Servo-steering control systems for vehicles

DETAILED DESCRIPTION According to the invention a servo-steering control means of the previously defined type is essentially characterised by the fact that is comprises first elastic means adapted to cooperate with the slide valve and to exert an axial force on this slide valve and second elastic means arranged between the drive shaft and the shaft connected to the steering mechanism, adapted to resist the relative angular displacement between the two shafts which tends to cause the axial force exerted on the slide valve by the first elastic means, the setting of the first and second elastic means being such that the equilibrium of the slide valve in its middle position, such that the jack is not actuated, is obtained when the angular separation between the two shafts is substantially nil.
By angular separation between the two shafts, is meant the angular separation with respect to the relative mean position of the two shafts between their two relative extreme positions determined by the play of their mechanical linkage.
Generally, the first elastic means exert an axial thrust on the slide valve towards the means adapted to transform the angular separation of the rotary members into a longitudinal movement.
Preferably, these first elastic means are constituted by a spring compressed between the end of the slide valve distant from the abovesaid means adapted to transform the angular separation of the rotary members into longitudinal movement and a part of the housing surrounding the slide valve, the abovesaid spring being supported notably through a cap against the end of the slide valve.
According to another characteristic of the invention, the shafts being coaxial, the second elastic means comprise at least one flexible rod or strip substantially parallel to the common axis of the two shafts and connected respectively to each shaft; preferably one of the ends of this rod is anchored in one of the shafts or in a part fast to this shaft, whilst the other end of the rod is supported simply against a radial surface of the other shaft, or of a part fast to this other shaft