IET running on diesel

[Horizon22]

I know there used to be restrictions in place for HSTs on 1 power car over the devon banks, are there similar for IETs?
I'm guessing you wouldn't want to risk a set with, as you suggest 3 or just 2 GUs units?

Its obviously dependent on size of train:
5 car - if 2 are out its advisory (possibly restricted to OHL running), if its 3 the train is definitely restricted (OHLE running only)
9-10car - if 3 are out its advisory, 4 out is probably restricted, 5 definitely.

That's why I say it depends on whether its a 5 (on a W.Country train probably attaching at Plymouth) / 9 / 10. The fewer coaches, obviously the bigger the impact but a 9 or 10 having 1/5 GUs out would not be a disaster.

 

[coradiafan2000]

I'm surprised it ran to time. A few months ago I did a journey from Cardiff to Paddington that arrived around 20 minutes late due to running on diesel power, and this was the reason for the delay given by the guard.

Why does this seem to happen? It's incredibly frustrating when so much money was spent electrifying the Great Western Mainline and these brand new trains aren't even able to use the wires sometimes.

 

[Horizon22]

I'm surprised it ran to time. A few months ago I did a journey from Cardiff to Paddington that arrived around 20 minutes late due to running on diesel power, and this was the reason for the delay given by the guard.

Why does this seem to happen? It's incredibly frustrating when so much money was spent electrifying the Great Western Mainline and these brand new trains aren't even able to use the wires sometimes.

Why? Some form of defect with the pantograph is normally the issue. It's not a very common issue; of the whole fleet normally there's only normally a maximum of 5 on diesel only (many of which are on depot operations)

 

[coradiafan2000]

Why? Some form of defect with the pantograph is normally the issue. It's not a very common issue; of the whole fleet normally there's only normally a maximum of 5 on diesel only (many of which are on depot operations)

Fair enough. It just never seems to happen with other electric trains, but of course if it say happened to an 801 the service would probably be cancelled so I guess I should be thankful it ran at all.

 

[irish_rail]

With one engine out on a 9 car (so 4 out of 5 engines) i can categorically state as a driver on this route the train would more or less keep to time between Penzance and Exeter.
There MUST have been additional problems. It is likely that further engines must have been lost on route and the Guard chose not to tell the passengers this, or may not have been told by the driver. For that level of time lost im guessing at least 3 engines not powering properly. Either that or another fault causing the delays. Was it a slippery day maybe?

 

[RPI]

With one engine out on a 9 car (so 4 out of 5 engines) i can categorically state as a driver on this route the train would more or less keep to time between Penzance and Exeter.
There MUST have been additional problems. It is likely that further engines must have been lost on route and the Guard chose not to tell the passengers this, or may not have been told by the driver. For that level of time lost im guessing at least 3 engines not powering properly. Either that or another fault causing the delays. Was it a slippery day maybe?

Beat me to it (I'm not a driver but work this traction/route almost daily) I was on a 9 car that got drenched on the sea wall and ended up limping to Exeter on one GU and was surprised at the almost adequate speed we achieved on that!

 

[Horizon22]

With one engine out on a 9 car (so 4 out of 5 engines) i can categorically state as a driver on this route the train would more or less keep to time between Penzance and Exeter.
There MUST have been additional problems. It is likely that further engines must have been lost on route and the Guard chose not to tell the passengers this, or may not have been told by the driver. For that level of time lost im guessing at least 3 engines not powering properly. Either that or another fault causing the delays. Was it a slippery day maybe?

Yeah as mentioned up-thread, there's no way 1 engine out would cause problems. It is likely to have been 2-3 and the Train Manager just announced it in plain terms "an engine out" or it was slightly misheard.

 

[LSWR Cavalier]

Maybe the driver was going gently for fear of losing more engines, perhaps s/he could see that some of the four were not working quite right.

 

[skyhigh]

It could be anything causing a speed restriction on the set in conjunction with the engine loss - BCU (Brake Control Unit) isolated on one coach, defective high tone on horn etc...

 

[TheBigD]

It could be anything causing a speed restriction on the set in conjunction with the engine loss - BCU isolated on one coach, defective high tone on horn etc...

I was on one from the South West last Wednesday where the guard announced due to brake fault we would be running 10mph below linespeed. That one lost 36 minutes en route...

Realtime Trains - 1A92 1415 Penzance to London Paddington

Realtime Trains is an independent source of live realtime running information for the Great British railway network.

www.realtimetrains.co.uk

 

[Horizon22]

I was on one from the South West last Wednesday where the guard announced due to brake fault we would be running 10mph below linespeed. That one lost 36 minutes en route...

Realtime Trains - 1A92 1415 Penzance to London Paddington

Realtime Trains is an independent source of live realtime running information for the Great British railway network.

www.realtimetrains.co.uk

Once you get past Taunton /Westbury late you almost inevitably get even further late behind a Bedwyn or Newbury stopper or a freight train. 10mph below line speed (for that long a journey) would have much more of an impact than 1 GU being out.

 

[david1212]

Beat me to it (I'm not a driver but work this traction/route almost daily) I was on a 9 car that got drenched on the sea wall and ended up limping to Exeter on one GU and was surprised at the almost adequate speed we achieved on that!

OT ish
I thought the IET / Class 80x were supposed to be ' Dawlish & Teignmouth Sea-Wall Proof ' .
What happened at Exeter ? Were the faults cleared so the service could continue under full power ?

 

[supervc-10]

I think the only thing 'Dawlish proof' is to reopen the whole route north of Dartmoor!

The IETs are designed to be more resilient but nothing is going to be completely Dawlish proof in the worst weather.

 

[irish_rail]

I think the only thing 'Dawlish proof' is to reopen the whole route north of Dartmoor!

The IETs are designed to be more resilient but nothing is going to be completely Dawlish proof in the worst weather.

Indeed. We are lucky to have had such an incredibly benign last few months with virtually no wind or rough weather at all. When it returns (and it always does) , fully expect more IET issues!

 

[Bikeman78]

Comparing pre-2019 (2015 as it's the WTT I have to hand) 1142 Paddington Swansea with current-day 1148 Paddington to Swansea

In 2015 the 1142 was timed 2h06m to Cardiff
In 2021 the 1148 is timed 1h53½m to Cardiff

Same calling pattern, similar dwells (3m total longer dwell across the 2015 schedule as far as Cardiff)

Even if you excused 5 minutes at Bristol Parkway for that regulation against the Northbound Voyager (which isn't allowed for in the WTT) we're still talking 4-5 minutes difference.

On diesel, yes HST and IET performance is similar – this isn't a coincidence, it was intentional; as such they're pretty evenly matched Cardiff to Swansea, IET makes up ground by being able to achieve shorter dwells. But an HST couldn't keep to IET electric timings; heck it would barely keep to the timings the 110mph Bristol Parkway 387s achieve. We're talking 2-3m faster Paddington to Reading, another 2-3m Reading to Swindon, another minute to Bristol Parkway. Yes, a top driver, engine fresh off exam and hard driving might come close – but you could do such astonishing antics with the IET as well and beat the timetabled times by some margin; as has been proven on various "speed runs" since IET introduction.

As I said in post #1, I've done Paddington to Cardiff and vice versa on HSTs in 1h53m a number of times, generally later runners that happened to get greens all the way. But yes I agree that the IET is impressive on electric.

These things have no problem doing 125 on diesel. I’m on one now that’s doing 124 according to my speedo app!

Personally I've never been on one that reached 125 on diesel. Despite the good timekeeping, the one that prompted this thread only got to 118 west of Reading.

 

[Railperf]

As I said in post #1, I've done Paddington to Cardiff and vice versa on HSTs in 1h53m a number of times, generally later runners that happened to get greens all the way. But yes I agree that the IET is impressive on electric.


Personally I've never been on one that reached 125 on diesel. Despite the good timekeeping, the one that prompted this thread only got to 118 west of Reading.

An IET will do 125mph on a downhill gradient.
As mentioned above, there will be time lost where diesel is used on sections timed for electric running. The ability to 'keep' time on the electric sections when running on diesel is usually due to the train absorbing the hidden recovery and performance allowances in the timetable and where drivers can reduce dwell times. The more responsive brakes also help to gain a few seconds here and there on each section of route.

 

[FGWHST43009]

Comparing pre-2019 (2015 as it's the WTT I have to hand) 1142 Paddington Swansea with current-day 1148 Paddington to Swansea

In 2015 the 1142 was timed 2h06m to Cardiff
In 2021 the 1148 is timed 1h53½m to Cardiff

Same calling pattern, similar dwells (3m total longer dwell across the 2015 schedule as far as Cardiff)

Even if you excused 5 minutes at Bristol Parkway for that regulation against the Northbound Voyager (which isn't allowed for in the WTT) we're still talking 4-5 minutes difference.

On diesel, yes HST and IET performance is similar – this isn't a coincidence, it was intentional; as such they're pretty evenly matched Cardiff to Swansea, IET makes up ground by being able to achieve shorter dwells. But an HST couldn't keep to IET electric timings; heck it would barely keep to the timings the 110mph Bristol Parkway 387s achieve. We're talking 2-3m faster Paddington to Reading, another 2-3m Reading to Swindon, another minute to Bristol Parkway. Yes, a top driver, engine fresh off exam and hard driving might come close – but you could do such astonishing antics with the IET as well and beat the timetabled times by some margin; as has been proven on various "speed runs" since IET introduction.

Maybe the HSTs have been slower since they got rid of the Valentas?

 

[hexagon789]

Maybe the HSTs have been slower since they got rid of the Valentas?

It'll be the move to more defensive driving that's the major one, that and increased recovery/pathing time. A lot of the last few years of HSTs on the GWML was populated by schedules that could be easily maintained without needing to exceed 110-115mph a lot of the time.

 

[Saj8]

Just thought I'd mention about the speed limiter that was mentioned up thread - the reason for the train only doing 124mph is not mph/kph conversion, it's because the train holds the speed at 1mph below whatever speed is set on the limiter. I don't know the reason why it does that.

 

[Bletchleyite]

Just thought I'd mention about the speed limiter that was mentioned up thread - the reason for the train only doing 124mph is not mph/kph conversion, it's because the train holds the speed at 1mph below whatever speed is set on the limiter. I don't know the reason why it does that.

My Ford Kuga pretty much does that (well, it creeps up the last mile per hour over a very long period). Presumably this is so it can't go over.

 

[irish_rail]

Just thought I'd mention about the speed limiter that was mentioned up thread - the reason for the train only doing 124mph is not mph/kph conversion, it's because the train holds the speed at 1mph below whatever speed is set on the limiter. I don't know the reason why it does that.

Due to measuring speed in kilometers ph and not mph. One reason why I don't use the speed set.

 

[Chiltern006]

80x units running on diesel don't normally keep to time on the ECML, and that's with many schedules still running on Class 91+Mark 4 sectional running times. When I recorded it on a TPE 802, the maximum speed the unit reached on diesel between York and Darlington was 112 mph, sufficient to keep to Class 185 timings used previously but not sufficient to keep to 80x on electric sectional running times, which all TPE services to/from Newcastle now use North of York.

On the occasions where I've had an LNER unit on diesel under the wires I've never checked the speed, but on each occasion the unit has lost time between each calling point.

was on a TPE one last Sunday and just scraped 125 past Northallerton

 

[XAM2175]

it's because the train holds the speed at 1mph below whatever speed is set on the limiter. I don't know the reason why it does that.

Presumably this is so it can't go over.

Due to measuring speed in kilometers ph and not mph.

I would expect it to leave a margin for response to uncommanded acceleration. The AFB system on a German locomotive (whether from ADtranz, Bombardier, Siemens, whoever) will always hang back by about 2 km/h so that it has time to bring in regenerative or rheostatic braking without exceeding the set limit.

On the other hand, the sloppy conversion rationale for the IET's speed set has never seemed plausible to me.

 

[D365]

Maybe the HSTs have been slower since they got rid of the Valentas?

Wrong. The MTU engines are rated at 2250bhp. Same as the Valenta.

 

[hexagon789]

Wrong. The MTU engines are rated at 2250bhp. Same as the Valenta.

2280hp at 1500rpm according to spec but 30hp will make little difference at all, especially given the traction motors are unaltered. And the performance was deliberately set up to mimic the Valentas as closely as possible anyway, which is why the engine speed in Notch 4 is apparently slightly higher for the MTU than the Valenta (1420 vs 1390rpm) because it gives similar performance in power output.

(Source taken is the Haynes IC125 Manual.)

 

[Dai Corner]

2280hp at 1500rpm according to spec but 30hp will make little difference at all, especially given the traction motors are unaltered. And the performance was deliberately set up to mimic the Valentas as closely as possible anyway, which is why the engine speed in Notch 4 is apparently slightly higher for the MTU than the Valenta (1420 vs 1390rpm) because it gives similar performance in power output.

(Source taken is the Haynes IC125 Manual.)

The fact that the Valentas were worn out whereas the MTUs were brand new may have given the latter an advantage?

 

[Whistler40145]

The IET could well have had a Pantograph defect, possibly unable to raise it or the unit might have tripped the circuit breaker and the Pan would automatically drop

 

[hexagon789]

The fact that the Valentas were worn out whereas the MTUs were brand new may have given the latter an advantage?

Depends exactly what hp they were putting out, a loadbank test of an ex-EMT VP185 power car had the power car producing, in Notch 5, a continuous output of 1,814hp at the traction motors. The continuous rating is 1,770hp - so in my view it would depend more on how well maintained the engines were rather than simply their age.

Some Deltic Napier engines were found to be inadvertently churning out close to 2,000hp in preservation after overhaul!

 

[Annetts key]

In terms of speed, the limiting factor is the line speed. Both the IETs (on OHL electric or diesel) and the HST 125s are limited officially to 125 MPH. And as has been said in this topic, both can get to and maintain 125MPH (+/- a couple of MPH).

I suspect the difference in performance of an IET running on OHL vs. diesel is reduced rate of acceleration.

Similarly, a HST 125 set has a reduced rate of acceleration compared to a IET running on OHL.

Before First pledged to run HST 125s only with operational ATP (which limits the maximum speed), some drivers were able to get ‘a little bit more’ out of them…

Also the actual load will slightly affect the performance (and the number of carriages in the case of the HST 125s).

A significant factor (as said earlier in the topic) may also be that defensive driving is encouraged now, whereas in the past it was, shall we say, a bit different. Certainly in the past a delayed HST 125 has managed to arrive at it’s terminal station on time, or within a couple of minutes of it’s booked arrival time…

 

[Railperf]

It'll be the move to more defensive driving that's the major one, that and increased recovery/pathing time. A lot of the last few years of HSTs on the GWML was populated by schedules that could be easily maintained without needing to exceed 110-115mph a lot of the time.

Ladbroke Grove saw speed limits in Paddington area decreased to 40/50mph. Reading area limited speed limits were decreased to 50mph for many years - increasing journey times. ATP in particular limited top speeds to appx 122/123mph for power cars with worn wheelsets.