Abstract: A locking wedge apparatus for fastening a printed circuit board within an elongated slot in a rack. The apparatus includes an elongated center wedge having sloped surfaces at its opposite ends and two end wedges abutting against the center wedge's opposite sloped surfaces. A screw interconnects the two end wedges, threadedly engaging a threaded bore in the remote end wedge. A friction nut is positioned on a portion of the screw's remote end that projects beyond the remote end wedge, and the apparatus is configured to include a pair of low-friction, abutting surfaces between the nut and the remote end wedge. This ensures that when the screw is fully loosened, the frictional torque applied to the nut by the end wedge is exceeded by the frictional torque applied to the nut by the screw. Further unthreading of the screw is thereby effectively inhibited.