🔍 Key Concepts

• Examine the shape of the gear teeth shown on the timing gears in figure "A" (are they straight/spur or helically cut?). • Understand the basic purpose of timing gears in a Roots-type blower—what has to stay in precise phase so the lobes do not touch? • Consider how the blower as a whole is driven by the engine versus how the two rotors are synchronized with each other.

💭 Think About

• From the illustration, decide whether the gears appear to have angled (helical) teeth or teeth that are parallel to the shaft (straight cut). How does that eliminate half of the answer choices? • Ask yourself: Do these timing gears have to match the engine crankshaft position, or do they mainly keep the two blower rotors correctly phased so they don’t collide? • Which option describes both the correct tooth style you see and the function that keeps rotor lobes at a precise clearance from each other?

✅ Before You Answer

• Verify from the picture whether the gear teeth are straight or angled; this immediately rules out two choices. • Confirm that in a Roots blower the timing gears keep the rotors from touching while maintaining a very close clearance. • Make sure the statement you pick does not confuse the gearing that drives the blower from the engine with the timing gears between the rotors themselves.