When it first debuted in 1999, the 797 had a nominal payload capacity of 327 tonnes.

The latest iteration, the 797F has grown that capacity to 363t, the magical 400 short ton mark.

According to Caterpillar, the 797 is the only mining truck in its size class to reach the 1000 truck milestone.

Its competitors include the Liebherr T282, the Komatsu 980E and the Terex MT6300. Those are all electric drive trucks.

The latter machine is part of the Caterpillar range these days, although it is no longer being made.

The first 797 placed in mining operations in 1999 is still in service, having clocked up more than 130,000 hours working in Canadian oil sands.

The largest populations of the trucks are in North America, South America and Australia and they are used in oil sands, copper, coal and iron ore.

Caterpillar global product manager, large mining trucks Sudhanshu Singh said the 797 had proved its ability to deliver high production in the most challenging conditions from the extreme cold and soft underfoot conditions of the Canadian oil sands to the high altitude, deep pit copper operations in South America.

"In a broad range of applications the 797F sets the production standard for ultra-class mining trucks," he said.

"That's a big reason why there are double the number of 797s at work today compared to the total number of all competitors' trucks in the size class."

To be fair, the Komatsu 980E was introduced in 2016.

A 20-cylinder quad-turbocharged Cat C175 engine powers the 797F, producing 2893 kilowatts. For applications that do not require the highest power, such as flat hauls found in many coal and iron ore applications, a 2647kW setting is available.

A variety of fuel maps are available to balance productivity and fuel consumption and a Tier 4 configuration is available too.

Caterpillar has assembled all 1000 of its 797s at its Decatur, Illinois facility.