Another TTD RollBack question

I was watching the TTD Maintance Video and it shows the train rolling back. Whenever i walk by TTD and see it roll back it takes a while for the fins to drop back down into the track, which at this point the train is moving very slowly. My question is that if the train is moving that slowly how does it get all the way back to the station on that little amount of energy?

Very Slowly. The fins go up and down several times in the process of TTD's train rolling back to the launch position. I think it takes a couple minutes before the train is in position to launch again.

Ya, I always see it start to hit the launching brake run but i never have waited to see it relaunch.

Isn't the launch run on a slight incline, which also enables the train to help (slowly, but surely) back to the launch position?

The brakes are held up by springs. They are pulled down with air pressure. After a launch the brakes are lock up and a timer starts. If the train clears the tower within specific time frame, then the brakes unlock and permit another train to enter the launch area. If the timer times out then the brake remain locked and a trouble light is generated. The train may clear the tower slowly, but usually it's a rollback.

The eddy brakes are very powerful at high speed. When a train isn't moving, they have no braking power at all. As the speed increases, the braking force increases proportionally. The launch and brake track gradient is large enough for the trains to break over static friction even when cold. When the brakes are up, the train will slow to a point where the force the train is pushed due to gravity down the slope is the same as the braking force of the eddies. The result is the train moves very slowly.

The ride must be switched to manual mode and reset. After that and several other conditions are met, the brakes can be unlocked and lowered manually. The catch is that the system isn't designed to hold the brakes down for longer periods of time so they pop up after a time interval. As the pressure in the tanks drop, then the brakes cannot stay down as long. When the train gets back to the launch position then it may or may not need to be moved back to the transfer. The ride is then placed in auto mode and the launch is then attempted again.

*** Edited 12/18/2005 6:00:15 PM UTC by ForgottenEE***

What TTD Maintenence video?

^I'm wondering the same thing.

It's like a I'm reading a book when I read ForgottenEE's post. I'm always learning new things. Thank you for that.

ForgottenEE - your description is quite accurate - good research. The only input I can give, if it's ok, is the magnetic brakes. They are constant. Each car on the train has sets of magnetics mounted under the car. They are mounted side by side (approx. 1-1/2 to 2" apart) and there are 2 of these sets side by side for the 2 fins. The magnetic field is so dense between the magnetics that nothing (the brake fins) can penetrate the field very quickly. These magnets are permenant and never change. When the train is in roll back mode it reverses back down the incline due to gravity and nearly stops due to the dense magnetic field. The fins are lowered quickly and often at this point to allow the train to continue backward a little faster or it would take forever (thus the fins are not in the magnetic field when down) no matter where the train is - in the launch area - in the trim brakes enroute the station or in the moveable brakes just prior to the station - if the fins are up - it is in a brake mode - even if the train is stopped it is braking due to the constant magnetic field. Hope this helps

Also that is why you see a lot of "heat waves" during full operation. The magnetic braking is discipating so much energy, everything gets real hot and when it rains just a little, will create steam on the fins.

ForgottenEE-That is a very informative post but I do beleive that there is a sensor on the "downside" of the hill that must be tripped to unlock the brakes. Not a timer.

~the clean up crew~

The TTD Maintance Video is just a link that i found on this website, it is http://capital2.capital.edu/admin-staff/dalthoff/adventures/dragster.html

clean up crew said:
ForgottenEE-That is a very informative post but I do beleive that there is a sensor on the "downside" of the hill that must be tripped to unlock the brakes. Not a timer.

~the clean up crew~

I didn't say that a timer unlocked the brakes, I just said that it generated a trouble light if goes off. I didn't mention that when the train clears the tower, the timer is nullifed. I did imply that though.

What I said about the brakes isn't exactly true. It's more of a basic example leading to how they actually work. They are quite dynamic and are very difficult to calculate and impossible to calculate directly.

It’s a good thing we have computers......oh wait....even they can’t always be reliable. :)

In any case, thanks for the basic info on the system ForgottenEE. I thought the brakes were entirely pneumatic....(i.e.) I didn't think springs had anything to do with the rising of the launch brakes.

We learn something new everyday.

I'd wondered about whether cylinders with that long of a stroke could be spring-return or not...looking at the plumbing I was wondering if they were air-driven in both directions.

That's the first time I'd ever seen my Dragster video referred to as a "maintenance video". When I hear the term 'maintenance video' I think about the hour-long video I have that shows how to change the skin on a Scrambler seat (sorry, not available on-line). :)

It took all season to shoot that Dragster video. As you can probably imagine, given the varying train lengths and styles...!

--Dave Althoff, Jr.

The brakes would eventually fall down if it wasn't for the spring return. The seals leak a very small amount. Almost never a noticeable amount but enough that the brakes would eventually fall with no pressure. Even after months of no air pressure during the winter, they stay up.

Millennium Force's cylinders have a small warning label on the bottom because of the spring force inside. I'm sure there is a way to get a picture from the bottom of the unload stairs. I remember back in 2002 when a cylinder was getting weak from a leak I think. They put a bungy cord from the brake to the maintenance handrail by the storage track to help open it.

Funny how I've never seen that video before Dave.. Good one though.

I really like the shot of Sandor ;)

I do belive that the breaks are entirely pneumatic. As shown in http://www.pointbuzz.com/Gallery.aspx?i=34 there are two yellow air lines running to the cylinders. In the bottom-right of the photo (under the Cedar Point on the train) you can see two yellow air lines running up the support. Also if you look at the rest of the up close launch pictures, these run all the way down the track.

~the clean up crew~
*** Edited 12/19/2005 5:43:58 PM UTC by clean up crew***

Forgotten EE: So you know the train must get moved all the way to transfer and clear launch before it can be switched to auto mode. and then the train can get moved into launch.

All the brake cylinders are spring up. There is a double loaded spring in each cylinder. This way if there is an air loss or power failure (which would disable the controls to the valving) the cylinders extend very quickly upward. The springs are very powerfull as you can hear the cylinders slam when they move upward.

The same with the brake chambers on Millinneum Force. If there is air loss or power failure the brake chamber has a large spring inside that slams the brake closed (these are mounted under the magnets on the bracket). (brake chamber is the same you see under a big truck on the highway, trucks have same thing if they loose air - instant stop)). Same on Demon Drop big brake - brake chambers used there also. B&M uses their own design cylinder on their brakes that is spring loaded to close.

All amusement rides are designed so that in power failure or estop everything goes to closed position - no exceptions and in nearly all cases this is done without the use of pneumatics. Only exception is older Arrow coasters that close by air and open with a small leaf spring.

Thanks for the clarifacation Jim. So if we're on Corkscrew and the power goes out....we're screwed. :)

~the clean up crew~