Composites Stabilize Diesel Train Engine Enclosures
A prototype diesel train engine housing made of a new polyurethane-based glass fiber sandwich material saves 35 percent weight and 30 percent cost over its steel and aluminum counterpart. (Source: Bayer MaterialScience)
Battar and skranish, thanks for the discussion about terminology. I'd never heard of a DMU before, but like most of our readers, I'm not an expert in this area. Ultimately, though, the focus of the article was what the materials can do in this application, and that was pretty clear.
Sorry to disappoint you, but I have never even been to the UK, and I do not fit the usual definitions of trainspotter (not a term used in the US), railfan, or foamer. My childhood photos do not include any of trains.
The rather confusing term "diesel light rail" is sometimes used in the US. I looked at the Austin Capitol Metro and North County Transit Sprinter websites, and neither offers any description of their trains. The Austin Metro and Sprinter websites both include numerous linked documents containing the term "DMU". The Vandalpedia pages for the rail lines describes Austin as a "tram train" - definitely not a term in the US lexicon, and Sprinter is described as a DMU.
The SMART website describes their trains: "SMART will use Diesel Multiple Unit (DMU) vehicles manufactured in Rochelle, Illinois, by Sumitomo Corp. of America/Nippon Sharyo. The DMU is quieter and cleaner than conventional locomotive-hauled equipment. These self-contained rail cars include on-board engines and are capable of using alternative fuels such as waste-derived bio-diesel."
The Portland Westside Express website does not directly describe their trains, but numerous PDF documents buried in the website use the term DMU. The Portland railcars, the only ones of their type, are FRA compliant and can run on mixed traffic rail lines without requiring temporal separation from freight trains.
An engineer from the UK company GEC Marconi once said to me, and I quote, "only a trainspotter would use the term DMU". Let me guess - you are from the UK, at one time in your youth you used to stand on railway platforms photographing trains, and you owned, or own, a Hornby model railway.
"This housing is located beneath the passenger compartment, i.e. between the car and the tracks. Not only does it shield the engine against flying stones and protect the environment from any oil that might escape, but in the event of a fire, it also stops the flames from spreading, thus meeting the flame retardant and fire safety standards for railway vehicles."
That pretty well describes a DMU. The "multiple unit" part of DMU means that more than one car can be coupled together an run as train.
skranish, thanks for your comment. The Fraunhofer press release http://www.fraunhofer.de/en/press/research-news/2012/march/building-lightweight-trains.html discusses this in the context of trains (including in the headline), calls this suitable for diesel engine housings on trains, and mentions both the engine and the cars, although it doesn't mention whether the cars are powered.
Everyone has missed the point here, because the original article is not very clear. There is no locomotive, what is being described is a DMU (diesel multiple unit) passenger car. They are not common in the USA any more - there are just three commuter systems (Austin TX, San Diego's Sprinter, Portland OR Westside) that use them. The Marin County SMART will also use them.
There used to be lots of them in the USA - the Budd RDC (Rail Diesel Car) could be found across the country.
DMUs are very common elsewhere in the world, especially the UK and Europe. The major problems with adoption in the use are 1) the FRA treats them as locomotives, with the required inspection schedules, and 2) international designs do no meet FRA rules for impact (buffing) strength.
Typically these cars have two diesel engines - often derived from truck engines - mounted UNDER the passenger compartment floor. The cover is intended to keep debris and weather OUT and any leakage IN. The RDCs had no such covers, which probably did not help their reliability.
Drawbar pull, weight, etc are not really the issues here. DMUs are self-powered, although some are intended to pull a single unpowered trailer. They are NOT designed to pull a train of unpowered cars.
This makes no sense at all. The locomotive must be heavy as the drawbar force is the product of the weight and the coefficient of friction of the wheels on the rails. The limit is the permanent deformation of the wheels and the rail. For more drawbar force, use multiple engines, totalling more weight.
Ann, it seems like this composite has the performance advantages -- light weight, good structural capacity -- that engineers want. How does it measure up to more traditional materials in terms of cost?
Beth, it's still a prototype in the testing phases, and no potential contract awards were mentioned. But since it's the German government funding the project, one might guess that it could be used in German trains, as well as the other applications mentioned: roof segments, side flaps, and wind deflectors for automobiles and commercial vehicles.
NIST's new five-year strategic plan for its Material Measurement Laboratory lists additive manufacturing materials development as one of the main areas it will support by developing measurements, data, techniques, and models.
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