Juddering on the 1806 HST Paddington to Frome 20/11/2013

Electric train

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Re: Juddering on the 1806 HST Paddington to Frome 20/11/2013

« Reply #15 on: November 22, 2013, 19:31:09 »

There is a difference between wheel slip and wheel slide

Wheel slip is where there the tractive effort exceeds the wheel to rail friction - prevention is by monitoring the current in the traction motors and comparing the currents and reducing the power to a wheel set that is about to slip, excessive slip causes burn marks on the rail head and flat tyres the wheel set will need to go the wheel lathe; can also on older type wheel sets lead to the tyre moving on the wheel, used to be marks on the "Gibson ring" to help spot this.

Wheel slide is where the braking force on the wheel causes it lock because of the loss of friction between the wheel and rail. Prevention is by measuring the rotational speed of each wheel set, the best solution is to compare wheel set to wheel set, if a slide is detected to release the brake monetarily excessive slides cases flat tyres, if you ever travel in a carriage and hear a tap tap tap and the train move off which get faster in rate as the train picks up speed that's a flat tyre and the wheel set will need to go the wheel lathe.

The visit to the wheel lathe is an expensive business


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Starship just experienced what we call a rapid unscheduled disassembly, or a RUD, during ascent,”

JayMac

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Re: Juddering on the 1806 HST Paddington to Frome 20/11/2013

« Reply #16 on: November 22, 2013, 19:38:12 »

Quote from: Electric train on November 22, 2013, 19:31:09

The visit to the wheel lathe is an expensive business

Which probably explains why FGW^▸ appear to have so many Mk3's in service with wheel flats. Hardly a week will pass by where I don't get to ride in at least one Mk3 with a flat. Not too much of an issue, noise or comfort wise, in a day coach, but a right PITA^▸ if you're over a bogie with a wheel flat in a sleeper coach.


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Super Guard

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Re: Juddering on the 1806 HST Paddington to Frome 20/11/2013

« Reply #17 on: November 22, 2013, 20:05:49 »

Quote from: bignosemac on November 22, 2013, 19:38:12

Quote from: Electric train on November 22, 2013, 19:31:09

The visit to the wheel lathe is an expensive business

Which probably explains why FGW^▸ appear to have so many Mk3's in service with wheel flats. Hardly a week will pass by where I don't get to ride in at least one Mk3 with a flat.

Even if it was a cheap exercise, i'm sure endless short-formed HST^▸ sets running around to sort out flats wouldn't be too welcome either - especially with the current railhead conditions being so bad.


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Electric train

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Re: Juddering on the 1806 HST Paddington to Frome 20/11/2013

« Reply #18 on: November 23, 2013, 12:38:28 »

Quote from: Super Guard on November 22, 2013, 20:05:49

Quote from: bignosemac on November 22, 2013, 19:38:12

Quote from: Electric train on November 22, 2013, 19:31:09

The visit to the wheel lathe is an expensive business

Which probably explains why FGW^▸ appear to have so many Mk3's in service with wheel flats. Hardly a week will pass by where I don't get to ride in at least one Mk3 with a flat.

The track engineer is not keen on flat tyres it undoes his / her tamping


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Starship just experienced what we call a rapid unscheduled disassembly, or a RUD, during ascent,”

Chris from Nailsea

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Re: Juddering on the 1806 HST Paddington to Frome 20/11/2013

« Reply #19 on: November 23, 2013, 13:20:18 »

Thanks for pointing that out, Electric train: it's not an aspect I'd actually thought of before.


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LiskeardRich

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Re: Juddering on the 1806 HST Paddington to Frome 20/11/2013

« Reply #20 on: November 23, 2013, 18:27:29 »

This mornings 0830 from Truro to Paddington had a large amount of wheel slip/ spin pulling away from every station (to Plymouth at least where I left the service) Cornwall had a heavy frost last night so I am assuming this would be the contributory factor. The roads were untreated when I dropped my daughters to their nanny's at 0700 this morning, and there was several patches of sheet ice I noticed between Redruth and Falmouth along the A393 around Lanner.


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JayMac

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Re: Juddering on the 1806 HST Paddington to Frome 20/11/2013

« Reply #21 on: November 28, 2013, 03:00:42 »

Wheel flat on my 0626 Clifton Down to Bristol Temple Meads Class 150/1 yesterday morning. Very noticeable at low speed and had me thinking the sound is very similar to what one used to get when travelling over jointed rail.


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