roll bar

noun2

1. •
   A strong U-shaped bar fastened to the frame of a vehicle, such as an off-road vehicle or a race car to protect the driver and passengers from being crushed in the event that the vehicle rolls over.
2. •
   An anti-roll bar.

   • The roll bar is a metal bar linking one side of the suspension to the other. It limits how much the car rolls during cornering. — 2004