Bi-mode regional units with third rail pick-up and pantograph?

[TheWalrus]

Hi

I'm wondering today about a bi-mode regional unit. Would it be possible to have a unit like a turbostar (run by diesel) with a pantograph and third rail shoe? This would be useful on routes such as Cardiff-Portsmouth. Providing GW electrification goes ahead, it could run 3rd rail Portsmouth-Southampton, diesel Southampton-Bath, then overhead Bath-Cardiff. I'm assuming this is not possible, but it could be, so I don't know. What are your thoughts on this?

 

[anthony263]

If Bombardier can do a Bi-Mode voyager/meridain then maybe a Bi-Mode turbostar could be built this could be good for some route such as Cardiff - Taunton if the Great western is electrified.

 

[Turbostar]

I can't see how it could be possible with a unit. Take a Class 357 unit for example, all the cars have electrical components underfloor in order to run & operate the unit. So where's the underfloor diesel engines gonna go, as well as all the components to go with them???

 

[TheWalrus]

@Anthony - That's what I'm thinking!
@Turbostar - They can do it with a 22X, so why would it be any different to a turbostar, which is made by the same manufacturer?

 

[DavidBusDriver]

The reason I think the Electrostar family have equipment under each coach is due to the distributed arrangement of traction motors compared with earlier Mk3 EMU's which have one powered coach per 4-car set, so that all the traction control equipment is mounted only on that coach, with ancillaries/auxiliaries on the adjacent Auxiliary Coach.

With a DEMU, which is what you would be proposing (in much the same way as the 22x bi-mode proposal), the traction motors operate in the same way as on an EMU, with the diesel engine(s) acting as generators to provide the AC/DC current for those motors through a bus line - the same bus line which could be fed with current from an OHLE or CRE pickup. A bi-mode conversion of the 22x family involves inserting an extra coach fitted with a pantograph, plus the associated transformer (and rectifiers etc if they use DC traction motors?) while the remaining four/five coaches provide the diesel generated electricity for off-wires running.

So what you could be suggesting is at least a 3-coach derivative of the Turbostar, comprising:

Coach A and C: Fitted with Diesel engine, fuel tank, CRE collector shoe, powered bogies. Traction Control equipment

Coach B: Pantograph, Transformer, Rectifiers, would have the option of powered/unpowered coach, I believe the 375/377 to have the pantograph coach unpowered.

Would be a real go-anywhere unit, and using a modular power-pack system like on current Turbostars, the extra weight of the diesel equipment has the potential to be removed upon further electrification to save on energy consumption.

A 2-coach version might be possible but I would guess most platforms on the national network are capable of at least 3 cars - of course more diesel generator coaches could be inserted into the formations, or even trailer coaches if the power/weight ratio allows.

 

[Turbostar]

@Anthony - That's what I'm thinking!
@Turbostar - They can do it with a 22X, so why would it be any different to a turbostar, which is made by the same manufacturer?

22X units are DEMU's. The engines & components power the motors to run the train, as I'm sure you know. Add the capability to pick up juice from either a 3rd rail or overhead, you'll need additional components as well as whats on board to convert the juice etc. Where's it gonna go???

 

[Flywaver]

http://en.wikipedia.org/wiki/SNCF_Class_B_81500

 

[Turbostar]

http://en.wikipedia.org/wiki/SNCF_Class_B_81500

Yes, but look where the diesel equipment is located, on the roof. Can you really see a unit being made to the same spec, that also conforms to the necessary requirements to run on Network Rail???

 

[TheWalrus]

22X units are DEMU's. The engines & components power the motors to run the train, as I'm sure you know. Add the capability to pick up juice from either a 3rd rail or overhead, you'll need additional components as well as whats on board to convert the juice etc. Where's it gonna go???

How should I know?! What if we settled for just overhead and diesel, without 3rd rail?

 

[TGV]

No no no no.... First up that B 81500 is a much simpler beast than what you're effectively proposing as a TRI-mode unit. It has diesel power and a single pantograph - which remember picks up DC supply (no heavy transformer). It would be possible technically to add to this a transformer AND 3rd rail gear - but commercially - it would be a complex bit of kit, where would it fill a commercial need and how many compromises would be made?

I'd certainly not be happy being involved with that project!!!

 

[starrymarkb]

I thought the AGC came in 25kv and 1500V flavours, some are both bi mode and dual voltage. It depend what the voltage is in the ordering départment

 

[swt_passenger]

Once you have crammed overhead and diesel into the same unit, adding third rail pickup wouldn't add any underfloor equipment of significant size.

For comparison you'll see that 350/1 and 350/2 are practically identical under the solebar...

But four and five car Desiros only have two motored coaches, Electrostar style distributed traction isn't the only possible solution.