Dynamically-monitored double valve with retained memory of valve states

摘要

A double valve for controlling a machine tool has a memory such that when the valve is in its normal deactuated state and the inlet air supply is cycled (e.g., turned from on to off or from off to on), then the valve remains in the deactuated (i.e., ready to run) state. When the valve is in a faulted state (e.g., intermediate position) and the inlet air supply is cycled, then the valve remains in the faulted state. The memory is achieved by a balanced condition of the movable valve elements when in the normal deactuated position and an unbalanced or latched condition when in the intermediate or faulted position.