CPT Transmission & Drivetrain Systems 2 — Questions and Answers
Question 1: What is the primary function of a torque converter in an automatic transmission?
- Multiply engine torque and transfer power to the transmission (Correct answer)
- Control shift timing via hydraulic pressure
- Regulate transmission fluid temperature
- Engage and disengage the drive axles
Correct answer: Multiply engine torque and transfer power to the transmission
A torque converter uses fluid coupling to multiply engine torque at low speeds and transfer power smoothly to the automatic transmission.
Question 2: In an automatic transmission, what component is responsible for holding or releasing planetary gear set members to achieve different gear ratios?
- Valve body
- Clutch packs and bands (Correct answer)
- Torque converter clutch
- Oil pump
Correct answer: Clutch packs and bands
Clutch packs and bands are hydraulically applied to hold or release specific planetary gear set members, producing different gear ratios.
Question 3: What is the purpose of the lock-up clutch inside a torque converter?
- Prevent torque converter from spinning too fast
- Mechanically connect the pump and turbine to eliminate slip at cruising speed (Correct answer)
- Allow the transmission to downshift under heavy load
- Control fluid flow between converter chambers
Correct answer: Mechanically connect the pump and turbine to eliminate slip at cruising speed
The lock-up clutch mechanically connects the converter pump to the turbine at cruising speeds, eliminating fluid slip and improving fuel efficiency.
Question 4: Which planetary gear set member, when held stationary, typically produces a reduction (lower) gear ratio?
- Sun gear
- Ring gear (Correct answer)
- Planet carrier
- Output shaft
Correct answer: Ring gear
Holding the ring gear stationary while driving the sun gear forces the planet carrier to turn at a reduced ratio, producing a gear reduction.
Question 5: Automatic Transmission Fluid (ATF) performs all of the following functions EXCEPT:
- Lubricating moving parts
- Generating hydraulic pressure to apply clutches
- Cooling the transmission
- Acting as a mechanical friction coupling (Correct answer)
Correct answer: Acting as a mechanical friction coupling
ATF lubricates, transmits hydraulic pressure, and cools the transmission, but mechanical friction coupling is the role of clutch discs and bands, not the fluid itself.
Question 6: In a continuously variable transmission (CVT), what hardware physically varies the gear ratio?
- Planetary gear sets and clutch packs
- Variable-diameter pulleys and a drive belt or chain (Correct answer)
- Sliding collar and synchronizer rings
- Hydraulic torque converter and stator
Correct answer: Variable-diameter pulleys and a drive belt or chain
A CVT uses two variable-diameter pulleys connected by a steel belt or chain; changing the pulley diameters continuously varies the effective gear ratio.
Question 7: What causes transmission 'shudder' during torque converter lock-up engagement?
- Excessive transmission fluid pressure
- Worn or contaminated lock-up clutch friction material (Correct answer)
- Low fluid level in the differential
- Faulty vehicle speed sensor signal
Correct answer: Worn or contaminated lock-up clutch friction material
Worn or ATF-contaminated lock-up clutch friction material causes inconsistent engagement, producing a shudder or vibration when the clutch applies.
CPT Transmission & Drivetrain Systems 2
What is the primary function of a torque converter in an automatic transmission?