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12th Jul 2020, 02:08 PM #16Diamond Member
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While I don't disagree with Snaptaps statement in the general sense, back in the late 1980s when I worked at an iron ore mine, they had 2 fleets of dump trucks, both with an 80 tonne capacity. The older fleet were Terrex 33-11s and were powered by Detroit Diesel engines, and the newer and generally superior fleet was made up of Caterpillar 777s, and while the Cats were generally more reliable, more fuel efficient and would out perform the 33-11s, when it came to downhill carting, the 33-11s were much better. They had rear drum brakes, and front disc brakes as I recall, and the Cat 777s had front discs and rear oil cooled multidisc brakes. These were a fully sealed unit, and I never saw inside them, but I understand they would be broadly similar to a motorcycle wet clutch. The problem was that the oil cooling just was not up to the job, and sure the operators could have just gone downhill in a very low gear, but time is money in mining, and the Terrex 33-11s would just cart a lot more dirt in the same time. You may be wondering how the rear drum brakes on the 33-11s could outperform the wet multidisc setup on the Cat trucks, as both fleets had similar front brakes, and the answer is that the Terrexes had retarders, which used the transmissions oil flow to brake the vehicle, and at the time Caterpillar did not offer a similar package, and just relied on their brake packs to do the job.
At the mine in my day, one part of the deposit was on one side of a steep river valley, so they had a long, steep downhill run, followed by a long uphill climb to get to the crusher, and the Terrex trucks certainly had advantages on that load cycle, and after I left that company, new owners built a long conveyer and shifted the crusher to the other side of the valley, and eventually installed another crusher in the same location the original crusher occupied. This would have eliminated much of the need for downhill, fully loaded carting, and they have changed truck fleets again to much bigger trucks, over 200 tonne from the previous 80 tonne, but I have no idea of the braking arrangement of the new fleet. Interestingly Caterpillar now offer a retarder braking setup as an option on the current version of the 777 truck.
I could well imagine that carbide coatings may be viable in the mining industry, especially if they are able to wring some extra life percentage increase out of them as less downtime for brake changes means increased availability, and a couple of extra loads may be all it takes to pay for the cost increase. I doubt that I will ever have a car with them fitted though, even at 1/10 th the price.
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12th Jul 2020, 02:56 PM #17Gear expert in training
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- Aug 2008
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- Melbourne
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I think that should read "Way to expensive to be practical for the transport industry now."
ABS and aircon used to be expensive options as well; I'm not suggesting that carbide coatings will become standard or even cheap, but I would be surprised if it didn't filter down at all.
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