by Adam Hart-Davis
Caterpillar 797 is one of the world’s most famous trucks, and
with good reason. An all-American, ultra class haul truck; its
current payload is a massive 400 tons.
797 is immediately recognisable for its enormous size. The current
configuration has the truck at over 21ft high and nearly 50ft long,
making it larger than many buildings. The machine’s operating
weight is over 680 tons, with each tire being nearly 6 tons each.
a price tag new of around $5 million, and tires costing in excess of
$40,000, the 797 is one of the most expensive trucks money can buy.
Their popularity however, means that getting hold of a used one would
require a specialist truck
for the 797 began in 1997, with Caterpillar wanting to meet the
demand from large-scale mines. It was the very first vehicle in the
Caterpillar line-up to be designed with the aid of computer software,
which meant it was built to a very high specification. The first two
trucks rolled off the line in 1998, with a payload of 360 tons, and
were exclusively used at Caterpillar’s testing grounds in
Arizona. The third and fourth went to Utah, to the Bingham Canyon
The engine designed to power this heavy brute was composed of two 12 cylinder engines placed in tandem making it a 24 cylinder engine. It's dynamics included having four stroke diesels being turbocharged with electronic unit injection and aftercooled. To help out in the power department, the 797 Caterpillar series had rear axel mounted seven-speed planetary transmissions.
2002, Caterpillar unveiled a replacement, the 797B, which enjoyed
several improvements over the original. They payload was increased by
20 tons, and to compensate for this, the original 3,211hp was upped
to 3,370hp using twin turbochargers. Customers first received the
797B in October that year.
to the 797B’s ability and popularity, the truck was not altered
until 2008. It was announced at MINExpo International in September,
but was not in production until a year later. Again, the truck
received was a powertrain and payload upgrade. The vehicle was
improved to carry today’s standard of 400 tons, and was given a
new engine. This engine, the C175-20 is far more powerful and yet
more efficient than the outgoing one. It has 3,793hp and will operate
at an altitude of 16,000ft.
Hart-Davis writes for http://www.trucklocator.co.uk.
Visit them for a wide selection of new and used trucks.