The Caterpillar 797 is a series of off-highway, ultra class, two-axle, mechanical powertrain haul trucks developed and manufactured in the United States by Caterpillar Inc. specifically for high-production mining and heavy construction applications worldwide. In production since 1998, the 797 series represents Caterpillar’s largest, highest capacity haul trucks. The current, third-generation model, the 797F, offers one of the largest haul truck payload capacities in the world, up to and has the highest payload capacity among mechanical drive haul trucks.
Initial development
In 1997, Caterpillar decided to begin the development of a payload capacity haul truck to meet the demand from large-scale mine operators wanting to reduce operating costs at mines using 80 to 90 short tons (73 to 82 t) per pass shovels. Engineers at Caterpillar's Mining & Construction Equipment Division in Decatur, Illinois, created a new design for the 797 using computer-aided design technology. This was the first time CAD tools had been used extensively to design a Caterpillar truck.
797 (1998–2002)
Caterpillar first unveiled a completed 797 on September 29, 1998, at its assembly plant in Decatur, Illinois. The first two 797s produced were transported to Caterpillar's Arizona proving grounds for testing. In the second quarter of 1999, the third and fourth 797s produced were the first to be placed in service with a customer at the Bingham Canyon Mine in Utah. Caterpillar put 18 additional 797s into service with mine operators worldwide as production development units.
Caterpillar began marketing the 797 in North America in 2000, with full worldwide marketing following in 2001. The first generation serial number prefix is 5YW.
797B (2002–2009)
Caterpillar introduced the 797B in the spring of 2002, replacing the first-generation 797. The 797B's increased payload capacity of is a increase over the first generation 797. Caterpillar increased the power output of the Cat 3524B EUI 24-cylinder diesel engine used in the 797 from net to net enabling the 797B to achieve a top speed when transporting a load, a increase over the first generation 797.
The first 797B units entered service with customers in October 2002.
797F (2009–present) Caterpillar introduced the 797F to the public at MINExpo International in September, 2008. The 797F replaced its predecessor model, the 797B, when the 797F entered full production in late 2009. Prior to the introduction of the Caterpillar 797F and the Bucyrus MT6300AC at MINExpo International in September, 2008, the Liebherr T 282B, introduced in 2004, was the only haul truck with a payload capacity of .
Compared to the 797B, the 797F has a higher payload capacity and a more powerful, more efficient engine. These changes allowed Caterpillar to meet mine operator's needs to increase operational efficiency and reduce costs by increasing the amount of material hauled per trip.
The 797F's increased payload capacity of is a increase over the 797B.
Caterpillar replaced the gross [net ] Cat 3524B EUI 24-cylinder diesel engine used in the 797B with the gross [net ] Cat C175-20 ACERT 20-cylinder diesel engine, enabling the 797F to maintain the top speed of the 797B while transporting a heavier payload.
Powertrain
The Caterpillar 797 series trucks employ mechanical drive powertrains in contrast to the diesel-electric powertrains of similar haul trucks offered by competitors. During initial development in 1997, a diesel-electric powertrain was considered for the 797, but this powertrain configuration was not developed because Caterpillar considered a mechanical drive powertrain more appropriate for market conditions at that time.
797 engine
A gross [net ] Cat 3524B HD EUI 24-cylinder, electronic unit injection, quad single-stage turbocharged, liquid aftercooled, four-stroke diesel engine powers the 797. The Cat 3524B HD engine is a tandem unit consisting of two 12-cylinder Cat 3512B HD engine blocks coupled to operate as a single engine with a combined displacement of 106 liters (6468 cubic inches).
797B engine
A gross [net ], quad turbocharged Caterpillar 3524B engine powers the 797B. The power rating of the 3524B is valid up to an elevation of or with a high altitude arrangement.
797F engine
A gross [net ] Cat C175-20 ACERT single block, 20-cylinder, electronic common rail injection, quad turbocharged, air-to-air aftercooled, four-stroke diesel engine powers the 797F. The power rating of the C175-20 is valid up to an elevation of or up to with a high altitude arrangement.