It appears in Google Maps satellite view, it's the southbound East London Line from platform 1 shortly before joining into the Down Sussex Slow.
There does seem to be an equivalent long gap northbound on the ramp down from the flyover. An isolation gap would have to be the length of a train as all shoes are cross connected.
Doesn’t seem to be long enough, but it is about 50m to the road bridge on the aerial view. Maybe the 378 isn’t fully cross connected.
Normally nothing as it's a DC supply (so no separate phases as with AC). But if one section were isolated then there is a risk of re-energising it via the power unit line that runs the length of the train and connects all the shoegear - if one shoe is on the live section, power will pass along the PUL to a shoe on the isolated section. This is why module DC of the rule book requires all shoes to be raised before a train moves from an energised to an isolated section.
The isolation issue may well be the reason, as the ELL is a different asset owner with their own maintenance rules.
The problem is, surelym the different voltages between tghe positive rail of the 4-rail system (typically about 500V - negative rail is typically minus250V) and the live rail of the 3-rail shystem typically about 750V. Having a 250V difference across the positive pickups along the train would probably be bad news.
I recall reading of an incident where that happened near Vauxhall whilst people were be evacuated from a train, the staff noticed the compressors strating up, signifying that the live rial had been re-energised. It seems another train had moved into the de-energised section, with the rear still in the energised section and able to bridge the gap.
Looks about right - therefore I imagine anything longer has to have some form of isolation applied.
The shoes are electrically connected only within a unit, so coupled units would be OK. Any units longer than the gap (measured from first shoe to last one) might need some special measures.
Do all trains have retractable shoegear?
It’s not always provided, a good example is the 444/450 fleet. Their shoes can only be raised by traincrew in emergency, one shoe at a time. I once stumbled upon a training set up at Bournemouth where staff were being shown how to do it on a demonstration bogie rig. I asked the instructor and he said the bogies had fittings to retrofit the necessary extra parts, eg blanked threaded sockets, but unless the units were ever converted to dual voltage the functionality wouldn’t be needed.
Yes that’s right, it was quite involved because the shoe and arm had to be safely held up with a strap once raised. I’m sure on a real train with them all cross connected the electrical safety risk must be high.
Yes, but in the sense that it possible to lift the shoegear out of the way on every train that runs on DC power from the third rail, even if it has to be done manually. On most DC-only units, the shoes are held down against the top of the 3rd rail by spring pressure, so you have to lift the shoes manually against the spring pressure using a wooden paddle then strap them in the raised position using a cable tie or something.
Most don't have shoegear at all!
Very much so! It only takes one shoe on live 3rd rail for all the other shoes to be live, even if they're dangling and not in contact with the 3rd rail.
I remember on the old EP stock the shoes fuses were at solebar level and completely exposed to prying hands on many platforms although im not sure anyone came to harm. Todays ones are fortunately covered
Also why does the DSD always go off when departing Surrey Quays when the train hasn’t even been moving for 1 second yet to warrant an activation?
