The RPM of "A" is 150 and hobbed with 84...

Question 1 of 270705eccefa3bacbc34ba4d47ccf

The RPM of "A" is 150 and hobbed with 84 teeth. If gears "B", "C", and "D" have 64, 24, and 36 teeth respectively, the RPM of "D" in the gear train illustration is __________. See illustration MO-0088.

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Question 1 of 27070

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🔍 Key Concepts

• Relationship between gear teeth and RPM (speed ratio N1/N2 = T2/T1 for meshed gears) • How a compound gear works when two gears (B and C) are on the same shaft and therefore have the same RPM • Overall gear train ratio from A through B/C to D

💭 Think About

• First, write the speed relationship between gear A and gear B using their tooth counts. Which gear is the driver? • Since gears B and C are fixed on the same shaft, what does that tell you about the RPM of C compared with B? • Use the RPM of C to find the RPM of D. Then simplify the overall ratio from A to D to check your math.

✅ Before You Answer

• Be sure you are using the correct formula: for two meshed gears, driver RPM × driver teeth = driven RPM × driven teeth • Confirm you have treated B and C as same RPM (compound gear) and only changed RPM again when going from C to D • After computing, see if you can simplify the complete ratio from A to D in one step using (teeth of driven ÷ teeth of driver) for each mesh, multiplied together, to verify your final choice