🔍 Key Concepts

• Relationship between direction of rotation and thread direction on rotating machinery • Why manufacturers may use left-hand (reverse) threads on parts that spin at high speed • What happens to a locking ring or nut if it had the same thread direction as the normal running rotation

💭 Think About

• Think about which way the bowl normally turns when the centrifuge is operating, and what that would try to do to a threaded locking ring as it spins. • Ask yourself: to keep the locking ring from working loose in service, should its threads be arranged so operation tends to tighten it or loosen it? • Match that idea (tending to tighten vs loosen) with the choices that connect normal rotation direction and assembly rotation direction.

✅ Before You Answer

• Be clear on the normal operating direction of the centrifuge bowl in this question. • Decide which thread direction will cause the ring to self-tighten under normal rotation rather than back off. • Eliminate any options where the rotation used to tighten the ring would obviously make it work loose when the machine is running.