Norbar Case Study
EziTite Hydraulic Nut for Bucyrus Eire 1370 Dragline Safety Rope Tensioners
BMA Saraji Coal Mine
About Saraji Coal Mine
The Saraji mine is an open pit coal mine located near Dysart in Queensland’s Bowen Basin. It is one of Australia’s largest mines, by recoverable coal reserves. Saraji mines the Moranbah Coal Measures, blending from up to 11 coal seams.
Refining a tensioning system for Bucyrus Eire 1370 Dragline
Dragline buckets are enormous pieces of machinery used on mining sites, capable of moving hundreds of tonnes of material in each pass. The large bucket excavator is controlled by a system of pulleys, chains and ropes that hoist the bucket.
On a Bucyrus Eire 1370 dragline, the primary function of the rear leg safety ropes is to provide strength and stability to the mast. The secondary function of the safety ropes is to reduce unwanted flex and movement, potentially leading to stress cracks occurring in the boom.
Norbar Australia was initially approached by BMA to develop and refine a tensioning system for the Integral Boom Support (IBS) ropes. The requirement needed to be lighter, safer, and less expensive than the previous method while also being quicker and easier to use.
The recommendations provided would enable the IBS ropes to be tensioned in a matter of hours as opposed to over several shifts.
It was the success of the IBS tensioners that prompted BMA to re-engage Norbar Australia to develop a similar system for the rear leg safety ropes.
A cause for concern
The previous method employed by BMA in tensioning rear leg safety ropes included a custom designed piece of 40mm BIS plate to be used in conjunction with multiple 100t hydraulic cylinders. This method lacked in three key areas:
Due to weight of tooling and the awkward nature of the task, tensioning the safety rope took multiple maintenance technicians several shifts to complete.
Due to the difficulties involved with the methodology of the previous process, the tensioning of the safety rope became a maintenance function and could be overlooked or applied inaccurately.
Neglecting maintenance can cause incorrect tension on the safety rope and result in cracking of the boom. By overlooking this maintenance function, the operators risked lost production time if unscheduled maintenance to the boom was required.
Several OH&S concerns were raised around the previous method. This included the manufacture and use of a BIS plate due to weight and lack of engineering. There were additional concerns around pinch point injuries and manual handling related issues associated with the use of a 100ton cylinder.
A lighter, safer, and less expensive alternative
In providing a safe and efficient method of tensioning the rear leg safety ropes, Norbar Australia recommended a bespoke version of the EziTite® Hydraulic Nut. This product significantly simplified the process by providing BMA with an ‘all in one’ hydraulic nut and tensioner. This product is custom engineered and fit for purpose.