186  Miscellaneous  Implements  Exhibited  at  Park  Royal. 
is  pivoted  a weighted  lever  (c)  carrying  a ledger  plate  which 
bears  against  a ledger  rigidly  connected  with  the  cam  (r). 
This  cam  is  carried  on  a lever  (<£)  similarly  pivoted  inside  the 
drum  but  projects  outside  of  the  casing.  The  lever  (^Z) 
carries  a rod  (c),  one  extremity  of  which  projects  into  a 
central  hole  formed  in  the  cam.  The  other  end  has  attached 
to  it  a spiral  spring  (/),  one  end  of  which  is  fixed  to  the 
weighted  lever  (c). 
When  the  engine  is  running  at  normal  speed  the  spring  ( f) 
holds  the  weighted  lever  (c)  so  that  its  ledger  engages  the  cam 
ledger,  the  cam  (v)  being  thus  held  rigid  and  operating  the 
vapour  valve  lever  on  coming  in  contact  with  it. 
Fig.  2.— Direct-acting  Centrifugal  Governor  (.\rticle  100). 
When  the  speed  is  exceeded  the  weighted  lever  (c)  moves 
outwards  under  the  influence  of  centrifugal  force;  the  cam 
lever  (d)  is  thus  de])rived  of  its  sujiport  and  is  only  held  in 
position  by  the  spring  (/)  which  yields  when  the  cam  strikes 
the  vapour  valve  lever  so  that  the  latter  is  not  actuated.  The 
speed  of  the  engine  is  adjusted,  whilst  running,  by  means  of  a 
taper  pin  which  is  introduced  into  the  central  hole  of  the  cam 
(v),  and  pushes  out  the  sliding  rod  (e),  thus  regulating  the 
tension  of  the  spring  (/). 
