🔍 Key Concepts

• How a Roots-type blower moves air (it is a positive-displacement air pump) • The purpose of small clearances between moving parts and the casing • What happens if clearances are too tight or too large in a blower

💭 Think About

• Ask yourself: are those clearances mainly about timing, oil, lubrication, or controlling how much air slips back instead of being delivered? • Think about which of the choices deals directly with the flow of air through the blower rather than with the gears, oil system, or bearings. • Consider what would happen to blower performance if the clearances became worn and much larger than designed—what specific problem would show up first?

✅ Before You Answer

• Identify that Roots blowers normally have no internal lubrication in the air stream between lobes and casing. • Remember that timing in a Roots blower is set by the external gears, not by the running clearances themselves. • Focus on which choice directly addresses air passing where it should NOT go because of excessive clearance.