Question

By now, you should have listened to the audio lecture, read the chapter, and taken the self-assessment and quiz. For this discussion activity, I want you to respond to the following question in the Discussion area in this learning module.

• Clamshells are one of the special excavator types and sometimes clamshells are compared with draglines. List and discuss at least three different points between the two (Dragline vs. Clamshell) in terms of operations, productivity, etc. Do research on the internet, if necessary.

Answer 1

- The dragline bucket is loaded and being pulled up by drag cable through the material being excavated and toward the crane. By this arrangement dragline offer a longer reach than the clamshell.

- Dragline excavate direction is the back and below direction, so we can use it to excavate the soils and materials, which is lower than stop machine surface. During the excavate period, drag line excavator will under the help of inertia force to throw out the bucket tooth pin with the far distance, so its excavate diameter and depth all very big. Whereas clamshell excavate direction is straight up and down, which used to excavate soils below the stop machine surface too. If the working area is softy soil areas, we can use the clam shell excavator to excavate the based pits and deeply open caisson.

- Dragline are adaptable to either land based or barge mounted operation. They are capable of excavation material at nearly in-situ densities and are easily controlled and maneuvered in small and confined areas, although somewhat less than clamshell. Dragline are capacapabe shallow water excavation