balance in brake

[kami]

hi guy
iam study on barake sys of formula and i want to design a brake system but i dont know which way is beter for it

[kami]

hi guy
iam study on barake sys of formula and i want to design a brake system but i dont know which way is beter for it

[PatClarke]

Kami, this site is a cooperative forum between people interested in FSAE. It is not a simple source of your car design!
Requests like this will either be ignored or will bring a lot of criticism on you! This place is NOT a shortcut to a FSAE car.

Brakes have been discussed many times on this forum.

So, what you do is this...
1. Click on the 'Find' button at the head of this thread.
2. Type 'Brakes' into the dialog box.
3. Click the 'Go' button.
4. Read and understand all the brake threads. Make notes, print off threads and make a dossier.
4. Go to www.google.com (http://www.google.com)
5. Type 'brake design' into the dialog box
6. Click the search button.
7. Spend days researching the websites you find.
8. Print out anything you find of interest and add to your dossier.
9. Source the Carroll Smith "..to Win" series of books (Google will help here too)
11. Read and understand what the great man had to say, and add more notes to your dossier.
12. Go visit your local brake repair shop, or even motorbike shop and talk with the mechanics about brakes.
13. Look at brake systems on any vehicle you get the chance (Google Image search will find millions of pictures)
14. Study Pascals Law
15. Research friction materials and rotor materials
16. Determine how much energy your braking system must dissipate.
17. Design your brake system!
18. Design a system to react the brake forces into the chassis.

Finally, be aware that brakes dont stop cars! Tyres stop cars! The brakes retard the rotation of the wheels and tyres. So you better learn something about tyres too!

Now, if that sounds too hard, well tough luck! Thats the way we all did it and there is no shortcut. You MUST understand your engineering decisions when you are under inquisition by the judges, otherwise the FSAE competition is not doing for you what it was intended to do...To generate real engineers.

Sorry if this seems harsh, but believe me, some other forum members would be much harsher.

Good luck in your search
Pat Clarke

[ben]

Amen to that! Can Pat's response be the second sticky?

Also, it would be nicer if everyone could fill out at least location and school/company name in their profile. It's considered a requirement in places like the ADAMS user group, and helps everyone know who they're talking to.

Ben

[kami]

hi thank you for your guide
at first that i begin my study i done many of your items that you suggested
but now i arrive a blibd and need your help
when i calculate the line presure and rotor diameter and .... i dont consider desing of adjustable beam or regulator for adjust brake
and i consider the weight distribution in my esign
by best regard, kami

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Suddenlee:
Kami, this site is a cooperative forum between people interested in FSAE. It is not a simple source of your car design!
Requests like this will either be ignored or will bring a lot of criticism on you! This place is NOT a shortcut to a FSAE car.

Brakes have been discussed many times on this forum.

So, what you do is this...
1. Click on the 'Find' button at the head of this thread.
2. Type 'Brakes' into the dialog box.
3. Click the 'Go' button.
4. Read and understand all the brake threads. Make notes, print off threads and make a dossier.
4. Go to www.google.com (http://www.google.com)
5. Type 'brake design' into the dialog box
6. Click the search button.
7. Spend days researching the websites you find.
8. Print out anything you find of interest and add to your dossier.
9. Source the Carroll Smith "..to Win" series of books (Google will help here too)
11. Read and understand what the great man had to say, and add more notes to your dossier.
12. Go visit your local brake repair shop, or even motorbike shop and talk with the mechanics about brakes.
13. Look at brake systems on any vehicle you get the chance (Google Image search will find millions of pictures)
14. Study Pascals Law
15. Research friction materials and rotor materials
16. Determine how much energy your braking system must dissipate.
17. Design your brake system!
18. Design a system to react the brake forces into the chassis.

Finally, be aware that brakes dont stop cars! Tyres stop cars! The brakes retard the rotation of the wheels and tyres. So you better learn something about tyres too!

Now, if that sounds too hard, well tough luck! Thats the way we all did it and there is no shortcut. You MUST understand your engineering decisions when you are under inquisition by the judges, otherwise the FSAE competition is not doing for you what it was intended to do...To generate real engineers.

Sorry if this seems harsh, but believe me, some other forum members would be much harsher.

Good luck in your search
Pat Clarke </div></BLOCKQUOTE>

[drivetrainUW-Platt]

I would ignore the adjustment beam and design around component size, the bias bar as its called is only for fine tuning, it should be set for center ( no bias) when designing then adjusted once a physical test has been made.

[kwancho]

So, in your design, do you have it optimised (using different calipers, pads, or master cylinders) to not require a brake bias adjustment bar? But then what happens if it rains? You have less overall deceleration, so less weight transfer, so you need more rear brake bias. And what if you don't have it perfectly set up? Basically, you should put the bias bar in your physical design (don't have to worry about it for your braking calculations), and then adjust it once you have the car built.

[bacoa]

hey guys...i've just finalized the design of brakes. BUt just need some clarification from you all. When u start the brake calculation what was the sustained deceleration that you all used? I assumed mine to be 1.5g (which has 1.3 max coefficient on tires and about 10% downforce). Is that too much? And i'm also not sure if i want do use steel tubing as the primary line to tranport pressurized brake fluid? Any suggestions will do..thanks..

[iolair]

IMO, a neat assembly.....something that could easily be incorporated in an FSAE car.....an extremely high quality/feather weight MC system that allows ballpark front to rear bore size adjustment and then a quick conditional balance bar dial in from the cockpit. I'm using it in my street rod.

http://www.pbase.com/image/61684770.jpg

http://www.pbase.com/image/61684771.jpg

John

[bacoa]

Hi john,
Could you tell me what's the name of this set of master cylinder? Looks compact enough..


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by iolair:
IMO, a neat assembly.....something that could easily be incorporated in an FSAE car.....an extremely high quality/feather weight MC system that allows ballpark front to rear bore size adjustment and then a quick conditional balance bar dial in from the cockpit. I'm using it in my street rod.

http://www.pbase.com/image/61684770.jpg

http://www.pbase.com/image/61684771.jpg

John </div></BLOCKQUOTE>

[CMURacing - Prometheus]

that set looks to be off the new tilton pedal assembly...correct me if i'm wrong, but it looks more expensive than the old set.

[Steve Yao]

Those are the Tilton Series 77 spherical mount master cylinders and Trunnion balance bar.

They are not inexpensive by any stretch of the imagination...and UW is using them this year. So John, your thoughts have already come to fruition.

Each MC is $385 retail. the Balance assembly is $625. Tilton will sell to FSAE teams directly with wholesale discount of ~28%, which still puts you back almost a grand for your brake pedal.

For us, packaging was a major issue, thus I designed a compact pedal assembly with these. By the time I went to buy them, I did not really have the time to sit-n-spin on a redesign, esp since brake calipers were already here. If I had done my research on cost earlier, they would probably not be on the car. Any motorcycle master cylinder will give you the same or better packaging, but with extremely limited range of bore diameters to choose from...

Any way, come by the University of Washington paddock at FSAE West if you would like a closer look.

[Steve Yao]

And back on topic:
In brake design, you have a desired output: Vehicle Deceleration; and an input: Force from the driver's leg. You can figure out what you want in each of these from testing and empirical data.

From these two quantities you size everything else using your vehicle dynamics (weight transfer), parts availability, cost, and/or weight.

As mentioned, try to size your components for zero bias(or close to it), and use the balance bar to get you the rest of the way(flexibility for different drivers, rain, etc.)

[vandit]

hi kami

if u r not in vicinity of books by "fred puhn" or "race car vehicle dynamics" , like i am then the simple way to go through the calulation is backwards(i.e is from wheels to mc).

&gt;&gt;by the size of ur rims get the approx. diameter of discs u can use according to packaging.

&gt;&gt;if ur team is not money constrained then they r quite cool calipers available with different companies. u need to do some r&d on the availability.

&gt;&gt;take some respectable assumption on decceleration and coeff. of friction of brake pads(if not available with dealer).the weight transfer and wheelbase and cg height.calc the braking torque required.

&gt;&gt;with that braking torque and effective rotor dia and caliper piston dia, pad coeff i think u can calc. the line pressure(may be i am missing something here)

&gt;&gt;once u know the line pressure and pedal input force u hav approx idea of what mc u require. again do some r&d on websites and products available.

the bad part is that i dont remember the equations and plz check with someone the above procedure.u will find them on this forum.guranteed.

[iolair]

Great....I would indeed like to see your pedal assembly. Thanks Steve! http://www.pbase.com/image/57341663.jpg

John