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Since 2018, WesTrac and Caterpillar® have worked with Yancoal to conduct a series of studies at Mount Thorley Warkworth, leading to significant improvements in understanding optimum machine size for application and noise emission improvements.
As WesTrac Mining Business Manager Craig Morris explains, improvements in sound performance were based on a strengthening relationship, collaboration and combined desire to ensure positive outcomes for all parties involved.
“A big part of being awarded this tender for dozer supply was working with Yancoal to understand the right machine size and numbers required for the application,” he says.
“Identifying that some applications could use a 70-tonne machine rather than 100-tonne machine ensured the equipment matched the application, as well as delivered the lowest total cost of ownership through capital investment, lifecycle costs and production.”
The collaboration began in early 2018 when a dozer study at Yancoal’s Mount Thorley Warkworth site identified the specific machines for the application and improvement areas from an operations and maintenance perspective.
This included how sound compliance levels could be better met in keeping with individual mine plan approvals and strict operating licenses.
In November 2019, Caterpillar developed further improvements to the undercarriage sound attenuation on its D11 dozers, which led to another trial at the Mount Thorley Warkworth site.
Specifically, the fitting of genuine Cat rubber dampeners to the external of the final drive hub which helped suppress vibration caused by power surges, impact and friction, softening sound coming from the drive system.
Previously, when a track link engaged on the high sprocket final drive, it would produce a clanging noise often associated with moving dozers.
But the Caterpillar-designed rubber ring or belt, fastened by stainless steel clamps around the sprocket underneath the link, proved to be the solution to get rid of the noise.
“With the large fleet of Cat D11 dozers already onsite at Mount Thorley Warkworth, Caterpillar and WesTrac approached Yancoal to partner on a project to prove out the new undercarriage sound product in an operational environment,” Craig says.
“The project was carried out on a D11 over a 5000-hour period and proved successful with a sound reduction of three decibels.
“Compliant sound numbers required were 113dBA and 121dB for Mount Thorley Warkworth and 112dBA for Moolarben with a maximum operator noise exposure of 80dB.
“Trial results on the new D11 delivered to site were 110dBA and 121dB, with an operator noise exposure of 73dB.”
The Caterpillar sound reduction advances were timely.
In 2019, Yancoal released a tender for a number of replacement dozers across Mount Thorley Warkworth and Moolaben in both the 100 tonne and 70 tonne classes.
In November 2020, WesTrac was awarded the tender and selected as preferred supplier for the new dozers to Yancoal’s NSW operations for three years, with supply starting in 2021.
Craig attributes a big part of the successful tender response to WesTrac’s understanding of Yancoal’s commitment to sound compliance.
“Sound compliance is critical for Yancoal’s operations at these sites, which is why we pay detailed attention to meeting strict noise requirements set by government departments, and the company’s own targets,” he explains.
“Thanks to Caterpillar’s design and factory fit systems, that have gone through a rigorous testing process, and Yancoal’s willingness to partner for field testing, we’ve achieved tremendous results.
“This was not just about selling dozers, it was about working with Yancoal to ensure the right machine for application that also met sound compliance requirements.”
As a part of the production study in 2018 it was also identified that the average neutral time across the dozer fleet on site was above global best practice.
To ensure these results were sustained post-delivery, Yancoal, WesTrac and Caterpillar developed a project to track unproductive dozing time to identify improvement areas for optimisation, which would ensure assets delivered the lowest total cost of ownership.
In addition, a production study recently carried out at a separate NSW coal mine between a Cat D11 and D11T used terrain high precision GPS to determine operating time.
A drone scan conducted at the start and end of the study period showed the new D11 had a seven per cent increase in production rate with a five per cent decrease in fuel burn.
Yancoal Heavy Mining Equipment (HME) Category Manager Matthew Staff, who looks after the purchase of HME across all Yancoal open cut sites Australia-wide, has spent years investigating sound suppression techniques.
In his eyes, the new Cat dampener design stood out as a far superior solution to previous attempts to achieve sound attenuation in dozers.
“At our sites in New South Wales the licence to operate guidelines for sound suppression are strict,” he explains.
“In NSW, sound suppression is a key contributor to making commercial investment decisions when it comes to machinery, particularly sites like Mount Thorley Warkworth, which is within 10km from the Bulga townsite.
“Due to the current sound package on the D11, WesTrac and Caterpillar engaged us for the sound trial, and we saw an excellent result.
“Data collected was used to inform a decision to swap out the current class of machines with the new and improved D11s.
“Caterpillar and WesTrac committed to a sound level of the 112dB that led to a commercial outcome – and we went ahead to commence fleet replacement.”
Matthew, who has been working with sound suppression for two decades, says it was incredible that such a simple, convenient solution to minimising dozer track noise had been discovered.
“Over the years I’ve been involved with trialling so many things on dozers - we used to build track frame covers and track slides to try to make them quiet.
“In the end, a rubber ring around the final drive has solved the problem.”
Matthew said dozer operators at Yancoal’s sites were impressed with the new Cat machines.
“Operator feedback from the new D11 has been overwhelmingly positive,” he said.
“They’re telling me it’s a good ride, has good visibility and is extremely quiet, so it’s making a big difference.”
Such is the positive impact, WesTrac and Caterpillar are entering into similar loader production studies at both Moolarben and Mount Thorley Warkworth this year.
A total of 20 Cat D11 and eight Cat D10 dozers will be consigned by WesTrac to Yancoal over the three-year agreement period. The first two D11 dozers were delivered to Moolarben open cut operation in mid-June 2021. To date, WesTrac has delivered another four D11 dozers along with five D10s to Mount Thorley Warkworth.