Car Pedal System

Hey, how are the gas, brake and clutch pedals linked to the engine, transmission, and brakes? I looked for diagrams on google but I couldn't find anything useful...

http://www.supercars.net/carpics/1934/2002_Ferrari_Enzo18.jpg

Basically, how are the pedals connected to the engine and brakes?

Gas pedals are typically linked with a mechanical linkage of bars (old school), a cable (typical) or electronically driven with a servo.

Brakes use a master cylinder to pressurize fluid, the fluid is transferred through a tube to the wheels where it uses the pressure to squeeze pads against the brake rotors or drums. So, the brake pedal has a pushrod attached to it which pushes a piston into a bore. Usually the brake master cylinder is on the firewall just in front of the pedal.

Clutches can be mechanical using a series of linkage rods (old school) or a cable (rare) or more typically a master cylinder just like the brakes. The pedal pushes presure through a tube to the clutch where the pressure is used to release the clutch plate.

on new cars, the gas pedal isnt even directly linked to the engine at all (curtis mentioned this too)
it is wired to a computer that then sends the information to the engine computer.
the advantages of this system are that there is great control of wheelspin.

for example.
my uncle recently bought a dodge magnum.
one day last winter, i was over at his house and he mentioned that the gas pedal was electronic.
to prove it, he took me and the magnum out and floored the throttle (in ~4 inches of snow) and at first there was wheelspin, but after a half a second, the computer took over and limited the throttle and prevented wheelspin.
we drove around the block at 35 mph with him flooring the throttle the whole way.

this would not be possible in an old car with a mechanical connection.

this would not be possible in an old car with a mechanical connection.

Yes it would.

oh true. But what about cars like the F40, and Mclaren F1? They had a mechanical connection right?

oh true. But what about cars like the F40, and Mclaren F1? They had a mechanical connection right?

To the best of my knowledge they had cables for the accelerator.

i meant that it would not be possible to only give the car part throttle when you had the gas pedal floored on a car with a throttle cable and no computers.
sorry for the confusion

i meant that it would not be possible to only give the car part throttle when you had the gas pedal floored on a car with a throttle cable and no computers.
sorry for the confusion

Its still possible.

But, I know what your talking about.

Your trying to say its very difficult to have very precise computer controlled throttle operation when there is a cable linkage between the pedal and the throttle body.

ok, i give up...

:banghead:

lol, do you have any pics or diagrams of the cables connecting the pedals to the engine?

http://www.stu-offroad.com/engine/throttle/3.jpg
theres one from a jeep.

http://www.v8engines.com/Gallery%202005/Weber500-linkages.jpg
theres one from some car with a V8 and a carb

http://www.wilcoxengines.demon.co.uk/images/vaxinj2.jpg
and heres a modified setup for a Vauxhall with FI

on the jeep pic, i think the unhooked part is for the transmission, but i'm not sure. it could also be some kind of throttle position sensor.

what he wants, is a pic of the entire cable set-up from pedal to engine/brakes.
come to think about it, what he really wants is for someone to show him how everything in a car works.

aha.

i neglected to add that once you leave the throttle cable in the pics, it is just a matter of attaching the other end to the gas pedal.

i'll draw a pic for the brakes.

http://i54.photobucket.com/albums/g103/GreyGoose006/brakingsystem.jpg
its not to scale, and the abs computer should be at each wheel, but thats the idea.

any more questions?

any more questions?


Thats a really bad diagram.

Instead:
There is only one ABS computer.
There are ABS sensors for each wheel.
The Master Cylinder is usually attached to the brake booster.
There is a separate high Pressure ABS booster/controller.

i know that the booster is attached, but i forgot to make space for it in the picture so i put it off to the side.
doesnt really affect how it works.

Hey, how are the gas, brake and clutch pedals linked to the engine, transmission, and brakes? I looked for diagrams on google but I couldn't find anything useful...

http://www.supercars.net/carpics/1934/2002_Ferrari_Enzo18.jpg

Basically, how are the pedals connected to the engine and brakes?

The picture made me nut. I love Ferrari. I know their just pedals, but they're some damn sexy pedals.

Thats a really bad diagram.



Do I need to drag you guys out by your ears? You two need to put on some boxing gloves and duke it out. :grinyes: The diagram works for some cars, but not others. For the level of understanding that NYKopter is seeking, it works fine.

:evillol:

(just kidding)

Hey-Soos-Krist-toe...
Hey, I got an idea---get off your butt, go out and actually look at a car!
Do it the Old School way!

lol thank you. Actually the diagram of how the pedals are connected was exactly what I was looking for. Just one last thing, so when you press the gas it just pulls the cable and opens up the throttle?

come to think about it, what he really wants is for someone to show him how everything in a car works.
hehe I wouldn't say no to that :D

if it is a mechanical connection... yes, exactly.

if there is a computer, then the pedal pushes in a sensor thingy that sends its position to a computer who reads the ABS computer for any reason why it shouldnt do what you say (a wheel is slipping). if it doesnt see any problems, then the computer sends a signal to another solenoid thingy that then opens the throttle.
all of this happens in about 1/32 of a second or so.

oh thanks. So the gas is mechanical, what about the clutch? Is that also connected through a cable?

cable or hydraulic link, usually.

there are also pneumatic clutch systems.
18 wheelers use a pneumatic splitter between gears.
high performance drag bikes (and maybe cars) use a pneumatic clutch too.

there are also pneumatic clutch systems.
18 wheelers use a pneumatic splitter between gears.

large commercial trucks also use pneumatic brakes, which is the "psssssst" sound you often hear from them.

hey while we're at it, how about a pneumatic gas pedal...

i think the Maclaren SLR uses a new kind of system for its brakes, but i cannot remember it at the moment.

there are pneumatic throttle controls.

they use an actuator, much like that on a turbo to open the throttle. you push the pedal and create a vacuum in the piping, the "bellow" in the actuator collapses and pulls the linkage back, opening the throttle.

right, but do you have an example.

heres an enigneering challenge...
a manifold vacuum operated throttle.

can you imagine the response
you open the throttle and the revs go up. vacuum goes down and it takes half an hour to get back to idle...

right, but do you have an example.

we have a cut-away engine at college with the system i described, i'll get a pic on wednesday if i can. it's a V6, maybe a Rover or Ford 3-litre. i'm not sure.

thats cool.
i've never heard of that before.

ok, i give up...

:banghead:

what he's elluding to is, you are talking about traction control. It existed before throttle-by-wire. Instead of limiting the throttle plate opening, the usual method was to simply limit the engine by cutting the injectors.

Modern TCS' still cut the injectors, but its only a subtle adjustment over the throttle plate manipulation.

i realize that tcs existed before computer throttles, but if you read my description of what happened, you will see that it would be very very hard to do by simply cutting injectors blindly.

i realize that tcs existed before computer throttles, but if you read my description of what happened, you will see that it would be very very hard to do by simply cutting injectors blindly.

not sure what you mean be "very very hard" they did it for years, and are still doing it. Whats so hard about it?

there's also the other traction control system, called the right foot.

lol thank you. Actually the diagram of how the pedals are connected was exactly what I was looking for. Just one last thing, so when you press the gas it just pulls the cable and opens up the throttle?


hehe I wouldn't say no to that :D

I guess somebody doesn't know how to read stickies. Try howstuffworks.com. They got pictures!!

touche, but howstuffworks doesn't have anything about how the gas pedal or clutch pedals are connected.

I guess somebody doesn't know how to read stickies. Try howstuffworks.com. They got pictures!!

he had a question, which wasn't answered in the detail desired so he asked in the proper forum in the proper manner.

what's the problem? i didn't see you make any effort to help.

this is a forum for EVERYONE, so let's be a little more tolerant, ok?

:1:

we all started somewhere,

i learn something new almost every day by reading the forums

he had a question, which wasn't answered in the detail desired so he asked in the proper forum in the proper manner.

what's the problem? i didn't see you make any effort to help.

this is a forum for EVERYONE, so let's be a little more tolerant, ok?

except this post:

Gas pedals are typically linked with a mechanical linkage of bars (old school), a cable (typical) or electronically driven with a servo.

Brakes use a master cylinder to pressurize fluid, the fluid is transferred through a tube to the wheels where it uses the pressure to squeeze pads against the brake rotors or drums. So, the brake pedal has a pushrod attached to it which pushes a piston into a bore. Usually the brake master cylinder is on the firewall just in front of the pedal.

Clutches can be mechanical using a series of linkage rods (old school) or a cable (rare) or more typically a master cylinder just like the brakes. The pedal pushes presure through a tube to the clutch where the pressure is used to release the clutch plate.

....DID answer his question.
The problem isn't that he didn't get a good answer, the problem is that he isn't mechanically minded enough to understand the answer.

he had a question, which wasn't answered in the detail desired so he asked in the proper forum in the proper manner.

what's the problem? i didn't see you make any effort to help.

this is a forum for EVERYONE, so let's be a little more tolerant, ok?

Sorry bout that. Didn't mean to come off as being a prick.:frown: Just thought he came and posted 1st before doing any effort to answer it on his own. Now I know better and I apologize to him for that rush to judgement.

except this post ....DID answer his question.
The problem isn't that he didn't get a good answer, the problem is that he isn't mechanically minded enough to understand the answer.

there's nothing wrong with a thread continuing on after an answer has been given, others add detail/opinion/examples/etc..

there's nothing wrong with continuing a discussion from the base question.



Sorry bout that. Didn't mean to come off as being a prick.:frown: Just thought he came and posted 1st before doing any effort to answer it on his own. Now I know better and I apologize to him for that rush to judgement.

No worries, we just need to be patient and tolerant. we all get like that, it's just a matter of stopping ourselves and seeing the whole picture.

everyone has to learn somewhere, and questions are always asked. no matter how simple or "stupid" they are, they're questions and we should never condescend to those with less knowledge.

Thank you Straight six. and importlover...its okay don't worry about it. But in all seriousness what if people stopped asking questions on AF...

this happens...
http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=1831

it's not the asking of questions, or even how you ask a question but rather the type of questions that you ask.

for example, here, the answer could've been found in any haynes manual.
in fact, i'm willing to bet that a great number of his questions could be answered by picking one up and looking through it.

haynes manuals are expensive...
borrowing wireless from neighbors is free...

you decide.

don't even need a library card to read manuals for free. Not that I'm arguing, but that was a pretty silly statement

my point exactly. The forums would be dead. And thank you Goose for bringing up that point. Its so much easier to go online and ask yourself...plus the chances of you understanding it are much better. You can't ask a book to explain it a different way or something