Wheels flats

[TractiveEffort]

How often are C4 performed, yearly?

Depends on the class. Can be mileage then time based if mileage not reached. More like 4-6 yearly.

 

[Raul_Duke]

Did they activate the Wheelchex? So that speed (50mph) is presumably in the DOTE?

50mph is the speed for a HABD activation but no HAB found, I can remember that much off the top of my head.

 

[hexagon789]

Depends on the class. Can be mileage then time based if mileage not reached. More like 4-6 yearly.

So, does that mean potentially a wheel could last 4 years then, excluding flats developing?

 

[randyrippley]

I see; presumably certain trains are more susceptible to wheelflats than others as well, so get 'detected' more often.

As I understand it, the class 86 fleet (as delivered) were a nightmare for it, wheelslips galore causing wheelflats and rail burns. The stations on the WCML were festooned with rail burns due to wheel slip. The station I knew best -Lancaster - at one stage had intermittent rail burns almost along the whole length of southbound platform 4, due to lockups under braking. Also had them due to wheelspin during starting, but thats another story

 

[Nippy]

Did they activate the Wheelchex? So that speed (50mph) is presumably in the DOTE?

50mph is the speed for a HABD activation but no HAB found, I can remember that much off the top of my head.

Yes, although it is now called 'Gotcha'. I was the signalman on the Slough desk that day, the alert goes to Control who advise us of the activation and what speed is required.

 

[hexagon789]

As I understand it, the class 86 fleet (as delivered) were a nightmare for it, wheelslips galore causing wheelflats and rail burns. The stations on the WCML were festooned with rail burns due to wheel slip. The station I knew best -Lancaster - at one stage had intermittent rail burns almost along the whole length of southbound platform 4, due to lockups under braking. Also had them due to wheelspin during starting, but thats another story

No idea if the 86s had it but I seem to recall the 87s had something called an anti-slip brake which would back-off on the power notches and lightly apply the loco brake to reduce wheelspin, though it wasn't as effective as a deft hand on the tap changer.

 

[Timrud]

Thanks for the replies, always interesting to learn

 

[Highlandspring]

Yes, although it is now called 'Gotcha'. I was the signalman on the Slough desk that day, the alert goes to Control who advise us of the activation and what speed is required.

GOTCHA is a proprietary wheel impact system marketed by Lloyds Register Rail; there are others on the market such as Resonate's (formerly DeltaRail's) Wheelchex.

The threshold for action to be taken by NR Control is an impact force of 350kN or greater but TOCs are also sent reports of impacts below this threshold to allow them to manage their wheelsets appropriately. There are four response levels for NR Control action, some of which have separate requirements for different classes of train.

 

[Nippy]

Yes ours used to be Wheelchex, they are now Gotcha.

 

[rebmcr]

Blimey, not much left with tyres now, AFAIK all passenger stock has monobloc wheels, some locos still have tyres.

I'm sure in Paddington 24/7 one of the maintenance guys said the tyres on a power car lasted 2 years or 4 turns on a lathe normally.

Well he was wrong, power cars are definitely monobloc and if they are condition tyre turned, they last longer than reactive turning, it depends how much is taken off each time how many times they can be turned. Minor damage is removed by the parking brake blocks, as they act as scrubbers.

It may be the way the programme was edited which gave that impression rather than the chap himself but I'm positive tyres were mentioned.

The term tyre turning is still used to cover all turning, this includes locos fitted with tyres and the vast majority of stock that don’t have tyres, maybe that’s where any confusion arose, but rest assured, power cars don’t have tyres and in extreme circumstances the wheel sets have been replaced in just over 12 months as an extreme, but they often go the distance of C4-C4.

The tyres were pictured on-screen and the fitter explained the threshold where the wheel beneath started. At least one power car is non-monobloc!

 

[hexagon789]

The tyres were pictured on-screen and the fitter explained the threshold where the wheel beneath started. At least one power car is non-monobloc!

So some power cars do have tyres, then?

 

[cjmillsnun]

The GWR HSTs have a poorer WSP system than some other HSTs, so are still prone to wheel-lock.

Source?

 

[hexagon789]

Source?

Several places tbh, the ScotRail HST introduction thread on this forum, rmweb, and a few articles in Rail Express and Today's Railways.

The ScotRail HST thread mentions (somewhere can't recall precise page/post) that the GWR powers ScotRail are getting will not receive WSP upgrades. Certainly from photos most (likely not all) GWR trailers seem to have the original BR-design WSP system (the orange box on the bogie frame is a giveaway). The other original system is the Lucas Girling one.

Certainly several trailers have been fitted with the new Knorr Bremse WSP but these don't seem to be GWR vehicles.

The Prototype HST trailers, Mk3a and First batch of HST trailers had the Girling system, the Mk3 Sleepers, Mk3b and all later batches of Mk3 HST trailers had the BR system.

the trouble with both original systems is that unlike the Knorr System, they do not randomly fully release brake applications on a 'test' axle in order to check the speed thus it is possible for wheel lock-up to occur as the older systems can be tricked into believing the train is stationary because of locked axles when it's not. At least that's how I understand it.

 

[No Fault Found]

The tyres were pictured on-screen and the fitter explained the threshold where the wheel beneath started. At least one power car is non-monobloc!

All power cars are monobloc!

 

[snowball]

I don't think it's been mentioned yet that the official term is slip when a wheel spins because the train is applying power, and slide when a wheel doesn't turn because the train is braking.

 

[hexagon789]

I don't think it's been mentioned yet that the official term is slip when a wheel spins because the train is applying power, and slide when a wheel doesn't turn because the train is braking.

I've known it as wheelspin for slipping under power, wheelslide for slipping under braking and wheelslip for referring to both together and the generic term for the systems which mitigate their effect.

 

[Raul_Duke]

Or as the old boys say, “She’s kicking her feet up.”

 

[hexagon789]

Or as the old boys say, “She’s kicking her feet up.”

I've also heard "lift off" used for when a train slides under braking.

 

[The Lad]

Or picking her feet up? Slide damages wheels, spin damages rails.

 

[edwin_m]

The tyres were pictured on-screen and the fitter explained the threshold where the wheel beneath started. At least one power car is non-monobloc!

I think the fitter was actually saying the groove in the wheel was the scrapping limit. If so it couldn't have been the inner edge of a separate tyre as it would have fallen apart if turned close to this limit.

 

[TractiveEffort]

Several places tbh, the ScotRail HST introduction thread on this forum, rmweb, and a few articles in Rail Express and Today's Railways.

The ScotRail HST thread mentions (somewhere can't recall precise page/post) that the GWR powers ScotRail are getting will not receive WSP upgrades. Certainly from photos most (likely not all) GWR trailers seem to have the original BR-design WSP system (the orange box on the bogie frame is a giveaway). The other original system is the Lucas Girling one.

Certainly several trailers have been fitted with the new Knorr Bremse WSP but these don't seem to be GWR vehicles.

The Prototype HST trailers, Mk3a and First batch of HST trailers had the Girling system, the Mk3 Sleepers, Mk3b and all later batches of Mk3 HST trailers had the BR system.

the trouble with both original systems is that unlike the Knorr System, they do not randomly fully release brake applications on a 'test' axle in order to check the speed thus it is possible for wheel lock-up to occur as the older systems can be tricked into believing the train is stationary because of locked axles when it's not. At least that's how I understand it.

Most of the GWR HST trailers have the Westinghouse system, but there are still some with BR systems, and both types of Girling ( vehicle powered and battery powered).

They are all older type systems that have less control than the modern systems, the way the logic compares the speed signals, the ability to hold brake cylinder pressure rather than just dump makes the newer systems more efficient.

GWR power cars all have the BR system, except 43053 and 43056, which have the Brush upgraded traction and WSP package.

 

[Mutant Lemming]

Are there any recorded instances where flats have caused a derailment ?

 

[hexagon789]

Are there any recorded instances where flats have caused a derailment ?

Not aware of any in the UK but the 1971 derailment in Salem, Illinois was caused by a wheelflat I believe.

 

[hexagon789]

Most of the GWR HST trailers have the Westinghouse system, but there are still some with BR systems, and both types of Girling ( vehicle powered and battery powered).

They are all older type systems that have less control than the modern systems, the way the logic compares the speed signals, the ability to hold brake cylinder pressure rather than just dump makes the newer systems more efficient.

GWR power cars all have the BR system, except 43053 and 43056, which have the Brush upgraded traction and WSP package.

I believe the nature of the older systems means that total wheel lock-up is theoretically possible. Considering how often the HSTs seem to struggle in poor adesion conditions on the Highland Mainline I'm surprised ScotRail are not going to fit a new WSP system to their HSTs.

 

[Mutant Lemming]

Not aware of any in the UK but the 1971 derailment in Salem, Illinois was caused by a wheelflat I believe.

I did think as much - always thought the issue was more damage caused to track and points by them.

 

[hexagon789]

I did think as much - always thought the issue was more damage caused to track and points by them.

There may well be an incident that occurred in Britain due to wheelflats but presumably they weren't serious enough to warrant much in the way of documentation.

 

[edwin_m]

There may well be an incident that occurred in Britain due to wheelflats but presumably they weren't serious enough to warrant much in the way of documentation.

There was the high speed derailment at Northallerton in the early days of the HSTs, quite scary but no major casualties.

An examination after the accident showed that the leading axle of the leading power car was seized. There were 'flats' worn on the tyres 280 mm long with the resulting false flanges on the outside of the tyres. The false flange on the outside of the right-hand wheel had struck the trailing crossover where it oined the main line and forced the rail wide to gauge subsequently overturning it and leading to the derailment.

http://www.railwaysarchive.co.uk/docsummary.php?docID=1155

 

[hexagon789]

There was the high speed derailment at Northallerton in the early days of the HSTs, quite scary but no major casualties.

I had thought that was due to a gearbox seizing at about 70 mph, perhaps that was a differebt incident? Not good regardless!

 

[edwin_m]

I had thought that was due to a gearbox seizing at about 70 mph, perhaps that was a differebt incident? Not good regardless!

The gearbox seized so the wheel wasn't going round, and soon acquired a large flat with a "false flange" on the outside (effectively there was a rail-shaped gouge in the whee) which derailed it at a set of points.

 

[hexagon789]

The gearbox seized so the wheel wasn't going round, and soon acquired a large flat with a "false flange" on the outside (effectively there was a rail-shaped gouge in the whee) which derailed it at a set of points.

So I wasn't completely mis-remembering. It's very lucky that the end result wasn't more serious.