One industry source told Longwalls that the latest model of Caterpillar’s venerable 793 series had been suffering severe cracking in the chassis.

A Caterpillar spokesman denied the cracking was severe but admitted there had been some 793F frame cracking in applications involving soft underfoot conditions.

“Repair producers are in place and Cat dealers are in the process of inspecting fleets and making necessary repairs at mine sites,” he said.

“Frame cracking does occur on mining trucks of all brands and models.

“Engineering design is directed at optimizing the truck for best return on investment.

“Materials science has not advanced to the point where anyone can offer a large mining truck frame that never cracks at a price that makes business sense.”

The spokesman said one of the strengths of the Caterpillar frame design was that it was field repairable with proper welding techniques.

This was amply displayed on a 793A truck that Caterpillar had on show at its Minesite at Night event during the 2008 Minexpo.

That truck, from the Sierrita Copper Mine out of Tuscon, Arizona, was still an operating vehicle back then.

Indeed, Longwalls understands the mine had some of the earliest 793s ever made and these trucks, while mothballed at the moment, are still perfectly capable of managing shifts.

Caterpillar representatives at the Mine Site at Night event were extremely keen to point out how the Sierrita maintenance people had been so proactive at field welding these cracks before they became too great.