Patent ID: 6296135
Filing Date: 2001-10-02
Classification: B61D

Abstract:
A vent-on-demand hatch cover for a hatch opening of a compartment in a railcar, wherein the hatch opening includes a coaming, said cover having an upper side and an underside and comprising:a resilient peripheral seal provided at the underside of the hatch cover engaging the coaming to define a substantially airtight seal between the cover and the opening,a peripheral opening adjacent the coaming for communicating with the outside atmosphere,a central opening at the underside of the cover for communicating with the compartment,an airflow passageway for interconnecting said peripheral and central openings,and means for normally closing the central opening to prevent the flow of air from the compartment and the entry of contaminants into the compartment and operable for allowing air to flow into the compartment when the air pressure within the compartment is less than atmosphere,said central opening including a valve seat, a valve member and means resiliently biasing said valve member into closed position on said valve seat, the upper side of the valve member being exposed to the outside atmosphere and the underside of the valve member being exposed to the compartment, whereby said valve member moves downwardly into the compartment to open said central opening.