How does the holding brake work on an Impulse?

Wednesday, July 10, 2002 8:55 AM

I remember hearing that Intamin megas use the advancing wheels to completely stop a train because the magnetic breaks could not fully stop a train. I also remember seeing small fin brakes on Volcano used for the same purpose.

I thought the holding brake on Impulses are magnetic. Do they really hold the train for a split second or do they just delay the drop?

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Wednesday, July 10, 2002 9:00 AM
I pretty sure they actually hold you. When you up there your body slams into the restraint and you still sit up there a little longer.
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Wednesday, July 10, 2002 9:06 AM

They are (I believe... correct me if I'm wrong) LIM's on the back spike that hold you up, not brakes.

They do, in fact, stop the train completely on the back spike (sometimes, the train will skid a little down the spike). I suppose they could hold a train up there as long as they want... or at least until the LIM's overheat.

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Wednesday, July 10, 2002 9:46 AM
That's right, they are LIMS, not just magnetic brakes. Thanks guys.
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Wednesday, July 10, 2002 10:35 AM

The LIM's fire at just a strong enough level to stop the train in place and counteract gravity...without overpowering it and moving the train back up the spike. The whole process lasts for just about a second.

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James Draeger
-Proud co-founder of the Coasterbuzz street team

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Wednesday, July 10, 2002 10:52 AM
Kip099, SFA rules and James Draeger all have it right.

They are not really brakes, they are motors which apply a 1G backward thrust to the train. A motor operating in this fashion is said to be operating "at stall"...that is, power is being applied, but the reaction plate is not moving because an outside force...in this case gravity...is preventing the reaction plate from moving in the direction the motor is going.

The Impulse coaster is really a very good demonstration of all the different things that LIMs can do, as it has acceleration in both directions, fine positioning, and operation at stall, all things that may be more difficult with other drive systems.

--Dave Althoff, Jr.

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Thursday, July 11, 2002 6:12 PM

Hmmm, they could reverse the thrust & slam the train downwards with a similar effect to a Turbo Drop.

I also wonder if they've ever held the train there for say 5 seconds or more in testing. The track should be strong enough for that. Maybe not if the LIMs overheat quickly.

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Thursday, July 11, 2002 6:28 PM

A neat little thing to look for... that 1G thrust Rideman is talking about is actually only programmed to counteract the weight of the train empty. When S:UE tests in the morning, it makes a complete stop aside of the tower, it doesn't slide down at all. But when you put bodies in the seats, that's when the LIMs don't put forth enough energy to keep the train motionless, it then slides down.

I wonder what would happen if the LIMs were up-ed a notch to make a 1.5 upward thrust on the train... it would push the train up when testing empty, but it would completely hold a full train when people got on.

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Jes
Jes's Roller Coasters DJ Jes MCS Please, Feel Free To Call Me Jes!
Six Flags Worlds Of Adventure 2002 Ride-Ops Crew

*** This post was edited by Zero-G on 7/11/2002. ***

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Thursday, July 11, 2002 6:28 PM
If the lim was accidentally set wrong would it fire the train up over the spike?

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SFGAm: 1)DV 2)V2 3)AE Blue 4)Viper 5)Bull


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Thursday, July 11, 2002 6:35 PM
If I'm not mistaken, the power converters for those perticular LIM's have physical limiters that resist any power surge over a set amount.

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Jes
Jes's Roller Coasters DJ Jes MCS Please, Feel Free To Call Me Jes!
Six Flags Worlds Of Adventure 2002 Ride-Ops Crew

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Thursday, July 11, 2002 6:44 PM
Bull fan: I'm sure there is some type of device/ programming to prevent that from happening, especially with todays technology, that kind of stuff shouldn't happen (LIM shooting a train over the spike)
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