CHAPTER 6 RIGGING Rigging is the method of handling materials using fiber  line,  wire  rope,  and  associated  equipment.  Fiber line and wire rope were discussed in chapters 4 and 5. We   will   now   discuss   how   these   materials   and equipment  can  be  used  in  various  tackle  and  lever arrangements  to  form  the  fundamental  rigging necessary  to  move  heavy  loads.  Additionally,  we discuss  the  makeup  of  block  and  tackle,  reeving procedures, and   common   types   of   tackle arrangements. Information is also provided on other common  types  of  weight-handling  devices,  such  as slings,  spreaders,  pallets,  jacks,  planks  and  rollers, blocking and cribbing, and scaffolds. SAFETY is paramount in importance. You will be briefed  throughout  this  chapter  on  safety  measures  to be  observed  as  it  pertains  to  the  various  operations  or particular   equipment   we   are   discussing.   Also, formulas  are  given  for  your  use  in  calculating  the working   loads   of   various   weight-moving   devices, such  as  hooks,  shackles,  chains,  and  so  on.  SAFE rigging  is  the  critical  link  in  the  weight-handling process. BLOCK AND TACKLE The  most  commonly  used  mechanical  device  is block and tackle. A block (fig. 6-1) consists of one or more  sheaves  fitted  in  a  wood  or  metal  frame supported by a shackle inserted in the strap of the Figure 6-1.—Parts of a fiber line block. block. A tackle is an assembly of blocks and lines used to gain a mechanical advantage in lifting and pulling. The  mechanical  advantage  of  a  machine  is  the amount the machine can multiply the force used to lift or  move  a  load.  The  strength  of  an  individual determines the weight he or she can push or pull. The ability to push or pull is referred to as the amount of force  the  individual  can  exert.  To  move  any  load heavier than the force you can exert requires the use of a machine that can provide a mechanical advantage to  multiply  the  force  you  can  apply.  If  you  use  a machine that can produce a push or pull on an object that is 10 times greater than the force you apply, the machine  has  a  mechanical  advantage  of  10.  For example, if the downward pull on a block-and-tackle assembly  requires  10  pounds  of  force  to  raise  100 pounds, the assembly has a mechanical advantage of 10. In a tackle assembly, the line is reeved over the sheaves of blocks. The two types of tackle systems are simple and compound. A simple tackle system is an assembly of blocks in which a single line is used (fig. 6-2,  view  A).  A  compound  tackle  system  is  an assembly of blocks in which more than one line is used (fig. 6-2, view B). Figure 6-2.—Tackles: A. Simple tackle; B. Compound tackle. 6-1