Shuttle loop rollback pully?

A friend of mine was at Astroworld the day Greezed Lightnin' opened and said it didn't make it back through the loop. He said a little 'thing' came down from the front spike and pulled the train up all the way to the very top, then released it.

It makes sense now, all those old shuttles have a cable and pulley on the spike. Anyone ever see this take place or have pictures?

I assume there's some kind of clamp on an axle that comes down, maybe mechanically releases the train at the top?

I don't remember details about that roller coaster but basically it makes sense as with any launch system (excepted with the Incredible Hulk where the launch toward the end of the lift tube is not vital) there is no failsafe guarantee that a minimal speed will be reached as for various reasons a launch can fail. Launched roller coasters are designed in a way which allows an easy evacuation of the trains if for any reason the initial launch or "in-circuit" reacceleration fails.

^^I don't see how this can happen. If it goes through the loop, how can it not come out of it?? There is a wheel on Tidal Wave when it was at SFGAm. It's like Vu's wheel. So, I guess so. To me, it doesn't make sense how this can happen.

How can it not make it back? In a word: friction.

FYI, you can see the pully just to the right of the nose of the car in this photo from Knott's Montezooma. You can also see the cable going vertically to the ground.

*** Edited 4/6/2007 12:34:57 AM UTC by Mamoosh***

With Greezed Lightnin' at SFKK, i think they use the weight to pull the train up the spike in the event of a valley. I've seen ol' lightnin valley a couple of times and they connect a cable to the front of the train and pull it up the spike.

Yep. Just because the train has enough energy to make it through the loop once, doesn't mean it will have enough energy to climb the spike high enough so the train can make it back through the loop.
I have never given that a thought until now though.

It was really odd to see Greezed Lightnin' valley. Especially during an 85 degree + day with little wind. But then again, Greezed Lightnin' doesn't exactly "fly" through it's loop.

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Vallean said:
Launched roller coasters are designed in a way which allows an easy evacuation of the trains if for any reason the initial launch or "in-circuit" reacceleration fails.

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I thought on Chiller they had a pretty tough time getting it out of the valley if the spike LIM's didn't fire. Hence the modifications...