Why Do Semi Trucks Have Flaps On The Back?

What are those flaps on the back of trucks?

The panels under the body of the truck are called aerodynamic panel skirts, side panels, or side skirts.

The panels that hang off the back are often called rear tail fairings, trailer tails, or sometimes boat tails.

Whatever you call them, their purpose is to reduce drag and save fuel..

Why are there flaps on the back of semis?

The flaps are aerodynamically easing the flow around the blunt rear end of the truck. This reduces the size of the recirculated air pocket behind the truck, which is low pressure and effectively “sucking” the truck backwards from its direction of motion.

Why do semi trailers have side skirts?

A trailer skirt or side skirt is a device affixed to the underside of a semi-trailer, for the purpose of reducing aerodynamic drag caused by air turbulence.

What are the little doors on the back of tractor trailers for?

On refrigerated trucks and trailers, the small rectangular door is called a fruit door. It’s mainly used for temperature control and monitoring. It also can be used to help air out the trailer.

What are fairings on a truck?

The purpose of a chassis fairing, sometimes called a chassis or fuel tank skirt, is to provide a clean aerodynamic surface and eliminate the steps, air, fuel and diesel fluid tanks, battery boxes, etc.

How much fuel do trailer skirts save?

According to a news release, researchers found that these panels — which are only utilized by 3 to 4 percent of the nation’s semi trucks — can reduce aerodynamic drag by as much as 25 percent, which represents about a 13 percent decrease in fuel consumption.