[Citroën innovations] The history of the DIRAVI steering system, Citroën's technological gem

Citroën has always cultivated its unique identity through bold innovations that have profoundly shaped automotive history. When one thinks of the brand with the chevrons, the image of the hydropneumatic suspension, a true magic carpet ride, immediately comes to mind. This technology, an absolute symbol of comfort, was much more than a mere signature; it was a matrix of innovation. By harnessing the power and versatility of its high-pressure hydraulic system, Citroën was able to explore new frontiers in braking, transmission, and, most notably, steering. It was within this fertile environment that the DIRAVI steering system was born—an engineering marvel that transformed the relationship between the driver, the car, and the road.

The genesis of a steering system unlike any other

The acronym DIRAVI stands for "DIrection à Rappel AsserVI," which translates to "power-assisted steering with controlled return." Behind this technical name lies a philosophy: to provide unparalleled driving precision and safety, regardless of speed. Created at the turn of the 1970s to equip the brand's new grand tourer, the Citroën SM, DIRAVI was the answer to a significant challenge: how to guarantee perfect stability in a powerful front-wheel-drive car capable of exceeding 220 km/h (137 mph). Engineer Paul Magès and his teams devised a system that broke with all existing conventions. Unlike conventional power steering, which simply reduces effort, DIRAVI is a fully hydraulic steering system. The steering wheel is not directly mechanically connected to the wheels when driving straight; instead, it sends a "command" to a hydraulic controller that operates the steering rack. This unique feature completely insulates the driver from road imperfections (such as potholes or ruts) and adverse reactions, like torque steer under hard acceleration.

Functionality in service of safety and ease

The operation of the DIRAVI system is based on several revolutionary principles. First, assistance is at its maximum when the vehicle is stationary, allowing the wheels to be turned from lock to lock with a single finger, making parking maneuvers incredibly easy. Second, and this is where its genius truly lies, the steering firms up progressively with speed. A centrifugal governor, driven by the gearbox output, adjusts the hydraulic pressure sent to the system. The faster the car goes, the firmer the steering becomes, preventing involuntary movements of the wheel that could be dangerous at high speeds. Finally, the "controlled return" function ensures that the wheels and steering wheel systematically and rapidly return to the center position as soon as released, even when at a standstill. This active self-centering capability provides exceptional straight-line stability, giving the impression that the car is running on rails. With only 2 turns of the wheel from lock to lock on the SM (compared to over 3.5 on many cars of the era), it offered outstanding responsiveness.

From the prestigious SM to the iconic CX: a remarkable career

The DIRAVI steering system made its debut in 1970 on the Citroën SM, where it became an inseparable technological signature, much like its Maserati V6 engine. It allowed this Grand Touring coupe to offer a unique driving experience, blending supreme comfort with top-tier safety. The innovation was so significant that it was also adopted by Maserati for its Quattroporte II and Khamsin models. After the SM's production ended, this exceptional piece of equipment was not forgotten. Citroën logically integrated it into its new high-end sedan, the CX, launched in 1974. Most versions of the CX were equipped with DIRAVI, helping to build its reputation as a grand tourer with imperial stability and comfort. It even carried over to certain V6 versions of the CX's successor, the XM, thus perpetuating this legacy until the early 2000s. Although expensive and complex, DIRAVI left a lasting mark, demonstrating that power steering could be an active safety feature in its own right.

With DIRAVI, Citroën proved that its quest for innovation was not limited to suspension comfort. The ease and serenity of the driving experience were already at the core of its concerns. By filtering out road disturbances and adapting its responsiveness to speed, DIRAVI significantly lightened the driver's workload, allowing them to focus on their trajectory and surroundings. This philosophy resonates strongly with the brand's current approach. Today, Citroën aims to reduce mental load behind the wheel through its "Advanced Comfort" program. This is achieved with plush seating, progressive hydraulic cushion suspension, but also with clean, uncluttered interiors, intuitive interfaces, and driving aids that make the experience simpler and more soothing. In this sense, the spirit of DIRAVI, which aimed to make driving both easier and safer, lives on. It is the legacy of a vision where technology is not an end in itself, but a means to provide well-being and peace of mind to the driver.