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Why Do Semi-Trucks Have a Bar on the Back?

Why Do Semi-Trucks Have a Bar on the Back?

Semi-trucks are heavy vehicles that are difficult to drive on roads. The regulating authority has made many rules regarding the safe driving of large trucks on highways.

Why Do Semi-Trucks Have a Bar on the Back? The Mansfield bars are metallic bars that are present on the back of a semi-truck. They can prevent the vehicles from sliding underneath the truck. They are named after actress Jane Mansfield and prevent head-on collision from the rear side. NHTSA has made it compulsory to install it on the rear side.

The underride guards have been present for many years. But they were not necessary to install on large vehicles. NHTSA reports the death of hundreds of people on roads due to the collision of semi with other automobiles.

What is the purpose of the bar on the back of the semi-truck?

The metal bars on the back of the semi-trucks are called Mansfield bars. They are also known as underride bars. They are used as a barrier between the rear end of the trailer and the vehicles behind it.

These trucks have larger tires and higher ground clearance than small automobiles. The absence of bumpers and high ground clearance can cause small cars to slide underneath the truck, and accidents can happen.

A minor collision between these two vehicles can cause massive road destruction. That’s why these metallic bars came into existence to prevent such accidents.

They are made from strong and durable metals like steel or aluminum. They are fixed to the rear end of the trailer. They also act as a shock absorbent and prevent the cars from sliding underneath the large trucks.

Why these bars are called Mansfield bars?

I always wonder how some tools and equipment got such unique names. I know you guys also think about how these names originated for a particular thing.

These bars are named after a famous actress, Jane Mansfield. Once, in June 1967, Jane was traveling late at night in foggy weather with her kids, lawyer, and driver. Due to extreme fog, the road was not clear.

Due to reduced visibility, the driver could not see a truck ahead of them. The driver could not respond quickly to prevent these two vehicles’ collisions. The car slid underneath the truck, and the actress died at the moment.

After this tragic incident, the regulating authority got to know the importance of the underlying bars. After that, these underride bars were named after the actress name Mansfield.

The administration made it mandatory to install a Mansfield bar behind the semi-trucks and other large trucks. There is no doubt that the presence of such a tool can save the lives of many people.

Are Mansfield bars effective in preventing accidents?

They have played a significant role in preventing collisions between semi-trucks and other vehicles. They have proven beneficial in protecting the lives of the people. They effectively prevent the car and other automobiles from sliding under the truck.

They are not strong enough to absorb the impact of collision completely. The cars behind a trailer can collide with them, and the drivers and passengers can get serious injuries due to this collision. A minor collision impact can break bones and cause other traumatic injuries.

The incorrect height of these bars can also cause collision between the vehicles. These scenarios have reduced the effectiveness of Mansfield bars.

Another thing is that these guards can prevent the collision at an angle. It can only avoid the head-on collision of cars with trailers. These guards are only present on the rear end of the trailer.

Automobiles taking turns or crossing the roads can easily slide underneath the truck. Vehicle driving within the blind spot of the semi is also not safe from accidents.

NHTSA rules regarding Mansfield bars

National Highway Traffic Safety Administration regulates all the rules regarding Mansfield bars. This administration made all the required changes in the structure strength and other characteristics of underride guards.

NHTSA passed the Mansfield bar regulation in 1953 for the first time. With time, the administration has changed the rules and regulations. They have increased the required strength of the metal bars to make them more effective.

According to the rules, these bars should be able to prevent collisions with vehicles driving at the speed of 35 miles per hour. But the possibility of cars sliding underneath from the sides is still here.

The attorney and lawmakers also urge the administration to make the sideways guards mandatory. This will make this equipment more effective in preventing accidents on the roads.

Can you drive a semi-truck without Mansfield Bars?

No, you can not drive a semi-trailer without the underride guards. NHTSA has made it mandatory to install these bars on all heavy trucks. NHTSA passed the legal rules regarding Mansfield bars in 1998.

If you do not comply with the legal requirements, the vehicle will not pass the safety inspection test. You won’t be able to drive a semi on heavy roads and highways. You’ll have to face all the legal consequences if caught driving a truck without these metal bars.

The administration is still trying to implement these rules strictly. The trucking companies are still reluctant to obey the rules and regulations of NHTSA.

They do not want to add the metal bars as it can increase the vehicle’s weight. The truckers will have to reduce the load from the trailer to fulfill the weight limitation requirements.

How to maintain Mansfield bars on a semi-truck?

The underride bars are made from metal and suffer from damage after prolonged use. The truckers have to take proper care of them for maintenance. Steel and other metals are susceptible to corrosion due to humidity and pollution.

Driving the truck in snowy or humid regions can cause these bars to get corroded. These guards are either welded directly to the semi-truck or fixed with nuts and bolts. Loose nuts and bolts can hold it in an upright position.

The welding can also get worn out after some time. You have to keep an eye on all the defects to keep them functional. Inspect them regularly and observe for any cracks and corrosion.

Paint them with a high-quality paint to prevent them from corrosion. Weld the broken parts of the bars and fill minor cracks in the metal beams. In case of severe damage, replace them with a new one.

Avoid driving on rainy days to protect the metal from corrosion. Tighten up all the nuts and bolts frequently to keep them in their respective places.

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