Device for adjusting the degree of preload of the springs in office chair mechanisms

Abstract

A device for adjusting the degree of preload of springs in office chair mechanisms which comprise at least two parts hinged together and elastic means ( 30 ) maintaining said parts elastically spaced apart, said device being characterised by comprising: -a first element ( 36 ) provided with at least one inclined surface ( 40 ) and coupled to one of the parts (to the elastic means), -a second element ( 42 ) provided with at least one appendix interacting with the inclined surface ( 40 ) of the first element, and coupled to the elastic means (to one of the parts), -means ( 46,48 ) for inducing axial rotation of one of said elements, means ( 54, 56 ) for blocking the rotation of the other element.

1 - 6 . (canceled)  
   
   
       7 . A device for adjusting the degree of preload of springs in office chair mechanisms, said device comprising at least two first and second parts hinged together, 
 elastic means maintaining said first and second parts elastically spaced apart,    a first element provided with at least one inclined surface extending helically,    a second element provided with at least one inclined surface extending helically and interacting with the inclined surface of the first element,    means for inducing axial rotation of one of said two elements,    means for blocking the rotation of the other of said two elements,    said first and second elements being coupled between the elastic means and one of the first and second parts.    
   
   
       8 . The device as claimed in  claim 7 , wherein the means for inducing axial rotation consists of a linkage perpendicular to the axis of rotation.  
   
   
       9 . The device as claimed in  claim 7 , wherein the means for inducing axial rotation consists of a worm engaging a toothing provided on one of two elements.  
   
   
       10 . The device as claimed in  claim 7 , wherein the means for inducing axial rotation consists of a pinion engaging a ring gear provided on one of the two elements.