people from operation. NOTE: completion operations. congregating around the crane when in Safe   lifting   is   paramount!   Project must  not  interfere  with  safe  crane CLAMSHELL  OPERATIONS The clamshell bucket is an attachment used with a crane for vertical digging belowground level and for placing  materials  at  considerable  height,  depth,  or distance. You can also use it for moving bulk materials from stockpiles to plant bins, loading hoppers, and conveyors.  It  can  be  used  to  dig  loose  to  medium compacted  soil. Clamshell operating procedures are as follows: 1.  Position  and  level  the  crane,  ensuring  the digging operation is as close to the radius as the dumping operation.  This  prevents  you  from  having  to  boom  up and down, resulting in a loss of production. 2. Select the correct size and type of bucket for the crane. 3.  When  lowering  the  clamshell  bucket,  if  too much pressure is applied to the closing line brake, the bucket will close and an excess amount of wire rope will unwind from the holding line hoist drum. To avoid this, you should release the holding line and closing line brakes  simultaneously  when  lowering  the  open clamshell into the material for the initial bite. Engage the  closing  line  control  lever  to  close  the  bucket. Control the digging depth by using the holding line control lever and brake. 4. If, during hoisting, the hoist line gets ahead of the  closing  line,  the  bucket  will  open  and  spill  the material. (This could also be caused by having too much wire rope on the hoist drum.) The operator must hoist both the closing and holding lines at the same speed to keep  the  bucket  from  opening  and  spilling  material. 5.  When  the  clamshell  bucket  is  raised  enough  to clear all obstacles, start the swing by engaging the swing control lever. Hoisting the bucket can be performed, as it is swung to the dumping site. The spring-loaded tag line will retard the twisting motion of the bucket if the swing is performed smoothly. 6.   Dumping   and   unloading   the   clamshell   is performed by keeping the holding line brake applied while  the  closing  line  brake  is  released.  Apply  the closing  line  brake  quickly  after  the  load  is  dumped  to prevent the closing line from unwinding more wire rope than is needed to dump the material. After the bucket is emptied, swing the open clamshell back to the digging site. Then lower the open bucket and repeat the cycle. The clamshell operating cycle has four steps: filling (closing)   the   bucket,   raising   the   loaded   bucket, swinging, and dumping. The boom angle for clamshell operations should be between 40 to 60 degrees. Be careful when working with higher boom angles, as the bucket  could  hit  the  boom.  A  clamshell  attachment  is not a positive digging tool. The height reached by the clamshell depends on the length of the boom used. The depth reached by the clamshell is limited by the length of wire rope that the hoist drum can handle. For the safe lifting capacity for the  clamshell,  refer  to  the  operator’s  manual  and  the crane capacity load chart. DRAGLINE OPERATIONS The dragline is a versatile attachment capable of a wide range of operations at and belowground level. The dragline  can  dig  through  loose  to  medium  compacted soil.  The  biggest  advantage  of  the  dragline  over  other machines is its long reach for both digging and dumping. Another advantage is its high cycle speed. The dragline does not have the positive digging force of the backhoe. The bucket is not weighted or held in alignment by rigid structures; therefore, it can bounce, tip over, or drift sideways  when  digging  through  hard  materials.  This weakness  increases  with  digging  depth. Dragline operating procedures are as follows: 1. Keep the teeth sharp of the dragline bucket and built up to proper size. 2. Keep the dump rope short, so the load can be picked up at a proper distance from the crane. 3.  Excavate  the  working  area  in  layers,  not  in trenches, and sloped upward toward the crane. 4. Do not drag the bucket in so close to the crane that it builds piles and ridges of material in front of the crane. 5. Do not guide the bucket by swinging the crane while  digging.  This  puts  unnecessary  side  stresses  on the boom. Start the swing only after the bucket has been raised clear of the ground. 6. A pair of drag chains is attached to the front of the bucket through brackets by which the pull point may be adjusted up or down. The upper position is used for deep or hard digging, as it pulls the teeth into a steeper angle. 12-34