Ask RideMan #1 - Magnetic Braking

http://pointbuzz.com/content/ask-rideman-magnetic-braking

Nice article Dave! I look forward to reading more of your answers.

Great read. Well done, Dave. I learned a thing or two.

So if I'm reading this correctly, LIM and LSM are basically opposites? LIM produces a magnetic field that pushes metal plates on the vehicle, whereas LSM has magnets on the vehicle itself? Is there an advantage to one system over the other?

Just when you thought you knew a lot about how this stuff works, BAM! Great article! Very informative and well written!

Very interesting read. Made me think of a question to ask you. Hopefully my question hasn't already been asked.

This is awesome! Thanks so much for answering my question! I'd always wondered about all that. I didn't realize that the same units were both brakes and propulsion on Maverick. :)

I do find this stuff fascinating. Wonderful job, Dave. :)

I really enjoyed that. It came just in time too. I finished watching the new season of "Orange is the New Black" yesterday. ;-)

birdman said:
So if I'm reading this correctly, LIM and LSM are basically opposites? LIM produces a magnetic field that pushes metal plates on the vehicle, whereas LSM has magnets on the vehicle itself? Is there an advantage to one system over the other?

They are not exactly opposites, but they work in different ways. With a LIM, the stator coils work against a magnetic field induced in the reaction plate. With an LSM, the stator coils work against the magnetic field supplied by the permanent magnets. There are direct analogs in the world of rotary electric motors. The LIM compares to a brushless induction motor, where the magnetic field in the coil windings induces a field in the wound or plate-core rotor and pulls it round and round. The LSM is more like the (possibly more familiar) brushed motors, which have either permanent magnets or electromagnet coil stators. Most DC motors are of this type.

It doesn't matter whether the stator is on the vehicle or on the track, although for practical reasons on a coaster you're not going to find a stator coil on the train, just as it doesn't matter whether braking magnets are on the track (Millennium Force, GateKeeper, Wicked Twister, Snake River Falls, Rougarou) or on the train (Dragster, Maverick). Again there are analogs to rotary motors...most motors have a fixed housing with a rotating shaft in the middle, but motors used in ceiling fans and bumper cars are usually just the opposite, with a fixed shaft and a rotating housing.

As for the benefits of either...as I understand it, LIMs are simpler to build and operate because the field in the reaction plate is always in sync with the stator field. LSMs are more efficient, can operate with a larger air gap between the magnets and the stator, and of course are particularly useful in an application like Maverick where a disconnected stator becomes a braking reaction plate.

--Dave Althoff, Jr.

I have an old Technics direct drive turntable from the 70s which I believe works just like Maverick, with the permanent magnets on the turntable platter and the stator on the chassis. Very interesting technology for something from the 70s.

Great example, Pete...there were a couple of those in Master Control over at WCBE-FM when I was contracting there back in the early 1990's. I wouldn't be surprised if they're still there.

--Dave Althoff, Jr.

Please excuse my ignorance but where are magnetic brakes located on Snake River Falls and when were they installed?

I remember working Shipwreak Falls, similar yet different ride at Geauga Lake and it essentially used the water to slow the boat after the drop and then good old fashioned "skid brakes" to lift the boat out of the current. Just like an old fashioned log flume.

The magnetic brakes are on the drop, closer to the top. Instead of fins they are metal strips. I'm not sure exactly when they were installed, but they were retrofitted after the ride was in operation for years. It was not too long ago, maybe 5 years or so.

Thank you sir! I never knew or noticed this and I usually don't ride water rides.

You're welcome, and I might add the Snake River Falls does slow the boat with water at the bottom, just like Shipwreck Falls and most other flume rides. The magnetic brakes are trim brakes, to lessen the impact into the water.

Yea, I assumed that much when you stated they were on the drop near the top. I can honestly admit to having never ridden the ride due to my general dislike of being wet at parks.

Anyone know if these were installed after the Knott's incident?

I believe they were installed long after the Knott's incident. So yes, after Knott's, but no connection.

Snake River Falls has about as much in common with Perilous Plunge as the Turnpike Cars had with a Corvette ZR-1.

--Dave Althoff, Jr.

Yea, for a long time I assumed they were both Intamin rides. After your article I was doing some research and learned SRF is an Arrow. Didn't see anything else other then an incident on the ride in 2013 in which a boat jumped the track after the drop, but that was blamed on low water level (source: Wikipedia so take it with a grain of internet salt).

The park did blame that SRF incident on low water level if I remember correctly. It was really as minor of an incident as it gets... especially compared to the STR lift hill accident that happened a month later. The media still got a hold of it and put it on the news though.