• Home
  • Download PDF
  • Order CD-ROM
  • Order in Print
Clamshell Operations
Pile-Driving Operations

Equipment Operator Basic - Beginning construction equipment operators manual
Page Navigation
  309    310    311    312    313  314  315    316    317    318    319  
7. The drag cable can be reversed end for end to prolong the life of the wire rope, reduce early wire rope replacement,   and  keep  wire  rope  cost  down. Remember,  the  drag  cable  should  not  be  lubricated. 8. When lowering the dragline bucket into the area to be worked, release the drag brake to tip the cutting edge down and then release the hoist brake. You do not have to drop the bucket to force the teeth into the material. The bucket is filled as it is dragged toward the crane  by  engaging  the  drag  control  lever.  The  cutting depth is controlled by releasing tension from the hoist brake. The dragline is NOT a positive digging tool. 9. The dragline cycle is filling the bucket, lifting the  bucket,  swinging  the  loaded  bucket,  and  dumping the load. 10. Since the dragline is not a rigid attachment, it will  not  dump  materials  as  accurately  as  do  other excavators. When a load is dumped into a haul unit or hopper,  you  need  more  time  to  position  the  bucket before dumping it. NOTE: When you are dumping into a haul unit, NEVER load over the cab. Additionally, make sure the operator is out of the cab and clear of the dragline or clamshell  bucket. 11.  The  boom  angle  for  dragline  operations  should normally be from 25 to 35 degrees. However, check the crane load chart to ensure this low boom angle does not exceed the capacity of the crane. At this relatively low boom angle, you must be careful when excavating and dumping wet, sticky materials, because the chance of tipping the crane is increased because the material tends to hang in the bucket. Dragline Employment The dragline can be used in dredging where the material handled is wet and sticky. It can dig trenches, strip  overburden,  clean  and  dig  road  side  ditches,  and slope  embankments. When the dragline is handling mud,  it  is  the  most  practical  attachment.  Its  reach enables it to handle a wide area of excavation while sitting in one position, and the sliding action of the bucket  eliminates  trouble  with  suction. Other uses of the dragline include the following: 1. In-line approach. When excavating a trench with the dragline, ensure the dragline and carrier unit are centered on the excavation (fig. 12-48). The dragline cuts or digs to the front and dumps on either side of the excavation. The crane moves away from the face as the work  progresses. 2. Parallel approach. The dragline can slope an embankment better by working it from the bottom to the top. The crane is positioned on the top with the carrier parallel to the working face, so it can move the full length of the job without excessive turning. 3.  Drainage.  A  dragline  is  ideal  if  earthwork materials have to be removed from a trench, canal, gravel pit, and so forth, containing water. Plan the work to begin at the lowest grade point, so drainage will be provided as the dragline progresses towards higher levels. NOTE: Digging underwater or in wet materials increase the weight of the materials and frequently prevent  carrying  heaped  bucket  loads. Ditching the excavation through swamps or soft terrain  is  common.  Under  these  conditions  the excavated material is normally cast onto a levee or spoils bank. 4.  Loading  haul  units.  When  the  job  requires excavated material to be loaded into hauling units, the excavation  should  be  opened  up  so  loaded  hauling equipment can travel on high, dry ground or on better grades.  The  spotting  of  trucks  and  dragline  should  be planned  for  minimum  boom  swing  with  the  truck  bed under the boom point and the long axis of the bed parallel with the long axis of the boom or at right angles to the boom. More spillage is to be expected from a dragline than from a front-end loader. Efficient  Dragline  Operation Other uses of the dragline operation include the following: 1. Although the dragline bucket can be readily cast beyond the length of the boom, the machine should be positioned  to  eliminate  casting. 2. Use heavy timber mats for work on soft ground. The mats should be kept level and clean. 3. When setting up for a dragline operation, you should  have  access  for  maintenance,  operating personnel,  and  hauling  equipment. 4.  Excavate  the  working  area  in  layers,  not  in trenches,  and  keep  the  slope  upward  toward  the crane. 5. Do not drag the bucket in so close to the crane that it builds piles and ridges of material in front of the crane. 12-35







Western Governors University

Privacy Statement
Press Release
Contact

© Copyright Integrated Publishing, Inc.. All Rights Reserved. Design by Strategico.