Abstract: An adjustable variable load brake control valve responsive to the degree of air spring pressure as determined by the load condition of a vehicle for delivering fluid under pressure to the brake cylinder in accordance with the supply fluid pressure as established by a vehicle operator up to a maximum pressure value which is dependent upon the ratio of the effective pressure area upon which the air spring pressure acts on and upon and the effective pressure area upon which the supply fluid pressure acts on and which ratio may be manually changed by increasing or decreasing the effective pressure area subject to the supply fluid pressure.