Hydraulic distributor for a servomechanism with reaction on the input component

Claim 1

A hydraulic distributor for a fluid operated servo-mechanism, more particularly for the servo-steering of a motor vehicle, comprising a primary component coupled to an input actuating component, and a secondary component, said primary and secondary components mutually couplable through a lost-motion coupling allowing a limited relative displacement between said primary and secondary components on each side of a central rest position, said primary and secondary components mutually defining at least one first pair of parallel fluid circuits between a source of pressure and a reservoir, each said circuit including at least first, second and third restriction means arranged in series in a direction of flow between said source of pressure and said reservoir and operable as a result of said relative displacement between said primary and secondary components so as to control a hydraulic assistance device having two opposing chambers each in fluid connection with a respective circuit of said first pair of parallel fluid circuits downstream of said first restriction means, wherein each said chamber of said assistance device is in fluid communication with said respective circuit between said second and third restriction means of said respective circuit, said first restriction means when brought into throttling operation adapted to introduce in said respective circuit a restriction of fluid flow which is substantially constant during said relative displacement, said third restriction means when brought into throttling operation adapted to introduce in said respective circuit a progressive restriction of fluid flow and which progressive restriction varies substantially linearly with said relative displacement.