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Challenges for Developing Dual Mode Locos
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royaloak
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Shouldn't be a problem getting all the equipment in with the 25.5 tonne axle loading, of course the access charges would be horrendous and there wouldn't be any room for passengers but hey ho!
Desiros are classed as heavy and they have a 12.5 tonne axle loading, 10 tonnes is the preferred maximim and it would be impossible to get dual mode, never mind triple, done within that.
Desiros are classed as heavy and they have a 12.5 tonne axle loading, 10 tonnes is the preferred maximim and it would be impossible to get dual mode, never mind triple, done within that.
On an MU you can of course spread out the load: basically you could take 210 (fantasy resurrection) ends and stick it on a 418 mid set.
A bit wasteful? to utilsie driving gear for all modes, there is the challenge of probably on stepping down from 25KV and low amps to 150 to 450 V range for ordinary Diesel Electric/ thrid rail traction motors at high ampages. Anyone more thechnical than this ?- as far as I go really.
A bare MTU v16 weighs less than 10 tonnes (according to a mate who lifts them out of fast ferries) The old CSVT v12 only weighed about 20 tons on on it's own and EE built a 78 ton 1850hp export machine with it in. Another 20 tonnes is fine on a Co Co or AIA ( or AAA as your royal oak actually had!). Bloody emissions exhausts take up a wad of space now ( see angels MTU powered 125s)
How much space is there left in a 92? Do they not priduce 3300hp on thrid rail?
That's one area that isn't a problem. There are already a number of dual voltage units on the network.
Axle loading on locos can be kept down with body mounted traction motors, eg class 91.
But is there room for a worthwhile size diesel unit in there? I can't see it. I just don't see the point of building anything so complex.
The phrase 'jack of all trades, master of none' springs to mind. Building a dual or triple mode loco that requires double heading far more than a dedicated diesel or 25KV loco, aren't these exactly the issues threatening to scupper the dual mode part of IEP?
Kingfisher200262
Member
I think you mean unsprung mass, not axle loading. One way or another, all the mass on the loco finds its way through the axles to the point of contact with the rail.
The issue with unsprung mass is that it is just that - unsprung, and as such puts shock vertical forces into the infrastructure, which are much more severe than all the mass that is above the springs and the dampers.
In the past, as in the case of the Class 91 loco, the unsprung mass was reduced by mounting the traction motors on the body and transmitted to the wheels via Cardan shafts and final drives.
Modern locos (and some MUs, including, I think the Voyagers / Meridians) generally incorporate a "hollow axle" system, which produces a similar outcome, but all the drive system is bogie-mounted.
To keep the total mass of the Polaris electro-diesel power car down to a target of 64 tonnes, (resulting in an axle load of 16 tonnes, assuming even weight distribution can be achieved) but provide multiple unit type acceleration, traction motors will be located on the power car and the first trailer car, adjacent to it.
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SWT Driver
Member
Can't really see a problem, surely it's not beyond new fangled technology to produce an upgraded Class 73/74!
I don't think the question is 'could we?' it's more of a 'should we?'. Whilst something like a Class 70 shows the ultimate in tractive effort and power available from just diesel power, it would certainly be the diesel side of a dual mode loco that would suffer dramatically. Realistically, could we expect much more than 1500hp from the diesel mode??
royaloak
Established Member
Voyagers have body mounted TMs and a cardan shaft to the final drive on the axle.
Kingfisher200262
Member
Thanks. I wasn't sure. Looking at the recent failed axle on a 222, that appears to have a hollow axle. Perhaps the final drive is connected via a quill, removing it from the unsprung mass also.
Unsprung weight is a bit of a red-herring: frame suspended TMs are becoming the norm on sparky high speed. Do 91 still have the body mounted TMs or were they not moved in the refurb?
well yeah, if you have to use an emmissions handling exhaust then you could shove in a T18 deltic engine at 3200hp plus which is only about 7 tons.
Otherwise a VP185 6 or 8 cylinder. With lower use for shunting, railhead and branch line to end destination, the engine hour-maintainance would not be so crucial.
Freight is one area for savings with shunts out to the wires, but also trains like london-lincoln/hull, leeds ( b4 it gets wires) Barrow, Aberdeen, etc etc also could be interesting.
Have there been any threads on the economics of loco hauled versus DMUs for longer trains ?
well yeah, if you have to use an emmissions handling exhaust then you could shove in a T18 deltic engine at 3200hp plus which is only about 7 tons.
Otherwise a VP185 6 or 8 cylinder. With lower use for shunting, railhead and branch line to end destination, the engine hour-maintainance would not be so crucial.
Freight is one area for savings with shunts out to the wires, but also trains like london-lincoln/hull, leeds ( b4 it gets wires) Barrow, Aberdeen, etc etc also could be interesting.
Have there been any threads on the economics of loco hauled versus DMUs for longer trains ?
captainbigun
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Nowhere to move them to! Still body mounted, gearboxes now Voith.
I think it could be done in two boxes on wheels , ie BO-BO +BO-BO as per some american stuff, that would reduce the axle loading to something very acceptable , and keep the power up at required levels, also increasing the tractive effort if it was all axles powered,... but the big question is , as usual , Why on earth do we need to do it. The technicalities would no doubt render the unit as 'prone to failure' or 'unreliable'. Still think its a total waste of research and design resources.
electro-diesels are fairly prevalent around the New York city area- the Long Island Railroad has locos that are the the reverse of the 73 arrangement- they have powerful diesel engines for mainline running, with low powered 3rd rail for operating in the tunnels and terminuses in the city.
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