Enerpac and Copper Fluid Systems (CFS) have come to the rescue of a Queensland coal miner looking for a way to safely and efficiently carry out maintenance on its dragline.

The hydraulics leader, in tandem with Queensland distributor CFS, devised a solution that incorporated its RACH306 lightweight aluminium cylinders. This allowed operators to get out on the boom to provide essential maintenance.

Such a system requires special tools offering a combination of high power, light weight, compact size and reliability, Enerpac said. This is where the RACH306 cylinders provided a lightweight solution for tensioning the intermediate boom suspension on the dragline, ensuring it continued to operate without causing excess wear on the main frame.

With a total weight of around 11 kg each, the aluminium cylinders are roughly half the weight of their steel counterparts and provide the same power, with a capacity of 30 t, the company said.

CFS Queensland Regional Manager, Mark Lorber, said: “The lighter weight makes a significant difference to the safety and comfort of maintenance personnel, as the only way to get the tools up on the dragline is to individually transport them out on the boom and spend time precisely positioning them there.

“The Enerpac gear is used to tension the intermediate boom suspension ropes by sliding over threaded rods with 30 mm studs at each of the adjustment points. Hollow cylinders are used because they can slide over the top of the stud. The Enerpac RACH cylinders provide a 6 in (150 mm) stroke with smooth, reliable performance.”

Tensioning these suspension ropes on draglines is an essential maintenance task for mining operations, according to Lorber. A slack or loose rope can cause additional stress, or even cracking on the main frame – especially when digging, he said.

Lorber added: “With draglines typically costing in excess of A$100 million ($64 million), regular preventative maintenance is a vital part of minimising downtime and avoiding unexpected costs. The major advantages of using Enerpac tools in this application are the quality of a market-leading brand, coupled with service support on-site.”

CFS custom designs dragline tensioning system boxes, with each box containing four Enerpac P80 hand pumps, four Enerpac RACH306 aluminium hollow plunger cylinders and MDG41-compliant hydraulic pressure hoses. Four boxes are used in total for each dragline machine, where they are mounted on each boom.

The tensioning system boxes are designed to be weatherproof and protect the hydraulics against dust, which is highly prevalent on open-pit coal mining operations. Additionally, the boxes have a separate shelf for the pump so that it is further protected from dirt, grease and other contaminants, the company said.

Enerpac’s RACH-Series cylinders, with strokes from 50-250 mm, weigh from just 5.2-9 kg for the 20 t models through to a maximum of 48.9-77.2 kg for the range-topping 150 t models. The cylinders are comprised of composite bearings on all moving surfaces to prevent metal-to-metal contact, resist side loads and extend cylinder life.

Complementing the RACH-Series cylinders are Enerpac’s lightweight hand pumps, models P-392 or P-802, which are constructed of composite materials including aluminium to comprise the optimum lightweight pump and cylinder set, according to the company. The cylinders can also be powered by fast-acting Enerpac electric, air and petrol pumps.

Features of the full RAC range include:

• Hollow plunger design allows for both pull and push forces;
• Composite bearings increase cylinder life and sideload resistance;
• Hard-Coat finish on all surfaces resists damage and extends cylinder life;
• Floating centre tube increases seal and product life;
• Handles standard on all models;
• Steel base plate and saddle for protection against load-induced damage;
• Integral stop ring prevents plunger over-travel and is capable of withstanding the full cylinder capacity;
• High strength return spring for rapid cylinder retraction;
• CR-400 coupler and dustcap included on all models; and
• All cylinders meet ASME B-30.1 and ISO 10100 standards.