Auld Reekie 3/03/19

Absolutely. I had many runs on the 2 hour 30 8 coach trains from Leeds to London and back in the 70s. Compared with anything else it was their acceleration that seemed so different. If on occasion a 47 was substituting, you knew you were in for a twenty minute late arrival even if nothing else went wrong like pathing problems. So 0 to 87 in five miles or so on Sunday was quite nostalgic.

 

I once had a class 40 on the 1530 Leeds deputising for a Peak..With 13 on for 480 tons it was my best ever with a 40, just 7 late KX including some checks. It struggled to keep sectional times of course but managed 87 down Stoke and 85 before Hatfield. It was the hill climbing that told though. 49.5 at Stoke Summit starting from Grantham eg. Sorry for the thread drift.

 

Has something passed me by about a certain Borders town? Iv seen various names used here recently.

Grant houses?
Granthouse?
Grantshouse?

It is Grantshouse isn't it?

Great to hear Tornado had a pleasant and uneventful run. This bodes well for the Ferryhill trips. When was the last time Tornado went over The Bridge?

Should be some sight/sound watching her go through NewMill/Carron Water area!

 

argh you've lost me The Other Bridge...the one that goes over The Other Big River...?

 

Tornado last ran over the Forth Bridge on 5th July 2015 hauling the two circular "Forth Bridge 125th Anniversary" tours organised by the SRPS, coinciding nicely with the same morning it was announced as a UNESCO World Heritage Site.

 

Guilty as charged, m’lud!

 

Yes.

 

I enjoyed the Tornado haulage but was gutted to be sitting behind a failed Deltic at Berwick station once again, on the same platform where D9000 'failed' on her inaugural main-line return to service run in November 1996. Especially gutted this time, as the 1 hour 30 minutes timing from Edinburgh to Newcastle seemed to be just about achievable, as we appeared to have a driver who knew how to handle a Deltic on a tight schedule. Based upon an excellent departure from Edinburgh platform 1. Getting fast timings these days for Deltic hauled charter trains is very rare indeed. In Deltic days a fast timing Edinburgh to Newcastle was about 1 hour 51 minutes on a D385 100mph timing (section YA 8th May 1978, 1400 ex-Waverley). This included 4 minutes recovery time.

I'd been logging the brief run from Edinburgh and we'd reached around 84/87mph when (presumably) the first traction motor flashover occurred. As we were running with both power units on full power, this meant that the second electrical 'field divert' had already been reached. I'm guessing that the second field divert is where Deltics are most susceptible to electrical flashovers, as both generators are connected in series and will be providing close to full power of 1320 (660 * 2) volts DC and 1650 amps to the three pairs of (series connected) EE538 traction motors.

On the test run it is also possible that Deltic 9 never reached the second field divert on both power units, as I assume that the class 31 is limited to just 75mph. I also wonder if the test run was conducted entirely with only one power unit running, as even over-weight 31s don't provide much dead-weight for a loco as powerful as a Deltic ? If only one power unit was used throughout on the test run then, the maximum voltage on each pair of traction motors would be around 660 volts DC - so chances of a flashover occurring would be very slim indeed. I know retrospect is a wonderful thing, but if Deltic 9 had had a high-speed loaded test run at 100mph then I guess that the flashover would have occurred on the test run, and we'd presumably have been booked a 67 for the return journey.

As an aside, the traction motors on a Deltic (and indeed the whole of the EE fabricated bogie) were originally interchangeable with the EE type 3s (apart from some minor fittings such as cab steps etc.). So the same EE538 traction motors were being driven at almost twice the power on a Deltic ! No wonder Class 37s were so reliable.

 

This technical information is much appreciated, thank you.

 

Seconded Don, an excellent report from David on a bittersweet day out. But who is JB?

Peter at the end of a bittersweet day (sunshine and showers) in Manchester

 

Surely with field diversion, highest voltage is reached just before each divert is achieved. By diverting some traction motor series field to release back EMF generated by the motors the current is increased and voltage reduced.

I’ve been on 33s with diverts not working and measured the main gen volts just over 800v, with all 5 diverts in, main gen volts around 690v.

 

Light engine moves for all older diesels are limited to 75mph due to brake force abilities so a 31 of 80 or 90mph normal limit wouldn't make any odds.

The eye watering sums stock costs to hire, especially around 10 carriages off Burton probably made it prohibitive to do a loaded test thus making it a light engine or nothing. I don't feel a 90 minute schedule for Edinburgh to Newcastle for a Deltic fresh off repairs was any good in hindsight as its a lot of pressure on the driver although nothing to say the same wouldn't have happened had it had a Saturday style path south as it's just one of those things with old equipment.

 

There is no guarantee it would have happened that way.

 

Agreed. There are no guarantees about anything, except for death and taxation.

However, more research seems to confirm my initial thoughts that Deltic flashovers are more likely just after the second field divert having occurred (at a nominal 78mph but often higher these days for some reason?). Unfortunately I wasn't paying full attention to the speed at which Deltic 9's second field divert occurred, as we stormed out of the Edinburgh suburbs. I was trying to eat leak and potato soup, at the same time as struggling to identify timing locations in the dark whilst facing backwards.

Brian Webb in "The Deltic Locomotives of British Rail", 1982, p76, para 5 states: "The <flashover> problem occurred mainly in the 80-85mph speed range, but the same traction motor was giving no trouble in Class 37".

R.M Tufnell in "Deltics <a> Super Profile, p.36, para 7, says much the same thing. Although the author incorrectly states that there are three field diverts when running on two power units (there are two I believe, and three field diverts when running on one power unit).

Assuming that Deltic 9 goes back on the mainline with these 'refurbished' bogies, she's going to have to complete a 'proper' loaded high-speed test run over a good distance. But that's just my humble opinion.

One last point. I remember reading somewhere (long ago) that traction motor flashovers were often triggered by the traction motor brush-gear bouncing off the commutator when the locomotive 'hit' point-work. This is one reason why flashovers are more likely to occur at higher speeds on rough track-work. Not found a reference to this yet though...

 

Enjoying your knowledgable posts, please keep them coming.

 

On your last point, there is usually a bigger gap between the brushboxes and commutator in traction motors, compared with generators; to reduce the likelihood of brushboxes striking the commutator.