Examkin

Question

Difficulty: EasyDownshifting Procedures

When executing a standard double-clutch downshift in a commercial vehicle, what is the correct chronological sequence of driver actions?

  1. 1Depress the clutch pedal and move the gearshift lever into neutral.
  2. 2Release the clutch pedal while remaining in neutral.
  3. 3Press the accelerator to rev the engine to the RPM required for the lower gear.
  4. 4Depress the clutch pedal again and move the gearshift lever into the lower gear.
  5. 5Release the clutch pedal smoothly and apply throttle as needed.

Answer

Depress the clutch pedal and shift to neutral, release the clutch pedal in neutral, rev the engine to match lower gear RPM, depress the clutch pedal again and shift into the lower gear, and release the clutch pedal smoothly.
Proper double-clutch downshifting requires moving into neutral, releasing the clutch pedal to connect the engine to the transmission input shaft, revving the engine to match the required RPM for the lower gear, depressing the clutch pedal again to engage the lower gear, and smoothly releasing the clutch pedal.

Step-by-Step Solution

1
Depress the clutch pedal and move the shift lever to neutral.
Disengages the current driving gear and places the transmission in neutral.
Allows the transmission gears to disconnect from the engine before matching speeds.
2
Release the clutch pedal while remaining in neutral.
Re-engages the clutch to connect the engine with the transmission intermediate shaft.
The engine must be mechanically linked to the transmission shaft so revving the engine increases shaft speed.
3
Press the accelerator to increase engine RPM to match the lower gear.
Engine speed and transmission countershaft speed increase simultaneously.
Because lower gears turn faster for any given road speed, intermediate shaft speed must be raised to match.
4
Depress the clutch pedal a second time and move the shift lever into the lower gear.
Engages the lower gear smoothly without gear grinding.
With rotational speeds equalized by the RPM match, the gear collar slides easily into position.
5
Release the clutch pedal and apply throttle.
Re-engages the drive train in the lower gear.
Completes the downshifting process, providing immediate power control and engine braking capability.

Key Concept

Double-clutch downshifting procedure and RPM matching
Estimated Time:45s
Rate this question

Topics

Downshifting Procedures

More questions from this topic