Guide to Semi-Truck Trailers: Styles & Uses

Semi-trucks have a variety of trailer options to choose from. Depending on the type of cargo they need to transport and the size of their payload, this will determine the size and style of the trailer they will need for the specific job. 

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Although there are several styles of trailers to use for hauling, they all have the same basic components. A typical semi-trailer consists of: 

• • Kingpin

    : which will slide into the fifth wheel of the tractor

  • Bed:

     either covered or uncovered

  • Axles

    : a minimum of two axles, with two tires on each side

  • Air Brake System (ABS)

    : this brake system includes both the trailer brake circuit and the parking brake circuit

  • Electrical

    : electrical hookups and wiring for rear lighting and signaling

  • Suspension

    : connects wheels, axles & brakes to the body of the trailer while also absorbing the physical blows of hauling freight

 

On top of the semi-trailers basic components, they can be customized with specific add-ons which are mainly for the purpose of improved aerodynamics. A more aerodynamic trailer significantly improves fuel economy by redirecting airflow to reduce drag. There are three main areas which cause drag:

1. 1. Between the cab and trailer
      • Panels have been engineered to extend off each side of the trailer and jut into that space, reducing the amount of trapped air inside.
   2. Underbelly of the trailer
      • Side skirts can be placed along the side of the trailer, in front of the rear axles, forcing the air to travel up the side of the trailer instead of underneath.
   3. Rear of the trailer
      • Trailer tails can be attached to the vertical sides of the trailer back. These allow the air to flow straight off the trailer instead of being pulled behind it, this alone can improve fuel efficiency up to 6%.

 

Styles of Semi-Trailers

Whether you&#;re driving a day cab or a sleeper cab, you will be hauling a certain type of trailer in order to complete your route. For any type of freight, there is a specific style of semi-trailer suitable for the hauling task at hand. They can be broken down into five different categories.

1. Flatbed Trailer
2. Dry Vans (Enclosed Trailers)
3. Specialty Trailers
4. Tank Trailers
5. Dump Trailers

 

Style 1:

Flatbed Trailers

Flatbed trailers are the most extensive and versatile category which has many kinds of trailers to fit the needs of specific freight. They are used in almost every area of the United States as they&#;re primarily utilized for shipping construction materials and various equipment. Here are the 4 variations of the flatbed trailer:

1. Flatbed & extendable flatbed

• This is an open bed trailer that sits at a consistent height. A two-axle flatbed has a GVWR maximum weight of 80,000 pounds and length of 48&#;. A three-axle flatbed has a GVWR maximum weight of 90,000 pounds and length of 53&#;. An extendable flatbed can extend anywhere from 48&#; &#; 80&#;. This is used for larger cargo that cannot be shipped via a standard flatbed.

2. Lowboy

• These trailers sit low to the ground which allows them to carry very tall freight. They can carry up to 95,000 pounds depending on the number of axles used and have a 24&#;- 29&#; long bed. This type of trailer is used for large construction equipment, infrastructure piping, farm equipment and oversized items that cannot fit on a standard flatbed.

3. Drop

• This kind of trailer combines two deck heights in one trailer. There are 3

  types of drop trailers:
  • Single drop &#; this refers to a trailer that has two deck heights. A standard flatbed height then drops to a lowboy height. It has the same length and weight restrictions as a standard flatbed.
  • Single drop stretch &#; has the same features of a single drop trailer but can extend anywhere from 48&#; &#; 63&#;. The maximum weight is 80,000 pounds GVWR.
  • Double drop stretch &#; this is a trailer that has two deck heights but begins at a standard flatbed height, then drops to a lowboy height, and back to a flatbed height, effectively forming a well in the middle of the trailer. The maximum weight is 90,000 pounds GVWR and can come any length between 29&#;- 65&#;.

4. Removable Gooseneck (RGN) & Stretch RGN

• These trailers are similar to a lowboy but the gooseneck, the component which attaches the trailer to the tractor, can be removed and the front end of the bed can drop down to create a ramp. This makes it perfect for carrying excessively long and tall freight. They have a minimum of three axles and can have up to 20 axles and carry up to 150,000 pounds, with a length of 29&#;. A stretch RGN can be up to 65&#; in length.

 

Style 2:

Dry Vans (Enclosed Trailers)

Dry Vans are some of the most commonly used trailers in the United States. They are fully enclosed, which protects the contents from weather and theft. These trailers range from 28&#;-53&#; in length. They haul anything from building materials, household goods, or even consumables. An interesting fact is that two-thirds of all trailers on the road are dry vans. Here are a few of the types of dry van trailers:

1. Reefer Trailer or Refrigerator Trailer

• This type of trailer features a compressor and full insulation so it&#;s able to transport cold or frozen products. They&#;re oftentimes insulated and have a refrigeration unit mounted on the front. These trailers carry various products, such as food, make-up, paint, pharmaceuticals and many other products, in a range of -22 to 80 degrees Fahrenheit.

2. Conestoga Trailer

• A Conestoga trailer has the benefits of a flatbed, where the freight can be loaded onto the bed from any side and in any configuration, but it has a rolling tarp-on-frame system that can fully enclose the cargo, giving it the same protection as a dry van.

3. Side Kit Trailer

• The side kit trailer&#;s side panels are made of fiberglass or plywood, with a tarp that covers the top of the trailer. These are used for carrying loose materials such as coal, grain and gravel.

 

Style 3:

Specialty Trailers 

Specialty trailers provide options for transporting specific materials. They can carry over 200,000 pounds depending on the specific use. Of the dozens of specialty trailers there are four common types:

1. Hazardous Material Transport

• These trailers are cylindrical in shape and are used to ship petrol, chemicals, and other hazardous materials.

2. Food Service

• These trailers are outfitted with mobile kitchens that can be used for conferences, festivals, or temporary kitchens while brick and mortar renovations are completed

3. Event Marketing

• These can be used for advertisements and displaying products to a wider customer base

4. Medical

• These trailers carry medical supplies and resources to onsite staff and are often outfitted for mobile clinic operations, such as a blood bank

 

Style 4:

Tank Trailers

1. Fuel Tanks

• Fuel tanks do exactly what you would expect them to: carry petroleum diesel & oils across the greater United States area

2. Pneumatic Tanks

• Pneumatic tanks are unique in that they haul plastic pellets, flour, cement and other dry products that are shipped in bulk

3. Specialized Tanks

• These kinds of tanks haul compressed gas, propane and other specialized chemical transport

 

Style 5: Dump Trailers

 

These types of trailers you may not see every day, but they&#;re very popular near work zones and construction sites. Those hauling dump trailers use this style to haul aggregate and materials to and from work sites and need to dump out their contents.

Are you interested in learning more about Semi-trailer tractor? Contact us today to secure an expert consultation!

 

High-Quality Trailers At North American Trailer

If you need to purchase a trailer, our dedicated sales team at North American Trailer is here to help during the buying process. Regardless of the type of trailer, regular maintenance and service are essential to keep your trailer on the road. If you&#;re in need of parts or trailer service in the greater Twin Cities, MN area, you can trust the team at North American Trailer to take care of you.

With over 35 years of experience and four locations across 2 states, you can count on us for all your trailer needs.

 

Trucking accounts for over 70% of all freight transported in the United States and is the preferred method of shipping most goods. While the truck may be the engine, the trailer carries the load and it&#;s important to select a compatible trailer to do the job at hand.

There are a wide variety of semi-trailer types available and depending on your load or freight, one will suit your needs better than another. Finding the right trailer for your job will make all the difference in ensuring the success of your project and facilitating the safe arrival of your goods. With this guide you&#;ll learn about the most common semi-trailer types and what each type is used for.

1. Flatbed Trailers

Flatbed trailers offer versatility and as a result are some of the most commonly used trailers. The name stems from the fact that flatbed trailers have a flat deck that is open on all sides and does not have a roof or a box to cover the load. This open layout makes it an easy trailer to load and unload but does not protect cargo from the elements of weather and roads. Flatbed trailers are perfect for shipping wide or large items as the load can be lifted from above with a crane or from the side with a forklift.

Flatbed Trailer Typical Cargo Types:

• Construction materials
• Heavy equipment and machinery
• Oversized or unusually shaped loads
• Lumber

Flatbed Trailer Legal Load Specifications:

• Flatbed Trailer Maximum Freight Weight: 48,000 lbs.
• Flatbed Trailer Maximum Freight Dimensions:
  • Maximum Trailer Length: 48 ft. &#; 53 ft.
  • Maximum Trailer Width: 8.5 ft.
  • Maximum Legal Freight Height: 8.5 ft.

2. Step Deck or Drop Deck Trailers

Step deck trailers, also known as drop deck trailers, are similar to flatbed trailers in that they are an open trailer but do have some differences. While flatbed trailers have only one level, step deck trailers have two deck levels that are known as the upper deck and lower deck.

The upper deck measures between 10 and 13 feet long and sits above the tractor unit. The lower deck measures between 38 and 40 feet long and sits a mere 3 feet and 3 inches above the ground. This lowered deck affords step deck trailers the ability to haul taller loads.

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:

• Step Deck Trailer Maximum Freight Weight: 48,000 lbs.
• Step Deck Trailer Maximum Freight Dimensions:
  • Maximum Trailer Length: 48 ft. &#; 53 ft.
  • Maximum Trailer Width: 8.5 ft.
  • Maximum Legal Freight Height: 10 ft.

3. Lowboy Trailers

Lowboy trailers are also known as double drop trailers because they have two drops in deck height that allow for an extremely low deck. The first drop is right after the gooseneck and the second drop is before the wheels. This additional dropdown feature is what makes lowboy trailers ideal for moving taller equipment without needing to obtain height permits.

Another advantage to lowboy trailers is that increased weight capacity can be achieved by adding extra axles. If you&#;re looking to haul large equipment such as bulldozers or other construction equipment, a lowboy trailer may be exactly what you&#;re looking for.

Lowboy Trailer Typical Cargo Types:

• Bulldozers
• Excavators
• Backhoe loaders
• Heavy machinery
• Oversized items

Lowboy Trailer Legal Load Specifications:

• Lowboy Trailer Maximum Freight Weight: 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.
  • Maximum Trailer Width: 8.5 ft.
  • Maximum Legal Freight Height: 11.5 ft. &#; 12 ft.
  • Maximum Legal Overall Load Height: 14 ft.

4. Reefer Trailers

Reefer trailers, also known as refrigerated trailers, are built with insulation and temperature controls. Typically, these trailers use refrigeration to enable the transport of perishable, chilled or frozen products, but they can also protect temperature-sensitive goods from frigid outside weather.

Reefer Trailer Typical Cargo Types:

• Produce
• Meat, poultry, fish, dairy
• Pharmaceuticals
• Plants and florals

Reefer Trailer Legal Load Specifications:

• Reefer Trailer Maximum Freight Weight: 42,000 lbs. &#; 45,000 lbs.
• Reefer Trailer Maximum Freight Dimensions:
  • Maximum Trailer Length: 48 ft. &#; 53 ft.
  • Maximum Trailer Width: 8.2 ft.
  • Maximum Legal Trailer Height: 8 ft.

5. Dump Trailers

Dump trailers are a type of hauling trailer that use hydraulics to lift the trailer bed up and tilt it to unload heavy hauls with ease and the help of gravity. Although dump trailers are oftentimes confused with dump trucks, dump trailers allow you to customize the trailer size to correspond to your load. Dump trailers are less expensive than dump trucks but still offer the ability to haul heavy payloads safely and efficiently.

You&#;ll find dump trailers are available with a frame or frameless. Frameless dump trailers allow for heavier payloads because they&#;re made of aluminum and are lighter weight. Steel frame dump trailers are a great choice for larger hauls, like equipment and large boulders.

Another thing to consider when selecting a dump trailer is the style of dumping. It&#;s helpful to compare 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:

• Gravel
• Sand
• Stone
• Fill dirt
• Trash
• Branches

Dump Trailer Legal Load Specifications:

• Dump Trailer Maximum Freight Weight: Dependent on local regulations
• Dump Trailer Maximum Freight Dimensions:
  • Maximum Trailer Length: 45 feet
  • Maximum Trailer Width: 8.5 ft.
  • Maximum Legal Trailer Height: 13&#;6&#;

End Dump Trailers

End dump trailers operate the same way most dump trucks do and unload cargo out of the rear of the trailer while the front of the trailer is lifted into the air. Because the load is shifted out of the bed of the trailer by gravity, the front of the box needs to be lifted high enough to encourage this movement to happen. This raised position lends itself to some instability and may be worsened by uneven ground or shifted loads. End dumps are not used to haul liquids because it&#;s difficult to make the rear gate watertight.

Side Dump Trailers

Side dump trailers are a newer concept developed to resolve the instability issues of end dump trailers. By tilting the trailer to one side to unload cargo, side dump trailers offer greater stability regardless of even and uneven ground. Side dump trailers allow operators to safely haul and release a variety of materials with a more rapid dump cycle.

Bottom Dump Trailers

Bottom dump trailers, also known as belly dump trailers, unload material directly from the bottom of the box. 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. Bottom dump trailers are not suitable for all types of materials considering fine material and liquid will likely leak out and the axles of the trailer must be able to clear the windrow.

6. Dry Van Trailers

Dry van trailers, also known as enclosed or box trailers, are fully enclosed and are used for shipping non-perishable goods. Although there is no temperature control, the cargo is protected from the elements of weather and roads. Freight is loaded at the rear of the dry van trailer and a loading dock is commonly used. Some dry van trailers also allow freight to be loaded from the side of the trailer or use moving floors.

Dry Van Trailer Typical Cargo Types:

• Non-perishable food and beverages
• Clothing and household goods
• Building products
• LTL shipping

Dry Van Trailer Legal Load Specifications:

• Dry Van Trailer Maximum Freight Weight: 42,000 lbs. &#; 45,000 lbs.
• Dry Van Trailer Maximum Freight Dimensions:
  • Maximum Trailer Length: 48 ft. &#; 53 ft.
  • Maximum Trailer Width: 8.2 ft.
  • Maximum Legal Freight Height: 8 ft.

7. Tanker Trailers

Tanker trailers are typically used to transport liquid and are manufactured from aluminum or stainless steel. Recognized by their unique shape, tanker trailers are cylindrical, and this is for good reason. Tanker trucks are built with a cylinder shape because this takes pressure off the tank itself, provides a lower center of gravity, prevents a liquid surge, and allows for easier extraction and cleaning.

Tanker Trailer Typical Cargo Types:

• Asphalt
• Chemicals
• Petroleum/Fuel
• Dry food
• Beverages

Tanker Trailer Legal Load Specifications:

• Tanker Trailer Maximum Gross Weight: 80,000 lbs.
• Tanker Trailer Maximum Freight Dimensions:
  • Maximum Trailer Length: 48 ft. &#; 53 ft.
  • Maximum Trailer Width: 8.5 ft.
  • Maximum Legal Freight Height: 13.5 ft.

There are a multiple types of tanker trailers and each one has a specific purpose.

Asphalt Tankers

Asphalt tankers offer superior temperature control along with insulation and at times a heating device. These traits provide the right environment for contents that need to be kept hot.

Petroleum Tankers

Petroleum tankers are usually always made of aluminum and range in size from 5,000 to 10,000 gallons. While some fuel tankers have one single compartment, most current tankers have multiple compartments so different grades of the same product may be loaded at the same time. Large plates with holes called tanker baffles are installed inside petroleum tankers to control fuel surge while in transit.

Pneumatic Tankers

Pneumatic tankers, also called dry bulk tanks, are emptied with a pump and blower using forced air. Product is unloaded beneath the tanker itself with a series of cone-shaped hoppers that are vacuum-sealed and fully enclosed. Pneumatic tankers are ideal for transporting materials such as dry sand, dry food, and chemicals.

Stainless Tankers

Stainless tankers are made of stainless steel and provide the highest level of protection from impurities. Ideal for storing de-mineralized water, highly refined products, corrosive materials, and highly pure materials, these also used as food tankers.

8. Tipper Trailers

Tipper trailers do exactly what their name suggests: tip to let gravity empty the load. These trailers use hydraulics to raise and tilt their platform. Perfect for hauling and dumping large debris, tipper trailers work well for bricks, rocks, gravel, and other heavy materials. Available in a wide variety of sizes and capacities, tipper trailers are highly desirable for any garbage removal or construction project.

Tipper Trailer Typical Cargo Types:

• Construction debris
• Agricultural materials
• Recycling items

Tipper Trailer Legal Load Specifications:

• Tipper Trailer Maximum Freight Weight: 42,000 lbs. &#; 45,000 lbs.
• Tipper Trailer Maximum Freight Dimensions:
  • Maximum Trailer Length: 43 ft. &#; 58 ft.
  • Maximum Trailer Width: 8.5 ft.
  • Maximum Legal Freight Height: 8 ft.

9. Schnabel Trailers

A schnabel trailer is a specialized type of heavy-duty trailer designed for transporting large and heavy cargoes, such as industrial equipment or machinery. The are frequently used in the movement of sections of the tower for energy producing wind turbines. It features a unique articulated design with multiple axles and a boom-like structure that extends over the trailer&#;s front end. This allows the schnabel trailer to carry extremely long and oversized loads, such as bridge beams or refinery columns, with dimensions that can exceed 100 feet in length and weigh up to several hundred tons. The maximum payload capacity of a schnabel trailer can vary depending on its configuration, but it is commonly capable of handling loads in the range of 500 to 1,000 tons.

Find the Semi-Trailer You Need at Hale Trailer

Now that you know about the most common types of semi-trailers, you have a better understanding of which commercial trailer type works best for your needs. Whether you&#;re looking to rent or buy, Hale Trailer Brake & Wheel, Inc. has the largest selection of semi-trailer types. Browse our selection of new and used semi-trailers online or stop in at one of our convenient locations near you.

Our knowledgeable team has extensive experience helping owners, operators, and fleet managers select the perfect equipment for any trucking job. Contact Hale Trailer today to find the semi-trailer that&#;s right for your project!

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