The crane had completed five years of service at the Hidden Valley gold and silver mine in Papua New Guinea.

Bishops Company principal Mark Bishop decided that, after five years of continuous service at the mine, the crane would have benefited from a rebuild to as-new condition so he swapped it with his 100t Liebherr and shipped the previous crane back to his workshop and machine shop facility in Port Moresby, about 250 km away.

"Replacement of such an important part of the crane as its slew ring was fundamental to his rebuild strategy, for which he required top quality, fast, efficient and safe professional bolting technology," said Enerpac PNG manager  Pat Molloy, who works in partnership with Enerpac distributor Bishops.

The tools selected for the task included the Enerpac S1500 torque wrench, supplied by Bishops Port Moresby. The torque wrench was actuated by an Enerpac ZU4 torque wrench pump.

The  ZU4208BE-Q pump features a 1.7hp universal electric motor that provides a high power-to-weight ratio and low-voltage operating characteristics.

This performance, coupled with the power of the 2.7kg S1500 (which, at 1898Nm, is the smallest of Enerpac’s Square drive range extending up to 34.079Nm) easily loosens bolts that have become frozen in place over time.

"Then the same pump and tool combination rapidly and safely retightens slew ring nuts to the exact and even torque ratings required for ongoing reliability and safety," says Molloy.

Operated by Bishops in-house staff, who are trained to world standards, the pump and wrench combination was also used as required in the refurbishment of the crane’s entire drive train, including transmission, brakes and steering rebuild and fitting of new suspension on the carrier. All hydraulic components have been refurbished, with new hoses throughout. Electronics, electrical and lighting have been upgraded or replaced. The machine has also had a cosmetic refurbishment, being refinished in yellow and grey to match the rest of Bishop’s Liebherr. PNG technicians trained by Liebherr, John Laho and Miu Hao, have been the driving force behind the task.