how engine work..

[AdBd]

Someone enlighten me. Which part of the engine that allows us to stop the car (ex. red light) when the gear is still in Drive and yet the engine doesn't lock up? :weed:

Second Edition: "Someone enlighten me. Which part of the engine that allows the engine to run even when we stop the car with the gear is still in Drive? :weed: "

[JohnnyPh]

- No parts of the engine allows you to stop the car (ex. red light). Engine can slow the car down. The brake that stops the car.
- When the gear is in Drive and yet the engine doesn't lock up, this is achieved by what's called the Clutch. The clutch is part of the transmission. There are two types of transmission: automatic and manual.
- Automatic transmission: the clutch is engaged when the engine's revolution is high enough (i.e. when you press on the gas pedal). Let me try to explain it in a simple law of physics. Let say, when you spin something fast, because of the centripital force, things tend to move outward radially. So based on this law of physics, when the engine spins the clutch fast enough, the internal part of the clutch will move outward and engage with the outer part which would transfer the force to the gears and move the car. So when you stop at the light, the engine spins slower, and thus the clutch disengages and so the engine is not transferring any force to the wheel. So the brake can easily stop the car.
- Manual transmission: besides the gas and the brake pedals, there is this called the clutch pedal. If you press it down, you disengage the clutch. If you release the pedal , the clutch will engage and thus transfers the engine's force to the wheels through gears.

If you are in engineering or in some practical fields, you will understand those things naturally. If you want to know about any physical, electrical or mechanical things in daily life, you can easily read and understand those things in books. Or you can just figure it out easily. After a certain amount of time and experience, you will find that things around you in life are just based on simple laws of physics.

[AdBd]

Thanks for the answer. Actually, my question is about the clutch. I am sure that i know it is the brake that stop the car lol. My bad anyway, the question wasn't even clear. I am not in engineering or anything, just a sudden curiousity.

[AdBd]

So what about when you hit the brake and the same time as you hit the gas pedal? The engine RPM can easily hit 3000RPM or which by what you said should be enough to engage the clutch yet the car can't move, but the engine still not lock up.

[My Love 78]

I think JohnnyPh must made a mistake, Automatic transmission used a thing call a torque converter, that will not kill the engine when in drive and when the car is a idling at a stoplight.

In a Manual transmission, there is no way of NOT KILLING the engine while the car is idling at a stoplight with the cluch engage, you need to disenage the clutch..

Your question about when the car is in "DRIVE" is silly, AdBd, ONLY AT have "DRIVE" MT don't have "DRIVE" they have "GEAR" ie 1st, 2nd, 3rd, and so on.....

[JohnnyPh]

In the automatic transmission, the torque converter was used to be called automatic clutch. It is the round thing inside the tranny and serves as a clutch but in an automatic way. Manufacturers and engineers just changed the name to torque converter. Mechanics and people still understand and think it as the clutch. I used the word clutch to simplify my explanation to him. If I introduced the torque converter, that might cause some confusion.

In auto tranny car, if you press on the gas pedal to 3000 rpm while the tranny is in drive and you still press on the brake, you are killing the torque converter (or automatic clutch) inside your tranny. The young street racers who drive auto tranny car usually have money to replace their auto tranny very often. Some of the old guys think they can drive with two legs to start quicker at the light, sometime if they don't do it right, they also kill their trannies. If you want quick pick up, drive a manual car. Nowsaday, on some newer cars, the auto tranny is as fast or sometime faster than manual tranny. There is the new shift-tronic tranny which is the auto tranny but you can shift gear manually without the clutch pedal.

There are some exceptions for drag racers:
- their rwd car is modified to have the brake work at the front wheel only, so at the start, they press on the brake and have the rear wheels spin to smoke.
- similarly, if it is a fwd car, the brake is modified to work at the rear wheel so they can smoke the front tires

If you have a fwd car, you can do the same thing as those drag racers by pulling your hand brake and go wild on the gas. But remember, you are shorten your tranny's life as you doing this.

There is another case where some young homeboy racers who drive auto tranny car and think they can race by putting the gear in Neutral next to Drive, go wild on gas and bam just pull the shift into Drive. They are killing the transmission gears in no time.

In short, if you race a bit and want to have some fun, then just get a manual tranny car. Also a rwd car because that helps as you see on serious sport cars, they are all rwd.

[AdBd]

"Your question about when the car is in "DRIVE" is silly, AdBd, ONLY AT have "DRIVE" MT don't have "DRIVE" they have "GEAR" ie 1st, 2nd, 3rd, and so on....."

By choosing Drive i just want to make an example that say the gear is till engaged.

[AdBd]

Anyway, i found this, quite helpful. 1 picture = thousand blah blah.

http://auto.howstuffworks.com/clutch1.htm