Train journey home.

[Dieselman]

Judging by the sound they make when pulling out of Paddington for example, the diesel engine shaft is directly connected to the generator which sends variable power to individual electric motors.
But that is a total guess. I might be very wrong.

Near enough. It's called Serial Hybrid.

 

[Dieselman]

9mpg, I thought it would be sub 1pmg - I could

How big is the fuel tank? It must be massive to be able to run up to Aberdeen to London without refuelling.

London to Aberdeen, say 600 miles.
600 @ 9mpg = 66.6 gallons 303 litres.
840g.km Co2. over say 400 passengers. 2g/km per passenger.

 

[Dryce]

Right, in other words the acceleration of the train may be slower, but it might just reach 125mph

The Intercity 125 is quite an old design, if you want really impressive diesel power try the Virgin Voyager trains.

The locos don't work very hard at speed and may well coast on the flat sections.

The 125 is an old design but they have recently been re-engined.

The Australians also have some.

Voyagers are just heavyweight diesel multiple units. Engines under each carriage. Not as bad as some of the older short haul units but internally they're not as refined as the old 125s or traditional loco hauled stock.

 

[Dryce]

Near enough. It's called Serial Hybrid.

I'd disagree on a technicality.There's usually no battery so no energy storage. The engine has to run all the time.

The electric generator and traction motors are really just being used as a transmission.

 

[st4]

http://en.wikipedia.org/wiki/British_Rail_Class_43_(HST)

All you need to know.

 

[Dryce]

Judging by the sound they make when pulling out of Paddington for example, the diesel engine shaft is directly connected to the generator which sends variable power to individual electric motors.
But that is a total guess. I might be very wrong.

Typically diesel powered trains are diesel-electric (as you suggest above) or diesel hydraulic. Some of the older multiple unit types were diesel-mechanical.

I don't think there are any diesel-hydraulic locomotives in use the UK except in preservation. There are modern diesel-hydraulic multiple units (eg. class 170s which are ubiquitious in Scotland).

 

[Dieselman]

I'd disagree on a technicality.There's usually no battery so no energy storage. The engine has to run all the time.

The electric generator and traction motors are really just being used as a transmission.

I understand the diesel-electric bit but thought if there was no battery it's a serial hybrid, where as it's a duplex if there is storage and two motor connections, e.g. engine and electric motor.

 

[st4]

Typically diesel powered trains are diesel-electric (as you suggest above) or diesel hydraulic. Some of the older multiple unit types were diesel-mechanical.

I don't think there are any diesel-hydraulic locomotives in use the UK except in preservation. There are modern diesel-hydraulic multiple units (eg. class 170s which are ubiquitious in Scotland).

They have 170's down south. I saw one in Liverpool Street which surprised me, as I thought we just had them. I do find the 170's comfortable and pretty quiet, but nothing beats a separate locomotive and coaches. I take it the 156 & 158's use the same system.

 

[Dryce]

When they are started from cold they produce an unbelieveable amount of smoke!

That's just pseudo-clag when it's a 66 shed.

37s know how to do it properly.

 

[Dryce]

I understand the diesel-electric bit but thought if there was no battery it's a serial hybrid,

I'm quite happy to stand (or sit) corrected.

I understood the serial hybrid as involving battery because to count as a hybrid it has to be able to move on electric power alone. Without the battery you simply have an electric transmssion system. ??

 

[Dryce]

I take it the 156 & 158's use the same system.

As far as I'm aware - yes.

Diesel-Hydraulic seems to be prefered for traditional multiple units and Diesel-Electric for the long distance units.

I don't like the 170s because of the placement of the doors. And the perpetual announcements. I actually like the 156s more. But I'm weird.

 

[Dieselman]

That's just pseudo-clag when it's a 66 shed.

37s know how to do it properly.

This one's doing a pretty good job...
http://www.youtube.com/watch?v=w4MjC1Ywofg&feature=related

 

[st4]

As far as I'm aware - yes.

Diesel-Hydraulic seems to be prefered for traditional multiple units and Diesel-Electric for the long distance units.

I don't like the 170s because of the placement of the doors. And the perpetual announcements. I actually like the 156s more. But I'm weird.

You are, bad train taste. 156's are noisy and slow and quite old hat now.

They run the 156 up the west highland line, and this is the train I get to work. For the life of me I don't know why they don't use a 158 or 170. I used to think it was that 156's were lighter, but they run a class 37 locomotive for the sleeper service and freight up that line.

 

[Colin_b]

That's just pseudo-clag when it's a 66 shed.

37s know how to do it properly.

They don't appear to be as bad, don't lay down quite the smokescreen that the 66's do.....

We did have a couple of 37 idling away all day today just upwind of the office today, No smoke, just the smell!

 

[Dryce]

You are, bad train taste. 156's are noisy and slow and quite old hat now.

Ah but I remember the older DMUs. The 156s were reasonably quiet (relatively rattle free) - 2+2 instead of 2+3 seating - and doors at each end (out of the way). I've had a lot of good naps on 156s.

They run the 156 up the west highland line, and this is the train I get to work. For the life of me I don't know why they don't use a 158 or 170. I used to think it was that 156's were lighter, but they run a class 37 locomotive for the sleeper service and freight up that line.

I don't think the 158s should be a problem as they use them on the Kyle line.

They use a class 67 on the sleeper these days and it's got a quite high axle loading - class 37 is less. (You also get regular 66s and the odd 47, 57, and Deltic up the WHL). I can't see why the 170s couldn't be used.

 

[Dryce]

They don't appear to be as bad, don't lay down quite the smokescreen that the 66's do.....

We did have a couple of 37 idling away all day today just upwind of the office today, No smoke, just the smell!

Anytime I've seen a 66 at work it's been more of a heat shimmer off the top rather than a grey mass of particulates.

Maybe it's a plot by the 37s to keep themselves going longer and into a fifth decade.

 

[verytalldave]

I didn't know I knew so many anoraks...............

 

[Kamisuma]

RR of steel wheels on rails is 1,000 times less than pneumatic tyres on tarmac.

???
Certainly nowhere near that magnitude of difference.
http://www.engineershandbook.com/Tables/frictioncoefficients.htm

Rolling resistance is just a different form of static resistance.

 

[Dryce]

I didn't know I knew so many anoraks...............

Takes one to know one.

You just didn't realise until now.

 

[Dieselman]

???
Certainly nowhere near that magnitude of difference.
http://www.engineershandbook.com/Tables/frictioncoefficients.htm

Rolling resistance is just a different form of static resistance.

Are you sure. I ask as it was defiantely covered as such and it makes sense. A rolling steel wheel on a steel rail doesn't deform anything like as much as a rubber tyre on tarmac. That takes energy.

http://en.wikipedia.org/wiki/Rolling_resistance

This indicates 200-300 times less resistance.