6 and the clutch plate 41 this friction material should if desired be affixed to the member 6 or to the clutch plate 41 in the same manner illustrated for the friction member 4 however the provision of such members made of special friction material is not required since the faces of the friction members may themselves provide friction surfaces in the usual way ultimately the specific nature and conformation of the friction members will depend on the operational requirements to which the friction clutch is subject instead of the illustrated disk shaped friction members friction members of conical configuration might be provided if desired the operation of the representative friction clutch shown in the drawings is as follows as long as the output shaft 2 is not displaced axially in the direction of the arrow because of the absence of a corresponding steering moment the friction members 3 and 4 are disengaged consequently the outer clutch member 1 driven by the pinion 8 does not transmit any servo moment to the clutch output shaft 2 the friction member 3 which is angularly linked to the outer member 1 and the pressure generating member 7 are free to rotate with this member the pressure generating member 6 which rotates with axial clearance in the.