What is a tractor trailer? A tractor trailer in the trucking transportation industry is referred to as a tractor (truck) that has a trailer attached to it. This combination is referred to as a tractor trailer. A tractor trailer is often called a semi-truck or 18 wheeler. In the picture below I have identified what is the tractor and which is the trailer.
The Tractor: the tractor is the truck. It is the part that the driver sits in (cab). The tractor has the engine and is what drives the tractor trailer.
The Trailer: the trailer is where the freight being transported is placed. The trailer will usually have a landing gear or legs that can be lowered. The landing gear on the trailer will support the weight that is in the trailer when it isn’t connected to the tractor or semi.
The trailer does not have an engine and or drive axles. (source)
Tractor Trailer Types
Many tractor trailers have wheels that are attached to the trailer, and the wheels can be repositioned or removed to even out the load that is on the trailer.
When the tractor is connected to the trailer it is called a tractor trailer or semi-trailer.
There are different types of trailers depending on what freight is being transported include:
· A Box Trailer (dry van) – Most popular trailer. An example of one is the image at the top of this article.
· Car Carrier Trailer – Usually used for transporting new cars from the manufacturer.
· Curtainsiders – Resembles the box trailer, but the sides of the trailer have movable curtains.
· Flatbed Trailers – Can haul a variety of freight that can be strapped to the floor of the trailer.
· Livestock Trailers – This type of trailer can have two levels and it is used for hauling sheep, pigs, etc.
· Refrigeration Trailers – The refrigeration trailers are a box trailer, but they have a reefer (Heating and Cooling Unit) attached to the front of trailer. This trailer is usually used for meats, frozen food, and fresh fruits and vegetables.
· Tanker Trailer – This trailer is used for hauling gasoline and other liquids.
· Side Bay Trailer – This trailer has panel doors on each side of the trailer, and when the door is opened it will has separate compartments. This type of trailer is usually used for beverage hauling.
· Dry Bulk Trailer – This trailer looks like a tanker, but this type of trailer hauls flour, sand, cement, and other dry powder items.
The trailer is hooked to a fifth wheel, which looks similar to a horseshoe, and the fifth wheel has a quick release that allows the trailer to be attached and unattached easily.
The trailer only has wheels that is located at the rear of the trailer, so the trailer is unable to move anywhere by itself.
A forward axle is connected to the towing engine, and this allows the trailer to carry the half of the weight of the load safely.
The average length of a typical trailer is fifty-three feet in length.
What is a Bobtail Truck?
A truck without a trailer attached to it is referred to as a Bobtail.
Bobtail is the description of a cat that has very short tails. A semi tractor that isn’t hauling a trailer is often called bobtail or bobtailing.
Some straight trucks that are hauling propane are also referred to as bobtails.
The United States Department of Energy calls the straight truck hauling propane a bobtail, because the tank is much shorter than the average petroleum trailers.
Truck drivers who have left the loaded trailer at its destination, then they have to head to another location to pick up another trailer usually call this running bobtail.
This is a picture of a Bobtail because there is no trailer attached to it:
What is the Difference Between a Tractor and a Trailer?
There are several differences between a tractor and a trailer.
The tractor is a truck that has been carefully designed to pull a trailer that is attached to the truck with the fifth wheel that is located on the rear axle.
· A tractor truck is also known as a semi-truck
· A tractor truck is also known as a big rig
· A tractor truck is also known as an 18-Wheeler
· A tractor truck can haul up to 80,000 pounds
· A tractor truck has the engine and power to pull a trailer
The trailers don’t have any front wheels, and the only way that the trailer can be used is when it is connected to the truck.
The trailer can roll and operate when the truck is connected, and the air pump from the truck’s engine will release the trailer’s brakes.
· A trailer does not have an engine.
· An average trailer is fifty-three feet in length
· The trailer has no front wheels
· The trailer is connected to the truck/tractor
There is a big difference between a tractor and a trailer, this is it:
One of the biggest differences between a tractor and a trailer is the trailer needs the tractor to become mobile. Together they can carry up to 80,000 pounds of goods across the country.
Why Are They Called 18 Wheelers?
Why are tractor trailers called 18 wheelers?
It’s simple, because the typical tractor trailer has 18 wheels!
The tractor has one wheel each on the front, and eight wheels (two each together) or four wheels on the left backside of the tractor and four wheels on the right backside of the tractor, then the trailer will have ten tires, which equals 18 wheels.
A tractor trailer that is has double trailers has more than 18 wheels, but these tractor trailers are still considered an 18-wheeler.
There are numerous names that refer to 18 wheelers, and they include:
· Big Rig
· Tractor Trailer
· Truck Trailer
Where Did the Name “Tractor Trailer” Come From?
The first tractor trailer was invented by Alexander Winston in 1898 in Cleveland, Ohio.
Alexander Winston’s started The Winston Motor Carriage Company of Cleveland, and in 1898 he sold his first 22 cars, but he needed a way to haul the cars to the buyers that purchased them.
The car buyers lived all over in the United States, which was several hundred miles from Cleveland, Ohio.
He created the tractor trailer, then he created an automobile hauler (Alexander Winston Named It), where he could haul the new cars to their new owners.
Alexander went on to manufacture the automobile haulers in 1899, and selling them to other car manufactures, which he called The Winton Motor Carriage.
The first trailer was more of a cart than a trailer. The trailer attached to the rear end of the tractor. This trailer could only carry one car. This type of trailer is similar to a flatbed trailer or also known as RGN (Removable Gooseneck).
August Charles Fruehauf should be credited for developing a semi-trailer too.
August was a blacksmith in Detroit, Michigan, and in 1914 he built a carriage trailer for a customer that wanted an easier way to transport his boat.
This design was a huge success, so he developed semi-trailers that could haul lumber and other items. August Charles Fruehauf incorporated the Fruehauf Trailer Company in 1918, and this company is still the leading and largest semi-trailer maker today.
Why Are They Sometimes Called Semi Trucks?
A semi truck is a combination of a tractor and trailer. Together they are a complete operating machine.
The trailer can only roll when it is connected to the tractor, because the trailer doesn’t have front wheels.
The semi truck is just another name for a tractor trailer.
What is the Difference Between Semi Trucks and Tractor Trailers?
A tractor is what plows the fields on a farm.
The trucking industry’s terminology is sometimes confusing.
The tractor with a tractor trailer has a very large engine that has the ability to pull 80,000 pounds, which is why it is called a tractor trailer.
A semi is referring to the trailer type.
A semi trailer doesn’t have any wheels on the front of the trailer, but just on the back of the trailer, so the weight is being supported by the tractor truck that is pulling the trailer.
There is very little difference between semi trucks and tractor trailers, they are essentially the same thing with different names.
What is the Difference Between Semi Trailers and Full Trailers?
A semi trailer can be detached from the tractor while a full trailer is not detachable.
A semi trailer can be attached and detached quickly.
Another tractor can attach the semi trailer if the tractor breaks down. A semi trailer has an easier time backing up than a full trailer can.
A semi trailer can have better traction during snow, because the drive axles are carrying more weight.
A semi trailer can tip over and jackknife while a full trailer doesn’t.
Tractor Trailer Fun Facts
A tractor trailer is known as other names, which include semi trailer, semi truck, and an 18-wheeler.
In 2016, over 175 billion miles were done with a tractor trailer. A brand new tractor can cost up to$200,000, and a trailer can cost up to $75,000.
Tractor trailers are a major asset to numerous industries in the United States.
A tractor engine is six times larger than an automobile’s engine.
Tractor trailers were created to run continuous and nonstop.
The only time that they have to be turned off is when the oil needs changed.
A tractor trailer holds approximately fifteen gallons of oil and they usually have twelve gears.
A tractor trailer’s engine was created to go over one million miles.
A tractor trailer has five axles, which gives them the ability to carry thousands of pounds.