US 4,283,992 AGranted

Servo boosters

AssigneeGirling Limited

InventorAlexander J. Wilson

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Abstract

A vehicle brake system in which an output member is axially displaceable by the application of differential fluid pressure, under the control of a valve operable by an input member, across a movable internal wall which divides a housing of the booster into a pair of fluid chambers. Displacement of the movable wall is communicated to the output member via a lever mechanism providing a mechanical advantage between said movable wall and the output member. The lever mechanism comprises first and second levers. The second lever is pivotable relative to the input and output members at respective pivot points. The first lever is pivoted to the second lever, with the movable wall acting on one end of said first lever and the other end thereof co-operating with the housing such that, upon a predetermined displacement of the movable wall, the first lever is pivoted and its displacement is transmitted with mechanical advantage to the output member via the second lever, the second lever simultaneously transmitting a reaction force to the input member.

Claims10

Dependent claims

A servo booster for a vehicle brake system of the type having a housing, a movable wall located within said housing and dividing said housing into two chambers, an input member operably coupled to an actuating pedal and adapted to control the differential pressure across the movable wall, an output member operably associated with said movable wall and axially displaceable by said movable wall through a lever mechanism, said lever mechanism comprising:

(a) at least one first lever;
(b) one end of said first lever being in engagement with a part fixed relative to said housing;
(c) the other end of said first lever being in abutting engagement with said movable wall;
(d) said first lever providing a mechanical advantage between the displacement of the movable wall and the resulting displacement of the output member;
(e) at least one second lever;
(f) means pivotally connecting said second lever to said input member;
(g) means defining a pivotal engagement between said second lever and said output member;
and
(h) pivotal support means on said second lever for said first lever;
said pivotal connection, engagement and support means of said second lever with said input and output members and with said first lever, respectively, being arranged that said second lever firstly transmits displacement of the first lever, in response to movement of said movable wall, to the output member and secondly transmits a reaction force to the input member.

7 more elements

Dependencies are inferred from the claim text.