A driver operating a commercial motor vehicle with an unsynchronized manual transmission is performing a double-clutch upshift. After moving the shift lever to neutral and releasing the clutch pedal, a slight delay causes the engine speed to drop significantly below the target RPM required for the next higher gear at the vehicle's current road speed. To successfully complete the shift without gear clashing, which of the following actions must the driver take?
- APress the clutch pedal fully to the floor to activate the clutch brake, which will match the input shaft speed to the gear and allow engagement.
- BKeep the transmission in neutral and coast without accelerating until the vehicle's road speed decreases to match the dropped engine RPM, then engage the gear.
- Apply the accelerator to raise the engine RPM back to the required synchronization point, then depress the clutch pedal and shift into the higher gear.Cevap
- DDepress the clutch pedal and apply steady pressure to the shift lever until the transmission synchronizers force the gear into place.
Cevap
The correct action is to apply the accelerator to raise the engine RPM back to the required synchronization point, then depress the clutch pedal and shift into the higher gear.
In an unsynchronized transmission, the rotational speed of the engine and the road speed of the vehicle must be perfectly matched by the driver to shift gears. Normally, during an upshift, the engine RPM is simply allowed to drop to meet the lower RPM requirement of the higher gear. However, if the RPM drops too low due to a delay while the transmission is in neutral, the driver must briefly apply the accelerator with the clutch released. This spins the transmission input shaft back up to the required speed. Once matched, the driver can safely press the clutch and complete the shift.
Adım Adım Çözüm
Anahtar Kavram
RPM Synchronization and Neutral Recovery in Unsynchronized Transmissions
Tahmini Süre:1m 30s