Question: Explain the process of Double Declutching.
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Subject: Automobile Engineering

Topic: Electrical System, Starting Systems & Alternator

Difficulty: Medium

ae(68) • 4.1k views
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modified 20 months ago by gravatar for dukare030296hemant dukare030296hemant90 written 3.3 years ago by gravatar for pardeepnitw1491 pardeepnitw14910
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  • In a constant mesh gear box, for smooth engagement of dog clutches, the speed of the main shaft gear and the dog clutch needs to be equal.
  • Therefore to shift from lower gear (i.e. 2nd) to higher gear (i.e. 3rd), the speed of the clutch shaft and the lay shaft must be decreased.
  • This is achieved by double declutching.
  • First, the clutch is disengaged and brought to neutral.
  • Then the clutch is engaged and the driver has to wait till the speed of the engine drops sufficiently for a smooth engagement. The driver can also apply brake gently to speed up the process.
  • After this, clutch is pressed again and the gear is moved to the higher gear (3rd gear).
  • As the speed of the clutch shaft is now same as the dog clutch, the dog clutch is engaged smoothly.
  • In this way, we can shift from 2nd gear to 3rd gear in a constant mesh gear box.
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modified 3.3 years ago by gravatar for Sayali Bagwe Sayali Bagwe2.2k written 3.3 years ago by gravatar for pardeepnitw1491 pardeepnitw14910
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written 21 months ago by gravatar for pardeepnitw1491 pardeepnitw14910
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In the constant mesh box, for the smooth engagement of the dog clutchs it is necessary that the speed of main shaft gear & the sliding ged must be equal. Therefor to obtain lower gear, the speed of the clutch shaft, lay shaft & main shaft must be increased. This is done by double declutching. The procedure for double declutching is as given below:
The clutch is disengaged & the gear is brought to neutral. Then the clutch is engaged & accelerator pedal pressed to increase the speed of the main shaft gears. After this the clutch is again disengaged & the gear moved to the required lower gear & the clutch is again engaged . As the clutch is disengaged twice in this process, it is called double declutching.
For changing to higher gear , however, reverse effect is desired i.e the driver has to wait with the gear in neutral till the main shaft speed is decreased sufficiently for a smooth engagement of gear.

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written 20 months ago by gravatar for pardeepnitw1491 pardeepnitw14910
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