PT ALVA PRIMA EMAIL  : ALVAPRIMA@CBN.NET.ID FENNER DRIVES BLOC KEYLESS LOCKING ASSEMBLY The B-LOC brand is synonymous with world class quality, engineering excellence and unrivaled customer support. Fenner Drives B-LOC Keyless Bushings provide a high capacity, zero-backlash shaft-to-hub connection by using the simple wedge principle. An axial force is applied by series of annular screws to engage circular steel rings and mating tapers. The resulting wedge action creates a radial force on the tapered rings, one of which contracts to squeeze the shaft while the other expands and presses into the component bore.