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Difficulty: MediumUpshifting and Double Clutching

During a double-clutch upshift in an unsynchronized commercial vehicle transmission, tapping the throttle while the gear selector is in neutral is required to synchronize engine and transmission gear speeds.

Answer: Answer

Answer

False
The statement is false because applying throttle while the transmission is in neutral is the correct procedure for downshifting, not upshifting. During an upshift, the vehicle transitions into a gear that requires fewer engine revolutions per minute to maintain road speed. Consequently, the driver must leave the accelerator released during the neutral phase of the double clutch, allowing engine and input shaft speeds to fall to the exact RPM needed to mesh smoothly into the higher gear.

Step-by-Step Solution

1
Analyze the mechanical operating speed requirements between lower and higher transmission gears.
Higher gear ratios turn the drive wheels faster relative to engine revolutions, which means the engine must operate at a lower RPM at any given vehicle speed.
Understanding gear ratio relationships determines whether engine speed must rise or fall during a gear transition.
2
Examine the physical effect of applying throttle during the neutral phase of double clutching.
Pressing the accelerator pedal while the clutch is engaged in neutral revs the engine and input shaft up rather than letting them slow down.
Double clutching connects the engine to the transmission input shaft in neutral so their rotational speeds equalize.
3
Evaluate the accuracy of the statement for an upshifting maneuver.
Applying throttle in neutral is the defining step of downshifting, not upshifting. For an upshift, the driver must keep the throttle closed so rotational speed falls.
Attempting to upshift after raising engine RPM prevents gear teeth alignment and leads to severe gear clash.

Key Concept

Rotational speed synchronization during double-clutch upshifting
Estimated Time:1m 0s
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Topics

Upshifting and Double Clutching

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