Abstract: A coupling device suitable for connecting an externally splined power take-off stub shaft to a corresponding internally splined yoke with a universal joint. The coupling mechanism includes an automatic release to the locked position and locks axially onto the shaft by way of locking balls. A collar with flexible tabs is manually rotatable to the unlocked position and is triggered to rotate to the locked position by the locking balls. When the externally splined shaft is inserted into the internally splined yoke, the end of the shaft trips the balls causing the flexible tabs in the collar to move radially outward, releasing the collar which rotates to the locked position. The collar rotates camming the balls on a formed metal ring inside the plastic collar to the locked position. Rotation is produced by a fully enclosed torsional spring connected to the collar and the yoke and prevents over-rotation in either direction.