Roll back info

Where would I find.. offical info on why roll backs happen for TTD and KK....

I need to show a friend that why it happens...

he believes me that KK andTTD are designed to have it..

but he wants to know why and I don't just want to make things up....

nor do I want to give him an answer that is made up from someone else! *** Edited 5/30/2005 2:24:55 AM UTC by Earnhardt2***

The trains dont make it over the top for whatever reason, a rollback is not supposed to happen.

Here's a cool video of a rollback:
http://www.cbsnews.com/stories/2003/05/29/earlyshow/contributors/melindamurphy/main556072.shtml

lol I know that it happens..

but I want the info on what causes it...

like is it they hydro fluid pressure or what...

that is what I want to show him *** Edited 5/30/2005 2:24:19 AM UTC by Earnhardt2***

I'm sure there are numerous reasons that can cause a rollback including but not limited to, weather (coldness, wind), moisture on the track, uneven weight distribution, malfunctions with the catchcar, hydraulic motor, cable, etc. etc. etc.

Weight of the train/people varying between cycles, different friction based on temperature, etc.

I just want a link,, if there is one.. but that is what I have been telling him

thanks for your post though *** Edited 5/30/2005 2:52:22 AM UTC by Earnhardt2***

I've actually heard that TTD is programmed to produce a rollback when the first train is sent after a shutdown/e-stop reset. This of course being an excellent way to test the hydraulic launch system, as well as to test the launch brakes prior to continued operation. *** Edited 5/30/2005 3:09:28 AM UTC by Fun***

^^^^ this is why i want real info.... "I hear" is like saying "I think" or "a janitor told me".... sorry

Well what are you expecting out of a discussion on the internet? Those who know, don't tell- those who tell, don't know.

AFAIK There is not official source explaining why rollbacks occur. Perhaps Rideman has something on his site(I don't know he link off hand) he would probably have the most definitave reasons.

You're going to have to take the word of people here, there are many who are quite knowledgable on this site who you should listen too, there are also others who as you know will post dribble. I would wait and see who posts. if someone posts "roll back occur because the trains are heavy enough" with no further explinations that should probably be ignored, someone who has a good Idea will go on to elaborate.

Earnhardt, you might get a more serious response if you took a little time to write a good post. Your posts so far in this thread have been mispelled, gramatically incorrect, over-punctuated, and just plain difficult to read.

Why should people spend the time to help you when you can't even spend the time to ask a correctly phrased question? *** Edited 5/30/2005 3:13:37 PM UTC by RollrCoastrCrazy***

rollbacks occur for a couple reasons. First of all, the weight of the train matters. Contrary to popular belief, the less weight, the less momentum as the train rises, which makes rollbacks more probable. Also, when the track is colder it is not as slick and this also increases the chance of a rollback. This is why sometimes after a 15 or 20 minute breakdown the first train dispatched will roll back - the track has had a few minutes to cool down. This is also why lots of trains often roll back during early morning test runs. *** Edited 5/30/2005 3:40:57 AM UTC by Raging_Bull***

---

RollrCoastrCrazy said:
Earnhardt, you might get a more serious response if you took a little time to write a good post. Your posts so far in this thread have been mispelled, gramatically incorrect, over-punctuated, and just plain difficult to read.

Why should people spend the time to help you when you can't even spend the time to ask a gramatically correct question?

---

LOL there is always one... and it ALWAYS seams to be a member of CB that is the spelling police. This is why I hate posting on here, but thanks for you help in aswering the question. ;)

thanks Danimal for your post. I guess I'll just wait for more to post. thanks *** Edited 5/30/2005 3:40:27 AM UTC by Earnhardt2***

I am actually not "the spelling police." In fact, I rarely point that out to anyone. The fact that you were complaining about a lack of responses from us actually prompted my negativity, now read the TOS and continue posting :)

1) It's a tricky process getting a launched coaster over the top of a vertical spike. If you don't fire it hard enough, you get a rollback. If you fire it too hard, you get excessive forces on the riders. You want to err on the side of going too slow so you don't get excessive forces. Of course, you also don't want to valley which can be a problem on a few launched coasters, such as the Hulk.

2) I'm not aware of all the parameters measured on the Intamin launched coasters to know every variable that is measured. I know that S&S's Hypersonic weighs the trains before launch.

3) Basicly, a number or variables are measured, and the force of the launch is adjusted according to the inputs. I'm not sure if they adjust hydraulic pressure or the cut off when the hydraulic flow is ended or both.

3) There is always some error in this type of measurement. It seems that at this time Intamin is not able to measure enought parameters accurately enough to ensure that rollbacks never occur. Of course mechanical issues can also occur.

4) If this sounds like I don't really know what causes the rollbacks, you are correct. I strongly suspect that they occur for several reasons. These can probably be divided into 4 groups, errors in measurement, things that vary that aren't measured at all, errors and simplifications in the algorithm in the PLC (computer), and failure of the mechanical systems to perform as design.

5) This isn't completely wild speculation. While I don't have much specific information on the Intamin launched coasters, I am currenlty working with a controls engineer who was involved in the contorls system for a launched coaster.

I do not know about TTD but for KK there are a couple of things that can cause rollbacks.

Also for KK there are a lot less of them so far then on TTD.

1. KK tests the weight of the car and then launches depending on the weight of the car. I think if its over a certain weight it launches at max.

The very few rollbacks that have happened on KK have been with cars that are not full.

I Was told by an actual ride op that when a car is not full they have to manually adjust the launch power and that if they set the power wrong it will under launch .IF this happens they send the car back to the station fill the car up and launch at max.

2. IF its the first couple of launches at the beggining there would be probably more friction on all the parts until they warm up so it would rollback.

3. There is a problem with the car. I have noticed on coaster celebration there was one car that constantly underlaunched and rolled back when empty because there was a problem and the car was taken off the track .

On KK the main reason though is because of the empty train .I think KKs comp is slightly different then TTD Can anybodyt confirm this? *** Edited 5/30/2005 6:18:42 AM UTC by majortom1981***

---

RollrCoastrCrazy said:gramatically

---

Hmmm...

-Jimvy! ;)

---

RollrCoastrCrazy said:The time to help you when you can't even spend the time to ask a gramatically correct question?

---

But...But...But...

Hey Pot! My name is Kettle...People may be more inclined to listen to your advice, were you to spell it correctly;).

[

LOL there is always one... and it ALWAYS seams to be a member of CB that is the spelling police. This is why I hate posting on here, but thanks for you help in aswering the question.

thanks Danimal for your post. I guess I'll just wait for more to post. thanks *** Edited 5/30/2005 3:40:27 AM UTC by Earnhardt2***

---

HAHAHAHAH, You think this site is bad? Trust me, there's another site out there that actually BANS users for mispelling. To be honest, just clean up your posts a bit and honestly, it will help with exposer and replies.