alcazar

iTrader: (2)

Anyone who cares, please sign this petition.

Petition to: Instruct the Department for Transport to, within six months, update the 1981 joint Department of Transport/British Rail ‘Review of main line electrification’ to take into account current installation and energy costs and rail traffic

At the moment, the Transport minister, Douglas Alexander, (yes, ANOTHER Scot), is putting it about that diesel trains are more eficient than electrics, so diesel is the way forward, and no more lines should be electrified.

Meanwhile, THREE lines are being electrified, or will be: guess what? they're ALL in Scotland.

Alcazar

fatherpierre

Diesel engines have come a long way in the last few years........

Joking - signed.

RichWalk

bring back Hoovers

alcazar

iTrader: (2)

Nah..........they ousted the Westerns, which, along with Deltics, were my favourites

Alcazar

ChrisB

Electrics are great until it gets windy. Then it all goes Pete Tong.

Took me four hours to get home from London the last time there was a bit of a breeze (normally ~2 hours). Thank deity for the IC 125s out of Paddington.

///\oo/\\\

Agreed.

Same issues trying to get back from London a while back. Electric lines went down, but the diesels kept running.

Most of our main Scottish network is diesel, and it works fine. Glasgow & Edinburgh to Inverness, Aberdeen and Fort William all diesel.

Commuter services around Glasgow and Edinburgh are all Electric and there is no discernable benefit, to be honest, and they are the ones that have issues in high winds & flooding.

Hoppy

The problem, as I understand it, with diesels is that there isn't a clutch strong enough to take the torque needed to haul a big train.

Electric motors don't need a clutch, so they either get their power from over-head lines, or diesel-electrics where the diesel motors are just electricity generators.

So if you can sort the transmission of a big diesel, wouldn't that save a lot of hassle and cost?

Richard.

PS I'm no expert - just what I've been told

Moonloops

I'd vote for the electrification of the government

alcazar

iTrader: (2)

The "high winds" thing is DIRECTLY attributable to government. Not Labour, this time, because THEY haven't sanctioned any electrification

It's our old friends, the Tories, who, when British Rail wanted to electrify a line, INSISTED they made a business case and it had to be done as cheaply as possible whilst raking in the most cash.

Result: they cut corners. Not on safety, obviously, but on the spacing between masts on the catenary, (the bit that holds up the wires).

They put the masts the MAXIMUM allowable distance apart This means the wires have insuffiient support/tension etc and swing in high winds, touch and come down

A by-product of this is the inability of our sytem to sustain speeds over 125mph: the trains set up a sort of "bow wave" in the wires, and the lack of support brings the wires down. This is NOT the case on the West Coast, where the masts are set at the best spacing for the maximum line speed. Problems on the West Coast are due to the age of the system: It was designed over 40 yeras ago and for a maximum of 100mph.

And yet the French can run HUNDREDS of trains daily at 186km/h on a PROPERLY engineered system. In fact, the new TGV Est has just set a world record of 553km/h (345mph), and will run at 220mph on a daily basis. They run LOADS of loco-hauled trains at 125 mph on ordinary lines and even run 100mph freights! The average maximum speed of a UK freight is 60mph.

The trains bought for the East Coast main line, (Kings Cross>Edinburgh) were bought with a design line speed of 140mph, but it can't be used.

Alcazar

alcazar

iTrader: (2)

No mate, no-one uses direct drive now, they're ALL diesel-electrics, where, as you say, the diesel engine runs a large alternator to supply current to traction motors, usually one per axle. Doesel mechanical, which DID have gearbox, clutch etc was really reserved for relatively low-powered shunters, of the order of 200hp. Compare that with today's large mainline diesels with 3500hp.

The UK and Germany flirted with Hydraulic transmission, which was superb when it worked, (there is a fully documented case of a driver at Paddington, fully opening the throttle of a 2700hp diesel hydraulic on the front of a heavy train. The torque was so high, it spun the wheels and welded them to the track!)

No "hydraulics" now exist except in preservation: problems with maintenance killed them.

Alcazar

CrisPDuk

There is significantly less energy lost by using a diesel generator to power AC traction motors, rather than using direct drive through a mechanical transmission too.

CrisPDuk

Which in turn had ousted the Kings and the Castles Superior machines in every respect

Do think there's a need for a thread calling our fellow 'anoraks' to stand up and be counted alcazar

SJ_Skyline

PMSL

Nimbus

Including HSTs?

I think we should bring back Steam Locos.

CrisPDuk

Yep, including HST's

They have a 2,200hp Paxman Valenta turbocharged V12, strapped to a thumping great Brush generator which powers four traction motors at each end

alcazar

iTrader: (2)

Oh good grief no! I'd rather keep it a bit quieter than that

being brought up 23 miles by rail from Doncaster, my boyhood was spent watching A4's A3's A2's and A1's. I'm eagerly awaiting the new A1 being completed, the first steam loco to be built in the Uk for over 40 years.

I just WISH I'd had a camera in those days, let alone colour film, or a video. As a little boy I was chucked out of the Plant many times.

Alcazar (and now you know where my username comes from........)

Hoppy

Alcazar, please tell more

If direct drive is still a non-starter (ha ha!) then is there a fundamental advantage to getting the electricity from an overhead line rather than an on-board generator?

What tricks have the French got that we haven't?

Richard.

PS Edited to ask Mr Duck why direct mechanical power losses out weigh the losses from converting diesel fuel into electric drive. If that is true, why aren't we all driving diesel-electric cars? Forgive my ignornace, just interested.

DaveD

iTrader: (2)

I guess designing a clutch to take 3,000 hp might pose a few problems!!

Diesel electric drive is useful on railways because of the large amount of torque required to get trains moving. For cars, it's probably an additional complication / expense that probably outweighs any benefits when used with a conventional engine. However, I think hybrid cars do use electric motors to drive the wheels.

Electric locomotives have the advantage of not having to lug the prime power unit, generator and fuel around with them. Electric trains also have the advantage of being able to use regenerative braking - that is being able to slow down by turning the traction motors into generators and feeding that power back into the National Grid.

Nigel H

Alcazar,

You're one the right lines for most of your stuff, except that you still get DMUs as opposed to DEMUs. The recent Class 185s and Class 180s are DMUs, the 220,222 and 223 (and 170s for that matter) are DEMUs. The E signifies that it has an electic drive. The 180s and 185s both have hydraulic drives from Voith which are big, heavy and complicated.

In comparison an EMU is much simpler and more reliable. Typically (and I know this is a gross exagerration (this is the internet after all) an EMU will be 2 or 3 times more reliable than a DMU.

CrisPDuk

The major advantage of using an external power source is weight. As you can imagine, a diesel engine capable of generating the 3,000+hp required for ain't light. OK the Deltics managed it but they were extremely maintenance intensive, and used a 2 stroke combustion cycle, which would not be acceptable today
As fast as they are, the HSTs are no match even for the 1960s built Class 86 electric locomotives when it comes to accelerating a fully laden passenger train, especially once you get into the north of England and the wastelands above Hadrians Wall, where it starts to get a bit hilly

The French don't have any tricks as such. What they do have is one, huge amounts of capital investment, and two, an abundance of open countryside through which they can run dedicated high speed lines

I don't know the full details, but energy losses due to friction are considerably less in electric generators/motors than they are through mechanical transmissions, which makes sense when you look at the number of parts involved, especially those in direct physical contact.

The other issue is one of control, an electric motor behaves in a progressive manner throughout it's operating range manner, making it's output far easier (read simpler and cheaper) to regulate. A big (and I mean big) turbocharged diesel engine is not exactly linear in it's power delivery, nor does it have a particularly broad useable power band, meaning expensive multi-geared transmissions are required for a rail application.

The final factor to take into account is that AC generators and traction motors are astonishingly reliable, even when subjected to the extremely harsh conditions encountered in a rail enviroment. The vast majority of locomotive failures in service can be attributed to diesel engine faults (usually exhaust, fuelling or cooling, rather than the engine itself*) rather than the electrical system.

*The exceptions to this were the previously mentioned Class 50 'Hoovers', which initially had a tendency toward generator flashovers (frying them, effectively), this was more down to the large quantity of untried new technologies they were fitted with, rather than any inherent fault in the basic design though.

{anorak mode off}

Hoppy

Thanks for the reply Mr D, but I can't sleep (4am here) and am still unclear. Get your anorak back on

I understand the French thing. The Brits invented railways in 1066 or something, and didn't foresee 21st century problems where a wider track would have been better. Also, our short platforms and sidings were probably a mistake in view of the demand for more carriages today. They also have five times the land mass with a similar population to ours so have a chance to build up speed, which is important for long distance travel. Not so in the UK where a steady 100mph will get you to most places pretty quickly - more quickly than it takes me to get from home/station/carpark/platform for a 45 minute journey to London. The French situation is therfeore not comparable.

But that apart, the OP was asking for more electrified lines and has explained some of the practical problems related to cost. Also that direct/hydraulic technogogy is still lacking for modern power outputs. So isn't diesel-electric the best solution?

I don't accept the weight problem, given the overall weight of an overloaded train. And can't we make a reliable diesel engine that would ultimately be more fuel-efficient compared to coal/gas from a power station many miles away? And if one power unit goes bust, isn't there another one at the back to get you home? But if a power line goes down, everything stops. Probably for a long time.

Thanks for your time,

Richard.

CrisPDuk

Aha, now I understand, you want to know the pros and cons of the infrastructure not just the individual locomotives. Probably not something that can be answered full in one shot post, but what the hell, I've got **** all else to do here today

Agreed the French example is irrelevant, but you did ask the question Anyway lets get onto your main point. Unless the train you are on is a multiple unit, i.e; Virgin Voyager, HST, commuter special, etc, the likelyhood is that it is composed of one locomotive pulling a quantity of carriages. Regardless of whether that locomotive is Diesel-Electric or Mainline Electric, if the locomotive fails your train stops, there is no back-up. To a certain extent the same is true of multiple units too, although they can sometimes continue to the next station on reduced power.
Freak weather conditions aside the likelyhood of the 25kV electrical system failing is remote, so to all inents and purposes can be discounted.

As to the power side of things, consider this:
An HST has two power cars each generating 2250hp giving 4500hp total. Back in their prime almost all of this 4500hp was required to get both power cars and their eight(west country) or nine(east coast) carriage trains up to 125mph on the reasonably level East Coast and West Country main lines.
A solo Class 90 25kV Electric locomotive, which weighs about the same as one HST power car, is capable of hauling 13 or 14 carriage trains over the steeply graded West Coast main line at well above the line max of 110mph.
A diesel engine capable of generating enough power to perform this feat would not physically fit in the confines of a locomotive body, nor would the rails take the weight.
Back to the original topic, electrification of suburban, commuter intensive rail networks has been recognised as the cleanest, most efficient method of transporting people en masse since the late 1920s, for two reasons, they have no emmissions in themselves, and they are exrmely reliable, with minimal maintennce requirements. The trouble is the intitial investment, in overhead catenary, overbridge rebuilding, etc, is massive, and takes a long time to recoup. This alone to a goverment, which is only ever interested in short term gain, is a bad thing

Hoppy

Thanks for that excellent response. It all makes perfect sense. You have a very large anorak

Your last couple of sentences explain a lot.

Cheers,

Richard.

matchmaker

matchmaker

Ahem. Many DMU's are hydraulic

matchmaker

The aforementioned Hoovers had an English Electric 16CSVT engine.


247 litre V16 putting out 2700 bhp at 850 rpm.

Friggin enormous engine when you see one - and heavy.

The Paxman Valentas in the HST are a mere 88 litres. Think Deltics were the same.


Another gricer

DaveD

iTrader: (2)

The overhead cables carry 25,000v ac. It is not safe to place this close to the gound as there is a serious risk of the electricity arcing - you could get electrocuted by just going near it!!

The old Southern region (around London and South East) do use a ground level supply system. A third rail is placed at the side of the normal running lines, but this is only at 750v dc - therefore safer from arcing, but still potentially leathal!!

PS: CrisPDuk, Hoovers use DC generators (along with the Deltics and most early diesel electrics from the 1960s). These need a commutator + brushes to get the electricity out from the rotating coils. In service, dust from the carbon brushes and general dirt and oil could collect on the commutator, creating a short circuit, and causing the flashover. A flashover could occur if too much current was drawn even on a fairly clean generator - hence why higher powered locomotives were more at risk from this problem.

More modern diesel electrics use AC alternators which have no moving contacts, and do not 'flashover'.

Oh, and the Hoover's English Electric 16CSVT also had four turbo chargers - not sure if they had dump valves though?!

Luminous

iTrader: (3)

It never ceases to amaze me how much knowledge there is on this forum about trains

All I know about them is that they are...
1) normally late
2) always over priced
3) rarely have free seats
4) and normally don't end up where I had hoped they would (far too hard to actually get on the correct one!!)

CrisPDuk

My bad

I'd forgotten about the older motors being 'dirty' DC