Aren't Azuma's supposed to be bi-modal?

[The DJ]

Coming back from Harrogate earlier this week we coasted to a stop just a few hundred yards north of Wakefield Westgate. Motionless for around 20 minutes but plenty of announcements. Apparently birds had struck and damaged one of the pantographs.

Being a 10-coach train (made up of two 5-coach trains) there were two pantographs.

We proceeded on to London at a greatly reduced speed apparently using the one good pantograph.

Isn't there supposed to be an alternative power source which could be used to maintain normal speed and avoid delay to following trains?

 

[Ianno87]

Coming back from Harrogate earlier this week we coasted to a stop just a few hundred yards north of Wakefield Westgate. Motionless for around 20 minutes but plenty of announcements. Apparently birds had struck and damaged one of the pantographs. Being a 10-coach train (made up of two 5-coach trains) there were two pantographs. We proceeded on to London at a greatly reduced speed apparently using the one good pantograph. Isn't there supposed to be an alternative power source which could be used to maintain normal speed and avoid delay to following trains?

On an all-elextric set, only a small "rescue" engine to proceed a short distance to the next station/loop at a reduced speed.

 

[Halish Railway]

Coming back from Harrogate earlier this week we coasted to a stop just a few hundred yards north of Wakefield Westgate. Motionless for around 20 minutes but plenty of announcements. Apparently birds had struck and damaged one of the pantographs. Being a 10-coach train (made up of two 5-coach trains) there were two pantographs. We proceeded on to London at a greatly reduced speed apparently using the one good pantograph. Isn't there supposed to be an alternative power source which could be used to maintain normal speed and avoid delay to following trains?

The issue is that the Diesel engines on the DfT specced IETs aren’t much better - They can just about get past 100MPH.

 

[sjoh]

On an all-elextric set, only a small "rescue" engine to proceed a short distance to the next station/loop at a reduced speed.

Presumably not an all electric set on account of it originating in Harrogate, though.

 

[30907]

The issue is that the Diesel engines on the DfT specced IETs aren’t much better - They can just about get past 100MPH.

But they aren't supposed to run on diesel all the way to London (or anywhere that has 125mph linespeed)?

 

[tbtc]

The issue is that the Diesel engines on the DfT specced IETs aren’t much better - They can just about get past 100MPH.

But they aren't supposed to run on diesel all the way to London (or anywhere that has 125mph linespeed)?

^^ this ^^

There was a lot of criticism of them among enthusiasts for not being able to match HST timings on diesel, but they were never intended to - the 100mph top speed is sufficient for pretty much every bit of unnelectrified track in the UK - having diesel capabilities is brilliant but speccing them to do 125mph on diesel would have been a waste.

 

[NotATrainspott]

A 10-car train will have four pantographs in total, but one will need raised on each set as there is no 25kV bus across the coupling. By default the pantographs at the extreme ends will be raised, to maximise the distance between the two and minimise the impact of the first pantograph setting up a wave in the contact wire. If the backup pantograph needs used on a two-train set, then the distance between the two will be reduced. This will presumably result in a lower maximum speed under the ECML wiring. Running multiple pantographs closer together at 125mph is possible but requires a higher spec of OHLE than was fitted to the ECML.

IIRC the Harrogate services are made up of a 5-car diesel and a 5-car electric set. The electric set single backup engine can be used to provide hotel power while the bi-mode set pulls/pushes it. This only works on low speed diesel extensions of the IEP network as you have only 4 engines in total for a 10-car set, rather than 6.

 

[SteelWeelApeal]

Could it reach a situation where an electric set towing a dead set will be quicker than the second set powering with the backup pantograph (and necessitating a slower top speed due to wire waving)? What speed could an electric set towing/pushing a dead set reach? They seem to have plenty of “spare” power on electric mode. Could this happen in practise?

 

[Journeyman]

^^ this ^^

There was a lot of criticism of them among enthusiasts for not being able to match HST timings on diesel, but they were never intended to - the 100mph top speed is sufficient for pretty much every bit of unnelectrified track in the UK - having diesel capabilities is brilliant but speccing them to do 125mph on diesel would have been a waste.

It's much more of an issue on GW services where the electrification was cut back, but on LNER services, I'm pretty certain that there's no unelectrified sections cleared for 125mph, or even that close to it. All the Scottish bits north of Edinburgh are 100mph max as far as I know.

 

[Nym]

I'm not sure what the DfT / Network Rail cleared intermediate running for, (Two pantographs six cars apart, the worst case if you have lost one of them). But I believe it's well into three figures.

 

[II]

A 10-car train will have four pantographs in total, but one will need raised on each set as there is no 25kV bus across the coupling. By default the pantographs at the extreme ends will be raised, to maximise the distance between the two and minimise the impact of the first pantograph setting up a wave in the contact wire. If the backup pantograph needs used on a two-train set, then the distance between the two will be reduced. This will presumably result in a lower maximum speed under the ECML wiring. Running multiple pantographs closer together at 125mph is possible but requires a higher spec of OHLE than was fitted to the ECML.

With 10-car trains on the GWML it is a 100mph maximum if it is the 1st and 6th vehicle pan in use, or the 5th and 10th. If it is the 5th and 6th vehicle pan (i.e. back pan on one unit, front on the other) then that gets reduced to 80mph. Not sure if that differs on the ECML, but it does cover the whole of the GWML including the old headspan sections that are still in use between Paddington and Airport Junction.