electromagnetic disk brakes

[cycleboy]

to me it seems like a pretty sound idea using electromagnets to attarct to the disk to pull the brake pads together but i would like some other opinions on my idea

 

[IRstuff]

Braking requires extremely high forces. I don't see that happening with a magnetic system.

TTFN

 

[SolderingGunslinger]

Electric drum brakes have been used on travel trailers for many years. My grandparents had a 1949 Airstream with 6-volt coils for the electric brakes.

The magnet would clamp to the stud side of the brake drum and the rotation of the wheel would push or pull a lever which actuated the brakes, pressing the brake shoes against the outer rim of the drum in the same manner a hydraulic cylinder would.

What would be your application?

I remain,

The Old Soldering Gunslinger

 

[cycleboy]

the brakin system would be used on motorcycles in the same way hydrualic brakes r used

now that more thought is put into to it a hydaulic brake shoe and disk could be adapted to work with this principle

 

[btrueblood]

You'd have to worry about the magnet (and the iron it's attracted to) staying cool, so that it/they doesn't lose effectiveness at high temp's.

 

[NickE]

you still are going to have a really hard time developing enough normal force to actually stop the vehicle, admittedly the fact that its a motorbike will help.

just cause I dont know; What is a good estimate of normal forces exerted by common 1-piston calipers? I know Goodridge tested my brake lines to like 3000psi. which woudl in the application have nominal pressures ~1200-1500psi. But I dont know the piston area in order to calc. the forces.

 

[GregLocock]

your piston is about 30mm in diameter

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[amorrison]

Some type of cam, gearing or lever system could produce the forces required - extra complications but . . .

 

[amorrison]

For starters try

http://www.suntes.co.jp/english/contents/products/disk_brake.html

http://www.ogura-clutch.com/products.html?category=2&by=type&no=3

You may want to take time off work to learn another language if you want to read these . . .

http://www.mayr.ch/deutsch/p_alt/bremsen/roba_stop_disk/roba_stop_disk.htm

http://www.tecnicaindustriale.it/freni_e_frizioni.htm

 

[Warpspeed]

A lot of copper and iron/steel magnetics would be required to generate enough braking force, all of it unsprung weight.

The whole electrical system would need to be upgraded to supply enough power to keep it working. All a very serious problem on a bike.

Eddy current brake retarders are used on large trucks and work well, but they are neither small or light weight. Jacobs engine compression brakes are far more popular.

How about using compression braking on your bike ? The sound would be unique ! But it could only work on the back wheel unfortunately.

 

[plasgears]

The electrobrake is in line with plans to automate everything for the future. Automatic interval control begs for an electrical system.

 

[GregLocock]

Given Mercedes recent experience with electrically activated brakes I doubt you'll see them on production cars again for 10 years or so.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[SolderingGunslinger]

I am not too sure I would be totally happy driving something with only electric brakes. I do enough driving in mountainous areas so I worry about losing the electrical system and my brakes.

In another thread, there has been a discussion of Engine Braking and how some feel it shouldn't be done. Losing the electrical system and brakes would necessitate engine braking......not a good thing.

IM not so HO, braking systems should be powered from a seperate source in the same way the instruments on an aircraft are not all powered from the same source.

I remain,

The Old Soldering Gunslinger

 

[Warpspeed]

Total loss of braking....never good.

That reminds me of a proposed unique emergency braking system I saw many years ago for large trucks. The idea was that a couple of heavy wedges attached to long chains could be released on either side ahead of the rear wheels.

These wedges could be dropped onto the ground in front of the rear wheels, the rear wheels riding up onto the wedges. The chains snap tight, and the whole truck drags to a fairly rapid halt. Rather primitive, but clever, I wonder what happened to that idea ?

 

[BenDutro]

Large truck brakes use a reverse-pressure fail safe where a large (LARGE!) spring forces the pads against the drum and the trucks pneumatic system holds them back. This way, if there is a failure in the air-brake system, the springs activate the brakes.

 

[MintJulep]

If I where to design an electromagneticly actuated brake system I would go spring apply, EM release. That way at least loss of power results in brakes being applied.

 

[Warpspeed]

Yes, but you might have to feed several hundred amps into the brake solenoids continuously to hold the brakes off. I can see some problems with that.

 

[SolderingGunslinger]

Large truck brakes use a reverse-pressure fail safe where a large (LARGE!) spring forces the pads against the drum and the trucks pneumatic system holds them back. This way, if there is a failure in the air-brake system, the springs activate the brakes.

So do railroad trains in North America, after a fashion. The trains use air pressure in a reservoir to set the brakes. This pressure pushes a piston which applies the brakes. A counter pressure is put against the other side of the piston releasing the brakes. If there is a train separation, the air rushes from the brake pipe and the train’s brakes are set. The air can be released from the locomotive gradually to allow an even slowing of the train, or the brakes can be set in emergency from the locomotive as well. It is a system invented by George Westinghouse a hundred and some-odd years ago. I understand that some European countries at one time used vacuum brakes, or perhaps they do to this day, the only difference is that one sucks and the other blows. The train stops (hopefully) and all’s good with the world.

When I tell people that I play with trains, they ask “What Gauge?” I say “Standard, Four Feet, eight and a half inches” I love the looks I get almost as much as shoving the Johnson Bar forward a notch or two, Blowing the 4-chime steamboat whistle, opening the cylinder valves and the throttle valve and pulling the Consolodation Steam locomotive out of the station with a load of daytrippers.

I remain, Electrical Engineer and Steam Locomotive Engineer…does it get any better than this?
The Old Soldering Gunslinger

Oh yeah, it isn’t any better than waiving to the people who stop their autos along the right of way and the little children who waive and grin. --SGS

 

[swall]

My previous employer made an electrical parking brake system for medium trucks (hydraulic discs were the service brake). The parking brake used a motor to drive an acme screw thread that would push the caliper piston against the pad. Sufficient clamp force was developed such that if the brake was applied while the disc was still hot,enough clamp force was maintained after the disc had cooled down and shrank.

 

[karlbamforth]

"If I where to design an electromagneticly actuated brake system I would go spring apply, EM release. That way at least loss of power results in brakes being applied."

I was racing a motorbike some years ago when I was hit by another bike, the impact damaged my brakes locking them on whilst I was still doing 70mph. I can tell you its no fun being on bike that can suddenly and unexpectedly apply its own brakes.
Keep working on it I'm sure there is a way around the problems.

Karl.