At the moment the engine line brings the crankshaft into the assembly jig, the ball‑centering attachment is placed on the shaft to define its exact axial position before the main bearings are pressed in. The ball sits in a precision‑machined socket, locking the shaft’s centreline while the surrounding tooling clamps the engine block. This simple action removes any angular play, allowing the automated bearing installer to apply uniform pressure and guaranteeing that the crankshaft will rotate true once the block is closed. Because the attachment can be quickly mounted and released, the same station can handle different engine families without re‑tooling, keeping cycle time low and repeatability high. The same principle is used downstream on the transmission housing, where the ball centering device aligns the input shaft while gear clusters are assembled, ensuring proper mesh and reducing wear on the first‑run units. In both cases the part acts as a non‑intrusive guide that makes precise alignment possible in high‑throughput vehicle production lines.