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Difficulty: Very hardUpshifting and Double Clutching

You are operating a heavy commercial vehicle equipped with an unsynchronized manual transmission and need to upshift to maintain momentum. Arrange the following steps in the exact chronological sequence required to execute a proper double-clutch upshift, paying attention to the mechanical purpose of each action.

  1. 1Simultaneously release the accelerator, depress the clutch pedal, and shift the transmission into neutral.
  2. 2Release the clutch pedal to reconnect the engine to the transmission input shaft while remaining in neutral.
  3. 3Allow the engine RPM and transmission input shaft to slow down to the synchronized speed required for the target gear.
  4. 4Depress the clutch pedal a second time to isolate the transmission and shift into the target gear.
  5. 5Smoothly release the clutch pedal while simultaneously applying the accelerator pedal to resume power application.

Answer

The correct sequence is: shift to neutral, release clutch, wait for RPM drop, depress clutch and shift to higher gear, release clutch and accelerate.
A double-clutch upshift requires two separate clutch depressions. The first depression allows shifting into neutral. The clutch is then released in neutral so the transmission input shaft speed can drop along with the engine RPM to match the higher gear's requirements. The second clutch depression isolates the transmission to allow the shift into the higher gear, followed by releasing the clutch and accelerating.

Step-by-Step Solution

1
Identify the initial action to break driveline torque.
Simultaneously release the accelerator, depress the clutch pedal, and shift the transmission into neutral.
You must disengage the engine from the drivetrain to pull the lever out of the current gear.
2
Identify the intermediate step in neutral.
Release the clutch pedal to reconnect the engine to the transmission input shaft while remaining in neutral.
In an unsynchronized transmission, the clutch must be engaged in neutral so the engine's speed dictates the input shaft's speed.
3
Determine the RPM management required for an upshift.
Allow the engine RPM and transmission input shaft to slow down to the synchronized speed required for the target gear.
Higher gears require lower engine RPMs for a given road speed, so the RPM must be allowed to fall before entering the gear.
4
Identify the action to complete the physical gear change.
Depress the clutch pedal a second time to isolate the transmission and shift into the target gear.
The transmission must be isolated from the engine once again to slide into the target gear smoothly.
5
Identify the final action to resume driving.
Smoothly release the clutch pedal while simultaneously applying the accelerator pedal to resume power application.
This completes the shift and reapplies power to the wheels.

Key Concept

The precise mechanical sequence of double-clutching upshifts in unsynchronized transmissions.
Estimated Time:1m 30s
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Topics

Upshifting and Double Clutching

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