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pulleysmore about pulleys


  1  definition  found 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
  Pulley  \Pul"ley\,  n.;  pl  {Pulleys}.  [F.  poulie,  perhaps  of 
  Teutonic  origin  (cf.  {Poll},  v.  t.);  but  cf  OE  poleine 
  polive,  pulley,  LL  polanus  and  F.  poulain,  properly,  a 
  colt,  fr  L.  pullus  young  animal,  foal  (cf.  {Pullet}, 
  {Foal}).  For  the  change  of  sense  cf  F.  poutre  beam, 
  originally,  a  filly,  and  E.  easel.]  (Mach.) 
  A  wheel  with  a  broad  rim,  or  grooved  rim,  for  transmitting 
  power  from  or  imparting  power  to  the  different  parts  of 
  machinery,  or  for  changing  the  direction  of  motion,  by  means 
  of  a  belt,  cord,  rope,  or  chain. 
  Note:  The  pulley,  as  one  of  the  mechanical  powers,  consists, 
  in  its  simplest  form  of  a  grooved  wheel,  called  a 
  sheave,  turning  within  a  movable  frame  or  block,  by 
  means  of  a  cord  or  rope  attached  at  one  end  to  a  fixed 
  point.  The  force,  acting  on  the  free  end  of  the  rope, 
  is  thus  doubled,  but  can  move  the  load  through  only 
  half  the  space  traversed  by  itself  The  rope  may  also 
  pass  over  a  sheave  in  another  block  that  is  fixed.  The 
  end  of  the  rope  may  be  fastened  to  the  movable  block, 
  instead  of  a  fixed  point,  with  an  additional  gain  of 
  power,  and  using  either  one  or  two  sheaves  in  the  fixed 
  block.  Other  sheaves  may  be  added,  and  the  power 
  multiplied  accordingly.  Such  an  apparatus  is  called  by 
  workmen  a  block  and  tackle,  or  a  fall  and  tackle.  See 
  {Block}.  A  single  fixed  pulley  gives  no  increase  of 
  power,  but  serves  simply  for  changing  the  direction  of 
  {Band  pulley},  or  {Belt  pulley},  a  pulley  with  a  broad  face 
  for  transmitting  power  between  revolving  shafts  by  means 
  of  a  belt,  or  for  guiding  a  belt. 
  {Cone  pulley}.  See  {Cone  pulley}. 
  {Conical  pulley},  one  of  a  pair  of  belt  pulleys,  each  in  the 
  shape  of  a  truncated  cone,  for  varying  velocities. 
  {Fast  pulley},  a  pulley  firmly  attached  upon  a  shaft. 
  {Loose  pulley},  a  pulley  loose  on  a  shaft,  to  interrupt  the 
  transmission  of  motion  in  machinery.  See  {Fast  and  loose 
  pulleys},  under  {Fast}. 
  {Parting  pulley},  a  belt  pulley  made  in  semicircular  halves, 
  which  can  be  bolted  together,  to  facilitate  application 
  to  or  removal  from  a  shaft. 
  {Pulley  block}.  Same  as  {Block},  n.  6. 
  {Pulley  stile}  (Arch.),  the  upright  of  the  window  frame  into 
  which  a  pulley  is  fixed  and  along  which  the  sash  slides. 
  {Split  pulley},  a  parting  pulley. 

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