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It was all going well for Virgin Cross Country's Voyagers until engine overhauls started.
Two things impressed me about the Bombardier Class 22X diesel electric multiple units, the neat, not to say ‘tight', packaging of the drive train raft and the use of three phase drive transmission. The raft, which houses the big Cummins 750hp QSK19 engine, transmission and auxiliaries and is bolted to the vehicle's underside was much neater than the equivalement on the Alstom Class 180, also QSK19 powered. And you would expect me to prefer electrons to the hydraulic transmission of the Class 180.
During the first six months of 2005, the performance of the Virgin Cross Country Voyager and Super Voyager fleets was ‘superb'according to VCC Managing Director Chris Gibb. Chris points out that when you get above around 10,000 miles per casualty, the impact on PPM becomes ‘very small indeed'.
When a Voyager did fail, the train crew were able to get it moving again quickly. And as with the Class 180s, the Class 22X will keep to time with one engine out.
Between January and June there were regularly 69-70 Voyagers in traffic. The standby loco-haulked set stabled at Crewe was used three times.
Then in June the QSKs started falling due for overhaul. As Chris Gibb puts it, you would expect an engine to come back from overhaul, especially by the Original Equipment Manufacturer (OEM), ‘as good as new.
‘This did not happen', he continues, ‘It came back worse than new and a jolly site worse than new'. How much worse? ‘Some of them failed within an hour of them being put up on the raft'.
Piston failures, leading to connecting rods coming through the crankcase, were one problem. This was not helped by valve guide problems causing dropped valves which also resulted in piston damage.
What was strange was that the engines were being overhauled in Cummins' own factories. You might expect third party overhaulers to cut corners or use ‘pattern' parts rather than spares from the OEM. But Cummins were rebuilding their own engines.
At this point there are some commercial sensitivities, since Cummins is a contractor to Bombardier who built and maintain the two fleets. Bombardier told me at the end of Novemner that Cummins have sorted the problem, that the latest overhauled engines are fine, and that their working relationship with Cummins is very good.
But when the problems started, while Bombardier kept VCC in the picture, Chris gibb took the view that Cummins was not responding to Bombardioer adequately and took independent action. What action can a TOC take in a situation where the only 750hp diesel that can fit under a Voyager is the QSK19 and even the mighty Bombardier is a small company in global terms with only a few hundred engines?
For once I see the point of the bus bandit TOC owners. With some neat lateral thinking Chris Gibb got the support of a much larger Cummins customer who buys large numbers of engines in a highly competitive market.
That customer is Stagecoach, which owns 49% of the Virgin Rail Group. And when Brian Souter is your customer and says ‘jump' the only answer is ‘how high'?
And Cummins have pulled out the stops, putting in the necessary product support, including an almost nightly presence at Depots, examining every engine on a train and fixing any faults. In parallel, the quality and quantity of overhauls at the Cumbernauld and Wellingborough factories has improved. On top of that Bombardier have people at the factories auditing the quality of the overhaul work.
Note ‘quantity and quality'. Cummins has had to up the overhaul rate so that Bombardier can catch up with the backlog. A joint programme has been developed with VCC which sees 18 engines replaced a week and Cummins are ‘just about up to that mark', according to Mr Gibb. ‘We are changing hell for leather to get rid of all the overhauled engines that were problematic' he adds.
In parallel, Bombardier is looking to some design modifications on the raft which should reduce the time to change an engine to an impressive five hours. This involves dropping the complete engine and transmission raft.
By now VCC would have expected to have changed 168 engines, the actual number will be 1,000. The work is done on the lifting road at Central Rivers depot, but since this road is also required to handle wheel changes, Crofton Depot is contributing two changes as week to the programme.
Meanwhile, after a life of idleness in the first six months of the year the Class 90 stand-by rake has been in regular use, sometimes supplemented by a second set. But, though serious technically and commercially, the engine problems have not been a major opertaional issue.
With 750hp beneath each vehicle, not only can a four car Voyager keep to time on three engines, the systems, such as auxiliary power feeds, are designed to allow the train to remain in passenger service. Indeed the philosophy was that a Voyager with an engine out would always return to Central Rivers for attention.
Chris Gibb is clear that VCC wouldn't have got through such a crisis without a massive impact on the passenger were it not for this redundancy. ‘The design of the train is very good and very workable' is is his verdict.
For all the QSK19 powered units a generic problem has been ejection of oil through the crankcase breather. Pressure builds up inside an engine while it is running, which is relieved by a pipe from the crankcase to the outside world, called a breather.
Normally all that comes out of the breather are hot air and oil fumes, but occasionally you can get liquid oil carrying over. If you have ever seen a Class 22X with oil streaks on the body side the breather was probably not breathing but spitting oil.
Four different solutions have been tried, easier on the Class 180 where you don't have to drop the raft to get at the breather. Meanwhile, VCC has fitted ‘catch tanks' to 10 Voyager engines for evaluation. The breather pipe is led into a container which ‘catches' any oil carried over.
What makes a solution to this problem particularly urgent is the fact that the location of the breather pipe means that oil drops directly onto the railhead. What seemed to be a uniquely severe leaf fall period on Great Western, turned out, after swabs taken from the railhead head been analysed, to be oil from Class 180s lubricating the rails.
QSK19s have also suffered from turbocharger disc failures. These are still being investigated but traction engineering chums think it could be caused by a classic digital/analogue mismatch.
A diesel engine coupled to an hydraulic drive work as a series of approximations. The driver calls for, say, 500hp, and if the engine and transmission agree that 510hp suits them best, then that's fine.
A digitally controlled three phase drive, as on the Voyagers is very precise. It's a bit like analogue and digital watches, With an analogue watch the time is ten minutes to five. Digitally it is 16:48:52 .
So the digital control says I want 500hp exactly, but the engine can't do this and hunts between a little bit over and a little bit under, which could stress the turbocharger. As a contribution to this theory, could readers listen to the engine on Voyager journeys and let me know if they hear any slight variations in pitch?
So much for my predeliction for electric transmission. It seems I was a bit out on the raft packaging.
Finally, there's that tightly packed raft which I admired so much. When FGW engineers measured the temperature inside the raft on the Class 180s, they winced and promptly upped the heat resistance of hoses and similar stuff on the engine.
According to Informed Sources it gets even hotter inside the Class 22X raft and the traction motors seem to be suffering from overheating. When you consider that asynchronous traction motors are pretty bullet proof, this is an unexpected problem. One theory is that the motor may be getting radiant heat from the engine exhaust.