Load-dependent brake force distributor

Claim 1

A load-dependent brake force distributor connected between a master cylinder and wheel brake cylinders comprising: a cylinder; a stepped piston disposed in a longitudinal slidable sealed relation in said cylinder; an input prssure medium chamber formed between one end of said cylinder and one side of said stepped piston; an output pressure medium chamber formed between the other end of said cylinder and the other side of said stepped piston; a first valve disposed concentrically of said stepped piston to connect said input chamber to said output chamber in its open position; a first arrangement connected to said stepped piston responsive to a load-dependent control force to open and close said first valve; and a second arrangement associated with and actuated by said piston to provide a direct connection between said input chamber and said output chamber when said control force fails; said cylinder having a first diameter and including a cylindrical projection extending therefrom having a second diameter less than said first diameter; said stepped piston including a first portion spaced from said cylindrical projection having a third diameter less than said first diameter, a second portion adjacent said cylindrical projection having a fourth diameter equal to said first diameter, and a third portion having a fifth diameter equal to said second diameter slidably sealed to the inner surface of said cylindrical projection; said first arrangement including a traction spring exerting a force dependent upon said load, a bar connected at one end to said cylindrical projection and at the other end to said traction spring, and a push rod connected between said bar and said third portion of said stepped piston; said cylinder including a transverse closing wall spaced from the adjacent end of said first portion of said stepped piston; said first and second portions of said stepped piston including a cavity disposed concentrically of the longitudinal axis of said stepped piston, an aperture at each end of said cavity, one of said apertures communicating with said input chamber and the other of said apertures communicating with said output chamber, said first valve being disposed within said cavity, and a valve spring disposed about said valve within said cavity to assist in the control of said first valve; said first valve including a pin projecting from one end thereof through said other of said apertures, said pin abutting said closing wall and opening said first valve againsT the force of said valve spring when a predetermined amount of said control force is applied to said third portion of said stepped piston; said second arrangement including a normally closed second valve which is open when said control force fails by the movement of said stepped piston away from said closing wall to cause said stepped piston to engage and open said second valve; said second portion of said stepped piston including a bevelled surface disposed in said input chamber; and said second valve is disposed in a perpendicular relation to the longitudinal axis of said stepped piston and extending through a wall of said cylinder in said input chamber; said second valve including a tappet extending therefrom to engage said bevelled surface to open said second valve upon failure of said control force.