Giant Drop Failsafe?

[jordang]

Hi guys, My first post here - so apologies if this has been asked previously (i did do a search and couldn't find anything).. Was wondering if anyone can describe how the 'failsafe' brakes works on the Giant Drop at dreamworld? Just a curiousity, thats all!

[Slick]

Are we talking about the magnets or the failsafe system in the event of "no electricity"? If we're talking about the magnets, all that happens is that they're basically work like aa north and against north, but at certain stages the force increases and decreases. You'll also notice that for docking there a two air compressor systems, which is what makes that whacking noise as you come back to the station. But incase there is a power-out, they can manually release each winch from the gondola using the west lift's board, which is basically the master board of the two. Please correct me if I'm wrong, because I would also like to know just a bit more....

[jordang]

Yeah, just curious how the electromagnetic braking system works - My understanding (i.e. that of a first-class newby :-) ) is that the gondolas have magnets on the back of each car and then the tower has some form of opposing magnet against it towards the bottom for braking. So are these magnets power dependent, or for example if the entire park had a huge power failure (just hypothetically) while the gondona was on the way down, the magnets would still work o.k?

[Richard]

On the backs of the gondolas are parallel magnets, aligned as N-S, such that they attract each other, and more importantly there is a horizontal magnetic field that moves from the North to the South edge. The fins seen on the towers are made from a non-magnetic alloy of some sort. I couldn't say for sure, but I'd expect copper and aluminium to be present. There is no magnetic attraction or repulsion present in slowing down the gondola. There is no attracting, no repelling or anything like that in the braking system. What does go on is a concept known as magnetic induction, and involves Faraday's Law of Induction and more specifically motional emf (electromotive force, synonymous with voltage). What this basically says is that when a body (the alloy fins fixed to the tower) is subjected to change in magnetic field (the magnets fixed to the gondola), two things will result: a force opposing the direction of motion (the braking force) and a current (which is what causes that hum when it hits the brakes). The current is a constant (based on the parameters of the setup - magnet strength and separation, alloy composition etc.), so therefore the force is a variable, i.e. the braking force is proportional to the speed of the gondola. This means a few things - the velocity of the gondola after some time in the braking will reach a constant speed which it cannot go below, as magnetic induction cannot physically stop a moving body. The two "arms" that the gondola hits coming into the station would actually be hydraulic, not pneumatic, and serve the purpose of slowing the gondola to a gentle stop. It is in no way reliant on electricity and the system is 100% failsafe.

[jordang]

So basically, the only way the brakes fail is if the laws of physics fail. Probably not gonna happen. :-) Thanks so much guys!!

[Nebuchanezzar]

So, Richard, I didnt quite get the gist of all youe explanation, can you dumb it downn a bit, cause I found it rather interesting.

[Richard]

Find yourself a physics textbook and find the section on "magnetic induction" if you're interested in it. It's not an overly difficult concept, but I wouldn't want to try and explain it in any greater depth here - it was a whole chapter in my university physics textbook.

[jordang]

Hey Nebuchanezzar, have a look at this: still a bit confusing for the physics newby (i.e. me) but it helped a bit. http://www.d303.org/schools/scn/stcnacad/s...urj/content.htm

[pandora440x]

Why is there an air compressor supplying air to the Giant Drop? Pneumatics or hydraulics?

[Richard]

Is the air compressor for the "rods" in the station, or whatever you want to call them? I just assumed they were hydraulic because that would be the logical choice for what they're doing, especially given the different properties of air versus liquids.

[DaptoFunlandGuy]

in regards to there being a failsafe, what would be the better choice in regards to an outage of power or other such event? hydraulic or pneumatic?

[dr_teeth]

in regards to there being a failsafe, what would be the better choice in regards to an outage of power or other such event? hydraulic or pneumatic?

this wouldnt matter much either way as the gondola in the event of power failure would be slowed to a safe speed by the magnetic braking on the tower...might stop at the bottom with a little clunk instead of nice and smooth as usual

[Slick]

I' not actually sure on whether or not the rods i'm talking about are air compressors, I just presumed because of some of the guages that were on the side, but I really didn't get a good glance, but next weekend will be great for further investigation.

[pandora440x]

I' not actually sure on whether or not the rods i'm talking about are air compressors, I just presumed because of some of the guages that were on the side, but I really didn't get a good glance, but next weekend will be great for further investigation.

Typical male, making assumptions at every turn! The items in question are indeed hydraulic, as Richard deduced. This will always provide for a smooth stop, even in the event of a power outage. This is assuming that the ride is loaded within the limitations of the braking system. The compressed air supply is used on the cable guides found along the sides of the tower. There are three of these on each lift, and their purpose is to retain the lengthy cables. (Think windy conditions.) The original design only provided one cable guide on each lift, however this did not prove sufficient for the length of cable in use, and some of the weather conditions prevalent at Dreamworld. Subsequently an additional guide was added below and above the original guide. One or all three guides can be selected for use, however Dreamworld has opted to use all guides as standard.