Construction equipment such as tractors, cranes, and backhoes all use linkages  ex- tensively in their design. Figure 1-1b shows a small backhoe that is a linkage driven by hydraulic cylinders. Another application using  linkages  is thatof  exercise  equipment  as shown in Figure  I-Ie.  The  examples  in Figure  1-1 are  all of consumer  goods  which you may encounter  in your  daily  travels.  Many  other  kinematic   examples  occur  in the  realm of  producer  goods-machines  used  to  make  the  many  consumer   products   that  we use. You are less  likely  to  encounter  these  outside  of  a factory  environment.  Once  you be- come familiar with the terms  and  principles  of kinematics,  you  will  no longer  be  able to look  at any  machine   or product   without  seeing  its kinematic   aspects.70588

1.5 THE DESIGN PROCESS Design, Invention,  Creativity

These are all familiar  terms  but  may  mean  different  things  to  different  people.  These terms  can encompass  a wide  range  of activities  from  styling  the newest  look  in  clothing, to creating  impressive  architecture,  to engineering  a machine  for  the  manufacture  of  fa- cial tissues.  Engineering  design,  which  we  are concerned   with  here,  embodies   all three of these activities as well as many others. The word design is derived from  the  Latin designare,  which  means  "to  designate,  or  mark  out."  Webster's  gives  several  defini- tions, the most applicable  being  "to  outline,  plot,  or plan,  as action  or work ...  to con- ceive, invent- contrive." Engineering design  has been  defined  as " ...  the process  ofap- plying the various  techniques  and  scientific  principles  for  the purpose  of defining  a de- vice,  a process   or  a  system  in sufficient   detail  to permit   its  realization ... Design  may be simple or enormously complex,  easy  or difficult,  mathematical  or  nonmathematical;  it may involve a trivial problem  or one  of great  importance."  Design  is a universal  con- stituent  of engineering   practice.    But  the  complexity   of engineering   subjects  usually   re-

DESIGN   OF MACHINERY CHAPTER    1

quires   that  the  student   be  served  with  a  collection   of structured, set-piece   problems designed to  elucidate  a  particular  concept  or  concepts  related  to  the  particular  topic. These textbook problems typically take the form of "given A, B, C, and D, find E." Un- fortunately, real-life engineering problems are almost never so  structured.  Real design problems more often take  the  form  of  "What  we need  is aframus  to stuff  this widget into that hole within the time allocated to the transfer  of  this  other  gizmo."  The  new  engi- neering graduate will search in vain  among  his  or  her  textbooks  for  much  guidance  to solve  such  a problem.    This  unstructured