As you have probably figured out by now the "B" stands for Bidirectional.

Motors like this are designed to change directions under a certain load or if stopped. (light bar in scanner?)

Like Alain said, contact the manufacturer to find out how they did it in this motor but it is most likely like Luciano shows with the CW/CCW built in on an actuator. Now if you feel lucky take one apart and see if they can be bugged into.