Why do trains need suspension?
15 July 2003, 03:45 PM
#1
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Probably a stupid question if you go on the rattly clunky Underground, but seeing as a piece of iron railway track seems pretty smooth and the joints pretty even, why do trains need huge big suspension affairs?
I ask as I went on a modern train the other day and you could whisper a conversation at 150mph and it was so smooth that you could balance a ping pong ball on yer nose all the way to Oslo
If the track is laid right…?
I ask as I went on a modern train the other day and you could whisper a conversation at 150mph and it was so smooth that you could balance a ping pong ball on yer nose all the way to Oslo
If the track is laid right…?
15 July 2003, 03:58 PM
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you could whisper a conversation at 150mph and it was so smooth that you could balance a ping pong ball on yer nose all the way to Oslo
....becuase the train had suspension...
15 July 2003, 06:13 PM
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shock absorbion, that's why. Even though the rails look prefectly laid they are not. The ballast is NOT at an equal depth, neither are the sleepers, plus the rails may look smooth, they are not, there are pits in the them. Plus the joints have gaps, mainly to allow for expansion.
Cornering is another factor too, as a fast curve will more than likely be slightly banked, thus a rigid base would not help that.
Guess you could say the same about cars, why do they need suspension? if it's a perfect road, you don't need it.
I know a little bit about track infrastructure as the old man used to head up a repair team, but now he heads up an ultrasonic testing team, and thus I get to hear about exactly where the dodgy bits of rail are on the South East network!
Cornering is another factor too, as a fast curve will more than likely be slightly banked, thus a rigid base would not help that.
Guess you could say the same about cars, why do they need suspension? if it's a perfect road, you don't need it.
I know a little bit about track infrastructure as the old man used to head up a repair team, but now he heads up an ultrasonic testing team, and thus I get to hear about exactly where the dodgy bits of rail are on the South East network!
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15 July 2003, 06:21 PM
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and thus I get to hear about exactly where the dodgy bits of rail are on the South East network!
15 July 2003, 06:25 PM
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You're quite correct. Scary is not the word! Seriously though, it's not that bad. there are one or two hotspots, Tonbridge being a main one. Why? well, it's where the Hastings and Paddock Wood lines meet up and thus is a "hub" for part of the network, so there is a lot of traffic. So if you're train is delayed, it's probably my old man's fault, has he has found a fault on the track and has got the line closed for repairs! And yes, I have travelled by train and shouted at him from the window when I've been delayed
16 July 2003, 10:18 AM
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In answer to the q, that train I went on was Oslo airport to the City Centre - absolutely superb (and that's a TOTAL public transport avoider speaking there!) You didnt even feel you were moving - maybe, as hinted at here, that is because the suspension moved about, but the train didnt...that's the way to do it! 4 times further & twice as fast for the same cost as the Heathrow Express (famous for being 'most expensive train journey in world' for distance v cost).
I'm very happy to have a physics lesson! I can see undulations and pot holes in the road - even on a smooth race track - but rails still look as smooth as a baby's bottom to me
D
I'm very happy to have a physics lesson! I can see undulations and pot holes in the road - even on a smooth race track - but rails still look as smooth as a baby's bottom to me
D
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