Why does a car engine keeps running idle even when the car is not in neutral gear no pedals are pressed ?

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I’ve seen several animations and gone through explanations that a transmission isolates engine shaft from the drive shaft for several purposes but how does a car engine keeps running even when it is not in neutral gear(any gear like R, 1, 2, 3…6) and no pedal has been pressed, so clutch is not pressed too so this means the engine shaft is connected to the transmission and if it is in any gear other than R the drive shaft is coonected to the transmission, right ?

If yes, then why doesen’t the car moves and how does the engine still keeps running idle ?

In: 6

4 Answers

Anonymous 0 Comments

When a car is idle, the engine is disconnected from (or only weakly connected to) the driveshaft.

In a manual car, where there’s a clutch, you cannot be stopped in a gear and have the clutch closed. If you do this, the engine stalls and comes to a halt because it is forced to move at 0 speed.

In an automatic, instead of a clutch there is a torque converter, which uses fluid to loosely couple the shafts. It’s like a clutch that’s always somewhere between open and closed. It always applies some force to the car, but at low engine RPMs this force is pretty small, and likewise the force slowing down the engine is pretty small.

Anonymous 0 Comments

If you have the neutral gear you have an automatic gearbox and then there is no clutch. What you instead have is a torque converter that hydraulically transfers the motion. It is not a fixed connection so the engine can round and the wheel can be still while you are in a gear.

If you have a clutch you have a manual gearbox and it has not had neutral gear. If you are not in a great there you have moved the cogwheels so there is no engagement and because of that, there is no connection between the input and output axis.

The is a connection between the input and output of the gearbox if you are in a gear, that includes if you are in R. But the gearbox can be out of any gear and then there is no connection.

So the answer to your question is that with the church release the engine is connected to the input of the gearbox. The output of the gearbox is connected to the wheel. But if you are not in one of the gears there is no connection between the input and output of the gearbox.

The clutch is there so when you put the gearbox into a gear one of the sides is not connected to anything that forces it to rotate. That way you can put it fully into gear and slowly reapply the engine power. If you would do that with the engine connected you will have a lot of forces on the initial part of the gear in contact and will damage them.

So the gearbox can remove the direct connection between wheels and engines. But it can be used to reengage the connection without damaging parts unless the car is stationary with the engine off.

Anonymous 0 Comments

Try getting up to 5th gear in a manual car and then decrease speed without changing down gears and see what happens

Anonymous 0 Comments

In a manual transmission car, if you put in let’s say gear 1 and release the clutch very slowly, the car will start moving and continue to move even without pressing the accelerator.

At this point, if you only press the break pedal, the car will stop and stall.

For a manual transmission car to be standing still while in a gear, clutch NEEDS to be pressed down