Company Insight

Taking a different approach to pivot wear from rock breakers with Expander®

The mining sector is notorious for being slow when it comes to embracing new technology.

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Hydraulic rock breakers are not unique to Australia’s mining sector, but they are utilised to a degree higher than most. Operations across the country – whether mining iron ore in Pilbara, coal in Bowen Basin, or copper in South Australia – rely on the heavy-duty machinery to break hardened rock without blasting.

Mounted on either excavators or pedestal booms, rock breakers are used for trenching, general excavation, secondary breaking for crushers, and more. They’re typically run around the clock in remote areas and subjected to harsh environments.

“The operating conditions in Australia really put these machines to the test,” says Paul Yoong, APAC Expander Sales Manager for global bolting solutions provider Nord-Lock Group. “But when a rock breaker goes offline, it’s not just that one machine losing productivity. It can bottleneck an entire site.”

In that context, traditional pivot joint and pin maintenance for excavator arms or booms that hold hydraulic rock breakers becomes about more than upkeep. It’s a production and cost issue most Australian mine operators don’t notice until it’s too late. Yet, the Nord-Lock Group’s line of Expander System pivot pin assemblies can help flip that script.

The challenges of pivot maintenance in mining

Pivots experience wear from vibration and movement in any application. Those attached to a hydraulic rock breaker, however, experience excessive wear, especially if there are traditional pins in the lug bores.

“Every time the hammer fires, that impact and vibration are transmitted through those pivot joints,” says Yoong. “And over time, the clearance between the traditional pin and the bore opens up.”

There’s always some clearance between traditional pins and lug bores in pivot joints. But when a lug bore wears into a more oval shape, the growing clearance creates looseness and play in the joint. Machine operators will initially notice rattling, then lose more and more control and precision over time, increasing the risk to worker safety and decreasing output.

Eventually, the pin will become misaligned or seized and render the machine inoperable. But removing it – an often dangerous procedure requiring thermal lancing or cutting with a grinder – and installing a new traditional pivot pin won’t fix the underlying issue.

“It becomes a compounding problem, because a worn bore wears out the next pin even faster than the last one did,” says Yoong, who explains a pivot joint in such a condition needs welding and line boring to restore its bore dimensions. “That typically means pulling the component into a workshop, which for a remote site can mean days, not hours, of lost production.”

A distinct alternative to traditional pivot pin designs

The Expander System is ideally suited for the challenges of pivot maintenance in the Australian mining industry.

Originally developed in Sweden in 1986, it’s an advanced pivot pin assembly engineered to eliminate lug wear permanently. Expander’s pivot pin technology has been successfully installed over two million times in different makes and models of machines around the world. It’s been used specifically for wear from rock breakers since at least 2009, when a Finnish manufacturer of breaker boom systems began using the assemblies as first-fit components. In 2016, Expander became part of the Nord-Lock Group, home to other solutions like Nord-Lock® wedge-locking washers, Superbolt® multi-jackbolt tensioners, and more.

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According to Yoong, the Expander System is a distinct alternative to traditional pivot pin designs with straight cylinders dropped into lug bores.

“The core difference is how it takes up clearance in the joint,” he says “Expander’s assemblies use a tapered pin with expansion sleeves. The sleeves are drawn up the taper and expand outward, locking the pin firmly against the bore with no clearance at all.”

When installed properly, the Expander System conforms to the wear pattern and ovality of a worn lug bore, removing the need for line boring and welding. That precise fit also means there’s no looseness or joint play, so it prevents further lug wear and provides more fixed support for load redistribution.

And the advantages of Expander over traditional pivot pins translate into serious benefits for mining operations like those in Australia that depend on rock breakers.

“You don’t have to accept lug wear as an inevitable cost”

Switching to the Expander System in pivot joints attached to rock breakers dramatically reduces downtime. Not only does it fit directly into lug bores as they are, but installation or removal is possible with just hand tools and typically takes 30 minutes to two hours.

“A maintenance crew can do it in the field without needing to send anything away or bring in a boring machine,” says Yoong, noting that traditional pivot pins can take up to a day or more to replace. “That matters a lot for remote Australian sites where turnaround time is everything.”

There are also substantial savings over time, from those reduced maintenance hours to the extended life of both pivot joint and machine. All of which optimise the total operating costs of a hydraulic rock breaker and directly result from eliminating the extreme lug wear it causes.

“Solutions like Expander’s show that you don’t have to accept lug wear as an inevitable cost of running rock breakers hard in tough conditions,” says Yoong. “These engineered alternatives address the root cause rather than just treating the symptom. For mining operations focused on uptime, that’s a pretty meaningful shift in how to think about pivot pin maintenance.”