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Did the A stock also use to struggle with leaf fall
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The concensus amongst 73 drivers is that LU bought some cheap steel on their wheel sets around 2016. Many of them had been driving for a decade prior to that without incident and suddenly they were putting flats on left, right, and centre.
The official independent report refuted that if recall, but the FOI link to the report doesn't appear to work anymore.
philthetube
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yes, they did but no as much as the 73 stock, 2 reasons for this, and their may be others,
They were driven with 2 handles, brake and motors separate, it was much easier to get the wheels turning then re apply brakes with this set up.
also the drivers tended to be much more experienced, very few staff leave the Met, the pic has much higher turnover of drivers.
They were driven with 2 handles, brake and motors separate, it was much easier to get the wheels turning then re apply brakes with this set up.
also the drivers tended to be much more experienced, very few staff leave the Met, the pic has much higher turnover of drivers.
The line north of Moor Park was particularly difficult and I believe that double blocking was used to enhance safety. There was an additional three minutes in the timetable southbound to allow for slipping and what we would now call defensive driving. The BR Class 115 units were also affected.
starlight73
Member
I may have got the link to this report through the Internet Archive:The official independent report refuted that if recall, but the FOI link to the report doesn't appear to work
(The PDF doesn’t open on this iPad; if it doesn’t work on a mobile device, try using a computer)
bramling
Veteran Member
The concensus amongst 73 drivers is that LU bought some cheap steel on their wheel sets around 2016. Many of them had been driving for a decade prior to that without incident and suddenly they were putting flats on left, right, and centre.
The official independent report refuted that if recall, but the FOI link to the report doesn't appear to work anymore.
ISTR the report (I think there’s been more than one) essentially said LU didn’t control vegetation management to the extent where the trains were operating outside of what they could negotiate without flatted wheels.
Clearly something changed during the 2010s, as it didn’t seem to be an issue before that. Whilst you’d for sure encounter trains with flatted wheels in the 1990s, on the Piccadilly Line it certainly wasn’t endemic then. Factors which could change
* something on the rolling stock
* vegetation management
* the way the trains are driven
It wouldn’t surprise me if there is some truth to the steel theory though.
As regards A stock, they didn’t really cope with adhesion that well. In the autumn *every* train would be running around with bad flats. I can remember a memorable autumn journey during engineering when they were running a Watford to Chesham special service. On the journey to Chesham the train could barely get movement, and on the way back the train was only just about being kept under control. The sounds and smells were very memorable.
Worked perfectly for me, thank you. It makes interesting reading (although I didn't trawl through all 122 pages). Amazing to see what level of detail these things go into.
Page 71 of the above report:
Although the Unions counter this by saying the reports into the metallurgical testing have not been made available to them
flythetube
Member
73 stock can deal with leaf fall by isolating the Rheo-static brake (forbidden) and / or braking much earlier than the normal braking point on approach to stations and pumping the brakes I.e release / apply / release / apply.
There are or were issues with the Rheostatic brake dripping out during braking sending the train lurching forward and necessitating an emergency application of the brakes to arrest the train.
Current drivers may be able to confirm this or give comment on how they best handle 73 stock!!
There are or were issues with the Rheostatic brake dripping out during braking sending the train lurching forward and necessitating an emergency application of the brakes to arrest the train.
Current drivers may be able to confirm this or give comment on how they best handle 73 stock!!
Central
Member
When 67TS ran on the Hainault Loop they ran with Rheo brake isolated.
It may be beneficial to briefly describe the 73 braking system and the impact it has in causing flatted wheels. There are 3 braking systems on the 73 stock, 2 of which are important to us. The traditional Westcode friction brakes which apply across all 6 cars briefly upon initial brake application (useful in low rail adhesion situations), and the Rheostatic brakes that automatically take over from the friction brakes after a few seconds, which are much stronger, and obviously apply just on motor cars 1&3 and 4&6. The Rheos should largely be avoided in outside sections during low rail adhesion.
Interestingly, LU trialled a unit this summer with isolated Rheo brakes on a Service 1 (minimum) brake application, but it was not acceptable to the H&S Reps, so LU didn't move forward with it.
The leaf fall briefing that train ops now get every autumn instruct operators to utilise the "Cadence Braking" technique - which is exactly as you say, a Service 1 brake application, then a release of the brake before the Rheostatic brakes apply, then another brake application, and release, and so on. The Rheo brakes are not supposed to be operative under 21 mph (or thereabouts), but there are large variations in when they will come on, including under 10mph in some units.
The 'lurching' you reference still happens but should not really occur in a leaf fall situation as it usually happens at much higher speeds such as before a SPAD or a station overrun. I think it's caused by a slight delay between the rheos dropping out and the Westcode and rheo brakes kicking back in when moving from a Service 4 (maximum) braking application to an Emergency brake application (or by dropping the handle, which has the same effect as an Emergency braking application).
Snow1964
Established Member
That makes me wonder if they changed the control systems around 2016 and they no longer act as fast or are as exact.
The other alternative suggests maintenance has become sloppy, and they are not fully checking and calibrating the braking units to exacting standards anymore. If that is the case (and might not be) I could easily understand if LUL doesn't want to admit publicly to lower standards of maintenance of brakes and their controls.
But it is logically obvious that if there are variations between vehicles, either the spec is very loose, or some are off spec and not corrected.
bramling
Veteran Member
There’s always been an element of variability between trains on rheo brakes - and this applies to some extent on much more modern trains too. Presumably for something like 73 stock it’s something which will have become more pronounced as the trains have aged.
So in practice if service 1
on one train is almost as strong as service 4 on another, this isn’t going to help keep the wheels turning.
I'm confident the RMT Fleet Reps would have reported that at the time. For all its faults, I don't believe LU management are duplicitous when it comes to safety.
Given how controversial the wheel flat issue is, and how much press ridicule it gets, I'm sure sufficient resources are thrown at the problem.
I'm sure the trains were perfect when they left the showroom(!), but over the last 50 years upgrades have taken place. Variations don't just occur between trains, they occur between different ends of the same train! Maybe some of them are simply unfixable at this stage of life?
I've always taken the view that it's part of skill set of a train op to deal with these variations. However, it's harder to accommodate externalities such as leaf fall in preventing wheel slide with harsh and unpredictable Rheo brakes.
Dstock7080
Established Member
Slight clarification, they shouldn’t begin to apply below 21/22mph but if already applied above that speed they will continue to be active down to around 6mph.
Good call.
I spy some weaselly wording. They say that the post-2016 wheels were tested and found to be "to specification", they don't say that they were the same as before the "supplier name change". I think the unions are right to be suspicious, and that full disclosure of the metallurgical tests would show some kind of difference. What that would be, we can only speculate.Worked perfectly for me, thank you. It makes interesting reading (although I didn't trawl through all 122 pages). Amazing to see what level of detail these things go into.
Page 71 of the above report:
Although the Unions counter this by saying the reports into the metallurgical testing have not been made available to them
bluegoblin7
Established Member
Entirely depends on the weather - it was running through normally on several days last week. There isn’t a firm plan to fully suspend the branch this year, rather it is being done based on weather and leaffall predictions, and real-world experience of train defects.
There is a lot more resilience in the base timetable to avoid having to have blanket measures this year.
There is a lot more resilience in the base timetable to avoid having to have blanket measures this year.
43096
On Moderation
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I never realised that the unions are engineering experts, not to mention specialists in metallurgy.
The decision is taken prior to start of traffic every day based upon the day’s adhesion forecast, stock availability and condition, plus any extenuating circumstances such as Rail Adhesion Trains being unavailable. As such, there is no set date, as you would have some days it is, and others when it won’t.
Any union is made up of Members. In the RMT's case those Members come from across all grades, so yes, there are literal engineering experts that run depots, manage the fleet, etc.
Members can also read reports (if said reports are made available to them). Of course, nobody needs to be an expert to read an executive summary.
They may however need a level of expertise to interpret what is in the report, and to consider whether the executive summary is fair or accurate in it's summary of the detail of the report.
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