The Caterpillar 797B is an off-highway, ultra class, two-axle, mechanical powertrain haul truck developed and manufactured by Caterpillar Inc. in the United States specifically for high production mining and heavy-duty construction applications world-wide. The 797B is the second generation of the 797 series. The 797B was introduced to the public in spring of 2002 and first entered service with a customer in October, 2002. The 797B remained in production until December, 2009 when Caterpillar started full production of the 797B's successor, the 797F. While it was in production, the 797B was Caterpillar's largest, highest payload capacity haul truck model.
Compared to the first generation 797, the 797B has a larger payload capacity and a more powerful engine. These changes allowed Caterpillar to meet mine operators' needs to increase operational efficiency and reduce costs by increasing the amount of material hauled per trip.
The 797B's increased payload capacity of 380 short tons (345 t) is a 20 short tons (18.1 t) 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 3,211 hp (2,394 kW) to net 3,370 hp (2,513 kW) enabling the 797B to achieve a 42 mph (68 km/h) top speed when transporting a 380 short tons (345 t) load, a two mile per hour increase over the first generation 797.
Unlike its primary competitors which use diesel-electric powertrains, the Caterpillar 797B employs a mechanical drive powertrain. Caterpillar is the only manufacturer of ultra class haul trucks that feature mechanical powertrains; all ultra class haul trucks offered by competitors employ diesel-electric powertrains.
A gross 3,550 hp (2,647 kW) [net 3,370 hp (2,513 kW)], twin turbocharged version of the Cat 3524B engine powers the 797B. The power rating of the 3524B engine is valid up to an elevation of 8,500 ft (2,591 m) or 15,000 ft (4,572 m) with a high altitude arrangement.
The 797B is equipped with a rear axle mounted, computer controlled, seven speed planetary transmission with an integral lock-up torque converter.
The Caterpillar 797B uses six 5,300 kg (11,680 lb) Michelin 59/80R63 XDR radial tires.
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