Abstract: A retaining ring locking device for preventing longitudinal relative movement of a shaft within a bore utilizes a flat or wire retaining ring. A groove is machined on the shaft as well as the bore and an access window is provided on either the shaft or the device containing the bore. The access window extends longitudinally from and beside the ring receiving groove formed by the alignment of the shaft and bore grooves to the exterior of the device and serves as the access point for threadable insertion of the retaining ring. The encapsulated design provides greater strength and eliminates the need for two separate retaining rings to prevent relative movement in two directions.