Listen to the last 2 or 3 coaches as they pass, doesn't sound to good!??
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A flat tyre?


Seriously, may be a flat spot on a 'rim', there must be someone here with some teknikkle nollidge…

Doug

Read somewhere that leaves on the line at this time of year creates breaking problems which can cause flat spots, so Doug may well be right.

(Made me think of F1)


Ed


PS Interesting thread title Ron :shock:

[user=1338]Ed[/user] wrote:

……………………………………..

(Made me think of F1)


Ed


PS Interesting thread title Ron :shock:

I've heard they occasionally leave the track but I thought it was a different type of track ………………….and a different meaning for "leaves" …….:cheers

not a flat spot, the whole tyre will be worn down,due for a new one fitted,
:thumbs;-):cool:
OWEN

I note there have been 59 views but only 4 comments ...................this is a railway forum gents so the thread title needs a bit of lateral thinking ............:cheers

Trust you to think of that Peter. :pedal

Solution?

Peter
Sometimes I hear a cavitation noise when one of the kids has a rear window in the car open partway on the expressway.
Thats outside the box.
Andrew

Ah that's easy to solve Andrew.  You could either get rid of the kids or, if that's not possible, stuff them into the gap between the window and the car body - a bit like a draught excluder.  It stops the noise ……………:cheers

Sorry for the hijack Ron - now back to Virgin Trains and their flat tyre ………………….:thumbs

Long time since I came across a virgin with a problem! 

Long time since I came across a Virgin……….



























it's all Abellio Greater Anglia around here.

I'm getting tyred of these innuendos, it's  virgin' on the ridiculous. …

Who are you calling ridiculous Doug? 

Perhaps it just a case of lateral movement on the axles (within tolerances of course). I hear it quite often in areas around here, especially if the track is getting close to renewal. Add to that the build up of grot on the rails and there you have it.

Ignore all trains proclaiming themselves Virgin.  They've been into more tunnels than most of us ………….


Obligatory crude joke over here's the teck-nickel stuff.

That's an HST set.  They cruise at up to 125mph in fixed formation sets.  What you can hear is a tiny flat spot - which might be a millimetre or less in width - on one wheel tyre rotating very fast and hammering the track with each revolution.

In an ideal world tyres are perfectly round.  They start out that way when fitted to the wheels.  Ignoring the minuscule and momentary flattening effect as the wheel contacts the rail (though that is necessary for traction purposes and without it the train would never move at all) it only takes one fractional moment of slip or brake-lock to create a flat spot.

The problem might be caused by unequal braking forces or slow release of brakes from the affected wheel set or by a momentary loss of traction through slipping on any low-friction substance on the railhead such as a leaf, insects, oil or even water.

It typically does not affect more than one or two wheel sets on a train unless the whole train has skidded along the rails which is an extremely rare event.  On fixed-formation sets it isn't easy to remove one vehicle while keeping the rest in traffic then arranging for the casualty to be tyre-turned on a wheel lathe.  But that is what is required.

In most cases minor flats will be left until the set is next rostered a classified examination at a depot where it can be dealt with.  Minor wheel flats are remarkably common on HST sets for this reason.

The hammer-blow does create extra unwanted stresses to both track and train but on the modern railway the logistics of dealing with these things immediately usually don't stack up favourably and they are left for days and sometimes weeks.  It's not considered a safety risk.

Major wheel flats where there is a huge clunk every time the wheel rotates and which can actually be felt by passengers travelling aboard a vehicle so affected require its immediate removal from service for ultrasonic checking and attention on the wheel lathe - very severe cases will require a complete wheel-set change.

That rang a bell Rick :thumbs

http://www.bbc.co.uk/news/uk-england-norfolk-34797519


Ed

I see in that report that they get objections to increased train noise if they cut trees down to cure the leaves on line problem. My answer would be take out all the deciduous trees and replace with evergreens, simples.

Selling point for the noise sensitive is that with leaves on all through the year  the noise level will be constant, not just quiet in summer and noisy after leaf fall. Just forget to mention that it'll be a few years for the new trees to grow enough to reduce noise level