What is double clutching?

Putting it into neutral every time you change gear. So it's from first into neutral, foot off clutch, foot on clutch into second, back to neutral, off clutch, on clutch into third etc etc. It's just for older cars and serves no purpose nowadays.

When you're driving along in a car and you go to change gear, you move it from one gear and put it into neutral, you then lift the clutch up and then put it down again and place into the next gear.

Double de - clutching is something we dont have to do any more, generally, unless driving a very old (probably pre 1975) car or an HGV. It's where you have to keep the engine running at just the right speed whilst the clutch is depressed during gearchanges (tricky to do) and was solved by the introduction of synchromesh. Also requires neutral to be selected between gears.

Double declutching is the act of revving the engine slightly in neutral after releasing the pedal usually during gearing down. This allows the cogs within the gearbox to spin at the same speed or sub-speed.Thus allowing the teeth to mesh and the gear to be engaged. This method was always used in heavy vehicles and in old cars with full "crash" gearboxes. It is still used in some modern trucks despite full synchromesh gears. Please disregard most other answers as they are totally or partially incorrect.

pushing down on th e clutch to remove frome one gear and the pressing it in again to go to next gear truckdrivers do this saves on repairs

Then shifting gears, pressing in the clutch all the way, letting it out a bit, pressing it in all the way again, shifting gears, then letting the clutch out. This was required a long time ago before synchronized gears in the transmission. It was needed to align the gears to allow them to engage. All new cars and trucks have synchronized gears in the transmission, making double clutching unnecessary.

i had an old land rover that used to require you to depress the clutch, move the gear into neutral, release the clutch whilst still in neutral, depress the clutch again, then engage the next gear... i think that is what you're referring to.

EL1 is right it was used before gearboxes got syncromesh, which means all the cogs etc have to be spinning at the right speed for the next gear to be selected, so you had to put it in neutral and rev the engine a bit before selecting the next one, or the gears would crunch madly, probably did anyway! it was tricky but you got used to it, however most of the cars back then only had three forward gears, and maybe a top speed of about 50 mph, you find it on vintage cars and pre 50's models, after that syncromesh was the standard.

wHEN YOU ARE ACCERLATING AND PUSHING THE CLUTCH AT THE SAME TIME