Abstract: In an anti-skid brake control system for overriding manual operation of the brakes of a vehicle having plural wheels on each of plural tandem axles, the rotational speed characteristics of each of those wheels simultaneously are monitored on an axle by axle and individual basis. When the wheels on either axle encounter an incipient or actual skid or any wheel encounters a locked condition, the system dumps a percentage, from part to all, of the brake operating fluid pressure then being requested by the vehicle operator. Appreciating that each axle of a tandemly spaced pair of axles, including the load transfer characteristics on such axle, acts individually, the present invention provides a deceleration summing circuit to monitor the deceleration characteristics of the plural wheels on respective axles. Moreover, all of the plural wheels on the tandem axles are monitored by a single wheel lock detector circuit and a single low speed control circuit.