Mobile Equipment
The critical role of draglines in coal mining means that reducing downtime can represent large improvements in production. Several draglines had a persistent issue with fatigue cracking in the boom lacing clusters, which are joints that create the structural integrity of the dragline boom. The OEM design dated from the 1960s, was complex to install, and crack repairs took a long time and were prone to errors. The sites engaged FIELD Engineers to provide a better solution.
FIELD Engineers combined sound, no-frills mechanical engineering with performance proof. Engineers used 3D laser scans of the OEM clusters and operational loads to create analysis models of both the OEM design and a new “spade cluster” design. Analysis confirmed that the spade cluster design changed the stresses during operation in a way that would reduce fatigue cracking – a combination of reduced tensile stresses and peak shear stresses that only occurred in areas of compression, where cracks will not propagate.
The new design represents a return to simplicity and fundamentals: avoiding complex geometries that make installation and maintenance hard, while improving operational performance with better first-principles design. Reductions in fatigue cracking mean less maintenance over time for a design that now also requires less installation time. In this case, FIELD Engineers’ understanding of dynamic loading combined with dragline expertise resulted in a repeat-use after-market upgrade that will continue to save significant maintenance time. Success required not only complex modelling skills and nuanced understanding of stress impacts on design, but the hands-on knowledge of maintenance processes that work in the real world.
This cost-saving component design is not a one-off. FIELD is known across the industry as the dragline experts, which shows in numerous components we have engineered for maintenance savings and greater operational performance. These designs all hold to the principles of simplicity in design, avoid overengineering, and change traditional approaches when they simply do not deliver. These other component designs include:
Eliminates fatigue cracking, speeds manufacture
This project addressed a known fatigue cracking issue in dragline mastheads, which are traditionally welded together from smaller components. FIELD Engineers used geometry and operational load history to build a model, using finite element analysis to determine loads for fatigue life calculations. Based on this information, engineers re-designed the masthead to be machined from 180 mm steel plate, rather than being welded. This design virtually eliminates fatigue cracking for a long service life and significantly speeds manufacturing time.
Accurate, repeatable measurements for life planning
Measuring the load in dragline rollers and the centre of gravity (CoG) is required to predict the remaining life and ensure components are not being overstressed. Both are essential for predicting future maintenance and avoiding breakdowns. FIELD Engineers innovated in this field to develop a load measurement system housed within the pin of a dragline roller. This roller is then introduced into the roller circle, with instrumentation within it and in the revolving frame and tub producing accurate measurements of the load (and the COG location) throughout the full roller circle. Development time for this system was minimised through using FIELD’s existing wireless data acquisition system, and expert dragline knowledge. The system can now be used repeatedly for accurate measurements, improved maintenance planning and overstress avoidance.
When everyone else is scratching their heads or telling you it can’t be done give us a call.
