Thesis (MScIng)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Thesis (MEng.) -- Stellenbosch University, 1997. / One copy microfiche. / ENGLISH ABSTRACT: This thesis desc1ibes the procedure followed in order to establish geometry changes to the current lig!1tweight dragline bucket lmilt by Wright Equipment Compan:Y to improve its performance. The bucket performs very well as is and big changes v , e not expected. This project was done as part of the Mechanical Engineering Masterr- Jegree requirements at the University of Stellenbosch, while being employed by Wriglh Equipment A scale model dragline was designed and built to be used in collecting the data. The most significant variables when considering dragline bucket filling were established and ranked according to their relative influence. The tests were done, using four different scale model dragline buckets and changing a 11umber of variables on each of them at different drag angles and in different digging conditions. Eventually it was found that a shorter, wider bucket with a lower hitch, resulted in improved performance as far as filling distance and filling energy requirements were concerned. The maximum required drag force was not increased, meaning stalling of the bucket would not be a problem. The changes do have some structural implications though aud should be investigated before any changes are made. / AFRIKAANSE OPSOMMING: Die tesis be£kryf die prosedure wat gevolg is om geometrie veranderinge aan die liggewig sleepgraatbak, wat deur die maatskappy Wright Equipment vervaardig word, te ondersoek. Die uiteindelike doel was om di~ produktiwiteit van die bak (gedefinieer as die hoeveel bogrond wat in 'n gegewe tyd geskuif word} te verbeter Die projek het deel gevorm van die vereistes vir 'n Meestersgraad in Meganiese lngenieurswese by die Universiteit van Stellenbosch. 'n Skaalmodel sleepgraaf is ontwerp en gebou vir gebruik in die versameling van die nodige data. Die belangrikste faktore betrokke by die vulling van sleepgraatbakke is vasgestel en in rangorde van belangrikheid gegroepeer. Vier skaalmodel sleepgraatbakke, waarop verskillende geometriese veranderinge gedoen kon word, is gebruik in toetse teen verskillendt sleephoeke en grondkondisies. Daar is gevind dat 'n korter, wyer bak met 'n laer sleeppUt"'t '1. v~rbetering in werkverrigting gee in terme van afstand om te vul en energie ve1·t.· :•.• Die maksimum sleepkrag benodig is ook nie verhoog nie, met die gevolg dat str:, l,' nie 'n probleeill sal wees me. Die voorgestelde veranderinge het egter struk.i.t..•' ic imt"i'---dsies wat eers ondersoek sal moet word voor enige veranderinge gedoen word.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / Dragline bucket designers are required to evaluate new bucket designs by building and testing scale buckets. Concerns about the reliability and accuracy of scale testing have been raised in recent years, but there was no alternative. However, recent advances in computing power and granular flow modeling are changing this and, we are entering an era where it is possible to numerically simulate dragline bucket filling. However, verification of the numerical simulation is necessary before useable data can be obtained. This thesis explains the algorithm used by modern discrete element codes to simulate granular materials. The process used to create the numerical model and calibrate the material will be discussed. An experimental test bench was also built to record experimental data for the verification the numerical model. As the project progressed it became clear that the time needed to run a single simulation dramatically limits the number of simulations that could be run. Consequently, different approaches that could reduce simulation time were also investigated. Unlike the other material parameters, there is no test that can be used to directly calibrate the damping. An array of numerical simulations were therefore conducted testing different damping schemes. The comparison performed between the numerical and experimental data showed that the numerical models could not accurately simulate the experimental measurements of the scale model dragline bucket. The numerical model did, however, predict many of the trends identified in the experimental simulation. With more realistic contact models and better computer facilities, nonetheless, it is highly probable that numerical models will be capable of simulating dragline bucket filling accurately. Further study is, therefore, justified.

Thesis (MEng) -- Stellenbosch University, 2000. / ENGLISH ABSTRACT: The utilisation ofDraglines to remove overburden in surface mining operations is often the process that determines the output of these operations. The bucket and its rigging have been identified as important components where design changes can improve the efficiency of the dragline. It is necessary to create a method to predict the dynamic behaviour of the bucket when various design changes are made to the rigging and the bucket. A rigid multibody dynamic method is formulated that can be used to predict the behaviour of any physical system that can be modelled as a set of connected rigid bodies. This multibody method is verified with analytic test problems and an experiment. A description is given how to use this rigid multibody dynamic method to model the dragline and predict the behaviour ofthe bucket during an operational cycle. / AFRIKAANSE OPSOMMING: Sleepgrawe word gebruik in oppervlakmynbouaktiwiteite om die mineraal neerslae wat ontgin word te ontbloot. Hierdie proses bepaal baie keer die produksie van die mynbou aktiwiteit. Die sleepgraaf se bak en die takelwerk van die bak het 'n groot invloed op die sleepgraaf se werksverrigting. Om die bak se werksverrigting te verbeter is 'n metode nodig om die dinamiese gedrag van die bak te voorspel. In hierdie dokument word 'n metode beskryf waarmee die dinamiese gedrag van enige stelsel bepaal kan word, wat as 'n stelsel van onderling-verbinde onbuigbare liggame beskryf kan word. Die korrektheid van hierdie metode is getoets met behulp van analitiese sowel as eksperimentele metodes. Daar word ook 'n beskrywing gegee hoe hierdie metode gebruik kan word om die beweging van die bak tydens 'n tipiese werksiklus te voorspel.