WHAT POWERS MASSIVE TRUCKS THAT CAN DRIVE OVER ALMOST ANYTHING?

The phenomenon of monster trucking is a relatively new one. American 4x4 enthusiast Bob Chandler is credited with creating the first monster truck in 1974 when he raised the suspension on his Ford F-250 pickup truck and fitted it with immense 122-centimetre tyres. He then attempted to traverse over two scrap cars in the vehicle, and was surprised at just how easily the truck accomplished the task. A legend was duly born.

Bigfoot 1, as it became known, was in fact a stock pickup truck, with a beefier frame and engine later added to complement the changes in ride height and wheel size. Weighing in at a monumental 5,000 kilograms, Bigfoot 1 wowed the crowds with its original stunts of driving straight over and squashing conventional cars.

Despite these early revelations of newfound motoring entertainment, vast improvements in the build were needed to prolong the life of a monster truck. This soon led to a new, more durable design being implemented.

By the mid-1980s monster trucks used stronger axle housings with ‘planetary gears’ in the hubs to help turn the wheels and reduce stresses and axle-shaft breakage. Planetary gears work by a main gear in the middle - called a sun - engaging with three surrounding gears - called planets - at the same time. Once engaged the planets rotate around the sun, running along the inside of a ring and giving a three-to-one gear reduction ratio.

These vehicles, now called ‘stage-two’ trucks, also received heavier frames and axles taken from larger vehicles - but the chassis couldn’t handle the extra weight. What’s more, a stage-two truck now weighed around 6,800 kilograms. They also operated the antiquated leaf springs as found on early cars, or spring packs that still offered a notoriously harsh ride with little travel in suspension. Inevitably during the early stages of racing competition, drivers often got hurt.