Fluid-pressure operated servo-motor assemblies for vehicle braking systems

Claim 1

A servo-motor assembly for a vehicle braking system comprising a housing having a bore, an output member and a pedal-operated input member working in said bore, means through which an effort from said input member is transmitted to said output member, said means comprising a movable wall working in said bore, means for applying a fluid-operating pressure to said movable wall to augment said effort, valve means located in said housing for controlling said fluid-operating pressure applying means, an operating assembly located within said housing for operating said valve means, said operating assembly comprising abutment means for transmitting a force to said output member, rotary valve actuating means located between said input member and said abutment means, said rotary valve actuating means being angularly movable to operate said valve means and being movable axially with respect to said abutment means through a limited relative distance, said abutment means and said rotary valve actuating means being in the form of pressure plates in adjacent faces of which are provided complementary inclined ramps with a ball co-operating with each pair of ramps in said plates, said ramps and said balls comprising means arranged so that axial movement of said rotary valve actuating means relative to said abutment means forces said balls relatively down said ramps to cause said angular movement of said rotary valve actuating means.