Open Cut » Maintenance & Equipment
This report presents the findings of a study conducted as ACARP Project Number C12035, which was aimed at investigating swing shaft failures on draglines with a view to developing some specific proposals for ameliorative measures.
A large proportion of the Australian dragline fleet comprises BE 1350/1370W and Marion 8050/8200 models. These models all have a fairly similar arrangement for supporting the lower swing shaft bearing and for attaching the swing pinion to the shaft. The study therefore focussed mainly on these models, and primarily machines operating in the eastern states of Australia. At the commencement of the study, WBM was of the view that the causes of a majority of swing shaft and pinion failures and the need for ongoing maintenance (eg. tightening of the pinion retaining bolts) could be linked to various design limitations with the current arrangement. This study aimed at quantifying what was needed to overcome the deficiencies so that the maintenance requirement could be reduced and the risk of failure minimised.
The first stage of the project involved contacting dragline planning and maintenance staff at various coal mines, to:
- obtain details of failures experienced over the life of the various draglines for which the dragline maintenance staff had some knowledge
- identify specific maintenance practices that have been adopted and found to be either advantageous or cause problems at particular mines; in particular to identify the various modes of failure that have caused swing shafts to be taken out of service
- identify which dragline models have traditionally experienced the most problems and whether quantifiable differences in certain of the models could be correlated with a greater or reduced likelihood of problems being experienced
- identify modifications that have been implemented over time on different draglines/series to overcome specific problems being experienced.
Following the initial contact with mine staff, WBM developed a number of possible concepts for modifying the design of the lower bearing support and pinion attachment to the shaft. These were then discussed with engineering staff at several of the mines for opinions on their ease of implementation and likely effectiveness. A brief explanation of various possibilities considered and some preferred options for ameliorative measures appear in this report.
Details of possible implications for implementing some of the preferred options have been provided together with indicative costing. This should allow individual dragline operators to carry out a feasibility assessment of a swing system modification incorporating any of the preferred options, as well as allow them to undertake their own cost-benefit analysis.
Another significant outcome of this project is that a lot of valuable information on the subject which has existed only in fragmented records and people's memories has been collected together and presented in this report.