Workbook, Heavy Duty Truck Systems, 6E
Chapter Eighteen – Answer Key
1. Technician A says that the number of planetary pinions in a carrier depends on the torque
load that the gearset is expected to carry. Technician B says that the planetary ring gear is
capable of exerting the most leverage on the axis of a planetary gearset. Who is correct?
2. Which of the following is an advantage of a simple planetary gearset?
3. When a planetary carrier drives the sun gear and the ring gear is held stationary, which of
the following would result?
4. Technician A says that multiple-disc clutches act as braking devices in heavy-duty truck
automatic transmissions. Technician B says that multiple-disc clutches act as power
transfer devices in heavy-duty automatic transmissions. Who is correct?
5. If a planetary carrier is held, the sun gear is the input, and the ring gear is the output,
which of the following would result?
6. Technician A says that a major difference between an Allison four-speed and an Allison
five-speed transmission is that the five-speed has an additional planetary gearset.
Technician B says that a planetary gearset is required for each gear range in a heavy-duty
automatic transmission. Who is correct?
7. When a low planetary gearset is used, it is located _____________________.
8. In an Allison four-speed automatic transmission, governor pressure is directed to which
of the following?
9. Technician A says that modulator pressure should be lowest at idle and increase with
accelerator pedal travel. Technician B says that the trimmer regulator valve is controlled
by modulator pressure. Who is correct?
10. Which type of hydraulic retarder uses a two-stage design that applies retarding force
directly to the driveline?