A refrigerated or “reefer” trailer is a heavily insulated and tightly sealed container, very similar to a dry van trailer with the difference that it 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.
Transportation of these loads are usually better paid since it requires a more specialized trailer. It also carries additional costs and risks. For example, the “Trailer Refrigeration Unit” or TRU requires regular maintenance, including but not limited to oil and belts change. In addition, there is the fuel cost involved to run the TRU. Most reefers come with a 50 Gal diesel tank attached to it.