Imaginary Locomotives

[Compound2632]

1 minute ago, whart57 said:

I presume the reasoning is that the power electrics can be self contained within bogies and you don't have to run high voltage cables through passenger compartments. The electric fields might be strong enough to mess up pacemakers

 

Rivet counting, it's the magnetic field induced by the electric current that is risky for pacemakers. But for a given power transmitted, the higher the voltage the lower the current and hence the smaller the magnetic field. Anyway, there can't really be a problem here since there are plenty of systems with EMUs running off overhead 25 kV or similar.

[DenysW]

One disadvantage of third rail that I've not seen mentioned is that it appears to need a reasonable length of coaches to pass over level crossings, etc. My recollection of using Southern Region into Waterloo into the early 70s was that no train was shorter than 4 coaches, even on byways like Guildford via Cobham out-of-hours.

[Compound2632]

11 minutes ago, DenysW said:

One disadvantage of third rail that I've not seen mentioned is that it appears to need a reasonable length of coaches to pass over level crossings, etc. My recollection of using Southern Region into Waterloo into the early 70s was that no train was shorter than 4 coaches, even on byways like Guildford via Cobham out-of-hours.

 

Well, that's another reason why it's suited to intensive-service commuter routes. 

 

As to Guildford via Cobham out of hours, what advantage would there actually be in forming the four-car units designed for the rush hour into shorter units for off-peak? 

[Hroth]

11 minutes ago, DenysW said:

One disadvantage of third rail that I've not seen mentioned is that it appears to need a reasonable length of coaches to pass over level crossings, etc. My recollection of using Southern Region into Waterloo into the early 70s was that no train was shorter than 4 coaches, even on byways like Guildford via Cobham out-of-hours.

 

The LMS 3 car units used on the Wirral section had a total length of 176 ft (car lengths 56/58ft), with pickups on the outer bogies of each set.  I suspect that units tend to coast over such gaps in supply.

 

 

[Miss Prism]

25 minutes ago, DenysW said:

One disadvantage of third rail that I've not seen mentioned is that it appears to need a reasonable length of coaches to pass over level crossings, etc. My recollection of using Southern Region into Waterloo into the early 70s was that no train was shorter than 4 coaches, even on byways like Guildford via Cobham out-of-hours.

 

2-EPBs worked on their own.

 

I think 2-BILs might have worked on their own on the south coast, but I can't remember now.

 

 

[The Lurker]

27 minutes ago, Miss Prism said:

 

2-EPBs worked on their own.

 

I think 2-BILs might have worked on their own on the south coast, but I can't remember now.

 

 

There were two car trains on the Medway Valley line which I think were 2-EPBs. They definitely crossed level crossings - for example near to Wateringbury.

 

I seem to recall that the Southern electric locomotives had flywheels to help them with gapping.

[whart57]

58 minutes ago, Compound2632 said:

 

Rivet counting, it's the magnetic field induced by the electric current that is risky for pacemakers. But for a given power transmitted, the higher the voltage the lower the current and hence the smaller the magnetic field. Anyway, there can't really be a problem here since there are plenty of systems with EMUs running off overhead 25 kV or similar.

 

That's as maybe. The fact is though that despite high voltage AC systems having technical advantages people are still choosing third rail systems for new lines. New networks in fact where there is no legacy system like LT or Southern have. Admittedly modern 3rd rail mounts the rail so pick up is from the underside and the top and sides are isolated but it is still not OH.

[Northmoor]

1 hour ago, Hroth said:

 

The LMS 3 car units used on the Wirral section had a total length of 176 ft (car lengths 56/58ft), with pickups on the outer bogies of each set.  I suspect that units tend to coast over such gaps in supply.

Years ago I worked with a chap who had been signalman at Ash Vale Junction and he recalled the interesting incidents when a 2-car EMU failed to coast satisfactorily across the gap!  It involved him holding a bar (possibly wood with a conductive central rod) and thick rubber gloves, which he had to hold between the shoegear and the third rail, so "jump" the train until the shoe contacted the third rail and the train could draw forward under its own power.  The HSE would have a fit.... (and rightly so).

[Nick Holliday]

1 hour ago, Miss Prism said:

 

2-EPBs worked on their own.

 

I think 2-BILs might have worked on their own on the south coast, but I can't remember now.

 

 

The West Croydon to Wimbledon branch was worked almost exclusively by 2 car units, the branch platform at West  Croydon only taking that length.  The first units after electrification were converted from the initial LBSCR South London Line AC stock.

[PhilJ W]

13 hours ago, 11ty12 said:

I return with another edit: a Robinson Mogul made out of an LNER D9

 

2 hours ago, Johnson044 said:

A rather handsome machine! Proportions are nice and it convinces. Pig to oil the link motion though. Wheels less in diameter by 6" would be a big improvement, I think.

And a greater gap between the pony truck and the drivers would improve the appearance. Only a foot or eighteen inches should be enough. 

[PhilJ W]

2 hours ago, DenysW said:

One disadvantage of third rail that I've not seen mentioned is that it appears to need a reasonable length of coaches to pass over level crossings, etc. My recollection of using Southern Region into Waterloo into the early 70s was that no train was shorter than 4 coaches, even on byways like Guildford via Cobham out-of-hours.

The Metropolitan Railway equipped their 'dreadnought' brake coaches at each end of their locomotive hauled stock with collector shoes. There were cable connections for when they were coupled to the Metropolitan Bo-Bo locomotives and they also collected power for the ETH with which the dreadnought stock was equipped. The District railway operated their smaller box cab electric locomotives in pairs but there is photographic evidence of a single locomotive pulling a train. The surviving operational Metropolitan electric locomotive, Sarah Siddons is now equipped with a motor generator set whereby a motor taking power from the third rail drives a generator via a flywheel the generator giving power to the traction motors. Even that system is obsolete as modern stock is often fitted with capacitors as on model railway stay alive DCC systems.

[whart57]

15 hours ago, Compound2632 said:

It's worth remembering that at the time the SR chose to standardise on the ex-LSWR 660 V DC third rail system rather than the LBSCR's 6.6 kV AC overhead system, 1,500 V DC had been adopted as the national standard for overhead electrification. Thus in terms of resistive losses etc., the third rail system didn't look too bad. It's given good service for over a century - which is rather longer than main line steam had at the time the third rail was adopted!

 

Speaking of 1500v DC you have to wonder what Netherlands railways policy will be long term. 25kV AC is used on the new high speed line and on the freight only Betuwe Line, but trains using those do have to negotiate sections using the older DC OH. Not sure how all that works, especially not sure how Eurostar cope given that DC was never part of the plan. (Other than the third rail stuff before HS1 was built)

 

I can remember the old blue Benelux sets of 65 odd years ago though which had a 1500v DC pantograph at one end for running in Holland and a 3000v AC pantograph at the other for running in Belgium

[PhilJ W]

I know some of the locomotives working under multiple voltages have two different pantographs for the different systems.

[AlfaZagato]

At the very least, the Chicago, Aurora & Elgin was almost universally third rail.   The only exclusion was the yard in Wheaton, IL, where overhead was used out of concern for worker safety.   The L is still third rail, as well.    

 

The CA&E ran a minimum of two-car sets, to deal with level crossings.    Crossings could only be made so wide as to allow a two-car set to bridge the gap.   I know their freight motors weren't particularly long, so as to allow occasional turns around the Loop, so I don't know what they did for crossings there.

[The Johnster]

We have reverted to trolleybuses in Cardiff, but they don't have poles or wires.  Battery electric 'Yutong' from China, assembled in the UK, and very effective. They can handle a full day's stop-start work with heavy loadings throughout much of the day,  Something like this on a railway underframe might be feasible for inner suburban work where high speeds are not needed and there is a lot of stopping and starting; it would certainly remove the need for the third  rail and associated infrastructure.  I assume they are charged overnight, which suggests a charge time of about 4 hours, and they are used on the busiest routes, racking up a fair bit of mileage in a day's work to suburbs 6 or 7 miles from the centre.  Newport has them as well, and uses them on their Cardiff services, about 15 miles at motorway speeds for service X30. 

 

The old trolleybuses, much bigger than the Yutongs and able to carry 96 passengers, could manage a short distance at low speed on battery power, but this was only of any use for moves within the depot or where one had to pass another trolleybus for service reasons at termini.

 

It may be time to reconsider third rail.

[PhilJ W]

Mentioning level crossings on third/fourth rail systems reminded me that on the London underground there were only ever two. One was an access road to a depot and the other was an occupation crossing at North Weald.                          

Edited January 8, 2022 by PhilJ W

[Sabato]

8 hours ago, DenysW said:

One disadvantage of third rail that I've not seen mentioned is that it appears to need a reasonable length of coaches to pass over level crossings, etc. My recollection of using Southern Region into Waterloo into the early 70s was that no train was shorter than 4 coaches, even on byways like Guildford via Cobham out-of-hours.

Even so, they could, under certain circumstances, be gapped.

 

One Saturday (in 1973/4) I was going down to Southampton Uni to see my  GF (now wife). I made a very early start from Waterloo and looking forward to having breakfast on the train. Remember the Bomo trains only had shoes on the 4-REP. I sat in the restaurant car, and we started away very, very slowly, probably under a single yellow on the platform end starter. There is an "advanced starter" only about 100 to 200 yards out, and there we crept to a stand. After  about 5 minutes the steward came to me and said, "Are you hoping for breakfast?" "Oh yes." I said. "Ah well, the kitchen is electrically powered and as the train is gapped we can't cook anything, not even mash some tea".

 

We sat across the "mainline" portion of the station throat for about an hour. During which time the operating people had to find a driver for the station 08, then shuttle it back and forth to get it behind us. A short nudge to get us on the juice, and we were away, a good hour down.

 

My journey home was interesting too, but for other reasons, probably not appropriate for this forum.

[The Johnster]

Don’t tell me; you got gapped again, the heating was off, and it was a good way to keep warm?

[Sabato]

16 minutes ago, The Johnster said:

Don’t tell me; you got gapped again, the heating was off, and it was a good way to keep warm?

I wish.

 

No, it was non-railway really. 

[Northmoor]

2 hours ago, PhilJ W said:

Mentioning level crossings on third/fourth rail systems reminded me that on the London underground there were only eve two. One was an access road to a depot and the other was an occupation crossing at North Weald.                          

An additional one has been gained on the "Overground": Bollo Lane in Acton, although this is a pedantic point as while part of TfL, was a service inherited from Silverlink and is NR infrastructure.  I think the depot one is within Acton Works itself.

[The Johnster]

2 hours ago, Sabato said:

I wish.

 

No, it was non-railway really. 

But I suspect it was still a good way to keep warm...

[tythatguy1312]

here's an unusual proposal I've heard of. Apparently the LNER considered a larger wheeled 2-8-0 for passenger workings for the West Highland line, where the K4's ultimately ended up dominating. What would this have been like?

[Compound2632]

7 minutes ago, tythatguy1312 said:

here's an unusual proposal I've heard of. Apparently the LNER considered a larger wheeled 2-8-0 for passenger workings for the West Highland line, where the K4's ultimately ended up dominating. What would this have been like?

 

I imagine the twisty nature of the route counted against an eight-coupled design. Plus I imagine there might have been infrastructure costs in terms of larger turntables at Fort William and Mallaig - though I an LMS Standard 8F had a slightly shorter overall wheelbase than a 5MT. What was the overall wheelbase of a K4?

[Traintresta]

On 06/01/2022 at 22:48, 11ty12 said:

I return with another edit: a Robinson Mogul made out of an LNER D9

Interesting idea that fits right in with the early era of Robinson loco's for the GCR.  Given that the GCR had American built moguls it is reasonable to think they would have developed their own version of the concept (even though all of the American built moguls used in this country were considered unsuccessful) as did the GNR.  Certainly the proportions of the boiler length to the standard sized firebox used by Robinson would probably have made for a more successful locomotive than some of his 4-6-0's, just like the Directors.

 

2 hours ago, tythatguy1312 said:

here's an unusual proposal I've heard of. Apparently the LNER considered a larger wheeled 2-8-0 for passenger workings for the West Highland line, where the K4's ultimately ended up dominating. What would this have been like?

It was to have 5'2" drivers, a 5'6"/5' taper boiler and a tractive effort 50% higher than the K2's but would have been too long for the turntables and too heavy for the bridges.

 

More interestingly, in 1947 a K6 was proposed with 5'2" drivers and a tender cab, with only a 15t axle load limit.  It was to be used on lightly laid branches but much like the Std class 2's, it probably would have been a bit late to the party.

 

 

 

What is even more interesting is that if the GCR had built the proposed 2-6-0 (drawing included) it could have served the West Highland route, probably better than the K4's, as it's larger wheels would have allowed faster running but it could have been as powerful as a K3, and it would have had a similar weight.  In the drawing attached, the maximum axle weight is the same as that of a K3, but overall weight is less so it would have been feasible.

Edited January 8, 2022 by Traintresta

[PhilJ W]

4 hours ago, tythatguy1312 said:

here's an unusual proposal I've heard of. Apparently the LNER considered a larger wheeled 2-8-0 for passenger workings for the West Highland line, where the K4's ultimately ended up dominating. What would this have been like?

They had problems with the P2's with regard to cracked frames thats why Thompson converted them to pacifics. That may well be the reason that the 2-8-0's were dropped. My own personal opinion is that the P2's should have been transferred south to haul the heavy wartime trains (20 coaches) on the ECML.