Skip to content
Home > Air Conditioning > What Are the Spinning Discs on the Roof of Vans? (Solved)

What Are the Spinning Discs on the Roof of Vans? (Solved)

  • by
  • 2 min read

Ever been behind a van and seen a spinning grey or black disc and wondered what they are and what they do?

I wondered what these roof vents do, so I found the answer.

Answer: The spinning discs on top of van roofs are called “Flettner vents”, they are utilised while transporting animals or food. Because the back of vans usually do not have windows, it is necessary to circulate fresh air, it also removes any smell.

Flettner van roof vent

Essentially, they draw out the air from the back of the van through this vent on their roof.

Since 1931, Flettner Ventilator has been a major manufacturer of spinning air vents for vans.

diagram showing how a flettner van roof vent works

Whenever a Flettner roof vent is mounted on a vehicle’s roof and air is moving around it, either as a result of the vehicle’s movement or as a result of the wind itself, the Flettner roof vent will spin and ventilate the vehicle.

Sometimes, there may be another brand of roof vent used but it will be based on the same principle.

Two or more different vents may be used in conjunction with each other.

diagram showing how to two van roof vents work
  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer.He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

Share this article
Available for Amazon Prime