Halt!

[Jer]

There was been something that has been bothering me for a long time now.

As we all know intamin rocket coasters use a hydrolic powered winch and catch car to launch the ride. And the train itself has brakes to stop, but what I'm wondering is what stops the catch car? Lets use Kingda Ka as an example of what is stumping me, that catch car brings the train so fast, and it has to have a **** load of momentum, so I dont think simply having bumpers would stop that catch car.

 

[Hixee]

It has tiny magnetic brakes that stop (or at least slow) the catch-car over a short section of track after the train disengages.

Simple really.

 

[lakeccrunner]

^ That brings up another question, at least in my mind. How does the train disengage from the catch-car before it hits the catch-cars brake run.

Or does the slowing of the catch car happen before the train disengages, and the train just continues to move along?

 

[Snoo]

http://en.wikipedia.org/wiki/Accelerator_Coaster

 

[Hixee]

^Yeah, save me typing:

When the train reaches full speed and all the pressure in the accumulators has been released, the catch-car, still connected to the train, enters its braking zone. The catch-car uses the same braking configuration as the train, but is much lighter, so it slows down very quickly. As the catch-car begins to slow down, the train's launch dog retracts - the shape where it drops into is a "v" shape, so the dog is forced back into position as it runs over the catch-car and is held in place by the magnet, as the train continues on its way.

 

[lakeccrunner]

^ That answered the next question I was going to ask about how the dog went back into position...You guys are good!

 

[Hixee]

Reading... just picked it up somewhere...

 

[kimahri]

I AM REPTAR!

I always though it would go into some breaking thingy majig but on a smaller scale but something popped up in my mind, S&S' Airpowered launcher's catch car's sort of, bounce back and forth when they let go of the train. I'm guessing that's just cause of the way air launches work. Could it work for Hydrualics?

 

[Hixee]

^I don't think so. As far as I understand, the hydraulic pressure spins a flywheel which pulls the train along. After the pressure is released there's no re-compression so no bouncing. On the S&S air powered launches the catch car is attached directly to the piston inside the big cylinder. As the piston reaches the bottom end of the cylinder there is an air build-up in front of it (and a vacuum behind) causing the catch car to start going 'backwards'.

Kinda had to describe, but I hope it makes sense.


[EDIT] Here's a diagram:

Basically the grey block is the catch car, which is forced down the cylinder (underneath the track) by the compressed air (shown as red) stored in a tank (not shown, but where the compressed air arrow comes from). This accelerates the catch car (as there is a pressure difference). As the catch car nears the end of the cylinder the air that was previously in front of it is now compressed, causing the catch car to stop, then start accelerating backwards. As the excess pressure from the tank as been released, the catch car just bobs back and forwards until it reaches the equilibrium. It's then pulled back to the start for the next launch.

Is that right? (loefet )

 

[Xpress]

Huh, you can sort of see the catch car brakes in this pic:

 

[lakeccrunner]

^ Nice. Those brakes are adorable. :lol:

You can see the dog in this picture. This is the only picture I've ever seen where you can see the dog.

 

[Xpress]

And here is some pics of Xcelerators catch car/track:

The car itself:

You can see the cutout where the catch dog sits in and scraps against when train and catch car separate.

The mechanism that keeps tension on the entire assembly:

Also pictured is the return cable/pulley.

More catch car track:

And the car zipping beneath the train:

Here is a video of the catch car returning to the station:

[youtube]http://www.youtube.com/watch?v=G-eEOXWHPzs[/youtube]

I can also get pics of the catch dog next time I'm at the park. You can sort of see it on the turn before the trains enter the station.

Just for those of us who have never been near an Accelerator coaster

 

[lakeccrunner]

I always thought it was pretty awesome how Xcelerator launches from inside the station. On TTD, Ka and Storm Runner (can't speak for the others, as I haven't ridden them), the only way to see the catch car and all that fun stuff is to ride front car.

Edit:

I didn't realize how far from the end of the launch track the train released from the catch-car.

 

[Xpress]

^That's why I posted them. Not everyone gets the luxury of watching the components do what they do best.

 

[Anonymous]

[EDIT] Here's a diagram:

Basically the grey block is the catch car, which is forced down the cylinder (underneath the track) by the compressed air (shown as red) stored in a tank (not shown, but where the compressed air arrow comes from). This accelerates the catch car (as there is a pressure difference). As the catch car nears the end of the cylinder the air that was previously in front of it is now compressed, causing the catch car to stop, then start accelerating backwards. As the excess pressure from the tank as been released, the catch car just bobs back and forwards until it reaches the equilibrium. It's then pulled back to the start for the next launch.

Is that right? (loefet )

It's pretty similar to an accelerator coaster in one way. but doesn't rely on a winch drum, but an continuous loop.
There is an image from Coastersandmore.de which shows how it all work pretty good, it's about halfway down in their Dodonpa article: CLICK

The Catch-car is connected with a piston on both ends with a long wire. Compressed air is forced into the cylinder from one direction which makes the catch-car and train go in the other direction...
It's the exact same principle they use for their tower-rides, screaming swings (even though they use a slightly different way to convert the linear movement to swinging)...