Class 717 replacing 313s: top speed

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adamedwards

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I'm assuming the new 717s for services into London Moorgate will have a 100mph top speed like the rest of the 700 series trains.

Assuming so, this won't make much difference to the stoppers as the line speed is, I believe 75 mph max. However, there are stretches along our local Great Northern lines where a higher speed might be worth while, for example Welwyn Garden City to Hatfield or Stevenage to Hertford North. Might the new trains be a trigger for this?

My other thought is how much difference the 100mph would mean when services bounce back in the peak from Finsbury Park to Welwyn GC as they are better able to use the fast lines. Would the time savings and better paths lead to better utilisation and therefore more services?

Over to the experts reading this for a response.

Cheers

Adam
(Usually on the 07:47 from Hatfield to Oakleigh Park, so I have a vested interest in the new trains!)
 
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zn1

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on the jobs 313 works on in north london - max speed isnt the issue, getting max amount of toe on the steel, 313 -315, 507-508 are very good at this, as well as being able to stop well on inner suburban and not have brake fading after a dozen stops in 20 minutes are the things the operators should be looking at

having a 100mph top whack on the 717 squadron wont really cut it i dont think, they will be geared or should be geared to the same ratio as their 313 grandparents, the gag is i always say if a system aint broken why fix it?

313 are old ladies now - but operators today can still learn hell of alot from em, they are near enough bullet proof, easy to maintain in todays overengineered railway.

in my opinion the pep 1976 fleets are still the best squadrons in britains railway fleet.

manufacturers should buy one rip, examine em and build on the experience.
 

D365

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in my opinion the pep 1976 fleets are still the best squadrons in britains railway fleet.

Silverlink and Southeastern apparently didn't do the best job of maintaining theirs...
--- old post above --- --- new post below ---
I'm assuming the new 717s for services into London Moorgate will have a 100mph top speed like the rest of the 700 series trains.

The London Overground Class 710s, like the 378s, are 75mph only. If anything I expect the 717s (what a pointless designation) will be built for 90mph.
 

southern442

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313 are old ladies now - but operators today can still learn hell of alot from em, they are near enough bullet proof, easy to maintain in todays overengineered railway.

in my opinion the pep 1976 fleets are still the best squadrons in britains railway fleet.

manufacturers should buy one rip, examine em and build on the experience.

They have definitely got a bit of character now that they are 40 years old! Clunky, noisy, grotty, heavy-duty trains, built to last and they certainly have done!
 

edwin_m

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Gearing is rather less critical on a modern three-phase drive where the electronics have much better control over the speed and torque than with DC motors. So the maximum speed may more to do with other factors such as how sophisticated the suspension is. The proportion of weight on motored axles is important for low-speed acceleration, sure-footedness and hill-climbing, being about two thirds with a 313 and less than one third on a 317, 319 and 321. Modern units are modular designs and the number of bogies fitted with motors will depend on the planned duty, so I would hope the 717s have quite a high proportion like the 313s.
 

Class377/5

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The Desiro City family acceleration is amazingly quick.think Victoria Line quick. It will knock spots off the 313s.

I believe the key to having the 717s is a tick box as they score higher than the 313s in the quality with all those extra mod cons they bring. Plus meaning plan for NCL to use ATO becomes a simple matter with a TL system transferred over.
 

whoosh

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Linespeed Stevenage to Hertford North is maximum 75mph. Linespeed Hatfield to Welwyn Garden City on the slow line is 75mph.

Where it may be advantageous to have a higher maximum speed for the train, is when working a limited stop peak hour service. There is one in the evening that is Welwyn, Hatfield, Potters Bar, Finsbury Park, Kings Cross, that is booked on the fast line from Potters Bar. That would benefit from a faster unit speed than 75mph. But is it worth the extra maintenance and cost of a higher spec, for just a handful of services?
 

A0wen

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They have definitely got a bit of character now that they are 40 years old! Clunky, noisy, grotty, heavy-duty trains, built to last and they certainly have done!

People have *very* selective memories.

On the 'built to last' statement - the 313s had endless teething troubles - far more than you'd see on current gen stock as various books can attest, specifics included:

- troubles with the Tripcock mechanisms needed for the Drayton Pk - Moorgate stretch.

- troubles with the passenger doors, some of which were opened on the move.

It took them a while to build up to an acceptable reliability level.
 

EveningStar

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- troubles with the passenger doors, some of which were opened on the move.

Strictly speaking that was more a design flaw rather than construction. Lack of effective interlock, as demonstrated by a very surprised BR press officer on a press demonstration run. In any case, tugging a handle sideways to start the door opening sequence is not a natural body movement ... in retrospect, a simple push button would have been a much better design. The replacement blanking plate on each door, including on the 507s which I believe never had the handles fitted from new, was an enduring reminder of not thinking through an idea.
 

notadriver

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I think the modern ethos is to have a 100 mph design speed for EMUs to allow flexibility. For example on Southern the 5 car 377/6 are used on metro stoppers. Of course some stock seem to have been geared for their route such as the 458/5s. I assume this is to get maximum acceleration from limited DC supplies which doesn't apply on AC power.


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D365

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In any case, tugging a handle sideways to start the door opening sequence is not a natural body movement ...

I'm aware of metro trains on the continent (built at around the same time which still make use of these handles. Though they rarely tend to reach their ≈50mph top speed.
 

craigybagel

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I think the modern ethos is to have a 100 mph design speed for EMUs to allow flexibility. For example on Southern the 5 car 377/6 are used on metro stoppers. Of course some stock seem to have been geared for their route such as the 458/5s. I assume this is to get maximum acceleration from limited DC supplies which doesn't apply on AC power.


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I seem to remember somewhere there was an issue with the 458/5s where they had to be regeared (100mph down to 75mph) because the low speed nature of their new work meant that the motors would overheat?
 

Robbies

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I seem to remember somewhere there was an issue with the 458/5s where they had to be regeared (100mph down to 75mph) because the low speed nature of their new work meant that the motors would overheat?

Certainly the ex - Class 460 units had to be down geared from 110mph to 75 mph, but the original class 458/0's I thought had been down geared already to 75mph to do the Reading route?
 

edwin_m

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I seem to remember somewhere there was an issue with the 458/5s where they had to be regeared (100mph down to 75mph) because the low speed nature of their new work meant that the motors would overheat?

Yes, I seem to remember they wanted the motors to turn faster so the cooling fans would also turn faster. I would have thought that would generate more heat, but never mind.
 

43096

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Certainly the ex - Class 460 units had to be down geared from 110mph to 75 mph, but the original class 458/0's I thought had been down geared already to 75mph to do the Reading route?

No. The 460s were geared for 125mph and the 458/0s were 100mph. They have all been re-geared for 75mph as part of the conversion. As stated it is so the motor spins faster so drawing more air through; without this there was a risk they would overheat.

All explained in an article on the project in Modern Railways by Ian Walmsley. He should know, he came up with the project when with Porterbrook.
 

notadriver

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Why would 460s have 125 mph gearing when the line speed is 90 mph? I don't think that's right.


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Robbies

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No. The 460s were geared for 125mph and the 458/0s were 100mph. They have all been re-geared for 75mph as part of the conversion. As stated it is so the motor spins faster so drawing more air through; without this there was a risk they would overheat.

All explained in an article on the project in Modern Railways by Ian Walmsley. He should know, he came up with the project when with Porterbrook.

I think that you will find that if you look at the original specification for the class 460's, that they had 110mph set so that they could do 100mph maximum speed which in some places on the route from Gatwick to Victoria is the linespeed.
 

neilb62

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My most vivid memory of 313's having learned them when the replaced 501's on the "DC" is the god-awful brakes..... All disc-braked 3-step brake units are poor but they really stick in my mind, and yes I have driven 455's too... :lol::lol:
 

craigybagel

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I think that you will find that if you look at the original specification for the class 460's, that they had 110mph set so that they could do 100mph maximum speed which in some places on the route from Gatwick to Victoria is the linespeed.

90mph max Gatwick to Victoria, and on the whole Brighton Mainline. There was a 100mph section just south of Gatwick, to Three Bridges, but IIRC it was for 319s only and in any case has gone now?
 

swt_passenger

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Why would 460s have 125 mph gearing when the line speed is 90 mph? I don't think that's right.

It was discussed at least twice in the 458/5 thread, originally on page 2 in early 2013, and is based entirely on Ian Walmsley's description of the work in his article for MR.

But it was 'never proved' if people were expecting engineering drawings or some other sort of proof to be turned up. As a gearing issue it would not have affected the displayed top speed limit of the unit, just the acceleration.
 

notadriver

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Hmmm I think you're right based on the fact that Javelins have 140 mph gearing and can keep pace with Electrostar EMUs up to 50 mph after which current is severely restricted on DC infrastructure


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