The Caterpillar 797 is a series of off-highway, ultra-class haul trucks built for high-production mining. It has been in production since 1998 and is Caterpillar’s largest and highest-capacity haul truck; unlike most trucks of its size it uses a mechanical drive rather than a diesel-electric one.
Caterpillar 797 at a glance
| Type | ultra-class off-highway haul truck |
|---|---|
| In production since | 1998 |
| Generations | 797 (1998–2002), 797B (2002–2009), 797F (2009–) |
| 797 payload | 360 short tons (327 t) class |
| 797B payload | 345 t (380 short tons) |
| 797F payload | 400 short tons (363 t) |
| 797 engine | Cat 3524B, 24 cylinders, net 3,211 hp (2,394 kW) |
| 797B engine | Cat 3524B, net 3,370 hp (2,513 kW) |
| 797F engine | Cat C175-20 ACERT, 20 cylinders, net 3,793 hp (2,828 kW) |
| Top speed | 68 km/h (42 mph), mechanical drive through a seven-speed planetary transmission |
| Tyres | Michelin 59/80R63 XDR, 4.028 m tall |
| Built at | Decatur, Illinois |
The payload of the first generation is given in the source as a 360 short ton design target and in the 797B section as 327 t; both figures are quoted here as they appear.
History of the Caterpillar 797
Development
In 1997 Caterpillar began work on a truck with a 360 short tons (327 t) payload, aimed at large mines that wanted to cut costs by matching 80 to 90 short ton shovels. Engineers at the Mining & Construction Equipment Division in Decatur, Illinois, designed it with computer-aided design, the first time CAD had been used so extensively for a Caterpillar truck. The first completed 797 was shown at the Decatur plant on 29 September 1998; two went to the Arizona proving grounds, and in the second quarter of 1999 the third and fourth were the first to work for a customer, at the Bingham Canyon Mine in Utah. Marketing began in North America in 2000 and worldwide in 2001.
797B (2002–2009)
The 797B arrived in the spring of 2002 with a payload of 345 t (380 short tons), 20 short tons more than the first generation. Its 3524B engine was pushed from 2,394 kW (3,211 hp) net to 2,513 kW (3,370 hp), which lifted the laden top speed from 40 to 42 mph. The first 797B trucks went into service in October 2002.
797F (2009–)
The 797F was shown at MINExpo in September 2008 and entered full production in late 2009. Its payload of 400 short tons (363 t) is 20 short tons more than the 797B, and the new C175-20 engine, a 20-cylinder single block of 4,000 hp (2,983 kW) gross, keeps the 42 mph top speed with the heavier load.
The drive
The 797 series uses a mechanical powertrain, in contrast to the diesel-electric drive of most rival trucks. A 1997 study considered diesel-electric, but Caterpillar judged mechanical drive better suited to the market. Power goes through a rear-axle-mounted seven-speed planetary transmission with its own lock-up torque converter. Each wheel is held by 54 nuts of 36 mm, torqued to 2,300 lb·ft, and the truck runs on six Michelin 59/80R63 XDR tyres of 4.028 m, which in 2009 cost about US$42,500 each.
Design and features
- Mechanical drive: a seven-speed planetary transmission instead of the diesel-electric drive usual in this class.
- 400 short tons: the payload of the 797F, the highest of any mechanical drive haul truck.
- C175-20 engine: 20 cylinders, 4,000 hp (2,983 kW) gross in the 797F.
- Huge tyres: six Michelin 59/80R63 XDR, 4.028 m tall and 5,300 kg each.
- Built in Decatur: the Illinois plant where the first 797 was shown in 1998.
Caterpillar 797 versions
- 797 (1998–2002): first generation, serial number prefix 5YW.
- 797B (2002–2009): 345 t payload and a more powerful 3524B.
- 797F (2009–): 400 short tons and the C175-20 engine.
The 797 is the largest truck of the range above the Caterpillar 777; the D348 engine of the first Caterpillar D10 had already proved itself in the 777 before it went into the dozer. More machines are in the Caterpillar collection.
Video: Biggest dumptruck in the world Caterpillar 797F
Video by Awesome Earthmovers on YouTube.
Sources
- Caterpillar 797, English Wikipedia: development, all three generations, engines, transmission, tyres, production
