reddragon
Established Member
It was because the class 319 was originally planned to be a Networker. In 1990 319s & Networkers were under construction
It was the proposed Porterbrook refurb program for the 319.
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That’s an impressive picture where a 319 manages to get plug doors and a completely new window arrangement like a networker.
First unit to be delivered to @northernassist in January
Current power to weight ratio of a 319 with no people. 7.05 kw/tonne with 400 65kg people on board 5.95 kw/tonne
For comparison to other classes, a 142 pacer has 6.9kw/tonne when empty a 153 has a 5.17 kw/tonne.
Power rating can be misleading as the short term rating is much larger than the usually quoted continuous rating which is why electrics will always accelerate faster than diesels.That means an empty Pacer has a higher power to weight ratio than a loaded 319!
How come 319's still always accelerate faster ?
Yes they have comparable acceleration to a Pacer from 0 to 30mph. Then they are significantly quicker from 25mph to 75mph with the ability to go all the way to 100mph unlike a Pacer.
That means an empty Pacer has a higher power to weight ratio than a loaded 319!
How come 319's still always accelerate faster ?
Yes they have comparable acceleration to a Pacer from 0 to 30mph. Then they are significantly quicker from 25mph to 75mph with the ability to go all the way to 100mph unlike a Pacer.
A diesel engine is set for an absolute maximum power output essentially by injector rate and air mass. Once that level is reached there is no more power available, (which is just as well as the maintenance regime is set to allow for that level of stress and wear).That means an empty Pacer has a higher power to weight ratio than a loaded 319!
How come 319's still always accelerate faster ?
Yes they have comparable acceleration to a Pacer from 0 to 30mph. Then they are significantly quicker from 25mph to 75mph with the ability to go all the way to 100mph unlike a Pacer.
And most of that limitation is due to adhesion limits rather than motor torque shortfalls.... In contrast the electric transmission can deliver full engine power to the rails over a wide speed range probably from 15MPH to max speed. ...
Surely electric rolling stock is stated as e.g. n x 224kW (300hp) motors, where the power is the continuous rating of the motor (at the nominal designed voltage on the trains). That power can be adjusted by onboard traction electronics to accommodate sub-standard supply infrastructure (3rd rail DC), low voltage conditions (ac or DC), high ambient temperatures, etc..It has become usual for diesel power to be quoted as engine output, whereas electrics are usually quoted as power at the wheel rim. A diesel’s comparable power will be lower due to auxiliary loads and transmission losses, so it is not a straight comparison.
Tbf it sort of looks like a combination of a networker and a class 700.It was the proposed Porterbrook refurb program for the 319.
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Not surprising considering the class 325 is basically a class 319 with the interior kitted out for parcels/letters and a Networker cab front fitted.Tbf it sort of looks like a combination of a networker and a class 700.
A hydraulic system as used on a pacer can only deliver full engine power at one spot speed around 60MPH. At low speeds (below 40MPH) when the torque converter is operating at lest 30% of the engine power is lost in heating the torque converter (inefficiencies) and the engine is also not operating at full power (because the speed is limited). In contrast the electric transmission can deliver full engine power to the rails over a wide speed range probably from 15MPH to max speed.
After all why do practically all locomotives use electric transmision
Getting bit off topic. The original pacers had uk made SCG mechanical gearboxes as previous dmu's. Unfortunatly for some reason reliability was very poor so German Voith hydraulic units as used subsequently on sprinter trains where substituted despite the 10% or so hit in fuel consumption.
Back on topic anyone know what the short term rating of a 319 is compared with its continuous rating.
In the days before electronics motors where often rated at up to double there continuous rating for short periods the limitation being temperature. I suspect these days it's the electronics which are the limiting factor
K
The lower performance that the 3rd rail units have was less of a problem on ex-Southern routes where maximum speeds rarely go much above 90mph. The ac electrified routes have been capable of sustained 100mph speeds since the '60s so trains there have been equipped with higher powered versions of EE507 like motors, e.g. GEC WT401 (class 309) and G315BZ (class 319) to allow them to operate in amongst faster LHCS services.all the old br southern units have 250hp ee507s from epbs veps cigs thumpers mlvs and indeed 455 standard motor to keep spares easy
If electric drive is that good why have DMUs tended to move away from it to hydrodynamic and latterly "mechanical" (actually bus type automatic gearbox) drive? Also except in the context of hybridisation you never see it in a road vehicle.
If Wikipedia is to be believed, by inference, 1320hp per unit on a Class 319. Ironically it is better than 4x EE507 or like-for-like replacements on a Class 455 (the other likely candidate for future Flex-es).
It's 4 axles per unit (all axles of the single power car). The other 'Mk3' derived BR-designed EMUs of the period have the same arrangement.Though only put down through 2 (or is it 4?) axles, which can cause trouble - the 319 I took from Euston yesterday was wheelspinning like nobody's business all the way up and picked up a fair bit of delay as a result, not to mention some heavy juddering which reminded me of Mk3 LHCS "snatch" you used to get.
Yes unfortunately the 319s do require skill in driving during time of the worst railhead conditions. On the MML, most drivers learnt how to handle them and if there was bad slipping it was indicative of exceptionally bad conditions.Though only put down through 2 (or is it 4?) axles, which can cause trouble - the 319 I took from Euston yesterday was wheelspinning like nobody's business all the way up and picked up a fair bit of delay as a result, not to mention some heavy juddering which reminded me of Mk3 LHCS "snatch" you used to get.
It's mitigated to some extent in a series-wound DC motor but I can't recall the exact mechanism at present. But I agree an AC motor, which only turns at close to the exact speed dictated by the traction electronics, will be better for adhesion.Yes unfortunately the 319s do require skill in driving during time of the worst railhead conditions. On the MML, most drivers learnt how to handle them and if there was bad slipping it was indicative of exceptionally bad conditions.
The benfit of three phase ac motors is that the frequency of the ac is varied to give spin speeds not much different to that which is needed for adhesion. A DC motor (especially one fed by a resistor chain) will draw less current once it speeds up so slipping is not mitigated by the drive current.
Yes.Is that one reason for the widespread use of AC motors, despite the extra expense of the control equipment?
ROG said ina press release in October that they would be testing on WMCL from early November. I haven't seen any signs of this happening. So more delays again it appearsHas there been anymore testing on the 769s, i've seen a post on youtube of 769434 but that was months ago.
ROG said ina press release in October that they would be testing on WMCL from early November. I haven't seen any signs of this happening. So more delays again it appears