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Thameslink/ Class 700 Progress
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The design is certainly built around the central driving position. The door window isn't intended to look out of so yes the decision is to use forward dispatch is the consequence of the trains design.
We both know how twitchy the railway can be when using things that aren't to standard or not intended for use etc.
We are still waiting for a new driving policy because of the 700's design :/
Does anyone know what the loud brain piercing high pitch noise the 700's make is? It stops when the train is stationary at a station but it doesn't go away when it is stopped at a signal.
Also am I right thinking that the tread brakes come on only a second or two before the unit comes to a halt? I'm assuming this based on the noise these sets make when they stop.
Also am I right thinking that the tread brakes come on only a second or two before the unit comes to a halt? I'm assuming this based on the noise these sets make when they stop.
Islineclear3_1
Established Member
I'm not aware of any "loud brain piercing high-pitch noise" unless you mean the noise 700s make when they round the tight curve into St Pancras due to the squeal of the wheel flanges
Is that the noise you mean?
You can hear it here
https://youtu.be/OnwrUqjSPzw?t=8m25s
when the doors open it stops, then when the doors are about to close it resumes
https://youtu.be/OnwrUqjSPzw?t=9m50s
Looking at clips from when it's under DC power it doesn't sound as bad.
https://youtu.be/iR5Ofhm3-Ug
https://youtu.be/OnwrUqjSPzw?t=8m25s
when the doors open it stops, then when the doors are about to close it resumes
https://youtu.be/OnwrUqjSPzw?t=9m50s
Looking at clips from when it's under DC power it doesn't sound as bad.
https://youtu.be/iR5Ofhm3-Ug
That sounds like it'll be the transformer, which is why it is only evident on AC. I guess that when the doors are opened and interlock is broken, it shuts off (or drivers are going into neutral at each station). Other Desiros are similarly shrill.
I also thought they might be doing it on purpose to stop pax from complaining. And if drivers can switch it off by going into neutral it'd be great if they could also do it while waiting at a signal. I happen to live pretty close to TL a and since they introduced 700's the moments when they sit outside have become painful to ears especially in the evenings/at nights. 377/387s aren't as nasty.
Seems Google has updated their maps. The Siemens test centre is full of the things, with one thats looks as if it's heading our way.
https://www.google.co.uk/maps/@51.1151387,6.2225075,384a,35y,39.35t/data=!3m1!1e3
https://www.google.co.uk/maps/@51.1151387,6.2225075,384a,35y,39.35t/data=!3m1!1e3
spark001uk
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There certainly are a fair few! I'm surprised at that tight turning loop to the east end of the sheds, that looks extremely sharp. Looks like there's some non-GB stock there also, as one would expect.
There's what appears to be a total of three 707s on the premises too, see if you can spot them!
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SpacePhoenix
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There certainly are a fair few! I'm surprised at that tight turning loop to the east end of the sheds, that looks extremely sharp. Looks like there's some non-GB stock there also, as one would expect.
There's what appears to be a total of three 707s on the premises too, see if you can spot them!
https://www.google.co.uk/maps/place...!4m5!3m4!1s0x0:0x0!8m2!3d51.115552!4d6.208904
Is that a class 374 there (or at least part of a class 374)?
There certainly are a fair few! I'm surprised at that tight turning loop to the east end of the sheds, that looks extremely sharp. Looks like there's some non-GB stock there also, as one would expect.
There's what appears to be a total of three 707s on the premises too, see if you can spot them!
All I could count was 6 sets of GB trains. Could be 700's or 707's. Hard to tell, but some looked stagecoach red, tho' they could be DB red?
The tight turn is on the tram test track. I think it's meter gauge.
I think there is a Eurostar Velaro sitting there as well.
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I think that he's misusing terminology. What it could be is the main traction inverter electronics (which will have inductors within it subjected to high audio frequency currents). I imagine that the inverters have a standby mode and one where power is available to drive the traction motors. When the train is parked at a station, particularly with the doors open, the safety interlocks presumably inhibit that mode, all required power coming from auxiliary supplies, ('hotel' and safety). When waiting at a signal etc., the train is under the driver's control so there is no need to drop into standby mode.
The main transformer handles 50Hz ac and will only produce a hum (or when heavily loaded, a 100Hz buzz) much of which comes from its casing and surrounding metal structures, owing to magnetstriction and vibration cused by induced magnetic fields.
I wouldn't describe the sound as 'brian piercing' though. If I was into hyperboles, I might suggest 'ear piercing', but my brain can't hear anything as it doesn't have any sound sensors, - I use my ears for that.
swt_passenger
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How did you work out his name...
How did you work out his name...
Ooops!
I wouldn't describe the sound as 'brian piercing' though. If I was into hyperboles, I might suggest 'ear piercing', but my brain can't hear anything as it doesn't have any sound sensors, - I use my ears for that.
Well let's say if someone wanted to torture someone then locking them with a 700 "ticking over" on AC in a station like STP would be a great way to do that and results would be guaranteed.
Another great example of that https://youtu.be/idR4dRWI8dw
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bramling
Veteran Member
Being on board a class 700 is a rather undesirable experience to many people as it is, even without the noise.
Having said that, the noise is not unlike that produced by the auxiliary converters on many modern trains, some of which can also be a little uncomfortable to the ear if one is in the immediate vicinity.
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Oh yeah, I never thought I'd miss 319's. Although Electrostars weren't that great either, one massive issue with these (to me at least) is the lack of ledge where you could rest your foot when sitting next to window. 319's and 700's have that.
I think that they are functional, they cope well with the ever increasing numbers of passengers, they are fast, and once the incompatibilities between the infrastructure and the trains are ironed out, should provide a reliable services for years. The seat issues etc., are trivial compared with not even being able to board a stuffed-full train. Many other London commuter routes will probably be similarly equipped in the next 10-20 years.
Trains haven't used tread brakes in years; they use big disc brakes now. Network Rail are a lot more proactive about cutting back vegetation, and all modern stock are fitted with sanding equipment and automatic wheel-slide protection (similar to ABS in a car) that means the wheels themselves don't routinely get contaminated, they do only in the very worst conditions.
700s have tread brakes on motored axles
That's true, but both north and south of London, the Thameslink routes do still have issues with leaf fall. The MKIII trains (e.g. 319, 321 & 455) with their single motor car configuration have had problems with adhesion right up to last year. Whilst regen. braking would be the preferred mode for all normal running, I was just suggesting that a driver-selected mode to occasionally apply tread braking alone may be an easy solution to clear the worst contamination en route. Although the class 700s have 50% of axles powered which should help, they also have very high torque available at the wheel and the intensive Thameslink timetable will I'm sure make maximum use of that performance. There may of course be other technical or operational reasons why such a facility wouldn't be permitted.
Peter Mugridge
Veteran Member
Catching up on dozens of e-mails from various Yahoogroups after being out all day yesterday, it appears that 700 022 was delivered on Sunday night / yesterday morning.
Paynetrain
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Could not see it there when i went past but noticed 700024 has the newer ThamesLink/ logo on it the first one ive seen with it on.
its only taken them 6 months looooooooooool
Deepgreen
Established Member
Which should have been done in the design, build and (most importantly) extensive on-route testing phases!
Deepgreen
Established Member
The 700s have tread brakes on some (motored?) wheels - the question is; when are they deployed and is it a manual or automatic process?
Well, I would expect them to be used whenever (along with the discs on trailer cars), to bring the train to a halt when there isn't enough speed to get any energy from the rotating motors. The other intended use would surely be in an emergency when either the system can't absorb any regen power (via the supply or into the resistors), or in a full emergency stop.
An option of using them for moderate service brake applications could give some benefit by cleaning the driven wheel treads.
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