Another effective locking fitting is a combination of a split pin and lock nut. The split pin drops through a hole in the threaded shaft and rests in a ridge on the surface of the nut (see animation below). The nut cannot become loose because the split pin stops it rotating.

This type of locking systems is seen on high speed rotating axles / shafts where vibration may slowly loosen the lock nut. On some machines / vehicles, if lock nuts loosen, serious accidents can take place. One disadvantage of this type of locking system is that the nut has to be threaded to the right place on the threaded shaft so that the split pin can be positioned accurately. On the other hand, the lock nut is securely 'locked' in position.

QUESTIONS:

1. Draw a simplified diagram showing the locking system seen above.

2. Explain how this locking system works.

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