Imaginary Locomotives

[rodent279]

5 hours ago, The Johnster said:

Are they though?  Back in the early 60s my brother in law was employed after graduating as an electrical engineer from Birmingham University by A.E.I., and one of his first tasks was to design switchgear on board the AL4 electric locos being built at the time for the automatic switching required for OHLE passing beneath bridges in urban areas, which was intended to be stepped down from 25kv to 6.6kv because of this clearance issue.  In the event the lower voltage was never used and 25kv supplied throughout the system, with not that many people having been fried as a consequence.

I can't remember the full details, but I remember my dad telling me something about tests done on insulators under bridges, with steam locomotives pouring out smoke & steam, and no flashovers occurred. As a result, the smaller clearances initially prescribed for 6.25kV were adopted.

[DenysW]

From wikipedia's Railway events for 1912:

 

November – The Royal Bavarian State Railways begins the process of standardising the Railway electrification system in German-speaking countries at 15 kV AC, 16.6 Hz

 

No date was given for the process having completed.

 

I have read separately that improvements in insulation materials were the reason that 6.6 kV could later be replaced by 25 kV at the same clearances.

[rodent279]

Air suffers electrical breakdown from around 25-30kV per cm, depending on atmospheric conditions. The minimum clearance for bare conductors to a structure such as a bridge needs to allow for the formation of ice, running water etc. An insulator needs to provide a sufficiently long and convoluted path so as not to provide a continuous path when wet or iced up, which is why they are not simply solid porcelain rods.

[rodent279]

2 hours ago, rodent279 said:

I can't remember the full details, but I remember my dad telling me something about tests done on insulators under bridges, with steam locomotives pouring out smoke & steam, and no flashovers occurred. As a result, the smaller clearances initially prescribed for 6.25kV were adopted.

That said.......

 

 

[PhilJ W]

1 hour ago, rodent279 said:

That said.......

 

 

There must be quite a bit of highly conductive carbon in the exhaust.

[rodent279]

3 minutes ago, PhilJ W said:

There must be quite a bit of highly conductive carbon in the exhaust.

Could be, or possibly just wet steam condensing in large amounts.

[PhilJ W]

9 hours ago, The Johnster said:

Are they though?  Back in the early 60s my brother in law was employed after graduating as an electrical engineer from Birmingham University by A.E.I., and one of his first tasks was to design switchgear on board the AL4 electric locos being built at the time for the automatic switching required for OHLE passing beneath bridges in urban areas, which was intended to be stepped down from 25kv to 6.6kv because of this clearance issue.  In the event the lower voltage was never used and 25kv supplied throughout the system, with not that many people having been fried as a consequence.

That reminds me of an incident at Southend many moons ago. There were telephone lines crossing the electrified tracks that due to failed supports had started to sag. They were still sufficiently above the 25Kv to not cause a problem until a pigeon settled on the telephone wires and pooped. It put the telephones out in that part of Southend.

 

4 minutes ago, rodent279 said:

Could be, or possibly just wet steam condensing in large amounts.

Steam cannot conduct electricity, neither can distilled water. It is the impurities in water that conducts electricity.

[rodent279]

39 minutes ago, PhilJ W said:

That reminds me of an incident at Southend many moons ago. There were telephone lines crossing the electrified tracks that due to failed supports had started to sag. They were still sufficiently above the 25Kv to not cause a problem until a pigeon settled on the telephone wires and pooped. It put the telephones out in that part of Southend.

 

Steam cannot conduct electricity, neither can distilled water. It is the impurities in water that conducts electricity.

Presumably the pigeon didn't fare too well either!

I guess that explains why they use distilled water in batteries.

Edited September 8, 2021 by rodent279

[rodent279]

1 hour ago, PhilJ W said:

There must be quite a bit of highly conductive carbon in the exhaust.

Looking at the video again, I wonder whether the jet of steam from the safety valves caused the wire to uplift, to the point where it flashed over?

[Clive Mortimore]

There was a reason for banning 8P locos form going under the wires back in the 1960s, the yellow stripe wasn't for fun.

[PhilJ W]

2 hours ago, rodent279 said:

Presumably the pigeon didn't fare too well either!

I guess that explains why they use distilled water in batteries.

All that was found was a few charred feathers and the charred feet stuck to the telephone wire. I don't think anything will fare too well having 25Kv up the jacksie. When a lead acid battery is charged the water in the sulfuric acid splits into hydrogen and oxygen. The hydrogen escapes to the atmosphere (thats why smoking is banned near batteries being charged) and the oxygen forms on the lead plates as lead-oxide. Distilled water is added to replace the Hydrogen. It only takes a minute amount of impurities to stop the process taking place.

Edited September 8, 2021 by PhilJ W

[Gibbo675]

5 hours ago, PhilJ W said:

There must be quite a bit of highly conductive carbon in the exhaust.

Hi Phil,

 

The biggest source of carbon on the underside of bridges and tunnels is the carbon from dirty diesel exhausts, in steam days it was knocked off by safety valves similarly to what caused the wires to be swayed in the video. The very reason that BR standard pacifics had their safety valves angled outwards yet strangely not continued on the smaller classes.

 

Quite some years back 76079 blew off in a tunnel east of Edinburgh Waverly and caused such a flashover it knocked out the breakers. This was caused by carbon deposits bridging between the contact wires and the cab roof and safety valves, there were a burns about the size of you thumb nail caused by the arc in the cab roof and a smaller on on one of the safety valves. Some of the carbon deposits later found on the top of the firebox were up to nine inches long and almost an inch thick, they also shewed burns caused by electrical arcing.

 

Gibbo.

[PenrithBeacon]

3 hours ago, Clive Mortimore said:

There was a reason for banning 8P locos form going under the wires back in the 1960s, the yellow stripe wasn't for fun.

The reason was that it was thought that the structure of the locomotive would be too close to the wire. This might cause a flash-over. I think that opinion changed after 1968 and the yellow stripe wasn't actually needed.

IIRC maintenance crews on pantographs found that the carbon pickup strip lasted for a lot longer post August 1968.

[AlfaZagato]

2 hours ago, Gibbo675 said:

The very reason that BR standard pacifics had their safety valves angled outwards yet strangely not continued on the smaller classes.

 

I'd imagine smaller classes didn't quite need the clearance.   I'd also think the BR Pacifics, which started at class 6, might have higher boiler pressures, which would be more volume being ejected more forcefully from the safety valves.

[MikeOxon]

Perhaps my imaginary 'under the wires' locomotive should have a chimney based on the funnel originally designed for SS France and subsequently used on many cruise ships:

 

 

Mike

[rockershovel]

46 minutes ago, MikeOxon said:

Perhaps my imaginary 'under the wires' locomotive should have a chimney based on the funnel originally designed for SS France and subsequently used on many cruise ships:

 

 

Mike

Looks like something you'd find on a minor Belgian tramway, probably in conjunction with outside frames, Joy valve gear and a half-round smokebox door

[tythatguy1312]

On 08/09/2021 at 21:12, rockershovel said:

minor Belgian tramway

You mean the Great Western Railway around the turn of the century?

[DenysW]

Could the GWR broad gauge loading (as a few pages back) have made this unsuccessful 1855 French design (L'Aigle, but it never soared) have worked by conversion to a 4-4-2, with the trailing axle far enough back to allow a reasonable size grate? I just like the idea of GWR with a split boiler, and entering into a 'My wheels are bigger than your wheels...' contest, and winning due to the extra possibilities of their broad gauge.

 

[Compound2632]

3 hours ago, DenysW said:

Could the GWR broad gauge loading (as a few pages back) have made this unsuccessful 1855 French design (L'Aigle, but it never soared) have worked by conversion to a 4-4-2, with the trailing axle far enough back to allow a reasonable size grate? I just like the idea of GWR with a split boiler, and entering into a 'My wheels are bigger than your wheels...' contest, and winning due to the extra possibilities of their broad gauge.

 

 

That does look reminiscent of some of the sketches of Brunel's outlandish failures, before he recruited Daniel Gooch from Robert Stephenson & Co. It's worth teasing the BG-ites by pointing out that the most successful BG locomotives were thoroughly Stephensonian.

Edited September 11, 2021 by Compound2632

[MikeOxon]

1 hour ago, DenysW said:

.......................I just like the idea of GWR with a split boiler, and entering into a 'My wheels are bigger than your wheels...' contest, and winning due to the extra possibilities of their broad gauge.

Way back in this thread on p.255 I pointed out [June 18, 2020] that the 'freak' locomotive 'Ajax' with its 10' driving wheels could have had its tiny boiler placed below the driving axle.

[rockershovel]

4 hours ago, MikeOxon said:

Way back in this thread on p.255 I pointed out [June 18, 2020] that the 'freak' locomotive 'Ajax' with its 10' driving wheels could have had its tiny boiler placed below the driving axle.

It's curious that some early designers, if that's the correct term at that formative stage, seemed to have lacked understanding of the most basic aspects of steam locomotive design - that the boiler needs to big enough to provide an ongoing supply of steam, and there needs to be enough weight over the driving wheels to provide adhesion and hence, traction. 

 

This wasn't unknown at the time. Builders like Stephenson and Hackworth, involved in constructing locomotives for tramways, certainly understood the principles. Stephenson did quite a successful job of identifying the task set to contestants at Rainhill and building a locomotive to execute that task, whatever else it did or didn't achieve

 

[tythatguy1312]

Ok, as I seem to mainly be good at bad, horrendous and insane ideas that have barely a sliver of a hope in a frozen hell of working... what if, say, the GNR developed an 0-4-2 for express trains?

[Compound2632]

33 minutes ago, tythatguy1312 said:

Ok, as I seem to mainly be good at bad, horrendous and insane ideas that have barely a sliver of a hope in a frozen hell of working... what if, say, the GNR developed an 0-4-2 for express trains?

 

Well, that's not so far out. Patrick Stirling built plenty of 0-4-2s for intermediate passenger work:

 

 

Derived from his earlier work at Kilmarnock and continued by brother James, though after the latter moved to Ashford he stuck to 4-4-0s - which Patrick never went in for, at all. 

 

One can imagine an express passenger version bearing the same relationship to this as Stroudley's Class B (Richmond/Gladstone) did to his Class D (Lyons).

[The Johnster]

And 0-4-2s were used on the Brighton and the LSW for express work. 

[tythatguy1312]

alright as an alternative to my idea that, for once, was smart enough to have been built by my example railway, what if the LB&SCR had used the K class as their basis for their infamous 0-6-0T?