The De Dion Suspension system came out of one of the industry’s first manufacturers, De Dion Bouton, although it wasn’t Count De Dion or Monsieur Bouton who invented the suspension but the Count’s brother-in-law Charles Trepardeaux who worked for them for a while.
Trepardeaux designed a way to keep the wheels on the ground when the vehicle was travelling. He originally designed it for steam tricycles and it was then redesigned for car use.
The suspension removes the differential from the suspension by bolting it to the body and then a tube connects both sides of the vehicle. This is a laterally telescopic tube that absorbs a bump. This means that there are no camber changes on rebound, which in turn means that the wheels are always aligned thus improving traction.
The tube also uses two universal joints instead of one, which adds to the weight that was reduced by removing the diff and mounting it to the body. Originally, the setup would have used leaf springs but in recent years, coil springs and shock absorbers have been used with the addition of a Panhard rod for further rigidity support.
Originally due to the way the suspension was designed, the brake drums and later discs had to be mounted inboard – i.e. near the differential. This meant that servicing was more difficult because you would have to split the suspension to do maintenance.
Current cars like Caterhams use the De Dion Suspension and have managed to use outboard discs for performance and simplicity. Some kit cars use De Dion tubes, as they are cheap to manufacture.