What Is The Bar On The Back Of A Semi Trailer Called

The bar mounted low across the rear of a semi-trailer is called a rear underride guard or rear impact guard. It is also commonly known as a Mansfield bar and is sometimes informally called an ICC bumper. Its purpose is to reduce the likelihood that a smaller passenger vehicle will slide underneath the trailer during a rear-end collision. This type of crash is known as an underride collision and can be particularly severe because the trailer may enter the passenger compartment above the car’s primary crash-protection structures. Federal regulations establish requirements for rear impact guards on many trailers, including aspects of their location and strength. The term “Mansfield bar” became widely associated with these devices after the 1967 crash that killed actress Jayne Mansfield. If you are identifying the part for an accident report, legal claim or repair question, “rear underride guard” or “rear impact guard” is the more technical terminology. Other rails on a trailer can serve different structural or protective functions.