Dragline Excavator

A dragline excavator is a piece of heavy equipment used in civil engineering and surface mining.

Draglines fall into two broad categories: those that are based on standard, lifting cranes and the heavy units which have to be built on-site. Most crawler cranes with an added winch drum on the front can act as a dragline. For example, this video shows a crane-type Linkbelt dragline in operation. These units (like other cranes) are designed to be dismantled and transported over the road on flatbed trailers. Draglines used in civil engineering are almost always of this smaller, crane type. These are used for road, port construction, pond and canal dredging, and as pile driving rigs. These types are built by crane manufacturers such as Linkbelt and Hyster.

The much larger type which is built on site is commonly used in strip-mining operations to remove overburden above coal and more recently for tar-sand mining. The largest heavy draglines are among the largest mobile land machines ever built. The smallest and most common of the heavy type weigh around 8,000 tons while the largest today weigh around 8,350 tons.

A dragline bucket system consists of a large bucket which is suspended from a boom (a large truss-like structure) with wire ropes. The bucket is manoeuvered by means of a number of ropes and chains. The hoist rope, powered by large diesel or electric motors, supports the bucket and hoist-coupler assembly from the boom. The dragrope is used to draw the bucket assembly horizontally. By skillful manoeuvre of the hoist and the dragropes the bucket is controlled for various operations. A schematic of a large dragline bucket system is shown below.

Read more about Dragline Excavator:  History, Operation, Draglines in Mining, Limitations, Examples, Technological Advances

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Ruston-Bucyrus - The R-B International Era
... of existing Ruston-Bucyrus designed cable excavator/crane models from the 22RB to the 71RB continued at the Lincoln factory with 'Improved Crane Dragline' versions also ... model developed from the 38-RB was offered for use as a crane or dragline excavator In 1990 RB bought from its rival Priestman, the design and manufacturing rights to Priestman's ... its CH series of fully hydraulic crane/dragline models with further models added in 1999 ...
Dragline Excavator - Technological Advances - UDD
... It represents the first fundamental change to draglines for almost a century, since the invention of the 'miracle hitch' ... This allows the dragline operator to have much greater selectivity in when to pick up the bucket, and in how the bucket may be dumped ... UDD machines generally have higher productivity than a standard dragline, but often have greater mechanical issues ...