Animation of a Hydraulic side pull  

    Hydraulic Action in an Injection Mold, usually means that a hydraulic cylinder has been incorporated into the design to enable a component (core pin, cavity steel, etc) to be moved at some phase during the injection molding cycle.

Typical components for Hydraulic Action are:
    The Hydraulic Cylinder
    Mounting Bracket, and relater connectors

    The timing control of the actuation of the Hydraulic cylinder is typically done via Electrical/Mechanical switches attached to the moldbase, or, more commonly directly attached to the controller of the press.