Post by norbitonflyer on Jan 27, 2019 16:26:25 GMT
The Great Northern fleet of 313s is now 44 units, enough for 22 six car trains - although I don't know if they are still all serviceable. There are to be 25 new six-car class 717 units. Of course, unlike a complete six car unit, three car units can be juggled to make one good six car train out of two failed ones by using the good unit from each one.
[ It is much more common to fail to get the pan down and change onto DC than the other way
That is probably not surprising, given that it couldn't have entered service from the depot if the pan was stuck down, so any fault would have had to arise in the relatively short time the train had been in the hole. But if it did fail to rise, the unit would effectively be trapped in the Drayton Park- Moorgate section until it was either fixed or dragged out. Where would it go in the meantime - presumably one of the platforms at Moorgate? Can Moorgate cope with a full service with one platform out of action?
With the 313s, such a failure would usually be easy to remedy as each 3-car unit has its own pantograph and if the pantograph fails to raise on one of them, the other unit can pull (or push) it out. Not only is the 717 one unit, but (unlike the 700s) it only has one pantograph................
I seem to recall that the 319s had some problems in the early day of Thameslink, because they used a similar system to the 313s (at the time the only other dual voltage units on BR), but the AC components were not used to being idle for such extended periods as the 319s required (round trips to Brighton, not to mention depot visits to Selhurst) and they sometimes refused to raise the pan when they got to AC country at Farringdon.
No NCL cannot cope with a platform out at Moorgate. Requires 50% of the service diverted to Kings Cross. Couple of failures of the 313s last week proved this point rather well.
A 717 failing to changeover means NCL shuts. Note one 313 failing to changeover requires the other one to haul it and creates problems too and due to the metro nature ends up with some services diverted.
Folk should remember that there is a crossover north of Drayton Park allowing a train to depart north from what is normally the Southbound platform.
While obviously it will cause disruption, its quite possible that should the unit fail to change onto DC then it could be terminated at Drayton Park and driven back north under AC. This is the standard procedure in the Thameslink core should a unit fail to swap AC-DC or DC-AC as the 12 car units are too long for the Smithfield sidings and both the traction supplies overlap between City Thameslink and Farringdon with suitable crossovers provided in this section.
The bigger problem at Drayton Park is if the unit fails to change from DC to AC, as rescuing it will most likely require the following unit to be used to push the defective one up to Finsbury Park.
Two units running I think. The only runs in passenger service last week were at 1037, 1137 and 1337 from Moorgate to Gordon Hill. (2G82, 2G72, 2G74). The 1237 departure, and all the return workings from Gordon Hill to Moorgate, were empty stock (5Gxx, 5Jxx in Real Time Trains). Note also that the trains do not call at Old Street, Essex Road, Hornsey or Harringay