Conveyor crossroads

THE New Inventors television show was axed last year but one of its episode winners is closer to making his mark on the way conveyors are designed for safety and performance.

Blair Price
Conveyor crossroads

Published in the March 2012 Australian Longwall Magazine

Given the amount of New Inventors fans from engineering ranks, it is perhaps of no surprise that management from various coal mines wanted news about what Les Dunn had to offer.

A conveyor specialist for decades, Dunn took his safety idler assembly invention from his shed to television screens around the country last July. New Inventors judges gave him the win over two other entries in that episode.

While the company could undergo a name change for better marketing outcomes, Dunn’s worldwide-patented conveyor related inventions are the property of Tamec Services, which aims to commercialise the technology this year.

The key invention covered on the television show was the Dunn Easy Assembly. Unlike most idler assemblies, which are fixed structures, Dunn’s is a semi-elliptical rail that houses rollers in slide-in, slide-out interlocked and ergonomically light, cassettes.

The design allows for rollers to be easily and safely changed through a slider beam from just one side of the conveyor, and importantly for the production-focused, while the conveyor is still running.

For projects around the world there is already discussion on how costs can be saved by building just one walkway to service conveyors instead of having one on each side. But from existing mines using these assemblies, the main topic is how long the rollers last.

Tamec director of business development Colin Longton, who helped introduce Vodafone to Australia more than 10 years ago, said this was due to the design of the semi-elliptical rail in the assembly.

“What we have found, even with old rolls, is that they last longer because the rail acts as a spring and absorbs a lot of vibration in the structure,” he told Australian Longwall Magazine.

Any downtime with conveyors can quickly cost vast sums in lost productivity.

Longton said one of the mines using this idler assembly has made a record of changing out 24 rolls in 53 minutes, while there had not been a single failure with the idler assembly in the field over the past five years.

What was not featured so much on the New Inventors was the other half of the equation – Dunn’s patented One Fits Rollers – named because of a single composite bearing and integrated multi-fit stub axle.

The multiple head handles various diameter discs to fabricate all roller diameters that are in common service, with associated patented slip-on mount adaptors to each end.

This allows them to be retrofitted to most conveyor systems.

These rollers differ from conventional designs by replacing a heavy solid axle with short sub axles and higher load-bearing capacity bearings. These components easily bear the biggest brunt of the weight from above.

Longton said an industry standard 600mm, 6-inch roller weighed about 28.5kg – compared to 13.4kg for the One Fits Roller in that size.

The lighter rollers feature a single outer lubrication sealed-bearing unit and a non-contact dust component. The sealed-bearing unit is fully enclosed in a Grade 304 stainless steel weather shield for electrostatic products which results in huge drag reduction compared to labyrinth-style sealing commonly found in roller ends.

Traditional designs have a breather hole the lets moisture and debris enter the tube and internal through shaft, with damaging results.

The One Fits blank block closure eliminates this issue and internally dissipates heat changes from the head. The combination of the bearing design combined with the seal results in negligible rim drag, resulting in longer bearing life and lower power consumption to drive the roll.

Tamec’s idler assemblies have been used since 2006 and the rolls since 2008.

One longwall mine is already in discussions to trial Tamec’s conveyor solutions as part of a retrofitting job to overcome issues with a dangerous section of its surface conveyor.

Using its Sydney-based partner Universal Bearings, plus its own workshop facilities in the Bowen Basin, Tamec has components made to its stringent conditions in China.

Plans are in place to vastly improve production volumes – especially for its rollers.

This will be the key market. Dunn has already spent months putting a total estimate on the amount of rollers in Australia’s mining industry – 6.3 billion.

As for when Tamec will launch an assault on the conveyor market, negotiations are underway with the federal government’s AusIndustry over commercialising its technology.

Longton expects the broader longwall sector could have the opportunity to take up three-month trials of its conveyor equipment this year.


A growing series of reports, each focused on a key discussion point for the mining sector, brought to you by the Mining Monthly Intelligence team.

A growing series of reports, each focused on a key discussion point for the mining sector, brought to you by the Mining Monthly Intelligence team.


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