It’s common to believe all semi-trucks can accomplish the same task if you’ve never driven one. Because it has no front axle, a semi-trailer already sets itself apart from a standard trailer. There are numerous varieties of semi-trailers, each with unique capabilities.
For instance, fragile materials cannot be transported on a flatbed trailer without a suitable enclosure. Only semitrucks with the proper temperature regulation are capable of transporting perishable goods.
There are 8 types of semi trailers. They are flatbed trailers, step deck or drop deck trailers, lowboy trailers, reefer trailers, dump trailers…
Here are all the various types of semi-trailers that truckers use today.
Table of Contents
The most diverse and expansive category of trailers, flatbeds come in a variety of styles to accommodate different types of freight. Since they are primarily used for shipping construction materials and various equipment, they are present in almost every region of the United States. Here are the 4 variations of the flatbed trailer:
Flatbed & Extendable Flatbed
- This open bed trailer has a constant height throughout. A two-axle flatbed has a length of 48′ and a maximum GVWR weight of 80,000 pounds. A three-axle flatbed has a maximum weight capacity of 90,000 pounds and a length of 53′. Up to 80 feet can be added to an extendable flatbed. This is used to transport heavier cargo that cannot be transported using a flatbed.
- Due to their low ground clearance, these trailers can transport cargo that is extremely tall. Depending on the number of axles being used, they have a bed that is 24 to 29 feet long and can carry up to 95,000 pounds. Large farm equipment, oversized items, and construction equipment that cannot fit on a standard flatbed are all transported using this kind of trailer.
- In a single trailer of this type, two deck heights are combined. There are 3 types of drop trailers:
- A trailer with two different deck heights is referred to as a single drop. The height then decreases to a lowboy from a standard flatbed height. The same weight and length limitations apply as they do for a typical flatbed.
- Single drop stretch trailers have all the same features as single drop trailers but can be extended by 48′ to 63′. 80,000 pounds are the GVWR maximum weight.
- A double drop stretch trailer effectively forms a well in the middle of the trailer by starting at a standard flatbed height, dropping to a lowboy height, and then rising back to a flatbed height. The GVWR is 90,000 pounds, and the length options range from 29 to 65 feet.
Removable Gooseneck (rgn) & Stretch Rgn
- These trailers resemble lowboys, but instead of a gooseneck connecting the trailer to the tractor, they have a front end that can drop down to act as a ramp. This makes it ideal for transporting excessively long and tall freight. They can have up to 20 axles, a length of 29′, a minimum of three axles, and a weight capacity of up to 150,000 pounds. Up to 65′ can be the length of a stretch RGN.
Step Deck Or Drop Deck Trailers
Although step deck trailers, also referred to as drop deck trailers, are open trailers like flatbed trailers, they do differ in a few ways. Step deck trailers have two deck levels, which are referred to as the upper deck and lower deck, as opposed to flatbed trailers, which only have one level.
Located above the tractor unit, the upper deck is between 10 and 13 feet long. It is only 3 feet, 3 inches above the ground, and the lower deck is between 38 and 40 feet long. Step deck trailers can tow taller loads thanks to the lowered deck.
Step Deck or Drop Deck Trailer Typical Cargo Types:
- Tall cargo that exceeds legal height limit on traditional flatbed trailer
Step Deck or Drop Deck Trailer Legal Load Specifications:
- Maximum freight weight for a step-deck trailer is 48,000 pounds.
- Step Deck Trailer Maximum Freight Dimensions:
- 48 feet is the maximum trailer length. – 53 ft.
- 8.5 feet maximum trailer width
- Ten feet is the maximum legal freight height.
As a result of the two drops in deck height that allow for a remarkably low deck, lowboy trailers are also referred to as double drop trailers. The first drop comes immediately after the gooseneck, and the second drop comes before the wheels. Lowboy trailers are the best choice for transporting taller equipment without the need for height permits because of their additional dropdown feature.
The fact that more weight can be carried by lowboy trailers by adding additional axles is another benefit. A lowboy trailer may be the ideal solution if you need to transport large machinery, such as bulldozers or other construction equipment.
Lowboy Trailer Typical Cargo Types:
- Backhoe loaders
- Heavy machinery
- Oversized items
Lowboy Trailer Legal Load Specifications:
- Weight Limit for Lowboy Trailer: 40,000 lbs. (with two axles) and up to 80,000 lbs. (with extra axles)
- Lowboy Trailer Maximum Freight Dimensions:
- Maximum Well Length: 24 ft. – 29.6 ft.
- Maximum Well Height: 18 in. – 24 in.
- The widest trailer allowed is 8.5 feet.
- 11.5 feet is the maximum legal freight height. – 12 ft.
- 14 feet is the maximum height for a legal overall load.
The construction of reefer trailers, also referred to as refrigerated trailers, includes insulation and temperature controls. These enclosed semi-trucks have substantial fans inside to keep the interior cool. They can also be used to transport some medications. They are frequently used to transport grocery items like meat and vegetables.
For minimal environmental deterioration, these semi-trucks also have additional insulation. More stringent weight restrictions apply to refrigerated semi-trailers. InTek estimates that these trucks can accommodate a maximum weight of 44,000 pounds of cargo.
See more about Width Of Semi Trailer: How Wide?
A type of hauling trailer known as a dump trailer uses hydraulics to lift and tilt the trailer bed so that heavy loads can be easily and safely unloaded with the aid of gravity. Although dump trailers and dump trucks are frequently confused, dump trailers let you adjust the trailer size to fit your load. Although less expensive than dump trucks, dump trailers can still transport large payloads effectively and safely.
Dump trailers come in both frame- and frameless variations. The lighter weight and aluminum construction of frameless dump trailers allow for heavier payloads. For heavier loads, such as machinery and large boulders, steel frame dump trailers are a fantastic option.
The method of dumping is another factor to take into account when choosing a dump trailer. The comparison of end dump vs. side dump vs. bottom dump trailers so you know which one is the right one for your project.
Dump Trailer Typical Cargo Types:
- Fill dirt
Dump Trailer Legal Load Specifications:
- Dump Trailer Maximum Freight Weight: Dependent on local regulations
- Dump Trailer Maximum Freight Dimensions:
- Maximum Trailer Length: 45 feet
- 8.5 feet maximum trailer width
- Maximum Legal Trailer Height: 13’6″
End Dump Trailers
The majority of dump trucks operate similarly to end dump trailers in that the front of the trailer is raised into the air while the cargo is loaded out of the back of the trailer. The front of the box must be raised high enough to encourage this movement because the load is pulled out of the trailer bed by gravity. This elevated position lends itself to some instability, which may be made worse by uneven ground or shifting loads. Since it’s challenging to make the back gate watertight, end dumps aren’t used to transport liquids.
Side Dump Trailers
A more recent idea, side dump trailers were created to address the instability problems with end dump trailers. Side dump trailers provide more stability on both even and uneven ground because they can be tilted to one side to unload cargo. With a quicker dump cycle, side dump trailers enable operators to haul and release a variety of materials safely.
Bottom Dump Trailers
Trailers that unload material directly from the bottom of the box are referred to as bottom dump or belly dump trailers. Most models today use a “clam shell” type of dump gate so that the contents can be windrowed, or released in a low ridge, long line instead of a single pile. Given that fine material and liquid will probably leak out and that the axles of the trailer must be able to clear the windrow, bottom dump trailers are not appropriate for all types of materials.
Dry Van Trailers
Some of the trailers that are most frequently used in the US are dry vans. Since they are completely enclosed, the contents are safeguarded against the elements and theft. These trailers are between 28 and 53 feet long. They move anything, including consumables, household items, and building materials. The fact that dry vans make up two-thirds of all trailers in use is interesting. Here are a few of the types of dry van trailers:
Reefer Trailer Or Refrigerator Trailer
- This type of trailer has a compressor and complete insulation so it can transport frozen or chilled goods. They frequently have a refrigeration unit mounted on the front and are insulated. These trailers transport a variety of goods in temperatures between -22 and 80 degrees Fahrenheit, including food, cosmetics, paint, pharmaceuticals, and many other goods.
- A Conestoga trailer has all the advantages of a flatbed, including the flexibility to load cargo onto the bed from any direction and in any configuration. However, it also has a rolling tarp-on-frame system that can completely enclose the cargo, providing it with the same level of protection as a dry van.
Side Kit Trailer
- The side panels of the side kit trailer are made of plywood or fiberglass, and a tarp covers the top of the trailer. These are employed to transport gravel, grain, and other loose materials like coal.
Tanker trailers are typically made of aluminum or stainless steel and used to transport liquids. Tanker trailers are recognizable by their distinctive shape and for good reason; they are cylindrical. Because a tanker truck’s cylinder shape relieves pressure from the tank itself, it has a lower center of gravity, prevents liquid surges, and makes extraction and cleaning simpler.
Tanker Trailer Typical Cargo Types:
- Dry food
Tanker Trailer Legal Load Specifications:
- Maximum Gross Weight for a Tanker Trailer: 80,000 lbs.
- Tanker Trailer Maximum Freight Dimensions:
- Maximum Trailer Length: 48 ft. – 53 ft.
- Maximum Trailer Width: 8.5 ft.
- 13.5 feet is the highest legal limit for freight.
There are various tanker trailer types, and each one serves a particular function.
In addition to insulation and occasionally a heater, asphalt tankers provide excellent temperature control. These characteristics offer the ideal setting for items that need to be kept hot.
Petroleum tankers typically have an aluminum construction and hold between 5,000 and 10,000 gallons. While some fuel tankers only have one compartment, most modern tankers have multiple compartments so that various grades of the same product can be loaded simultaneously. Inside petroleum tankers, large plates with holes known as tanker baffles are installed to control fuel surge while in transit.
Dry bulk tanks, also referred to as pneumatic tankers, are emptied using a blower and a pump that uses forced air. A series of cone-shaped, fully enclosed hoppers that are vacuum sealed and used to unload product beneath the tanker itself. Materials like dry sand, dry food, and chemicals are excellent candidates for transportation in pneumatic tankers.
The highest level of impurity protection is offered by stainless steel tankers. These are also used as food tankers and are excellent for storing highly refined products, de-mineralized water, corrosive materials, and highly pure materials.
Tipper trailers do as their name implies and lean to allow gravity to empty the load. To raise and tilt their platform, these trailers use hydraulics. Bricks, rocks, gravel, and other heavy materials are easy to transport and dump using tipper trailers. Tipper trailers are highly desirable for any construction or garbage removal project and are offered in a wide range of sizes and capacities.
Tipper Trailer Typical Cargo Types:
- Construction debris
- Agricultural materials
- Recycling items
Tipper Trailer Legal Load Specifications:
- Weight Limit for Tipper Trailers: 42,000 lbs. – 45,000 lbs.
- Tipper Trailer Maximum Freight Dimensions:
- 43 ft. is the maximum trailer length. – 58 ft.
- 8.5 feet is the maximum trailer width.
- Maximum Legal Freight Height: 8 ft.
You now have a better understanding of which commercial trailer type will suit your needs given your knowledge of the most prevalent semi-trailer types. Hale Trailer Brake & Wheel, Inc. can assist you whether you want to rent or purchase. has the largest selection of semi-trailer types. Visit one of our convenient locations near you or browse our inventory of new and used semi-trailers online.
Thank you for reading.