Driveline braking
Driveline braking
(OP)
Would mounting a disc brake on to the drive shaft multiply the braking ability at the wheels because of the gears? Or would the disc need to have a large diameter to overcome the torque coming back through the driveshaft from the coasting vehicle? Just another quick qusetion, that I think I already know. Are driveline brakes legal for the road? Or does there have to be a brake on each wheel? If it makes any differance it is on a 1 ton truck.





RE: Driveline braking
The power dissipation requirement would be double for a single driveshaft brake vs two wheel brakes.
Also, having one wheel go airborne would make the driveshaft brake completely ineffective (differential).
RE: Driveline braking
RE: Driveline braking
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Regards
pat
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RE: Driveline braking
I used to have a model t ford with transmission brake. It got really exciting on ice.
I have also seen Driveshaft brakes used for parking brakes on many trucks from the factory.
In Arizona drivehaft brakes are not legal for service brakes, we get hasseled for them on our rockwell axles on lifted trucks. There is not a clear answer if they are suffient for parking brakes as we are required to have the parking brakes hold 2 wheels.
They also generate a lot of heat, I assume because all the braking action is one rotor instead of two. But they require a lot less pedal pressure.
jburgess
RE: Driveline braking
Use a small eddy current retarder if you wan't drive line braking, they are used on everything from mini-buses to prime movers. There ideal & can be 12 or 24v, look up Telma retarders they've got what you wan't.
RE: Driveline braking
RE: Driveline braking
RE: Driveline braking
It still has a larger number of points for failure between the drum and the tyre contact petch.
Regards
pat
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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Driveline braking
RE: Driveline braking
Cheers
Greg Locock
RE: Driveline braking
Rod
RE: Driveline braking
Anybody watch American Hotrod? Did anybody see that Jaguar rear-end they put under the '56 Chevy, or have you seen a Jag rear end at all? The have the brakes up near the differential, and then have a drivehsaft going to each wheel.
Another problem I forsee with putting a brake disk on the driveline before the differential is that it isn't protected from all of that stuff on the road, especially water and dirt, that normal brakes are by the wheel.
RE: Driveline braking
I saw american hotrod, but the rear end in the '56 had a drop out center section, I thought maybe a 9" ford in a custom setup? The inboard disc brakes would reduce the unsprung weight at the wheel.
Back to driveline brakes. With large tires (16r20) it is difficult to get parking brakes to hold on a incline. The reduction in torque require to hold is a big advatage. Another problem in converting to disc brakes there is a very limited selection of calipers that include a parking brake.
Jburgess
RE: Driveline braking
"Did anybody see that Jaguar rear-end they put under the '56 Chevy, or have you seen a Jag rear end at all? The have the brakes up near the differential, and then have a drivehsaft going to each wheel."
What he described is of course inboard disc brakes, with the brakes mounted on the inboard ends of the axle shafts, and not remotely related to this discussion of DRIVEshaft mounted brakes.
Big problem with driveshaft-mounted brakes: what do you do when the u-joint fails?
RE: Driveline braking
RE: Driveline braking
I know they are used in F1, so should be durable enough for a drag race car, and should significantly reduce the inertia of the wheel hub assembly.
I guess I will start with a Google search
Regards
pat pprimmer@acay.com.au
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RE: Driveline braking
If you are still interrested in Carbon/Carbon, you will require high density medium quality and a coefficient of friction .35 or more(Im sure you already know this), the cost is $250-$400 per kilogram, and should weigh around 2KG per disc and pad. Good luck in finding a manufacturer willing to supply you with low quantities though usually its 500KG minimum, there is one company I know off that sells them at US $1200 per wheel, pads and discs so alot more than the $250-$400 per kilogram but at least they supply low quantities.
Let me know if you are interrested and I'll provide you with the info on where to get it and save you some time. These are for only the discs, so you will have to make your own hats.
RE: Driveline braking
http://www.ntsb.gov/publictn/2002/HAB0219.pdf
This is a larger vehicle than the one in the subject topic, but the reactions where the rubber meets the road are the same, and this report helps explain it in a very technically detailled way.
rmw
RE: Driveline braking
Thanks for your help, but if the number of Zeros in the Carbon/Ceramic disk cost is correct, that makes them A$30,000 per wheel or $120,000 per car. That is way above our budget.
I may have hijacked this thread, but as the original question was about reducing drive-line inertia by removing weight from the brake system, I felt it was relevant.
I will start a new thread just in case an affordable solution comes up.
Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Driveline braking
Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Driveline braking
On a high performance vehicle, heat dissipation and wear are going to be the biggest problems, and fitting a small diameter transmission brake is probably not going to be a very good solution.