Porterbrook Cl.769 'Flex' trains from 319s, initially for Northern

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Bornin1980s

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The 195s would use a 172 type gearbox. Am I right in saying that such a gearbox can enable a 100 mph unit to perform adequately on a 60-75 mph service?
 

Chris125

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To be fair re 170s, it is possible to re-gear those to 75mph but better acceleration, and possibly also to increase fuel efficiency at the same time by switching to a mechanical gearbox.
Hybrid conversion is looking the most likely change now, if the prototypes deliver as promised:

Rolls-Royce and Porterbrook launch first hybrid rail project in the UK with MTU Hybrid PowerPacks

Noise emissions in stations are cut by around 75 percent (20 dB(A)). Fuel consumption and CO2 emissions are reduced by up to 25 percent. NOx emissions can also be reduced by up to 70 percent and particulate emissions by around 90 percent.

The total operating costs of rail vehicles with MTU hybrid drives are also significantly lower, and even brake pads and discs experience reduced wear due to energy recuperation during braking. As a result of the additional power of the electric machine, train operators also have the option to improve journey times through better acceleration.
 

anamyd

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I've read the link and still don't grasp the idea. Is it a replacement of the current engine with a smaller engine, battery and electric motor/generator/regenerative brake using existing transmission and final drive?
The new engines will still be 12-13L, just the modern equivalent of the original ones which were made by the same manufacturer (probably with added on SCR), so a sort of cross between the 172 and 195 engine. The battery hybrid systems will replace the original hydraulic transmissions. I'm curious as to what they'll be reclassified as...
 

Bletchleyite

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The new engines will still be 12-13L, just the modern equivalent of the original ones which were made by the same manufacturer (probably with added on SCR), so a sort of cross between the 172 and 195 engine. The battery hybrid systems will replace the original hydraulic transmissions. I'm curious as to what they'll be reclassified as...
EDMUs, I guess, so either 2xx or 7xx.
 

Billy A

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..... The battery hybrid systems will replace the original hydraulic transmissions....
You'd think so, but as far as I can make out the hybrid power unit will use a ZF conventional automatic box when the engine is doing the work (so mechanical transmission in rail parlance) plus electric drive for when the batteries are in use. Both can be used simultaneously.
 

anamyd

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You'd think so, but as far as I can make out the hybrid power unit will use a ZF conventional automatic box when the engine is doing the work (so mechanical transmission in rail parlance) plus electric drive for when the batteries are in use. Both can be used simultaneously.
Appreciate the correction :)
 

apk55

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An electric transmission system means you can get means you can get more out of the diesel engine. You can get full engine power over a wide speed range particularly at low speeds whereas with a torque converter system the power output a low speeds is very limited (and it is very inefficient) Only at a fixed speed near the max speed can you get full engine power.

After all why are practically all locomotives Diesel electrics.
 

a_c_skinner

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Back on topic...

Is that how the 769s will work? Run the engines at constant optimum revs and keep the DC bus at 750V by for example manipulating the power electronics and the engine throttle?
 

hwl

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Pretty much, yes, I'd imagine. Same as any generator. Just imagine it as a big mains generator plugged into the 750V bus.
Except you don't need to worry about frequency (unlike static power generation) as it gets rectified hence wide range of engine speeds combined with fuel injection rates are possible from almost idle upwards.
 

driver_m

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Whether it's of any use as a comparison to the 769 engine I'm not 100% , but a 221 in neutral will be running at 1000rpm and at full power, about 1800rpm. And will be within a range starting from about 1150rpm when taking the lowest possible power using the PBC .and then tending to sit at 1795 in most power positions on The PBC
 
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aformeruser

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Wouldn't it be nice if it ran under its own power, switching to electric at Nuneaton?
That would confound a few naysayers. ;)
And surely it could move quicker if it is able to run at 75mph on diesel and 100mph on electric, given the loco path booked is for 75mph diesel running.
 

Bertie the bus

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Wouldn't it be nice if it ran under its own power, switching to electric at Nuneaton?
That would confound a few naysayers. ;)
It would be even more of a wheeze if it stopped en-route and ran as a passenger service but that isn’t going to happen either. If it does run there is an STP from Leicester L.I.P. to Brush.

Even if it is a 769 is doesn’t mean entry into passenger service is imminent. Allerton had a 319 many months before they were introduced for fitter familiarisation.
 

Bornin1980s

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Except you don't need to worry about frequency (unlike static power generation) as it gets rectified hence wide range of engine speeds combined with fuel injection rates are possible from almost idle upwards.
Does that mean the engines would be able to run at varying speeds, with the voltage remaining the same, but the current changing?
 

apk55

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Does that mean the engines would be able to run at varying speeds, with the voltage remaining the same, but the current changing?
I would imagine that the engine speed would be the optimum speed to achieve the demanded power at maximum efficiency. At intermediate power setting this would be between idle and full speed.
 

MikePJ

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I would imagine that the engine speed would be the optimum speed to achieve the demanded power at maximum efficiency. At intermediate power setting this would be between idle and full speed.
To give a bit more detail, mechanical output power from an engine is shaft speed multiplied by torque. That’s converted into electrical power, which is voltage multiplied by current. On the 769 genset the output voltage is constant, so to supply more power to the motors it will increase the output current. That extra power will be supplied by the diesel engine increasing both its shaft speed and torque, because internal combustion engines produce very little torque at idling speed and need to be “revved up” to increase output torque and output power.
 

slicedbread

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And surely it could move quicker if it is able to run at 75mph on diesel and 100mph on electric, given the loco path booked is for 75mph diesel running.
Is the idea to get a speed on diesel of 90 mph, which I think was the speed bandied about at the start of the project?
RailEngineer had an article mentioning 87 mph which I guess is close.
 

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