A manifold actuator assembly is provided with a manifold comprising a block, and a hydraulic actuator connected to a solenoid valve within the block. The solenoid valve controls hydraulic, linear movement of a rod of the hydraulic actuator. The manifold actuator assembly may be used in a metering system to open and close movable gates disposed downstream from a meter roller before product enters a distribution system. The manifold actuator assembly may also be used as a locking apparatus to lock and unlock members in a wide variety of applications.