opening,  very  much  like  the  opening  in  the  box-end wrench. The 12-point socket needs to be swung only half as far as the 6-point socket before it has to be lifted and fitted on the nut for a new grip. It can therefore be used in closer quarters where there is less room to move the handle. (A ratchet handle eliminates the necessity of lifting the socket and refitting it on the nut again and again.) Sockets  are  classified  by  size  according  to  two factors. One is the size of the square opening, which fits on the square drive lug of the handle. This size is known as the drive size. The other is the size of the opening in the   opposite   end,   which   fits   the   nut   or   bolt.   The standard toolbox can be outfitted with sockets having 1/4-, 3/8-, and 1/2-inch-square drive lugs. Larger sets are  usually  available  in  the  tool  room  for  temporary checkout. The openings that fit onto the bolt or nut are usually graduated in 1/16-inch sizes. Sockets are also made in deep lengths to fit over spark plugs and long bolt ends. Socket Handles There  are  four  types  of  handles  used  with  these sockets.    (See    fig.    1-32.)    Each    type    has    special advantages,  and  the  experienced  worker  chooses  the one best suited for the job at hand. The square driving lug  on  the  socket  wrench  handles  has  a  spring-loaded ball that fits into a recess in the socket receptacle. This mated  ball-recess  feature  keeps  the  socket  engaged with the drive lug during normal usage. A slight pull on the socket, however, disassembles the connection. RATCHET.—The  ratchet  handle  has  a  reversing lever that operates a pawl (or dog) inside the head of the tool. Pulling the handle in one direction causes the pawl to engage the ratchet teeth and turn the socket. Moving the handle in the opposite direction causes the pawl to slide  over  the  teeth,  permitting  the  handle  to  back  up without moving the socket. This allows rapid turning of the nut or bolt after each partial turn of the handle. With the  reversing  lever  in  one  position,  the  handle  can  be used for tightening. In the other position, it can be used for loosening. HINGED HANDLE.—The hinged handle is also very convenient. To loosen tight nuts, swing the handle at  right  angles  to  the  socket.  This  gives  the  greatest possible leverage. After loosening the nut to the point where it turns easily, move the handle into the vertical position and then turn the handle with the fingers. SLIDING   T-BAR   HANDLE.—When   you   are using  the  sliding  bar  or  T-handle,  the  head  can  be positioned  anywhere  along  the  sliding  bar.  Select  the position that is needed for the job at hand. SPEED HANDLE.—The speed handle is worked like  the  woodworker's  brace.  After  the  nuts  are  first loosened  with  the  sliding  bar  handle  or  the  ratchet handle, the speed handle can be used to remove the nuts more quickly. In many instances the speed handle is not strong   enough   to   be   used   for   breaking   loose   or tightening the nut. The speed socket wrench should be used carefully to avoid damaging the nut threads. Accessories Several    accessory    items    complete    the    socket wrench  set.  Extension  bars  of  different  lengths  are made  to  extend  the  distance  from  the  socket  to  the handle.  A  universal  joint  allows  the  nut  to  be  turned with the wrench handle at an angle. Universal sockets are  also  available.  The  use  of  universal  joints,  bar extensions, and universal sockets in combination with appropriate handles makes it possible to form a variety of tools that will reach otherwise inaccessible nuts and bolts. Another accessory item is an adapter, which allows you to use a handle having one size of drive and a socket having  a  different  size  drive.  For  example,  a  3/8-  by 1/4-inch    adapter    makes    it    possible    to    turn    all 1/4-inch-square drive sockets with any 3/8-inch-square drive handle. TORQUE WRENCHES There  are  times  when,  for  engineering  reasons,  a definite force must be applied to a nut or bolt head. In such cases a torque wrench must be used. For example, equal force must be applied to all the head bolts of an engine. Otherwise, one bolt may bear the brunt of the force   of   internal   combustion   and   ultimately   cause engine failure. 1-23