If you spend a lot of time on the road, you will see countless 18 wheelers every day. Also known by several names like big rigs, semi-trucks, semis, tractor-trailers, semi-trailers, or semi-trailer trucks, these are vehicles that are made by combining a powered truck and trailers. These large trucks are used all over the country to take goods to and from each state.
A typical 18 wheeler will have two or three axles, but those designed to pull heavy-duty commercial construction equipment may have up to five, with some being lift axles.
The most common 18 wheeler layouts include a forward engine, one steering axle, and two driving axles. The fifth-wheel trailer connections on most tractor vehicles are movable fore and aft to allow for weight distribution modifications over the rear axles.
Here are some fun facts about 18-wheelers.
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How Long are 18 Wheelers?
An 18 wheeler is typically 70-80 feet long, combining the tractor and trailer.
Depending on some factors though, the length may vary significantly.
Sleeper cabs, which have a bed inside for truckers hauling further away from home, are typically roughly 20 feet long, though this can vary depending on the manufacturer and specification.
A typical dry van trailer is 53 feet long and measures around 70 feet when extending a few feet over the vehicle. Double or pup trailers are typically 28 feet long, whereas intermodal containers might be 20 or 40 feet long. Tanker trailers, flatbed trailers, and several other trailer types come in various lengths.
Companies can often get creative with the length of equipment for unique freight demands, but each state has its own limitations on overall length.
How Much Do They Weigh?
18 wheelers can have a gross vehicle weight of up to 80,000 pounds with both the tractor and trailer under most weight restrictions. This is normally shared between the steer axle and the drive and trailer tandem axles, with the steer axle weighing up to 12,000 pounds and the drive and trailer tandem axles weighing up to 34,000 pounds.
Oversized loads that exceed those restrictions require special permission.
The type of CDL (Commercial Driver’s License) a truck driver has also influences the amount of weight they may transport (e.g., Class A vs. Class B CDL).
How Tall are They?
The average 18 wheeler is 13’ 6” tall.
Why do 18-Wheelers Drive Slower than Other Vehicles?
Have you ever been stuck behind a slow-moving truck and wondered why they do lower than the speed limit? Many 18 wheelers have built-in speed limiters (also known as governors) to enhance fuel-efficiency, which is good for the environment. For example, Schneider’s speed stance for many tractors is 63 mph.
This is why, if one semi-truck travels at a speed of 2 mph faster than the other, two semi-trucks may pass each other for long periods.
In some states, trucks have their own set of speed limits. Going at a slower speed is also beneficial if the truck has to perform an emergency stop for some reason.
How Long Does it Take for Them to Stop?
The average time it takes an 18-wheeler to come to a complete stop is 40% longer than it takes a vehicle. So if a truck is traveling at 55mph and the driver applies the brakes, the vehicle will take the distance of 2 football pitches to completely stop.
These measurements are influenced by the weight of the truck’s load, whether it’s bobtailing, road conditions, weather conditions, and other things. Trucks only have ten brakes, not eighteen, and anti-lock brakes are now standard equipment on all new trucks.
What is Bobtailing?
A truck driver is considered to be “bobtailing” when he is not dragging a trailer. Driving just the cab section of a truck is referred to as this.
Ironically, because the trailer’s stabilizing weight is missing, bobtailing can be quite dangerous, especially in bad weather. It can also affect how well the driver can break and come to a complete stop.
How Many Miles Can They Go on One Tank of Gas?
With 300-gallon tanks and a 7-mile-per-gallon average fuel efficiency, 18 wheelers can travel roughly 2,100 miles on a tank of diesel fuel (not widely used gasoline).
Of course, each driver must be aware of the size and efficiency of his or her truck’s gasoline tank. Many companies offer fuel optimization solutions to assist drivers to make the most of their fuel breaks while staying safe, and Schneider is a pioneer in the area when it comes to fuel efficiency.
How Well Can They Drive Up and Down Hills?
There are ten forward and two backward gears on most modern trucks, though some trucks may have anything from 13 to 18 gears. Truck drivers also utilize a double-clutch shifting system to match the engine’s RPMs to the appropriate gear for that RPM range.
When traveling up or down an incline, a truck driver must select the appropriate gear based on the engine’s RPMs. This might cause a “slow” ascent and downshifting when leveling out after a hill.
What Happens if They Blow a Tire When Driving?
18 wheelers have two sets of tires, known as a tandem system. This is a backup in case one tire blows on the road. If this happens, the other tire will continue to hold the weight of the truck and keep the whole vehicle steady until the driver can stop safely and make repairs.
What’s a Jack-Knife Accident and How Does it Happen?
When a truck’s trailer is at a 45-degree angle from the cab, it’s more likely to cause a jack-knife accident. When a driver comes to a sudden stop on a wet or slick road, the vehicle may begin to skid and slide. A jack-knife will occur if the trailer starts to spin towards the trailer faster than the cab.
In addition to jack-knifing, tractor-trailer trucks are prone to all types of accidents because of their sheer size. In regards to a trucking company’s crash records, anyone can check the safety history of a trucking company through via the Safety and Fitness Electronic Records (SAFER) System.
An 18-wheeler’s 5th wheel is placed directly behind the cab. It’s a huge round metal plate that connects and secures the trailer to the truck above the driving tires.
How Much Does an 18 Wheeler Cost?
The cost of an 18-wheeler is influenced by a variety of factors. A new taxi usually costs between $80,000 and $140,000. New trailer rigs range in price from $30,000 to $70,000.
What is their Average Lifespan?
18 wheelers have a lifespan of about 10-15 years on average, however, this varies widely based on maintenance standards, the type of freight transported (80,000 pounds and city driving vs. lightweight long hauls), and driver competency.
A high-mileage driver can travel over 120,000 miles in a single year, but many trucks can travel over one million miles in their lifespan.
How Much Freight is Moved by 18 Wheelers?
18 wheelers handle around 71 percent of freight by weight, totaling about 11.5 billion tonnes of freight, according to the American Trucking Association (ATA).
According to the ATA, freight volumes will increase by 35% by 2029, implying that driving jobs will continue to grow, making one of the many benefits of truck driving job security.
What Amenities are in the Cab?
Each trucking company specifies different amenities for their drivers, and each manufacturer offers different spec options, but in general, modern trucks are like homes away from home, with plenty of driver-friendly features.
Schneider’s 2020 truck demand for example includes APUs (auxiliary power units), power inverters, refrigerators, memory foam mattresses, and other items in addition to automated transmissions.
Do 18 Wheelers Have Manual or Automatic Transmissions?
When most people think of trucking, they conjure up pictures of intricate shifting patterns. Many vehicles still have manual transmissions, but some companies are beginning to move towards more automated transmissions.
The word “automated” refers to vehicles that are ostensibly manual but have the majority of their shifting done by a computer (in part to enhance fuel-efficiency) and allow the driver to override the computer.
A CDL (Commercial Driver’s License) with an automated restriction that permits you to work in a variety of jobs is available.
Frequently Asked Questions
Why are Trucks 53 Feet Long?
There’s a reason trucks are 53 feet long. For a long time, the 48-foot dry van was the de facto norm in shipping due to laws that limited overall vehicle length to 75 feet. After the laws were changed, the industry adopted the 53-foot trailer. There’s enough room for 13 rows of pallets and a foot more to close the door.
How Long Can a Trailer be in Texas?
In Texas, an 18 wheeler trailer can be 65 feet in length at maximum. They can also be no taller than 14 feet, and no wider than 8 1/2 feet. The combined length of the cab plus trailer cannot go above 65 feet either.
What States Allow for Triple Trailers?
Mainly states in the west allow for this, as their roads are flatter and straighter. In total, 13 states allow for triple trailers including Nevada, Nebraska, Arizona, and Oregon.
So there you have it – everything you need to know 18-wheeler trucks. We hope you’ve enjoyed all of the cool facts that we’ve given you, and perhaps it will give you something to think about next time you pass one of these trucks.