If the brakes close when air pressure is lost (in response to fof) how exactly can the "bleeding" (which means release of air pressure) happen? If you lose air pressure, you lose it. Many fin brake systems are designed to be closed by design, without air pressure. The air pressure is what opens the fins to allow the train to move. In your scenario the air not only closes them, but opens them too?
There are many different brake systems in use. The term "fail safe" in regards to air brakes means that in the event of power/pressure loss, the coaster can be safely brought to a stop by having the brakes return to their natural position, closed.
Skid brakes could be set in both ways, either in the up (stop) position or the down position. I often see trains on these chained or locked.
Magnetic brakes are designed to slow a train but not hold it (in most cases). There are typically fin brakes or drive wheels to hold the train in place. Think of how a freefall (using rare earth magnets) comes to a stop. It slows the carriage immensly, but then allows the carriage to continue the descent at a very slow set speed to the platform. These are considered the most "fail proof" in that if you lose power, the ride will still stop safely each time.
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Waiting for the CP announcement to be made so that about 1000+ posts will be made complaining about it.
Many fin brakes are also both closed *and* opened by air pressure. Take a look at Automated Control Solution's website, which explains how their brakes work and are fail-safe: http://www.acontrolsolution.com/products/ridebrakes.html .
Typically, I don't believe "bleeding" should naturally occurr. However, I've been told that maintenance sometimes "bleeds" brakes on a nightly basis, hence the chaining of the trains.
Magnetic brakes cannot bring a train to a complete stop.
-Nate
Umm, Have you heard of the folowing rides: Millennium Force, Superman: Ride of Steel, Vertical Velocity, Wicked Twister, and Superman: Ultimate Escape?
These are all examples of coasters that use, exclusively, magnetic brakes in the brake run. They have some interesting ways to constantly physicaly remove the brakes, actually, because the ones that actually stop the train are so powerful that they can't easily get the train moving again.
I dont *think* the impulses have kicker wheels. I am led to believe that they are not really *stopped* but are brought to an infinitesimally small velocity such that the force applied to the train by the fricton of the wheels on the rails finally *stops* the train.
As for Volcano, I dont like that ride much and as such have not spent much time studying the mechanics.
lata, jeremy
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"To get inside this head of mine, would take a monkey-wrench, and a lot of wine" Res How I Do
Pretty much all air-powered brakes on coasters (all since at least the 70s) use air pressure to OPEN the brakes, not close them. That way, if an air line should rupture, the brakes will clamp down into the closed/emergency position. I think it's unusual a park would use a rail lock nightly to secure trains when brakes are supposed to do that in the first place.
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the member formerly known as MisterX
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Lifts are for wimps. Real enthusiasts use the power of their minds to make the trains go up the first hill.
Ok, maybe some coasters use air pressure to do both, but not most. Almost every coaster I know of uses air pressure to open the brakes, not close them.
Oh, and the chain hookup on the back, not always to keep it in place. On most coasters that have this, the maintenance shed is under the station, (e.g. Corkscrew, Iron Dragon) the chain hookup is there to slowly lower the train into the maintenance shed.
As for where coasters park, it all depends on blocking, maintenance convenience, and the amount of storage bays. I'll use CP as an example. Raptor parks all three trains in the storage bays. B&M have made it really simple to transfer the trains, and the storage bays are really the only place to get abover the wheel assemblies to check them out. Iron Dragon on the other hand has no maintenance catwalk to allow inspection of a train in the transfer track. For this reason, all 3 trains are left on the track This means one must be parked on a lift, since only 2 can stack. They could transfer one down to the storage shed, but this involves hoisting with the chain which is much more time consuming.
It all depends on what is convenient really.
Brakes made by Arrow and Vekoma are air-bladder brakes. With only a few exceptions, these brakes are of very simple construction: there is a fixed caliper frame into which are fitted the brake shoes. The brake shoes are held open by a pair of leaf springs, and the air bladders fit in between the caliper frame and the brake shoe. The air bladder is basically a piece of fire hose clamped shut on both ends and hooked to an air line. When air is applied, the bladder inflates and closes the brake. When air is vented, the springs pull the brake shoes back, forcing the air out of the bladders and out through the air line and valve with a "woosh". Hence the "woosh" as the train starts moving. Of all the Arrow and Vekoma coasters I have seen (about 57 total at last count, most recent being the Silver Streak at Canada's Wonderland) only two...Big Bad Wolf at Busch Gardens Williamsburg and River King Mine Ride at Six Flags St. Louis...use a slightly different arrangement with a cantilevered brake caliper. This caliper is held closed with eighteen coil springs (nine on each side), and opened with a pair of air bladders. A few of these coasters (notably River King Mine Ride and Dollywood's Tennesee Tornado) now use a canister-type spring-closed air-opened brake for train parking or in addition to the standard air bladder brakes; Cedar Point's Cedar Creek Mine Ride was recently converted to all canister-brakes at the blocking points.
Anyway, any coaster equipped with these air-bladder brakes is protected against failure through the use of redundant braking systems and multiple air supply pressure tanks so that a loss of system air pressure will not cause a loss of braking power in the short term...lose the air compressor and there is enough reserve pressure to get all the trains cycled and emptied. But standard maintenance practice is to drain the air tanks on a nightly basis to prevent moisture buildup in the system that can cause corrosion and failure of the pressure tanks. So the trains must be wheel-chocked or safety chained in place wherever they are parked unless parked on the lift. If this is not done carefully, this can happen :)
Most other caliper brake systems are pressure-released. Skid brake systems can be pressure apply, pressure release, or pressure to go either way. Intamin's magnetic calipers apparently require pressure to go either way on some of their rides.
I hope that clears up some of the confusion and perhaps ends some of the argument...
--Dave Althoff, Jr.
I'm sure that's true... what I am saying is that, at least at my park, while parking trains on the lift is possible, we don't because we can park them in the brakes without worrying about "bleeding." You can leave them in any brake area for quite some time and not worry about any movement.
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the member formerly known as MisterX
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Lifts are for wimps. Real enthusiasts use the power of their minds to make the trains go up the first hill.
Actually, I know very well how coaster brakes operate. True, that a sudden loss of power or main air pressure will cause a brake to close. Most fin brakes have two air tanks, one to open the brake and one to close. A stop solenoid keeps the close tank switched over. A signal from the control system is required to activate the stop solenoid and switch over to the open pressure tank. If power fails, there is no longer an open signal, so the brake closes. If main line air pressure is lost, the control system detects this and will automatically turn off all brake outputs. However, air naturally moves from higher pressure to lower pressure, so having no air pressure for hours on end will cause the air in the individual brake tanks to slowly bleed out through the hose connections and trains will SLOWLY creep forward as evidenced in RideMan's picture in the above post.
This is the way most fin brakes operate. Some coasters (Togo stand-ups, for one) are sprung shut with coils and simply require air to open. However, this puts more stress on the braking mechanism than with the other type of brakes because the train is forcing against a solid object instead of air pressure. This is one reason Togo stand-ups are very maintenance intensive, and also the reason King Cobra and others were so freaking loud when hitting the brake run.
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Face/Off Crew '99-'00
Top Gun Sup '00
King Cobra/Days of Thunder Sup '01
Beast Sup '02
Wild Thornberry's River Adventure Sup '02
*** This post was edited by HelixSpiral on 10/29/2002. ***
General Public said:
I'm sure that's true... what I am saying is that, at least at my park, while parking trains on the lift is possible, we don't because we can park them in the brakes without worrying about "bleeding." You can leave them in any brake area for quite some time and not worry about any movement.
Then i guess your park doesn't have an Arrow coaster.
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So you believe that you are studying us, then kindly explain why you are the ones trapped in your seats.
Magnum is one of the rides that uses air pressure to close the brakes. Also, the main purpose of the chain on Magnum IS to hold the train in place because the chains (one at the back of the station and one on the transfer track) are about two feet long so they aren't used for any other purpose than a safety system.
To put Magnum to bed for the night, the first empty train is stopped in the safety brakes outside the third tunnel. The next train is stopped on the lift automatically when it reaches the peak or stopped low on the lift by the operator to keep people from saying, "look it's stuck!" At this point, the ride is switched to transfer mode with the turn of a key and the transfer table is moved over, and then the controls are switched back to run mode. Following a 75 second delay, the safety brakes can be released and the train comes around from the safeties to the transfer track and is "bumped up" and chained. Then the ride is put back into transfer mode and the table moved back over. Then the ride goes back to run mode and the blocks are cleared (turning a key left and right). At this point, I believe there is another 75 second delay before the lift can be started and the train from the lift comes around and stops in the readies (because of the train in the station). Finally, the train from the station is dispatched and sent around where it stops automatically in the safeties outside the third tunnel. Push e-stop, turn the controls to off, remove the key and that's it! Besides paperwork and cleaning of course... ;)
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-Matt
2001 Magnum Crew
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the member formerly known as MisterX
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Lifts are for wimps. Real enthusiasts use the power of their minds to make the trains go up the first hill.
Well, if the air compressor doesn't get switched off at night, then there's no problem leaving the trains in brakes. It's also entirely possible that maintenance comes after the ride is in bed to shut the compressor off and secure the trains. Just because ride ops don't secure the trains doesn't mean they don't get secured.
-edit: BTW, I'm not trying to argue here, just sharing what I know. :)
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Face/Off Crew '99-'00
Top Gun Sup '00
King Cobra/Days of Thunder Sup '01
Beast Sup '02
Wild Thornberry's River Adventure Sup '02
*** This post was edited by HelixSpiral on 10/29/2002. ***
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So you believe that you are studying us, then kindly explain why you are the ones trapped in your seats.
(SF)Great American, Jeremy is right. Magnetic brakes cannot bring a train (or a car, as in the case of a drop ride) to a complete stop. Most rides have kicker tires to fully stop the ride. Volcano has very tiny brake fins in addition to the magnetic brakes.
As for understanding how air pressure is used to close the brakes (and how it's still fail-safe based on the default brake position), think about it this way - if not air pressure, what do you THINK is used to hold the brakes shut? :-)
-Nate (who finally understands how this all works)
Coatser brakes work on the exact same principle as train brakes.
The default position of a trains brake system is closed but when too much air is used and the air bleeds off the pressure equalizes and the brakes open. This is how runaways occur.
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*** This post was edited by MagnumForce on 10/29/2002. ***
-Nate
-Nate
Helix,
It's alright. Your results may vary. Every park does stuff different. Our park doesn't use rail locks at night. Mechanics just park the trains in the brakes, turn the power off, and wait for tomorrow morning. Plus routine inspections etc.
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the member formerly known as MisterX
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Lifts are for wimps. Real enthusiasts use the power of their minds to make the trains go up the first hill.
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