Caterpillar 797s more than just crude power
Apr, 15 2004
Agile giants a mammoth boost to production
Caterpillar 797s more than just crude power
EDMONTON, Canada -- It is no accident the dump trucks in northern Alberta oilsands mines sport a model name that evokes a mental image of a jumbo jet.
A Caterpillar 797 could carry 26 Volks-wagen Beetles in the back without crushing the bugs, calculates Mike McDowell, mining product manager at Finning Canada.
Even a mechanical engineer whose stock in trade is mammoth equipment shows a touch of the wow factor when describing 797s. In McDowell's catalogue, "this is by far the biggest machine. They're impressive."
Built on the scale of a two-storey mansion, the vehicle is 14.5 metres long, nine metres wide and seven metres tall. When raised to dump a load, the back towers 15.3 metres into the sky.
Loaded with 400 tonnes of oilsands, a 797 weighs about 700,000 kilograms, including its 6,814-litre fuel tank. Fluids such as oil and coolants weigh more than 10 tonnes. The top of a six-footer's head barely brushes the wheel hubs.
This is an agile giant. Maximum speed is 68 kilometres per hour in the automatic transmission's seventh gear, with the 24-cylinder, 3,550-horsepower diesel engine spinning at 1,950 revolutions per minute.
A 797 climbs slopes in the 10-per-cent range, steeper than any grades on the TransCanada Highway. More important in the oilsands -- where the mines are horizontal instead of deep, and slippery instead of steep -- the vehicle masters bitumen mud with a mechanical drive train and a traction control system. The traditionalist design harnesses engine torque more directly than rival diesel-electric mine trucks.
The driver sits at a height of 6.5 metres and climbs into the cab on stairs angled across the front. Operators compare the sensation to being in the upstairs bathroom of a two-storey house. Driver training in Keyano College in Fort McMurray starts in a virtual cab akin to an aircraft flight simulator.
To make the drivers' 12-hour shifts endurable, much ergonomic science goes into features such as air suspension seats, instrument sight lines, climate control, and sound insulation which holds noise in the cabs down to less than 80 decibels or about the level of a passenger car on a freeway.
The giant truck is not just crude mechanical power. The technology includes seven on-board computers which monitor, manage and record mechanical performance, plus options such as a global positioning system as an aid for traffic control and guiding road maintenance.
The 797 is largely a made-in-Alberta technology package. It was developed in the oilsands with mid-1990s field trials. Until two were sold recently to a copper mine in Chile, the only customers for the trucks were oilsands operations.
A 797 is not cheap. For Finning, the world's top Caterpillar agency, with 9,800 employees including 800 in Edmonton, a fleet of 23 for the Albian Sands consortium was the biggest order in company history: $130 million for the trucks plus $150 million for a five-year parts and maintenance contract.
Vancouver-based Finning has delivered 71 of the colossal trucks to all three of the Alberta oilsands mines, including 34 to Syncrude Canada and 14 to Suncor Energy as well as the Albian fleet.
To the oilsands miners, which worked with Caterpillar on developing the 797, the vehicle is worth its cost. Syncrude calls the industry's conversion to the truck-and-shovel system of strip mining a key ingredient of its expansion to replace depleting conventional oil reserves.
The name of the game in the oilsands is volume, or economies of scale. Developers strive to spread multibillion-dollar project costs thin across millions of barrels of production.
It takes about two tonnes of oilsands to make a barrel of synthetic crude oil. Until the new generation of giant trucks was born, the mines used vast bucket wheels, draglines and conveyor belts. The old system was slow and prone to breakdowns. Moving the equipment was a megaproject in itself.
To attain current oilsands mine production rates in the range of 155,000 to 230,000 barrels per day, 797s deliver their 400-tonne loads at a brisk pace of 32 to 48 per hour or more than one every two minutes around the clock seven days per week.
Syncrude and the provincial government described the accelerated operations made possible by the trucks when they recently announced support for a new research chair at the University of Alberta that will specialize in improving mine control.
"A cornerstone of technological innovations is the use of trucks and shovels in place of draglines and bucket wheels," the research partners said.
"The change in methods ... resulted in a tighter coupling between the mining and extraction processes. With dragline mining, a four-day buffer existed between the mining and extraction of oil from the sands. With the current shovel and truck methods a 20-minute buffer exists. Decisions on mining operations now have a more immediate impact on downstream extraction operations."
No claims to perfection are made even for the 797.
"This isn't a final product. It's something we continue to work on and develop," McDowell said. "We'd like to take it a step further and improve the reliability and durability even more." And "I don't think you can say they're not going to get any bigger."
The Edmonton Journal
A new Sandvik crusher at Lafarge’s Pitt River Quarry in British Columbia, Canada, boost production after the main frame cracked on its existing 54-in cone crusher. More
Video: Reinforcing porous concrete by North Dakota State University More