Abstract: An electrically actuated relay valve or adaptive braking modulator for a vehicle fluid pressure braking system includes a housing having a fluid pressure inlet, a pair of vents communicating with the ambient atmosphere, and a brake application effecting mechanism. The inlet communicates with a chamber defined within the modulator, amd this chamber is in turn communicated to the brake application effecting mechanism. An electrically actuated valve controls communication from the inlet into the chamber, and is shiftable from a first condition permitting substantially uninhibited communication from the inlet to the chamber to a second condition communicating the chamber to one of the vents when an incipient skidding condition is detected. A pressure differential responsive valve element controls communication between the chamber, the brake application effecting mechanism, and the other vent.

Abstract: A mechanically actuated disc brake includes a wedge actuator which urges an extensible, force transmitting member toward the disc brake rotor in order to effect a brake application. A ratchet mechanism is carried by the extensible member and by a piston slidably mounted within the brake housing. The ratchet mechanism is responsive to movement of the extensible member toward the rotor in access of a predetermined amount in order to effect elongation of the extensible member to limit retraction in the piston, so that retraction of the friction elements is similarly limited. The extensible member also cooperates with a manual adjustment mechanism which may be used to manually adjust the brakes or to "back-off" the extensible member to permit movement of the friction elements away from the disc in excess of the predetermined amount when the friction elements must be removed when the brake is serviced.