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

[978wta]

I can't hear the rear unit doing anything in that video - only sounds like the front one is powered to me?

I thought the same as you can definitely hear the Diesel engines along with the traction motors on the first set but not so on the 2nd set.

It could be the way the camera has picked up the sounds or was it simulating a drag??

 

[AM9]

I thought the rear one was the most noticeable, sounds like it's just coming on to the turbo?

I agree with samuelmorris, assuming the driver didn't shut off the power as he passed, th motor whine only came from the first unit. Listening for the noise from the engines can be misleading as their power demand is determined by the draw of power from the generators, but the speed it's control sets to supply that power may not always be the same.

 

[samuelmorris]

Even at idle you'd expect to hear at least some noise from the rear unit, I really don't hear anything, having rewatched it, only rail noise from the rear unit.

 

[modernrail]

The track on that video looks to be in a bit of a state. Is that the Southport line and is that pretty poor track or just a trick of the light/camera angle etc?

 

[Grumpy Git]

I thought the rear one was the most noticeable, sounds like it's just coming on to the turbo?

After watching it again, I take that back. All the noise seems to be coming from the last carriage of the first unit.

 

[Peter Sarf]

Off topic but the insanity of numerous different couplings seems obvious to me at least.

Oh don't worry, they are all standard. It just that is would be nice to have a standard standard .

 

[krus_aragon]

Oh don't worry, they are all standard. It just that is would be nice to have a standard standard .

Obligatory xkcd link.

 

[Mogster]

I thought the rear one was the most noticeable, sounds like it's just coming on to the turbo?

I thought the turbos and associated intercoolers were removed due to lack of space and packaging problems under the carriages.

 

[samuelmorris]

I thought the turbos and associated intercoolers were removed due to lack of space and packaging problems under the carriages.

Surely not, they wouldn't put out sufficient power without them. It sure sounds like a turbo is in operation in that video.

 

[Mogster]

Surely not, they wouldn't put out sufficient power without them. It sure sounds like a turbo is in operation in that video.

I thought the lack of turbocharging was responsible for the only moderate power available to the motors on diesel?

This is only from info on here over the years, may be wrong.

 

[gallafent]

Obligatory xkcd link.

(And an earlier quote from Andrew Tanenbaum: "The nice thing about standards is that you have so many to choose from." — Computer Networks, 2nd ed., p. 254. https://en.wikiquote.org/wiki/Andrew_S._Tanenbaum )

 

[edwin_m]

I got the impression the amount of power on diesel was less than on electric but still pretty reasonable for a diesel - performance is claimed to be at least as good as a 4-car 150.

 

[a_c_skinner]

I got the impression the amount of power on diesel was less than on electric but still pretty reasonable for a diesel - performance is claimed to be at least as good as a 4-car 150.

That was the claim of the initial modelling over the Buxton line IIRC. Mind you that may differ from actually driving one up there.

 

[edwin_m]

That was the claim of the initial modelling over the Buxton line IIRC. Mind you that may differ from actually driving one up there.

Agreed, but the initial modelling wouldn't have given that result unless the installed power was comparable (so one Flex engine raft is worth two Sprinter engines).

 

[Greybeard33]

Agreed, but the initial modelling wouldn't have given that result unless the installed power was comparable (so one Flex engine raft is worth two Sprinter engines).

Which indeed is roughly in line with the gross engine power output figures (2*390kW on a 769 versus 4*213kW on a 4-car 150).

 

[northernbelle]

I thought the same as you can definitely hear the Diesel engines along with the traction motors on the first set but not so on the 2nd set.

It could be the way the camera has picked up the sounds or was it simulating a drag??

It wouldn't surprise me - all the recent rolling stock testing and validation I've been aware of in recent times has had to include a 'drag' scenario - Hitachi chose Dainton Bank between Exeter and Plymouth as the location to test a dead 5-car IET being started away by another on the severe gradient.

 

[samuelmorris]

I thought the lack of turbocharging was responsible for the only moderate power available to the motors on diesel?

This is only from info on here over the years, may be wrong.

520hp is still a fair amount of power to get from an engine, to get that without a turbo it'd have to be enormous, not something you'd fit underneath the passenger compartment, it'd have to go in a power unit cabinet like on a 755 or a thumper. Using turbochargers on large diesel engines has been standard practice for many years.

 

[AM9]

Agreed, but the initial modelling wouldn't have given that result unless the installed power was comparable (so one Flex engine raft is worth two Sprinter engines).

Surely it isn't just about the absolute power the installed engine can give. There's differences in overall unit weight, (nearly 160t for a 769 vs about 144t for a 150), then there's the gearing of the units, 769 is for 100mph vs 150 for 75mph. Those two both weigh against the 769s, but the torque/output speed profile of a diesel engine/generator/DC motor is far more flexible than that of a diesel engine/torque converter, so there are reasons to believe that even in a stopper role, the 769 may be no worse than a 150 and probably a lot kinder to the engine in service.
One thing that has so far not been mentioned here is that when a 150 (2-car) has a failed engine, not only is the tractive effort halved but so is the adhesion. On the 769's case, although if 319 experience is to go by, motors do get disconnected for various reasons, they are generally getting an easier life in the north-west so that is less likely, however if an engine fails, performance would of course hardly be stellar but adhesion would not change at all so a limping home train is unlikely to completely stall on difficult gradients/railhead conditions, (unless the 750VDC bus is split between pairs of motors when running on diesel).

 

[AM9]

520hp is still a fair amount of power to get from an engine, to get that without a turbo it'd have to be enormous, not something you'd fit underneath the passenger compartment, it'd have to go in a power unit cabinet like on a 755 or a thumper. Using turbochargers on large diesel engines has been standard practice for many years.

And on smaller ones, although diesel engines in new cars are nearing the end of their useful mass sales life, the turbo option is virtually universal.

 

[samuelmorris]

And on smaller ones, although diesel engines in new cars are nearing the end of their useful mass sales life, the turbo option is virtually universal.

Sure, I only qualified large engines as when you cover small you get to things like portable generators, cherrypickers etc. that probably don't have them.

 

[LDECRexile]

Shots of 769442/450 at Southport yesterday

 

[Bertie the bus]

It wouldn't surprise me - all the recent rolling stock testing and validation I've been aware of in recent times has had to include a 'drag' scenario - Hitachi chose Dainton Bank between Exeter and Plymouth as the location to test a dead 5-car IET being started away by another on the severe gradient.

They're not testing them. Testing is supposedly complete. They are now doing driver training in preparation for entry into service.

 

[Grannyjoans]

While these 769's are a long way off a 195/331 or even a 158, they've got to be an improvement over 150's.

 

[Mogster]

While these 769's are a long way off a 195/331 or even a 158, they've got to be an improvement over 150's.

More carriages from Southport of any flavour will be an improvement...

People suggest that a 319 is significantly better than a 150 as a passenger, I don’t really see much difference. I think it depends on wether you prefer the predominantly bay seating the 319s tend to have. For all their problems inside a 195/331 is a far nicer place to be than on any of Northern’s other stock.

 

[Grannyjoans]

The Driver's cab of the 319/769 is an improvement over the 150. Still not great though.

 

[Peter Sarf]

Obligatory xkcd link.

Oh yes that really sums it up !.

 

[Grannyjoans]

For all their problems inside a 195/331 is a far nicer place to be than on any of Northern’s other stock.

I thought some of the better 158's are just as good from the passenger point of view

 

[Bovverboy]

For all their problems inside a 195/331 is a far nicer place to be than on any of Northern’s other stock.

I thought some of the better 158's are just as good from the passenger point of view

My admittedly limited experience of 170s says that the type would take some beating, too.

 

[rustbucket]

My admittedly limited experience of 170s says that the type would take some beating, too.

A good condition 170 is very good!

 

[anamyd]

The engines definitely still have the turbos and intercoolers; that matches up with the 523hp rating from a 12.8-litre Diesel straight six. Also, I don't think "optional turbos" have been a thing on big Diesel engines since the 90s, and at that on smaller (6-litre-ish) road engines e.g. Cummins 6B vs 6BT. Naturally aspirated (so-called "non-turbo") engines haven't had new-build rail use since the 1st gen DMUs.

What I'm now not sure about is how many engines have been fitted under each of the units' two trailer vehicles. I was under the impression that it was one engine per trailer vehicle (two engines per unit) but the Wikipedia article is stating two engines per trailer vehicle (four engines per unit) - which is right...?