[Phil G4SPZ]

Hi Jim. You have a PM.

The use of the term ‘catastrophic’ to describe a gear train failure in a clock mechanism is not over-dramatic because the extent of the catastrophe is usually limited to the clock itself. I’ve heard the word used in phrases like “catastrophic gearbox failure”, “catastrophic engine failure” and so on in aviation, shipping, railways etc., meaning an instance where extensive damage is caused to the mechanism concerned.

A fractured pivot in a clock can cause the geartrain to become unmeshed, allowing the spring to unwind at an uncontrolled rate, usually severely damaging other components in the process. There have been cases in tall tower clocks where a train fault allowed the weights to fall unrestrained to the ground, causing structural damage - I think this even happened to the Tower of Westminster clock once.