably fixing the handle with respect to the shaft.    
     
     
         18 . An adjustable length golf club, comprising: 
 a shaft having upper and lower ends;    a club head attached to the lower end of the shaft;    an insert that is inserted into and fixed to the upper end of the shaft,    wherein a portion of the insert protrudes from the upper end of the shaft, and wherein the protruding portion of the insert has external threads;    a handle having an aperture configured to receive the protruding portion of the insert and the upper end of the shaft, wherein interior threads that are configured to cooperate with the exterior threads on the insert are formed on an inner surface of the aperture, and wherein the handle can be screwed down over the insert and the upper end of the shaft to adjust a combined length of the handle and shaft; and    a releasable fixation mechanism that releasably fixes the handle with respect to the shaft.    
     
     
         19 . The adjustable length golf club of  claim 18 , wherein the releasable fixation mechanism comprises a locking plug located in the handle and having exterior threads configured to cooperate with the interior threads of the handle, wherein a shaped socket is formed in an upper face of the locking plug such that a driver with a shape corresponding to the socket can be used to screw the locking plug along the threads in the handle to reposition the locking plug in the handle, and wherein a lower face of the locking plug is configured to engage an upper end of the insert to fix the handle with respect to the insert and the shaft.  
     
     
         20 . The adjustable length golf club of  claim 18 , wherein exterior threads are formed on an exterior surface of a lower end of the handle, and wherein the releasable fixation mechanism comprises a locking collar having interior threads configured to cooperate with the exterior threads on the lower end of the handle, and wherein screwing the locking collar onto the exterior threads on the lower end of the handle causes the handle to be compressed against the shaft to fix the handle with respect to the shaft.  
     
     
         21 . The adjustable length golf club of  claim 18 , wherein the releasable fixation mechanism comprises: 
 a groove formed on an outer surface of the insert, wherein the groove extends along a longitudinal axis of the insert; and    a fastener that passes through the handle and into the groove to fix the handle with respect to the insert and the shaft.