An eighteen wheeler is a vehicle technically known as a semi tractor trailer. Other common names include big rig and lorry. The purpose of an eighteen wheeler is to tow its cargo that is contained in the trailer which is detachable from the engine. These vehicles are mainly used in transporting commercial freight such as fuel, construction materials, food and other consumer products.
The semi tractor trailer itself does not have eighteen wheels but the addition of the trailer provides the extra wheels which give it the name eighteen wheeler. When an eighteen wheeler is traveling without a trailer it is referred to as bobtailing.
The tractor portion of an eighteen wheeler normally has ten wheels which are dispersed throughout its three axles. The front wheels are called the steer wheels which maneuver the vehicle and the two rear axles turn the drive wheels which give the eighteen wheeler its power. The vehicle’s trailer has an additional two rear axles which use eight wheels to support the rear. The front portion of the trailer sits on top of the rear drive wheels of the tractor and is coupled by what is known as the fifth wheel.
An eighteen wheeler is a powerful machine and as such is constructed very differently than smaller trucks and passenger vehicles. First, the average length of an eighteen wheeler towing one trailer is about 80ft (24.4m) long. It typically has 10 gears, as opposed to five in cars with standard transmissions, two of which are used to reverse. An eighteen wheeler stops with a combination ten hydraulic and air brakes rather than the four brakes in passenger vehicles.
Additionally, the average eighteen wheeler weighs around 40 tons (36 287.389 6 kg) compared with an average 2.5 tons (2 267.961 85 kg ) and so it takes almost twice as long to stop than an average car or pick up truck. Stopping a tractor trailer can be even more difficult when it is transporting heavier loads or when there are inclement weather conditions.
Driving an eighteen wheeler requires special training and skill due to the vehicles immense size, weight, and difference in mechanics than those of passenger vehicles. In the United States, a person must hold a class A commercial driver’s license to operate an eighteen wheeler. Additional regulations apply depending on the type of cargo to be transported such as hazardous materials. In Europe drivers are required to obtain an EC driver’s license and in Australia a class HR or HC license. Most countries in the world have regulations and requirements for the operation of an eighteen wheeler.
