Load responsive hydraulic pressure control mechanism of an automotive vehicle

Claim 1

A load responsive brake pressure control device for a vehicle equipped with hydraulic brakes and adapted to vary the braking forces acting on the vehicle wheel depending upon vehicle load, said device comprising: a cylinder secured to one of two vehicle masses, one of which is sprung and the other unsprung, a differential hydraulic piston movable within said cylinder, and defining two oppositely acting chambers fluid coupled respectively to the master cylinder and the braking circuit for at least one vehicle wheel, a normally open valve operatively coupled to said piston for movement to an open position in response to the application of hydraulic fluid to said chambers with said valve controlling intercommunication between said two chambers, and spring means operatively connected between said piston and said other vehicle mass for normally urging said valve to the open position, said spring means being connected to said piston by a lost motion connection and being preset such that under vehicle empty or lightly loaded conditions said piston may be shifted by application of said applied hydraulic pressure to said piston from said master cylinder and/or by mechanical force exerted by said vehicle masses on said spring means to move said piston into completely open, partially open and closed valve positions by application of said hydraulic pressure acting on said differential hydraulic piston, without further action of said spring means, with intercommunication between said chambers being cut off in said closed position.