| 摘要 |
Rotary directional-control valve for power-assisted steering mechanisms of the type including coaxial cylindrical elements 32, 33 capable of a limited relative rotation about their common axis, in which the internal element 32 is mounted to rotate in the bore of the external element 33, the latter being mounted so as to rotate in a fixed casing 30, in which the distribution circuit particularly defined by these elements 32, 33 is made up of fluid openings and cavities connected between a fluid source 15 and a reservoir 17 and which includes two working pressure take-offs 18, 19 for producing variable-cross-section fluid passages operating by overlap during a limited relative rotation of the said elements 32, 33 and for obtaining an increase in pressure in one or other of the working pressure take-offs 18, 19, characterised by the fact that one of the two leakage channels 43, 44 which open out into an auxiliary cylindrical chamber 40 of the casing 30 in which there is mounted, with displacement, the active element 41 of a bypass passage valve 42 which allows the said leakage channels 43, 44 communicate, particularly in response to the change in speed of the vehicle, is supplied in series via the pressure orifice 18 through a reducing orifice of adjustable flow rate 48. <IMAGE>
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