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Tri-mode unit with dual-voltage capability. can it be built?

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RobShipway

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A few TOC's need trains where they could be replacing both EMU's and DMU's. Many have gone for the bi-mode or tri-mode option such as the class 8xx, 755 or 756. Or have gone with trains being traditionally powered, that can be converted at a later stage if needed.

For for some routes, you may be able to put in OHLE but in some areas where you have obstacles such as tunnels, it may not be so easy to place OHLE through the said tunnel. This is where I like the idea of the class 756 units. They have a pantograph to use overhead where available and diesel plus battery packs where OHLE is not available. The 756's can just run on the battery packs through a tunnel, so all that needs to happen with the Infrastructure is that the OHLE is placed both before and after the tunnel entrances.

Now, you may ask why am I asking about Quad mode. Well, I can see the likes of the a similar design of flirt train like the class 756 replacing the class 171's with Southern on the London Bridge - Uckfield and Eastbourne - Ashford services.

The next question would be why not add this question to the Uckfield thread, well the question is about whether you could build a tri-mode 756 as is being built for TFW and have it also be able to use 3rd rail?
 
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yorkie

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I don't understand what the four sources of power would be on a ''quad'' mode unit?

Hydrogen, diesel, electric supply and batteries?
 

RobShipway

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I don't understand what the four sources of power would be on a ''quad'' mode unit?

Hydrogen, diesel, electric supply and batteries?
Four sources would be OHLE, diesel, battery and 3rd rail.
 

XAM2175

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Four sources would be OHLE, diesel, battery and 3rd rail.
All forms of external traction current are considered to be the same one mode, so you're describing a tri-mode unit with dual-voltage capability.
 

XAM2175

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True. I will change the title of the thread.
And the answer to your new question is yes, such a unit can be built. Dual-voltage capability is nothing new; it's been done on 'conventional' EMUs for decades now.
 

RobShipway

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And the answer to your new question is yes, such a unit can be built. Dual-voltage capability is nothing new; it's been done on 'conventional' EMUs for decades now.
Because my thought is such that you have a train similar to the class 756 where it can run on either OHLE, diesel or battery, but also run on third rail. But unlike the class 756, these trains would have to be such that they have gangways at either end as on the class 377/378's etc..... so that the units could work in multiple with each other as either 3 or 4 car trains coupled together, but could also work with existing units.

If the trains are used with multiple TOC's, then they may have to have different couplers to work with existing trains from that TOC.
 

skyhigh

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If the trains are used with multiple TOC's, then they may have to have different couplers to work with existing trains from that TOC.
Even if they had matching couplers to existing stock, it'd only be for emergency rescue unless you modify the software to work with the existing units at each TOC
 

Aictos

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For the existing diesel islands that see GW, SWR and SN services then surely then instead of thinking of batteries, 3rd Rail and Diesel why not just use 3rd rail and Diesel?

After all, SNCF uses Bombardier 81500/82500s that operate off OHL and Diesel so no reason why a train manufacturer couldn't apply that logic to providing a train that has the ability to use diesel or 3rd rail.
 

D365

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If a TOC asks for it, it will be built.

Onto the next question ;)
 

Peter Mugridge

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Aren't GWR's class 769/9s tri-mode in that they have 3rd rail, overheads and diesel power sources?

Meaning this already exists?
 

Alex365Dash

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Aren't GWR's class 769/9s tri-mode in that they have 3rd rail, overheads and diesel power sources?
External electric power (3rd rail/OHLE) is considered a single power source for the purpose of this thread. Hence the 769/9 would have two power sources - electric and diesel.

OP’s suggestion involves electric (both 3rd rail and OHLE), diesel and battery.
 

RobShipway

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External electric power (3rd rail/OHLE) is considered a single power source for the purpose of this thread. Hence the 769/9 would have two power sources - electric and diesel.

OP’s suggestion involves electric (both 3rd rail and OHLE), diesel and battery.
Correct, where possibly the diesel generator at a later stage could possibly be replaced by hydrogen power.

The units would then be able to fill many rolls and potentially create services where before you may have had to swap from an EMU service, to a diesel service with my idea you could do both those services with one train possibly.

Aren't GWR's class 769/9s tri-mode in that they have 3rd rail, overheads and diesel power sources?

Meaning this already exists?
The thread did originally have a title of Quad powered train, but as XAM2175 stated in an earlier post I am describing tri-mode unit with dual-voltage capability. The class 769 with GWR, is basically a dual-voltage unit with diesel generators added. Other operators class 769 units where they have had 3rd rail shoes removed, are bi-mode units with having power from OHLE and Diesel.
 

D365

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The thread did originally have a title of Quad powered train, but as XAM2175 stated in an earlier post I am describing tri-mode unit with dual-voltage capability. The class 769 with GWR, is basically a dual-voltage unit with diesel generators added. Other operators class 769 units where they have had 3rd rail shoes removed, are bi-mode units with having power from OHLE and Diesel.
You’re describing exactly the same thing. All 769s are bi-modes, the ”tri-mode” designation came from somebody misunderstanding the meaning of it.
 

swt_passenger

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Aren’t
You’re describing exactly the same thing. All 769s are bi-modes, the ”tri-mode” designation came from somebody misunderstanding the meaning of it.
But the somebody ‘misunderstanding’ the term was their owner, Porterbrook?
 

HST43257

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I’d quite like to see a trimode IET for Cross Country. Third rail mainly for the Bournemouth to Basingstoke stretch.
 

Irascible

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Diesel/battery/3rd rail should be simple & not require much excess kit, they'll all output vaguely the same sort of thing - 25kv AC does need a not terribly small transformer & some more electrical gear though, so probably not something to cart around if it's not used often. As long as you can fit the gear in somewhere & it can generate electricity you can have as many modes as you like, though.

Not sure what a combined diesel and/or hydrogen fuelled steam boiler driving a turbogenerator to charge a battery buffer would be... I guess if you threw in a heating element you could not only feed it off any electrical supply without much extra gear but you could call it dual-hybrid too!
 
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