A monster truck is an automobile, typically a pickup truck, which has been modified or purposely built with extremely large wheels and suspension. They are used for competition and popular Sports Entertainment and in some cases they are featured alongside Motocross races, mud bogging, tractor pulls and car-eating robots.
Typically, a monster truck show involves the truck crushing smaller vehicles beneath its huge tires. These trucks can run up and over most man-made barriers, so they are equipped with remote shut-off switches, called the Remote Ignition Interuptor (RII), to help prevent an accident if the driver loses control at any time. At some events, only one truck is on the course at a time, while most feature two drivers racing each other on symmetrical tracks, with the losing driver eliminated in single-elimination tournament fashion.
In recent years, many monster truck competitions have ended with a â€œfreestyleâ€ event. Somewhat akin to figure skating with giant trucks, drivers are free to select their own course around the track and its obstacles. Drivers will often try a â€˜Donutâ€™, also called a Cyclone, which involves spinning the truck in a high speed circle, and maybe even deliberately rolling the truck over. Additional items for the drivers to crush – usually including a motor home – are frequently placed on the track specifically for the freestyle event.
A modern monster truck is more of a scaled up, four wheel drive dune buggy. As such, they generally arenâ€™t actual â€œtrucksâ€ and only maintain their name due to the common style of fiberglass bodies used on the vehicles. Trucks now have custom built tubular chassis, with four-link suspensions to provide up to four feet of travel. Mounted just behind the driver on most trucks are the engines, which are typically supercharged, run on methanol, and have displacement up to 575 cubic inches.
The trucks have many safety features, several required just to run in the small arenas that the trucks frequent. The aforementioned RII is one of three kill switches on each truck, the other two being one within the driverâ€™s reach in the cab, and another at the rear of the truck so that all electrical power may be shut off in the event of a rollover. Many trucks are constructed with the driver sitting in the center of the cab for visibility. Most cabs are shielded with Lexan (or comparable polycarbonate), which not only protects the driver from track debris, but also allows for increased visibility. Drivers are required to wear firesuits, safety harnesses, helmets, and head and neck restraints. Most moving parts on the truck are also shielded, and high pressure components have restraining straps, both in case of an explosion.