P'art of the day: Citroen Hydropneumatique Suspension

Today's part was first used on the rear of the '54 Citroen Traction Avant a real contemporary engineering tour de force, the hydropneumatic system achieved major recognition in '55 when it was used on all four corners of the Citroen DS, a timeless design icon

















The Hydropneumatic designation hinted at the innovative operation, instead of using regular steel springs the car was suspended by pressurised oil (hydro) and gas (pnuematic).

While the part itself has no remarkable aesthetic qualities the grace with which it operates is breathtaking, the advantages of the hydropneumatic system were two fold, phenomenal bump absorption, allowing the car to glide across uneven terrain... (As this rather abstract period advert demonstrates)



.. and a self leveling effect which allows the cars attitude and ride height to remain unaffected by static loads (passengers, luggage, etc) and dynamic loads (cornering forces, acceleration and braking) even in extreme cases which would really perturb conventional suspension systems, as illustrated in this excellent 70's Citroen GS ad