Dual-circuit pressure control valves

A dual-circuit pressure control valve comprising:

• two control pistons disposed in a housing in a parallel side-by-side relationship, each of said two pistons being associated with a different one of two brake circuits;
• an arrangement to apply a preloading force to each of said two pistons such that, upon failure of one of said two circuits, said preloading force on that one of said two pistons associated with the other of said two circuits is increased, said arrangement including a carrier bridge synchronizing a point of application of each of said two preloading forces by allowing a slight relative movement between said two pistons when both of said circuits are operative, said carrier bridge including
• a pivot axle extending parallel to a plane containing a longitudinal axis of each of said two pistons, and
• two lever arms each rigidly secured to opposite ends of said axle;
• each of said two preloading forces being generated by a common helical spring;
• and
• a spring retainer overlapping both of said points of application against which said spring abuts.

A dual-circuit pressure control valve comprising:

• two control pistons disposed in a housing in a parallel side-by-side relationship, each of said two pistons bein associated with a different one of two brake circuits;
• an arrangement to apply a preloading force to each of said two pistons such that, upon failure of one of said two circuits, said preloading force on that one of said two pistons associated with the other of said two circuits is increased, said arrangement including a carrier bridge synchronizing a point of application of each of said two preloading forces by allowing a slight relative movement between said two pistons when both of said circuits are operative, said carrier bridge including:
• a pivot axle extending parallel to a plane containing a longitudinal axis of each of said two pistons, and
• two lever arms each rigidly secured to opposite ends of said axle,
• said axle being a torsion rod;
• each of said two preloading forces being generated by a common helical spring;
• and
• a spring retainer overlapping both of said points of application against which said spring abuts.