Class 90 on the ECML

[TomJ]

Travelling down from Leeds to London I have just noticed we are being pushed by a shiny red DB 90. Is this a regular working or cover for an engine failure? And does it have an implications for the timetable if it's top speed is slower?

Either way it's a nice to have a change from the usual 91. Definitely looks more like a proper loco to me!

[4630]

There have been a couple of DB Cargo class 90s on hire to Virgin Trains East Coast for the last few months deputising for non-availability of class 91s.  They are usually restricted to the services to Leeds and Newark where their 110mph top speed has less of an impact on time keeping, although I recall that there has been the odd visit to Newcastle too.

 

90039 waits at London Kings Cross on the evening of 16th March 2017.

 

[DY444]

Class 90s have better acceleration than Class 91s so they try to use them on the Leeds and Newark turns with the most station stops to minimise the effect on timekeeping.

[JeffP]

 

Class 90 on a Leeds train, Kings Cross 23/12/16

[Foden]

Class 90s have better acceleration than Class 91s so they try to use them on the Leeds and Newark turns with the most station stops to minimise the effect on timekeeping.

 

That's a very interesting and surprising fact.

[45125]

That's a very interesting and surprising fact.

 

The 90s and 91s had the same acceleration when new, however due to the 91s been prone to slipping at all speeds the ramp up rate was retarded to overcome this.

[Bomag]

Class 90s have better acceleration than Class 91s so they try to use them on the Leeds and Newark turns with the most station stops to minimise the effect on timekeeping.

 

The max power of the 90s is over 7000hp whereas the 91s is 6300hp. Contiuous power is 5000hp and 6100hp respetcively so even without the lower top speed 90s still run out of 'puff'. I think one of the diagrams has either the 15:05 or 15:35 ish deparures to Leeds on it, back when they were ding the 91/1 upgrade the 15:35 was diagramed for a 90 - it was always the one to go for as they avoiding useing that set in place of failed 91 on a Newcastle or Edinbugh service. 

[DY444]

The max power of the 90s is over 7000hp whereas the 91s is 6300hp. Contiuous power is 5000hp and 6100hp respetcively so even without the lower top speed 90s still run out of 'puff'. I think one of the diagrams has either the 15:05 or 15:35 ish deparures to Leeds on it, back when they were ding the 91/1 upgrade the 15:35 was diagramed for a 90 - it was always the one to go for as they avoiding useing that set in place of failed 91 on a Newcastle or Edinbugh service. 

 

The 90s "run out of puff" because the gearing is different.  The 91s are slower off the mark because their higher gearing means the control system has to limit the traction motor current at lower speeds compared with a 90.

[45125]

The 90s "run out of puff" because the gearing is different.  The 91s are slower off the mark because their higher gearing means the control system has to limit the traction motor current at lower speeds compared with a 90.

 

AS stated early the traction control on the 90s and the 91s used exactly the same traction electronics and was only changed with all the wheel slip problems. Even as recently as two years ago a class 90 card appeared on a 91 and caused one or two minor problems.

[DY444]

AS stated early the traction control on the 90s and the 91s used exactly the same traction electronics and was only changed with all the wheel slip problems. Even as recently as two years ago a class 90 card appeared on a 91 and caused one or two minor problems.

 

I made no reference to the similarity or otherwise of the traction electronics.  Northern Line tube trains and Pendolinos have exactly the same traction electronics so that means nothing in terms of the relative performance of the two.

 

What I said is the traction electronics have to manage things differently in a Class 90 compared to a Class 91 as a result of them having different traction motors and different gearing and consequently different current/speed characteristics. 

Edited April 3, 2017 by DY444

[pete_mcfarlane]

This begs the question of what speed an ECML stopper actually manages to get up to between Grantham and Newark, even with a 91. It takes about 10 minutes, so most of that must be spent accelerating or braking. 

[hexagon789]

I was once told it takes an IC225 about 5-5.25 mins to get up to 125mph from a standing start, thought this is obviously dependant on good rail conditions. For comparison an IC125 in 2+7 formation is, according to BR documentation, capable of doing 0-100mph in 3 mins 15 secs and then 100-125mph in a further 4 mins, in other words 0-125mph takes about 7.25 mins.

 

So it would seem that an IC225 could get up to 125mph between Grantham and Newark, though the line is not 125 the whole way. Starting out from Grantham it's 100mph for about 0.5 miles, then 115 for about 2.5 and finally up to 125 for the last 11.75 miles into Newark.

[Ken.W]

Initially one, now two class 90s are now on hire to cover for 91 non-availability, they seem to be going through a program of works visits for overhaul at present.

The 90s are limited to the shorter distance stopping services to Newark / Leeds to limit effects on timekeeping making use of there better acceleration.

Also, only Kings X drivers have been trained to operate them, which effectively limits there operation to that anyway. Although KX crews do work as far as Newcastle, they'd be unlikely to be working the same set back, and there's very few Newcastle terminators now anyway, with no-one to work them further north.

 

Comparisons between the 91s and other traction are interesting, although they appear slow when observed starting away, once they do (eventually) get going they're certainly not the sloaths generally imagined. Two points to bear in mind, firstly as mentioned, as they're geared for high speed running tractive effort at low speed needs to be limited. it's rather like starting your car in second or third gear. Secondly, with all traction, particularly diesels, acceleration tails off markedly as maximum speed is approached, the 91 however is designed for a 140 mph maximum, so approaching the max permitted 125, the 91's still not approaching it's maximum and wants to keep going - acceleration's still high.

91 v HST; leaving Darlington southbound (virtually unrestricted) an HSTs much quicker starting off, the 91 very slow starting then not really getting going till about 60. The HST will take virtually to Northallerton to reach 125 though, the 91 will do so around Cowton (roughly half-way). The 91 can then stop at Northallerton, make it's lethargic start, and still pass Thirsk at 125!

91 v Voyager; again the Voyager appears to be faster accelerating. You'll often see them leaving York Northbound immediately ahead of a 91, which has to wait till it's cleared the first section (past Siemens depot) before dispatch can commence, so by time it's ready to leave and makes it's labourious start, it's usually on a green, which makes the voyager around Skelton Bridge, well clear of the 60 restriction and accelerating into the distance while the 91s making it's slow start. Once the 91s clear of Skelton and getting into it's stride though, the gap reduces to the extent that if the voyager's one that stops at Northallerton, the 91s standing at the signal behind it.

91 v 185; the TPE 185 units again have a rapid initial acceleration. As a Southbound 91 receives 'ready to start' at York, a 185 passes leaving from an adjacent platform, rapidly up to the permitted 30, then is clear of Holgate and the restriction as the 91 just starting off and accelerating into the distance as the 91 gets going... as the parallel Main and Leeds lines diverge at Colton Jn, the 185's being passed with the 91 up to 110

On the question above about Grantham to Newark, remember it's also downhill all the way from Peascliffe

[Daveb0789]

On 04/04/2017 at 03:07, Ken.W said:

Initially one, now two class 90s are now on hire to cover for 91 non-availability, they seem to be going through a program of works visits for overhaul at present.

The 90s are limited to the shorter distance stopping services to Newark / Leeds to limit effects on timekeeping making use of there better acceleration.

Also, only Kings X drivers have been trained to operate them, which effectively limits there operation to that anyway. Although KX crews do work as far as Newcastle, they'd be unlikely to be working the same set back, and there's very few Newcastle terminators now anyway, with no-one to work them further north.

 

Comparisons between the 91s and other traction are interesting, although they appear slow when observed starting away, once they do (eventually) get going they're certainly not the sloaths generally imagined. Two points to bear in mind, firstly as mentioned, as they're geared for high speed running tractive effort at low speed needs to be limited. it's rather like starting your car in second or third gear. Secondly, with all traction, particularly diesels, acceleration tails off markedly as maximum speed is approached, the 91 however is designed for a 140 mph maximum, so approaching the max permitted 125, the 91's still not approaching it's maximum and wants to keep going - acceleration's still high.

91 v HST; leaving Darlington southbound (virtually unrestricted) an HSTs much quicker starting off, the 91 very slow starting then not really getting going till about 60. The HST will take virtually to Northallerton to reach 125 though, the 91 will do so around Cowton (roughly half-way). The 91 can then stop at Northallerton, make it's lethargic start, and still pass Thirsk at 125!

91 v Voyager; again the Voyager appears to be faster accelerating. You'll often see them leaving York Northbound immediately ahead of a 91, which has to wait till it's cleared the first section (past Siemens depot) before dispatch can commence, so by time it's ready to leave and makes it's labourious start, it's usually on a green, which makes the voyager around Skelton Bridge, well clear of the 60 restriction and accelerating into the distance while the 91s making it's slow start. Once the 91s clear of Skelton and getting into it's stride though, the gap reduces to the extent that if the voyager's one that stops at Northallerton, the 91s standing at the signal behind it.

91 v 185; the TPE 185 units again have a rapid initial acceleration. As a Southbound 91 receives 'ready to start' at York, a 185 passes leaving from an adjacent platform, rapidly up to the permitted 30, then is clear of Holgate and the restriction as the 91 just starting off and accelerating into the distance as the 91 gets going... as the parallel Main and Leeds lines diverge at Colton Jn, the 185's being passed with the 91 up to 110

On the question above about Grantham to Newark, remember it's also downhill all the way from Peascliffe

Also the 185 can’t accelerate straight away on the Leeds lines having to traverse point work. 90 mph starts soon after Holgate Jct on the up main. 

[adb968008]

Interesting reading this thread now its all over….

 

ar least 1 class 90 was pretty much an everyday occurance until mid-2019.