US Patent 10882233 Valve stem actuation

An apparatus and method for actuating a valve stem between an open position and a closed position and for taking one or more valve gated nozzle out of service is disclosed. The hot runner includes a valve gated nozzle having a valve stem, the valve stem coupled to a piston that is held against an actuation plate via pressurized air. When a valve stem becomes stuck in a gate of the hot runner, the actuation plate can continue to move while the piston remains stationary. The valve stem may also be protected from an over force situation such as if the valve stem encounters an obstruction as the actuation plate is moving toward the closed position.