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| Re: Flat wheel spots on the R46 (350658) | |||
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Re: Flat wheel spots on the R46 |
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Posted by Train Dude on Sat Dec 9 21:18:55 2006, in response to Re: Flat wheel spots on the R46, posted by SelkirkTMO on Sat Dec 9 20:59:23 2006. The problem is not with dynamic braking per-see. Dynamic braking does shift the paradyne of subway car operation, however.For example, cars with dynamic brake do not coast unless the propulsion system is locked out. In coast westinghouse cars generate up to 140 Amps of braking current in coast and GE SCM cars can generate as much as 300 Amps. Hence the car is either always accellerating or braking. One problem related to dynamic brake, though, is when the air brake system does not recognize that the car is in dynamic brake and you get "air over dynamic" which effectively doubles the braking effort on those wheels. I believe that the biggest contributor to the problem was the change-over to composition shoes. While lighter and providing better braking effort, they do get hotter faster and can cause wheel tread surface problems as mentioned previously. |
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