Nave with a touch ring of the gauge of frequency of rotation of a wheel 
 
 
 | 
 
  | 
 And – a nave of a forward wheel; 
  
 – a nave of a back wheel;  
  
 1 – a touch ring; 
  
 2 – a nave | 
  
 
Touch rings 1 are built in naves of 2 wheels, therefore a touch ring it is possible to replace only in gathering with a nave.    |