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What is a reefer trailer? - Facts about the coolest trailer

A grey Schneider semi-truck backs a white reefer trailer towards a loading dock.
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June 21, 2021

Estimated reading time: 2 minutes

Perishable products are among the highest consumed goods in America today. Some of the most consumed or used perishable products in the U.S. include:

  • Fruit and vegetable produce.
  • Dairy products.
  • Meat and poultry.
  • Seafood products.
  • Pharmaceuticals.
  • Flowers.

These products are all categorized as “reefer freight” and the main characteristic of these products is that they spoil quickly. To combat this problem, truck drivers use transportation equipment called “reefer trailers” to help haul perishable products.

But what does "reefer" stand for?

What is a reefer trailer?

A refrigerated or “reefer” trailer is a heavily insulated and tightly sealed container that has a Trailer Refrigeration Unit (TRU) mounted on the outside of the front wall, to control the temperature inside the trailer.

The main purpose of a reefer trailer is to maintain the temperature of freight at the time it is loaded. It is not used to increase or decrease the temperature of the freight during transportation.

For example, ice cream is loaded frozen and the TRU keeps it frozen during transportation so that it is still frozen when it arrives at its destination.

Regulating a trailer’s temperature in this way helps maintain the quality and prolong the shelf life of the freight being hauled.

How does a reefer trailer work?

Reefer trailers are the same size as an average semi-trailer, meaning that they are essentially 53-foot-long refrigerators on wheels. As you can imagine, reefer trailers rely on a some powerful technology to refrigerate that large of a space for such a long period of time.

Five white drop-and-hook reefer trailers sit at the loading dock of a business, waiting to be unloaded.

The following are a few of the pieces of technology that work together to ensure that reefer freight maintains its temperature while being transported:

  • Trailer Refrigeration Unit (TRU): The TRU is a self-contained refrigeration unit, consisting of a small diesel engine and refrigerant compressor, with its own diesel fuel supply from a tank mounted under the trailer. This unit monitors the interior temperature of the trailer compartment(s) and cycles as needed to maintain the programmed temperature.
  • Insulated container: Reefer trailers have walls that are insulated with foam and doors that create an air-tight seal. This ensures that the temperature remains constant throughout the entire length of haul.
  • Air circulation: Reefers require proper air flow to maintain a constant temperature throughout the entire trailer, meaning that air must circulate throughout the trailer. That’s why some reefers have an air delivery chute attached to the interior roof. This chute is used to distribute air from the front of the trailer to the back. Most reefers also have metal channels in the floor that create enough space to circulate air evenly under the freight being hauled.
  • Temperature control: The temperature is controlled and set per the customer requirements and is set from a control panel on the driver’s side of the TRU. Along with providing cooling, a TRU can also provide heating if needed, to maintain the required temperature of the freight.

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About the author
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Schneider Guy loves the "Big Orange." He's passionate about the trucking industry and connecting people to rewarding careers within it. He's been the eyes and ears of our company since our founding in 1935, and he's excited to interact with prospective and current Schneider associates through "A Slice of Orange."

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