GWR IET's with at least one engine turned off.

[Clarence Yard]

The Hitachi engineers are very keen to keep the torque fluctuations to a minimum and on the test runs that I was on, I could see the demand levels recorded on the TMS and there was no wheel slip but plenty of variation in a very “unmuzzled” unit as it took power. I repeat - there was no wheel slip.

When you have three fully working engines in a 5 car unit, you will be fine but as soon as performance starts to drop off on one, the electronics call for more power and you will work all three harder. The engine that is falling off will continue to be under stress and, let’s say it gets hotter, the safety systems will cut it out at a certain temperature. Meanwhile the other two will now be working even harder.

The duty cycle on GWR units calls for sustained hard running, at various speeds, and that puts a medium term as well as a long term stress onto the engines. So you get faults “before their time” in the expected wear profile and you will then clog up the repair facility with engines requiring work.

What you do not want is the engines pressurising in these circumstances so that they blow their coolant out of the top or oil out of the bottom. You can replace seals as many times as you like but you are not doing the engine any good whatsoever unless you reduce that stress on it. Pro-active maintenance of various sub-systems, such as radiators, helps here.

 

[Railperf]

The Hitachi engineers are very keen to keep the torque fluctuations to a minimum and on the test runs that I was on, I could see the demand levels recorded on the TMS and there was no wheel slip but plenty of variation in a very “unmuzzled” unit as it took power. I repeat - there was no wheel slip.

When you have three fully working engines in a 5 car unit, you will be fine but as soon as performance starts to drop off on one, the electronics call for more power and you will work all three harder. The engine that is falling off will continue to be under stress and, let’s say it gets hotter, the safety systems will cut it out at a certain temperature. Meanwhile the other two will now be working even harder.

The duty cycle on GWR units calls for sustained hard running, at various speeds, and that puts a medium term as well as a long term stress onto the engines. So you get faults “before their time” in the expected wear profile and you will then clog up the repair facility with engines requiring work.

What you do not want is the engines pressurising in these circumstances so that they blow their coolant out of the top or oil out of the bottom. You can replace seals as many times as you like but you are not doing the engine any good whatsoever unless you reduce that stress on it. Pro-active maintenance of various sub-systems, such as radiators, helps here.

Yes - torque flucatuations at those horsepower / torque levels can be catastrophic. But here is the question. After five years experience of running at higher power levels than planned for due to the curtailed electrification - why has the expected wear profile not been refined to allow for the additional faults that are regularly occurring? Surely this needs to be taken into account and measures taken to mitigate this? Unless of course that's what Hitachi are telling Dft, and DfT are unwilling to pay for - hoping that Hitachi can provide enough units to limp around without causing too many delays?

 

[Snow1964]

Right, I don't confess to know much about the engines (as drivers we are basically told they are there and when they don't work, thats about it). But what strikes me , is the acceleration is very quick up to 40 mph and then trails off. Would it be kinder to the engines if they were slower to 40mph (ie like HSTs) then acceleration improved as they hit the mid speed range. This may be more appropriate to an intercity train (whereas the first 40mph is more relevant to commuter stock). As I said, my knowledge of engines is poor to put it mildly, but is there any chance that changing the acceleration like this (ie slower to start but quicker from 50mph say) help in doing less damage? It would certainly make for a smoother ride (a personal bugbear is when a driver just whacks it straight to full power causing that nasty jerk pulling away and potentially causing people finding a seat to lose balance! ) Can someone with knowledge of engines explain if this would likely help or not???

They have electric drives, the engine speed is not directly relevant to speed, as the engine drives an alternator, not the axles

 

[hexagon789]

So the continuous 'power at rail' on diesel for say a 5-car 802 (with all three engines working!) might be as low as 2/3 that on OHLE - anyone got any hard figures?

To the nearest 10hp: approx 720hp, except LNER 800s - approx 610hp.

Less for the vehicle supplying Auxiliary Power - this runs at a higher engine output but gives a lower traction output.

 

[Railperf]

They have electric drives, the engine speed is not directly relevant to speed, as the engine drives an alternator, not the axles

Engine speed is related to the amount of electrical power available from the alternator to the motors. Lower engine speed equals lower alternator speed equals low power -high engine speed equals high alternator speed equals high power.

As I understand it the computers controlling the traction system are mapped out to provide a certain amount of power corresponding to the train speed within a programmed acceleration curve - acceleration rate at a given speed.

Under full electric power the traction system sends as much power available from the OLE to the motors to deliver a fixed acceleration curve.
In diesel mode - the difference is that the GU's cannot deliver as much power as is available from the OLE. So the computers control how much power the GU's can deliver to the motors to achieve a different acceleration curve.

You might think that it is simply enough to run the engines at full power to run the alternators at full speed so they can deliver the maximum amount of electrical power. But it is more complex than that. Even at full power, the electrical load can vary depending on whether the train is going uphill or downhill and it has to respond to the driver's changing throttle positions. It is during these phases that the diesel engines mapped power and torque curves can affect the smoothness of the changes in power and its effect on engine speed- and in turn stress on mechanical components.

Just ask any car engine tuner - diesel engines in particular - what happens when the torque curve is too aggressive. Usually car tuners will have to change many mechanical components to deliver higher reliability at higher horsepower and torque levels. probably in this case, the MTU engine would need major mechanical redesign to be able to deliver the 940hp on this duty cycle with higher reliability.

 

[3RDGEN]

What about routes to Penzance????.....

Little journey time improvement but electrification never covered the South West so what little is gained at the London end you lose further west. Plymouth - Penzance is now a near clockface 30 minute frequency so again a big capacity and frequency increase on 2013.

 

[800001]

LNER and TPE sets run at speeds up to 125mph on diesel on Sundays between Newcastle/Edinburgh; GWR sets run at 110mph on diesel every day.

Do the LNER ones actually achieve 125mph in diesel?
I thought they get to about 115-117.

Also on the section where LNER have to run in diesel in a Sunday (Longniddry to Chathill), isn’t the track speed mostly 100mph? So by running in diesel isn’t affecting the performances

 

[hexagon789]

Do the LNER ones actually achieve 125mph in diesel?
I thought they get to about 115-117.

Also on the section where LNER have to run in diesel in a Sunday (Longniddry to Chathill), isn’t the track speed mostly 100mph? So by running in diesel isn’t affecting the performances

'Up to' simply meaning that's the maximum permissible; as opposed to being physically restricted to 100mph in diesel mode.

 

[DanNCL]

Also on the section where LNER have to run in diesel in a Sunday (Longniddry to Chathill), isn’t the track speed mostly 100mph? So by running in diesel isn’t affecting the performances

Chathill to Berwick is mostly 125mph. Berwick to Dunbar is 95mph or lower throughout apart from the last few miles before Dunbar. Dunbar to Longniddry is mostly 110mph.

 

[Master29]

In 2013 typical journey times,

London - Swansea was 3hrs now 2hr 45.

London - Cardiff was 2hrs now 1hr 50.

London - Bristol was 1hr 45 now 1hr 35.

Times vary but in general electrification and the new fleet has cut journey times and capacity increased too.

Absolutely they have on the South Wales and Bristols but not so much on the West of England.

 

[Railperf]

Chathill to Berwick is mostly 125mph. Berwick to Dunbar is 95mph or lower throughout apart from the last few miles before Dunbar. Dunbar to Longniddry is mostly 110mph.

I found that TPE 802's on their 940hp setting easily matched 2+9 HST performance on that stretch. More responsive and accurate braking seemed to offset slightly slower acceleration

 

[Energy]

Little journey time improvement but electrification never covered the South West so what little is gained at the London end you lose further west.

Indeed electrification was always planned to stop at Newbury. 800s would have only operated to Exeter (9 car) and Paignton (5 car) with Penzance being 222s IIRC.

 

[Railperf]

1A82 0911 Penzance Paddington 802111 - 9-car losing time heavily estinated to be running on just three or maybe two engines - 20 late departing Taunton

 

[Clarence Yard]

It was on three - it has been running on four for a couple of weeks now and had another one go down en route.

 

[Railperf]

It was on three - it has been running on four for a couple of weeks now and had another one go down en route.

What's the current situation? How many units currently on 1 or more engine out today?