NegativeGs Posted July 17, 2020 Share Posted July 17, 2020 13 hours ago, RayFields said: Below is the best post I have found that accurately describes why B&M coasters sometimes exhibit a "rattle"...Personally I don't find Diamnodback's rattle to be excessive and I think Banshee's rattles is heavily accentuated by the restraints. If Cedar Fair wanted to fix these rattling issues on these or any of their B&M coasters then they'd simply have to increase the size and stability of the footers for said rides *************************** Here's the post The rattle as I understand it is a shimmy in the train during high G movements on a B&M. During high G on some of the B&Ms the train will get a shimmy to it which is a side to side motion as you are moving forward. It has a tendency to rattle the train giving it the B&M rattle name. The train will shimmy so much that it actually makes the train rattle. Cause... The cause of this has to do with the footings that the coaster sits on top of. When the footings area not installed correctly or are not large enough they will move a little as the train goes over that section of track. The movement may only be millimeters but its enough to reverberate up to the train that is in high G. Partly you have to remember you have a 50,000 pound train amplified by 3 G making the applied force in the the track and structure over 150,000 pounds. Any movement in the footings is sent back to the train. The most notable one I have ridden is Goliath at SFOG. On the first and second drop at the bottom you will get the shimmy. During one of the tours I did we were standing under the coaster and noticed that the footing and ground moved as the train went by. That movement is what causes the train to rattle. On Fury 325 I asked that question about footings. ON Fury, half of the rides footings are connected deep in the ground to bed rock. A hard layer of ground usually deep in the ground that is more or less solid rock. You connect the footings to it, then to the support, to the track. The problem area that could effect Fury is on the out run near the tunnel. That part is not on bed rock. But the park feels they built large enough footings so that it wont be a problem. So far Fury has no real rattle so it has stayed stiff... What causes the footings to move over time. Several things can cause it. Not large enough or deep enough footings. The constant downward force of the train each time it passes. Bad ground around the footings where the dirt can compress under the footings. Wet and dry seasons or if you are in a frost line area where the ground can freeze moving the footing More or less the rattle is a shimmy in the train, mostly caused by bad footings or bad ground conditions. Can it be fixed, Sure. Dig up the footings and increase the size or better ground. Will items like this be fixed, typically not as the parks arent going to spend the money until it starts to do damage to fast to trains or track. I rode Banshee twice today. It seems to me the rattle is getting slowly worse. As a structural engineer, I do not believe the foundations are primarily at fault for the B&M rattle. If successive coaster builds at Kings Island had foundation issues (because of weak or compressible soil at the park) these issues would be considered by the structural engineer designing the foundations for the future coaster. A significant amount of site exploratory and office design work is involved in foundation design. However, the cost of a substructure is typically small compared to the cost of its superstructure. So, why cut a few $100K on foundations, at the expense of ride quality on a $24M ride? Same applies to Orion at $30M. If a foundation needs repair, it does not necessarily need to be dug up. There are many less intrusive and more cost-effective repair methods. Quote Link to comment Share on other sites More sharing options...
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