How do Launch Track Brake Fins work?

[Temleh]

Hi guys,

My question is, what failsafes are in place on Intamin Hydraulic Launch coasters (such as TTD) to ensure the brake fins rise as soon as the train passes them during a launch? Are they counterweighted or...? Baring in mind if the fins didn't raise and a rollback accord there would be a serious accident!

Thanks in advance,


Matt.

 

[PeskyTrimBrake]

There are magnets under the train. So, what the break fins do is that it "juggles" the charges and switches polarity constantly so that it pushes the train the other way to a halt in the case of a rollback (positive + positive = repel). Sensors feel the train pass by and unlock the brake fins.

Well, thats at least how LSMs work... Not too sure about Accelerators

 

[MouseAT]

I'm not sure how the system works in terms of a mechanical fail safe, but I think there are usually two sets of fins controlled independently, so there's probably some form of redundancy there. Apparently the brake fins rise after a certain time has elapsed, not after a sensor detects that the train has passed them.

The brake fins aren't magnets on the accelerators. They're solid copper fins. The only magnets are mounted on the trains. (Some other rides use a similar but reversed arrangement but with magnets on the track and copper fins on the coaster, but there are still only one set of magnets involved). As the brake fins and magnets pass each other it induces an electric current in the fins, which in turn creates a magnetic field (similar to an electromagnet). The fins get warm in the process, so I suspect a lot of the energy from the train is ultimately dissipated as heat. Take a look at http://en.wikipedia.org/wiki/Eddy_currents for more information.

 

[Hixee]

I'm not sure how the system works in terms of a mechanical fail safe, but I think there are usually two sets of fins controlled independently, so there's probably some form of redundancy there. Apparently the brake fins rise after a certain time has elapsed, not after a sensor detects that the train has passed them.

This sounds right to me. My guess is that they're pulled down by some sort of actuator before the train launches, then they simply spring up when the actuator releases (whether that's after a given time or by sensors I wouldn't know, although I'd guess time for simplicity). That way a complete electrical failure of the system would cause the brake fins to rise into place, and therefore 'securing' the system.

The brake fins aren't magnets on the accelerators. They're solid copper fins. The only magnets are mounted on the trains. (Some other rides use a similar but reversed arrangement but with magnets on the track and copper fins on the coaster, but there are still only one set of magnets involved). As the brake fins and magnets pass each other it induces an electric current in the fins, which in turn creates a magnetic field (similar to an electromagnet). The fins get warm in the process, so I suspect a lot of the energy from the train is ultimately dissipated as heat. Take a look at http://en.wikipedia.org/wiki/Eddy_currents for more information.

Just to add my two cents to this, MouseAT is absolutely correct. The fins are nothing more than laminated layers of metal (I wouldn't know what types off the top of my head, but copper would be a pretty large constituent). Having the layers allows you to better dissipate the heat by using other metals with better thermal properties. Eddy currents form in the fins as a magnet is passed over them, which (as MouseAT correctly says) generates a magnetic field in the fin. Crucially (and the beauty of this system) is that the generated magnetic field opposes that of the magnetic field creating the eddy currents, causing the braking force.

It's a wonderfully elegant system really... :lol:

 

[Taxi]

I've been under the impression that they require power to lower. The up position is their default position, so when no power is applied they rise up.

 

[bmac]

I've been under the impression that they require power to lower. The up position is their default position, so when no power is applied they rise up.

Can confirm, once pressure is released (via hydraulic or air pressure) they set into their default position. Even with Thunderbolt's case with the brake fins on its lift hill they are up when there is no pressure in the system.

 

[Taxi]

^Ah. I've always just assumed that's how they worked. It only makes sense, especially if you want to avoid any accidents.