Dual function pusher-puller plow blade system

A plow blade system adapted for mounting to a vehicle, the blade system having a blade orientable transversally to a longitudinal orientation of movement of the vehicle and having two opposite ends, and two side wall assemblies; each side wall assembly having a primary sidewall portion mounted to a corresponding end of the blade, the primary sidewall portion extending longitudinally from the corresponding end in a first longitudinal working direction, a sidewall extension slidably mounted to the primary sidewall portion, and a sidewall actuator mounted between the primary sidewall portion and the sidewall extension and operable to selectively slidingly extend the sidewall extension in a second longitudinal working direction opposite to the first longitudinal working direction and retract the sidewall extension within the primary sidewall portion.