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Why do loose screws only get looser, not the other way round? (part 2)

Our readers provide yet more evidence that screws don’t always get looser

22 February 2023

Loosen bolt in daylight close up.; Shutterstock ID 1195047430; purchase_order: -; job: -; client: -; other: -

Shutterstock/Jiranart Aonnoum

Why do loose screws only get looser and not the other way round, even if there seems to be no resistance to the latter? (continued)

Richard Brent
Tinamba, Australia

Some cars and trucks have left-handed threads on their left-hand wheels. This is so that, when the brakes are applied suddenly and the wheels stop or slow their rotation, angular momentum will try to tighten rather than loosen the wheel nuts.

If you need to change a tyre on such a vehicle, you will have difficulty unless you remember to turn the wheel brace in the correct direction.

Stuart Jameson
Solihull,…

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