Abstract: The present invention is an improved mechanical linear locking device, with a single locking coiled spring. When firmly coiled, the single locking coil spring is able to grip a smooth rod and prevent axial motion. When the single locking coil spring is uncoiled, slightly, it releases its grip on the smooth rod, allowing axial motion. The single spring linear adjusting lock device is used in an armrest with memory. The present invention uses a rod, a return spring, an annular bearing, a sleeve, a two-piece housing, a coil spring, a bushing, and a cylinder with protruding trunnions.