How do brakes work?

Saturday, July 26, 2003 3:41 PM
Thanks to RideMan, I know that the default position of brakes on roller coasters is closed. That way, in case of a power-outage, collisions can be prevented.

However, I don't understand how, without power, brakes can still stop a speeding train. Without power, how does a brake maitain pressure to stop a train? Yes, I realize that the brakes are closed, but what keeps them closed?

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Intelligence is a God given gift: Know how to use it.

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Saturday, July 26, 2003 4:02 PM
Most systems use a leaf spring system of some kind. Picture a breakrun 4 feet long.. then picture 5 foot pieces' of steel that are bowed and attached to each end of the 4 foot section adn against a backing plate, thus creating a great amount of pressure to keep them closed. The brake system pushes against that pressure to open them, hence when a power faliure occurs, the pressure from the leaf spring snaps them shut. Not all systems are this way but a majority of them are.

The newer Intamin magnetic systems work a little different. Dragster and Xcelerator for instance use spring-loaded accuators. The air pressure lowers the brake fin. Loss of power or air causes the accuator to return to it's extended position thus extending the brake fin up to be exposed to the magnets. (The braking system on Intamin Impulse coasters work in the opposite way. The accuator moves the magnets while the brake fin is on the train.)

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June 11th, 2001 - Gemini 100
VertiGo Rides - 82

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Saturday, July 26, 2003 8:18 PM
Arrow brakes, if I remember Dave's explanation correctly, are kept closed by air pressure. Standing in line, for example, on Iron Dragon, you can see the air bladders along the brakes. When the brakes vent, they open. It's "safe" because there are tanks that hold the compressed air. Unless they all lose pressure at the same time, they'll do their job.

I think many of the brakes on wooden coasters actually work in the reverse sense, requiring air pressure to open. Truth be told, I've never really looked that hard.

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Jeff - Webmaster/Admin - CoasterBuzz.com - Sillynonsense.com
DELETED! What time does the water show start?

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Saturday, July 26, 2003 8:56 PM
I've always wondered if some coasters are actually fail safe as far as brakes are concerned. On Cyclone, I don't hear any air pressure at all, which leads me to believe they could stay in either position in the event of a power outage.

However, those springs on Flashback (SFNE) are very strong and the sound they of the metal on metal when those things close is like pool balls hitting eachother magnified by 100.

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SFNE Central- Online Six Flags New England Resource

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Sunday, July 27, 2003 1:25 AM
Jeff,

You're right that Arrow (and maybe Vekoma?) brakes are kept closed by air pressure. I remember when I had a tour of the Vampire, they say how they have to park two of the trains on lifts and stick a scaffolding pole through the track/wheel assembly on the train left in the station to stop the trains rolling off over night when the air seeps out of the brakes.
*** This post was edited by Marcus Sheen 7/27/2003 7:29:30 AM ***

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Sunday, July 27, 2003 9:51 AM
Yep Jeff, Arrow is just like that. Kinda of a weird way to do it if you ask m. You loose all pressure at some point and your brake open? That's not real bright.

As for Cedar Point, I know when trains are parked for the night on transfer or the ride is shut down for an extended period of time. The trains are attached to chains to prevent rolling.

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June 11th, 2001 - Gemini 100
VertiGo Rides - 82

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Sunday, July 27, 2003 11:56 AM
I believe air pressure is used to open brakes on wooden coasters. I noticed as cars roll past the transfer track brake, it doesn't open until the last second (I guess to preserve air pressure). Same as coming into the station, the brake appears closed as you're going into it but it opens just as soon as the brake fin crosses it (again I believe to preserve air pressure). This seems like the smarter way to me but then again I'm no professional.
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Sunday, July 27, 2003 12:16 PM
What about X? That is Arrow, but uses magnetic brakes (on the main brake run, anyway) - how do they park this over night*? Does it use normal brakes for holding the train in the station.

(* this is assuming the trains are actually on the track, and not in bits in the maintenance bay!)

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Monday, July 28, 2003 6:16 AM
Yes, Arrow brakes, at least on their older coasters, use air pressure to close...the pressure is supplied by a reserve pressure tank, and I presume the supply valve requires power to close. That way if power is lost, the valve opens and the tank pressure goes to the brakes. Arrow made the system fail-resistant by using redundant pressure systems and more brakes than necessary.

Using a pressure-applied system makes sense first because it is a very simple brake caliper design, second because it makes it very easy to change the braking force...lower the pressure, and you have a trim brake. Increase the pressure and you have a block brake. In fact, some coasters were set up that way: two pressure systems on a particular set of brakes, one high, one low, and an A/B valve between them would determine whether the brake was a station approach trim or a block safety brake.

Of course the problem with a pressure-apply system is that if you lose air pressure in the system, you also lose your brakes. Hence the redundancy built into the system by doubling up the brake calipers.

I know Arrow has built pressure-release calipers that are similar to the pressure-apply calipers, but held closed by eighteen tiny little coil springs and opened by an airbag. I've seen these on the Big Bad Wolf at Busch Gardens Williamsburg, and on the River King Mine Ride at Six Flags St. Louis.

Older wooden coasters that have pneumatic brakes on them sometimes use skid brakes instead of caliper brakes. In those cases, the brake is held in the set position with a counterweight (on the Phoenix at Knoebel's, for instance, that's what the bucket of cement hanging from the brake run is for...).

Oh, and if you are worried about the reliability of a pressure-applied braking system, please note that all automotive braking systems are pressure-apply systems.

--Dave Althoff, Jr.

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Monday, July 28, 2003 7:33 AM
On modern cars, automotive systems are redundant though with dual master cylinders, each master cylinder feeding one front and one rear brake in most cases. Also you can use the parking brake in an emergency, though speaking from experience I can testify that the parking brake won't stop you very fast. It can also spin you around if you aren't careful.

Another example of using gravity for brakes is the counter weights on Intamin magnetic brakes. However, I think that these reduce the force required to close the brakes rather than provide the primary closing force. At least they didn't close the brakes effictively at SFNE.

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Monday, July 28, 2003 7:58 AM
Can spin you around? I thought that was its sole purpose! :)

lata, jeremy

--doing 180's with handbrakes since 1997....

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Monday, July 28, 2003 8:57 AM
How long do your tires last Jeremy? I had the experience of arriving at a toll booth and discovering that the single master cylinder on a '65 VW beetle had failed. This would not have been a good time to do a 180.
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Tuesday, July 29, 2003 7:57 AM
You don't need brakes on a car, esp if its manual trans, I drove back from Evansville Indiana to the eastside of Cleveland w/ no brakes in my 626 turbo, got tricky through louisville, cincy, and columbus, and on the hills in kentucky. Even when I had my mustang, I rarely used brakes, used to downshift most the time and only use to use the clutch when starting off and reverse.
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Ride the Conneaut Lake Blue Streak!
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Tuesday, July 29, 2003 8:27 AM

Fxnib said:
...and columbus...

That crazy driver on I-71 was you?! ;)

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Wednesday, July 30, 2003 6:11 AM

Red Garter Rob said:
As for Cedar Point, I know when trains are parked for the night on transfer or the ride is shut down for an extended period of time. The trains are attached to chains to prevent rolling.

I can't really think of any rides that are tied up at night other than Corkscrew's one train on the side track. Most coasters are left with all trains simply parked somwhere in a closed set of brakes. Some trains (Gemini and Iron Dragon for instance) are even winched/cycled nightly.

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James Draeger
CP Ride Maintenance 2003

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Wednesday, July 30, 2003 8:09 AM
Well I'm not sure if this is the same way everywhere, but when I go to take a break I have to clock out and then I have 15 minutes in the break room to spend before my break is over. I usually get two a day and then an hour lunch break.

Oh wait you said Brake not break....um, well...nevermind. ;)

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SW:):)SH Shaddy(president of LEMCCDWBLI)
MidwestInfoGuide.COM

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Wednesday, July 30, 2003 8:47 AM
So, Draegs...

What do you do when it's time to drain the air tanks? The Arrow rides don't have spring-close brakes on them...drain the tanks, and the brakes open.

--Dave Althoff, Jr.

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Wednesday, July 30, 2003 8:53 AM
The arrows opearte on the exact same principle as railroad air brakes. That is why a railroad car has to be tied down by hand brakes so it does not begin to roll, once the air bleeds out of the resevoirs the brakes open.

This however makes emergencies more failsafe as any drop in brakeline pressure whatsoever causes the brakes to close and stay closed for a long enough period of time that it's not really an issue. If Intamin's were set up this way the S:ROS incident would have never happened.


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If given the choice I'd choose a hamburger over a hotdog anyday of the week.

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Wednesday, July 30, 2003 10:24 AM
I wouldn't be too certain of that, MagnumForce. On the Intamin brake, as nearly as I can tell, air pressure is used to move the calipers in both directions, and a loss of supply air means that only the counterweight (if present) is used to set the brake.

If you lose air pressure on an Arrow coaster, the supply valves will shift to the 'brake close' position. But if the problem is in the line between the reserve tank and the caliper, then the caliper will not close! Air will simply vent through the blown hose. And that's essentially what happened on Superman. Now Arrow recognized that their system isn't failsafe, so they made it failsafe through redundancy...losing one air hose won't kill all the brakes. Intamin made that same change on S:ROS after the incident (item 4 in the press release; text available on my web site).

--Dave Althoff, Jr.

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Wednesday, July 30, 2003 10:39 AM
It has redundancy Dave but that still doesn't mean it's not the exact same system.

You have your compressor which fill each resevoir throughout the system. Once the system is charged you open a valve and opening this valve and the resultant loss of air pressure causes the brakes to close.

If the Intamins would have had a system similar to this, the loss of air pressure when the hose blew would have immediately closed the brakes.

The fact that George Westinghouses system is still in use on trains over 100 years after it's inception proves just how well the system works.

If an air hose were to break on a train, the train would immediately go into an emergency brake application with no input from the engineer whatsoever.

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If given the choice I'd choose a hamburger over a hotdog anyday of the week.

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