Wheel slip protection system

An anti-locking brake module comprises a housing having a first port coupled to a brake pipe (10), a second output port coupled to a brake cylinder (24), and a third port coupled to atmosphere. A blocking valve (72) is in fluid communication with the first port and a vent valve (74) is in fluid communication with the blocking valve (72), the second port and the third port. At least one sensor (64a-d) is coupled to an axle (66a-d) on the railcar. A microprocessor (48) coupled to the blocking valve (72), the vent valve (74) and the at least one sensor (64a-d) is configured to calculate one of a wheel speed of the railcar axle (66a-d) and a deceleration rate of the railcar axle (66a-d) based on signals received from the at least one sensor (64a-d), and compare the calculated one of the wheel speed of the railcar axle (66a-d) and the deceleration rate of the railcar axle (66a-d) with a reference value. In response to the comparison, the blocking valve (72) and the vent valve (74) are activated to vent brake cylinder air pressure out of the third port. A power supply is operatively coupled to the microprocessor (48).