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Difficulty: MediumUpshifting and Double Clutching

A driver must double clutch properly when shifting gears in a heavy commercial vehicle with an unsynchronized manual gearbox. Place the following operational stages in the correct sequential order from first to last to complete a standard upshift.

  1. 1Release the accelerator pedal, push in the clutch pedal, and move the gearshift lever into neutral.
  2. 2Release the clutch pedal completely while remaining in neutral.
  3. 3Allow engine speed (RPM) to drop to match the required input shaft speed for the higher gear.
  4. 4Push in the clutch pedal a second time and move the gearshift lever into the next higher gear.
  5. 5Release the clutch pedal smoothly and press the accelerator pedal to resume acceleration.

Answer

The correct order begins with releasing the throttle, pressing the clutch, and shifting to neutral; followed by releasing the clutch in neutral; allowing engine RPM to drop to the target speed; pressing the clutch and shifting into the higher gear; and finally releasing the clutch while applying throttle.
Executing a proper double-clutch upshift requires disengaging the lower gear into neutral, releasing the clutch pedal to link the input shaft to engine speed, letting engine and shaft RPM decrease to match the higher gear ratio, pushing the clutch in again to engage the higher gear, and smoothly releasing the clutch while applying throttle.

Step-by-Step Solution

1
Disengage the active gear and engine power simultaneously.
The transmission enters neutral with driveline load removed.
Releasing the throttle and depressing the clutch removes drive load so the gear selector slides freely out of gear.
2
Release the clutch pedal with the shift lever in neutral.
The transmission input shaft is coupled to the slowing engine flywheel.
Coupling the input shaft in neutral forces it to slow down along with the engine.
3
Wait for engine and input shaft RPM to fall to the target level.
Gears reach synchronized speeds matching the higher gear ratio at current road speed.
Higher gears turn slower relative to road speed, requiring lower RPM before engagement.
4
Depress the clutch pedal and guide the lever into the destination gear.
The higher gear engages cleanly without gear clash or grinding.
Disengaging clutch torque during engagement protects the gear teeth while meshing.
5
Smoothly release the clutch and reapply throttle.
Drive torque is smoothly restored to the drivetrain in the new gear.
Gradual clutch engagement prevents driveline shock and maintains steady vehicle momentum.

Key Concept

Standard sequential double-clutching procedure for upshifting in non-synchronized commercial vehicle transmissions.
Estimated Time:1m 0s
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Topics

Upshifting and Double Clutching

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