Question

Difficulty: MediumUpshifting and Double Clutching

After departing a logistics terminal, you reach the target engine RPM in third gear and prepare to upshift into fourth gear using an unsynchronized manual transmission. In what exact sequence must you perform the steps of a standard double-clutch upshift?

  1. 1Release the accelerator pedal and depress the clutch pedal simultaneously.
  2. 2Move the gear shift lever out of the current gear into neutral.
  3. 3Release the clutch pedal completely to allow engine and input shaft RPM to fall to the required speed.
  4. 4Depress the clutch pedal again and move the gear shift lever into the next higher gear.
  5. 5Release the clutch pedal smoothly while reapplying pressure to the accelerator pedal.

Answer

The correct chronological sequence for a double-clutch upshift is: (1) Release the accelerator pedal and depress the clutch pedal simultaneously, (2) Move the gear shift lever out of the current gear into neutral, (3) Release the clutch pedal completely to allow engine and input shaft RPM to fall to the required speed, (4) Depress the clutch pedal again and move the gear shift lever into the next higher gear, and (5) Release the clutch pedal smoothly while reapplying pressure to the accelerator pedal.
Executing a proper upshift in a commercial vehicle equipped with an unsynchronized manual transmission requires double clutching in a precise five-step sequence. First, the driver cuts throttle and depresses the clutch to pull out of gear. Second, the lever is moved into neutral. Third, the clutch is released while in neutral so the transmission input shaft can slow down along with the decelerating engine to reach the lower RPM required by the higher gear. Fourth, the clutch is depressed again to allow the lever to engage the higher gear. Fifth, the clutch is released as throttle is applied to resume driving power.

Step-by-Step Solution

1
Release the throttle and press the clutch pedal down at the same moment.
Engine power is decoupled from the transmission drive gears.
Relieves drivetrain torque tension so the transmission can slip out of third gear without grinding.
2
Guide the shift lever from third gear directly into neutral.
The transmission enters neutral position.
Prepares the gearbox for intermediate shaft speed matching.
3
Let the clutch pedal all the way up while the transmission remains in neutral.
The input shaft is coupled to the engine and its rotational speed drops as engine RPM falls.
Essential for upshifting because the higher gear requires a lower input shaft speed to match vehicle road speed.
4
Press the clutch pedal down a second time and slide the shift lever into fourth gear.
Fourth gear engages cleanly without gear clash.
Disengages the clutch once the speeds have equalized, permitting clean engagement of the higher gear collar.
5
Smoothly release the clutch pedal while pressing the accelerator pedal.
The vehicle continues accelerating in fourth gear.
Completes the shifting cycle and restores engine driving power to the wheels.

Key Concept

Standard 5-step double-clutch upshifting procedure for unsynchronized heavy vehicle manual transmissions
Estimated Time:1m 0s
Rate this question