Abstract: A plow having a frame attached to a vehicle and a pair of hinged plow blades pivotally mounted on the frame, a first single acting hydraulic actuator extending between the frame and a first one of the plow blades, a second single acting hydraulic actuator extending between the frame and a second of the plow blades, a first tension spring extending between the first one of the plow blades and the frame, a second extension spring extending between the second plow blade and the frame. Each of the single acting cylinders includes a piston on a cylinder, characterized by each single acting hydraulic actuator includes hydraulic valve elements for locking the blades in position to prevent loss of material mass behind the blades when the plow is being used to back blade. In one embodiment, the single acting hydraulic actuators include a counterbalance valve located in the position of the cylinder to provide hydraulic locking and overload protection.