Trimode cl 769 to operate Reading to Oxford and Gatwick.

[whole diary]

[IndustryInsider]

Hopeless!

[stuving]

I commented earlier that the traction system  was part of the 319, not the conversions. In the latest case of failure that's even more relevant, as at Redhill it was running on third rail. I've heard that 319s had a poor reliability record in this area, and that does seem to be the case.

In 2015, DfT^» (Department for Transport - about) hit GTR with a section 55 improvement notice, for its number of cancellations. GTR's excuse generator came up with some explanations for the poor fleet reliability on Thameslink and Southern operations, citing "Inherited door system and traction motor failures on the class 319" and "...failures on a small number of train systems in the class 387/1 introduction". As further detail, they said:

The two highest failure factors are doors and traction motors and this plan focuses on these two issues.

A door system intervention was undertaken by the previous franchisee between May 2014 and
September 2014. This was intended to improve the performance of the door system across the fleet.
However the work resulted in a much higher failure rate and the underlying door performance
worsened.

Traction motors and motor alternator sets on Class 319 units require a very high level of
maintenance attention to their commutators to remain reliable. The small number of maintenance
roads in Bedford coupled with the very high fleet mileages and the time consuming and intrusive
nature of the work, provided insufficient depot pitted road access for it to have been delivered
effectively. Consequently the condition of the commutators on the Class 319 traction motors and
motor alternators has deteriorated over recent years. This has led to electrical flashovers as a result
of poor commutation resulting in significant delays and cancellations.

I guess that's what you get if you choose to do up old trains. I wonder how much work Porterbrook did on those areas? The GWR^▸ (Great Western Railway) ones do have new 3-phase inverters to cope with the extra load of cabin air cooling, so presumably they at least don't still have the old motor alternators.

[Surrey 455]

A door system intervention was undertaken by the previous franchisee between May 2014 and
September 2014. This was intended to improve the performance of the door system across the fleet.
However the work resulted in a much higher failure rate and the underlying door performance
worsened.

Traction motors and motor alternator sets on Class 319 units require a very high level of
maintenance attention to their commutators to remain reliable. The small number of maintenance
roads in Bedford coupled with the very high fleet mileages and the time consuming and intrusive
nature of the work, provided insufficient depot pitted road access for it to have been delivered
effectively. Consequently the condition of the commutators on the Class 319 traction motors and
motor alternators has deteriorated over recent years. This has led to electrical flashovers as a result
of poor commutation resulting in significant delays and cancellations.

The previous franchisee being First Group a.k.a. First Capital Connect. You'd think that someone at First Group would have remembered the previous problems with these trains before a different subsidiary took them on.

[GBM]

The previous franchisee being First Group a.k.a. First Capital Connect. You'd think that someone at First Group would have remembered the previous problems with these trains before a different subsidiary took them on.

Surely that depends on whether the DfT^» (Department for Transport - about) instructed First to take/use them?

[onthecushions]

The d.c. traction motor and pneumatically operated doors are not exactly key NASA space technologies. There is a little more excuse for software but that has had decades on the learning curve.

The 769 problems say more about present UK^▸ (United Kingdom) rolling stock engineering expertise than they do about the relatively simple 319 stock. This should last indefinitely, like the 4SUBs which went to the torch in full working order with only wear and tear maintenance over their (several) lives.

OTC

[RichT54]

A recent comment on RailUK forums

A friend at GWR^▸ (Great Western Railway) has said 769s are having problems on the gradients of the NDL and that's just the empty test runs. Little confidence at GWR that a train full of passengers and suitcases just won't make it. Slim to zero chance of the 769s entering service on this route apparently.

https://www.railforums.co.uk/threads/gwr-class-319-769-information-discussion.174866/post-5560691

[onthecushions]

A train's performance on a gradient does not depend on whether it is diesel or electric but on its adhesion and therefore tractive effort. This in turn depends on axle load, number of driven axles and rail conditions, where friction can vary typically between 12% and 30%. A  diesel might be less inclined to slip as it could not lay down as much power as when under electric drive.

There are a number of c1:100 gradients at the Eastern end, the worst is 1:96, not the 1:40's experienced in the Pennines!

OTC

[RichT54]

Does it have to be a problem due to lack of adhesion, or could it be that the motors would not have sufficient power to actually turn the wheels against the weight of the train trying to roll back down the slope?

[onthecushions]

By analogy, an 08 shunter with three axles and only 400/260hp can move almost anything, although not very quickly!

OTC

[paul7575]

319s coped with a quite significant gradient between City T/L and Blackfriars for years…

[Electric train]

319s coped with a quite significant gradient between City T/L and Blackfriars for years…

And the loadings at peak times far exceeded any loading they will encounter on the North Downs.

It would be interesting to know what the failures are? 

Is down the legacy equipment on the train these failures could be in part due to the age of the equipment, this can be helped by heavy overhaul, and new / refurb equipment
Is due to the knowledge / experience of the maintenance staff; then this should improve over time  is it down to the new systems and the fine tuning of these
Is it the new systems, then fine tuning and experience should improve this.

If it is a combination of all 3 then that will take some concerted effort to resolve

[nickswift99]

319s coped with a quite significant gradient between City T/L and Blackfriars for years…

But they were using electric traction not diesel.

[grahame]

A train's performance on a gradient does not depend on whether it is diesel or electric but on its adhesion and therefore tractive effort. This in turn depends on axle load, number of driven axles and rail conditions, where friction can vary typically between 12% and 30%. A  diesel might be less inclined to slip as it could not lay down as much power as when under electric drive.

319s coped with a quite significant gradient between City T/L and Blackfriars for years…

But they were using electric traction not diesel.

Is the 769 heavier (having extra diesel engines and fuel tanks) so heavier weight on the drive wheels, and thus better traction (though less power) .   Or is the extra weight over unpowered wheels, meaning the same traction on the powered wheels and indeed a reduced performance because it has a heavier base load in the train as a whole?

[RichT54]

319s coped with a quite significant gradient between City T/L and Blackfriars for years…

But they were using electric traction not diesel.

I thought the 769 still used the electric traction motors when running on diesel. The diesel engines just drive alternators which generate the electricity.

[ellendune]

319s coped with a quite significant gradient between City T/L and Blackfriars for years…

But they were using electric traction not diesel.

I thought the 769 still used the electric traction motors when running on diesel. The diesel engines just drive alternators which generate the electricity.

But when using diesel power the traction motors can only provide enough power if the alternators can supply that power.  If the diesel engines or the alternators are not powerful enough it doesn't matter how powerful the traction motors are.