smonline channel
introduction
contributions
registration
sm news
webmaster
specifications
architecture
aerodynamics
engine
gearbox
drive train
steering
brakes
suspension
equipment
sm history
prototypes
production
sport
sm Mylord
sm Opera
sm Espace
sm présidentielle
sm world
sm data
sm colors
sm production
sm sales
serial numbers
sm images
sales brochures
sm glamour
sm downloads
your sm
sm restoration
buyers guide
engine rebuild
sm restoration
sm links
internet
mailing list
books
magazines
sm clubs

virtual garage channel

ertv channel

home

sm steering

Citroën SM steering

The steering on the SM really broke new ground in 1970. Citroëns hydraulic wizard, Paul Magés had the system ready for 10 years, but it first appeared in production form in the SM. The DERAVI (direction à rappel asservi) has a vary fast ratio requiring only two turns from lock to lock. The variable power assistance gives maximum assistance for parking and maneuvering and very little or none at all when the car is driven at speed. Another new idea was the self centering action of the steering. When there is no driver applied effort on the steering wheel the wheels will come back to the straight ahead position. The variable assistance is regulated by a regulator driven from the gearbox. A centrifugal mechanism operates hydraulic valves to increase or reduce assistance in accordance with vehicle speed.

Although this system requires some getting used to (typical first time drives will be oversteering the car swerving from side to side with sweaty hands) after about 10 minutes you start to appreciate the systems relaxed, precise and very safe qualities and after another 10 minutes you're wondering who not all cars are equipped this way. With the use of electronics in modern cars some manufacturers are now putting similar systems into production

Rack-and-pinion steering with servo-assistance varying according to vehicle speed and angle of deflection, with power-assisted return to center (automatic return to straight-line position. even at rest). A centrifugal regulator coupled with the gearbox acts on a hydraulic valve which determines the effort to be applied to the steering wheel. so that this effort varies with the vehicle's speed. Gearing ratio: 1: 9.4. Turning diameter between curbstones: 34's 1/2'