Chair control

Abstract

A chair control has a threaded element with a thread extending along an axis. A retainer limits axial freedom of the threaded element and a user control rotates the threaded element. A spring backstop is threaded to the threaded element and a spring with a projection has this projection stopped against the spring backstop.

1 . A chair control, comprising: 
 a threaded element having a thread extending along an axis;    a retainer for limiting axial freedom of said threaded element;    a user control for rotating said threaded element;    a spring backstop threaded to said threaded element; and    a spring having at least one projection, said at least one projection stopped against said spring backstop.    
   
   
       2 . The chair control of  claim 1  wherein said user control comprises a hand crank.  
   
   
       3 . The chair control of  claim 2  further comprising: 
 a first gear joined to said hand crank for rotation therewith; and    a second gear meshing with said first gear, said second gear coupled to said threaded element for driving said threaded element to rotate.    
   
   
       4 . The chair control of  claim 3  wherein an axis of rotation of said second gear is coincident with a central axis of said threaded element.  
   
   
       5 . The chair control of  claim 4  wherein said thread effectively provides about five turns per inch.  
   
   
       6 . The chair control of  claim 4  wherein said threaded element is a threaded shaft.  
   
   
       7 . The chair control of  claim 4  wherein said threaded element is a bolt, a head of said bolt being coupled to said second gear.  
   
   
       8 . The chair control of  claim 7  wherein said thread of said bolt is a triple start thread.  
   
   
       9 . The chair control of  claim 7  wherein said head of said bolt has a multi-faced side and wherein said second gear has a corresponding multi-faced bore engaging said bolt head.  
   
   
       10 . The control of  claim 6  further comprising a main frame and a backrest bracket, said spring acting between said spring backstop and said backrest bracket.  
   
   
       11 . The control of  claim 10  wherein said retainer is a retaining member held to said main frame.  
   
   
       12 . The control of  claim 11  wherein said first gear is a worm gear and said second gear is a pinion.  
   
   
       13 . The control of  claim 12  further comprising: 
 a gas control lever; and    a user control arm co-axially mounted to said hand crank for rotation through an arc, one of said control arm and said lever having a boss and another of said paddle and said lever having a receptor for receiving said boss such that rotation of said paddle through said arc pivots said lever.    
   
   
       14 . The control of  claim 3  further comprising a block supporting said first gear and said second gear, said retainer being joined to said block.  
   
   
       15 . The control of  claim 14  wherein said block has a depending resilient arm having a land on either side of a protuberance.  
   
   
       16 . The control of  claim 15  further comprising a cam finger supported for rotation, an end of said cam finger abutting said arm whereby said cam finger has two stable positions, one on each side of said protuberance.  
   
   
       17 . The control of  claim 16  wherein said user control is a first user control, and further comprising a second user control for rotating said cam finger.  
   
   
       18 . The control of  claim 17  further comprising a back rest lock operated between a lock position and an unlock position by rotation of said cam finger between each of said two stable positions.  
   
   
       19 . The control of  claim 1  wherein said spring has at least one helically wound section and said projection extends from an end of said at least one helically wound section.  
   
   
       20 . The control of  claim 19  wherein said spring has a second projection extending from an opposite end of said at least one helically wound section.  
   
   
       21 . The control of  claim 20  wherein said control further comprises a back bracket and wherein said second projection abuts said back bracket.  
   
   
       22 . A spring tensioner for a chair control mechanism, comprising: 
 a hand crank;    a worm gear rotated by said hand crank;    a pinion and captive bolt rotated by said worm gear;    a retainer limiting axial freedom of said bolt.    a spring backstop threaded to said bolt.