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Excavators, Draglines, and Clamshells
Published in John E. Schaufelberger, Giovanni C. Migliaccio, Construction Equipment Management, 2019
John E. Schaufelberger, Giovanni C. Migliaccio
A contractor has decided to use a dragline to excavate a ditch to drain storm runoff from her construction site. The dragline bucket and fairlead are to be mounted on a 40-ton crawler crane with 70-foot boom. The material to be excavated is a hard, tough clay weighing 3,000 pounds per bank cubic yard with a swell of 22%. Given the density of the material to be loaded, the contractor has determined that the largest heavy duty dragline bucket that can be safely mounted on the crane has a rated capacity of 2 cubic yards. What is the estimated production rate of the dragline in bank cubic yards per hour, if the average depth of the dig is 12 feet and the average angle of swing is 120o? The contractor plans to operate the machine about 40 minutes per hour.Rental and operating cost for the dragline is about $132 per hour, and the operator’s wage is $55 per hour. What is the estimated unit cost per bank cubic yard for excavating the ditch?If the ditch to be constructed is 5 feet wide, 18 feet deep, and 700 feet long, how many days will it take the dragline to complete the excavation, if the contractor works eight hours per day?
Mucking, casting and excavation
Published in Ratan Raj Tatiya, Surface and Underground Excavations, 2013
A dragline is a single bucket excavator in which the bucket is pulled by a drag rope (hence the name - dragline) over the face towards the equipment itself, as shown in figure 6.9(a). It differs from the face shovel, described in the preceding section, in that the bucket (1) is not fixed rigidly to the boom but hangs from flexible ropes. The bucket is hanged to the rope by the lifting chains and their separating bar (fig. 6.9(a)). These chains are joined together and are attached to a load-line (4) (drag rope). They are also attached to a dumping line (8) whose other end is fixed to the front end of the bucket after passing over the bucket hoisting block (7). This block is at the junction of the hoist line (5) and bucket chains.
Notch stress factor of welded thick-walled tubular dragline joints by effective notch stress method
Published in J.A. Packer, S. Willibald, Tubular Structures XI, 2017
N.L. Pang, X.-L. Zhao, F.R. Mashiri, P. Dayawansa, J.W.H. Price
Dragline is large mining equipment with a boom length of about 100 m, used to lift a total bucket weight of approximately 180–210 tonnes. The boom of a dragline machine may be made up of welded, large thick-walled circular hollow section (CHS). These connections consist of a main chord member with 3- to 5-lacing members, all welded to the chord at one point forming complex overlapped joint. Multi-planar double overlapping CHS NN-joint consisting of 4-lacing members is the most common type of joint in the dragline boom (Pang et al. 2005). Constant monitoring of dragline structures has shown that fatigue cracks are prevalent in the dragline CHS connections and hence making the draglines susceptible to fatigue failure.
Using machine learning algorithms to predict cast blasting performance in surface mining
Published in Mining Technology, 2022
Sheo Shankar Rai, V. M. S. R. Murthy, Rahul Kumar, Mujigela Maniteja, Ashok Kumar Singh
A dragline equipment system is defined by a smaller fleet, higher operating efficiency, low production costs, and low environmental and carbon footprints (Zevgolis et al. 2018; Rai et al. 2021). Another significant advantage of dragline operation is its application in high bench mining, resulting in steeper excavation slopes and thereby resulting in a lower quantity of OB per tonne of coal produced (Figure 2). Hustrulid et al. (2013) in their study found that for every 10° flattening of the pit slope of a 150 m deep open pit, the OB was doubled in volume.