The Mechanical Diode (MD) one way clutch is a positive locking mechanism. During lock up, steel struts are interposed between locking features on the facing surfaces of two disks. The movement of struts into a lock position as a shaft motion reversal is attempted is of interest in assessing the reliability of the one-way clutch. This paper presents the results of a study which predicts strut movement into lock position by examining the forces on the strut at each stage of the locking action and the response of the strut mass and surrounding fluid to these forces. Locking action is found to occur in a few microseconds with typical component sizes and lubricants.