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| Pendolino pantographs | |||
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| 08:00, 25 October 2009: | Report | Quote | ||
| Shenfieldrider Member Send a message Joined: Mar 2005 Posts: 54 |
When I arrived back in Euston recently I noticed that pantograph at the Northern end of the platform was lowered, and that at the southern end of the train had been raised. Is there a reason for this change, i.e. better operational capability (less likely to cause problems with OHLE in a particular direction), sharing the "wear and tear" on both pantograph arms? | ||
| 20:30, 26 October 2009: | Report | Quote | ||
| Paul Scott Member Send a message Joined: Jan 2007 Posts: 2375 |
That's what you would expect to see I think. Apparently Branson insists they always run with the leading pan up, cos it looks better. So the north end pan won't be raised until after the driver has turned round the train? Paul | ||
| 22:16, 26 October 2009: | Report | Quote | ||
| Mark B! Member Send a message Joined: Apr 2006 Posts: 1229 News credits: 1 |
That might be a myth - I saw somewhere that it was at Alstom's suggestion  | ||
| 22:21, 26 October 2009: | Report | Quote | ||
| O L Leigh Member 
Send a message Joined: Jul 2005 Posts: 752 |
I don't know the reason why the Pendo has to use both pans, but sharing out the wear means that there are fewer penalties in terms of running costs. A pan needs to be refurbished after a certain mileage. Sharing the work betweens two pans means that the refurbishment will come around only half as often as would be the case if the train had just a single pan. However, there are now two pans to be done rather than just the one. It's double to cost but only half as often, so the cost penalty is zero because the total cost over the entire life of the train would be no different than if the train had just a single pan. Then again I could be miles off. O L Leigh Limited blog archive: Click Some railway pics: Click  | ||
| 22:34, 26 October 2009: | Report | Quote | ||
| Mark B! Member Send a message Joined: Apr 2006 Posts: 1229 News credits: 1 |
I do know a Pendo is pretty much two 4 coach half-sets (with a trailer in the middle) | ||
| 23:52, 26 October 2009: | Report | Quote | ||
| O L Leigh Member
Send a message Joined: Jul 2005 Posts: 752 |
Indeed it is, but then both halves are connected together with a 25kV "bus". Two pans does confer some operational advantages. If one falls off there is still the other as a back-up. O L Leigh Limited blog archive: Click Some railway pics: Click | ||
| 10:11, 27 October 2009: | Report | Quote | ||
| Paul Scott Member Send a message Joined: Jan 2007 Posts: 2375 |
I don't think they ever have two pans up at the same time though. At 125 mph it sets up waves in the catenary, and the second pan wouldn't get proper contact. Paul Number of edits: 1. Last edit: 10:17, 27 October 2009 | ||
| 10:16, 27 October 2009: | Report | Quote | ||
| Paul Scott Member Send a message Joined: Jan 2007 Posts: 2375 |
I'm sure it could be a myth - could also be there are dynamic effects on the pan that make one better than the other in a particular direction at full line speed. Paul | ||
| 13:11, 27 October 2009: | Report | Quote | ||
| Skoda Member Send a message Joined: Feb 2009 Posts: 30 |
As the pendos were originally specified, they were to run at 140 mph and due to the nature of desing of the WCML overhead wires, there was a potential issue with wire "bounce". This was dealt with in 2 ways ; In some locations, OHL "damping" was added to the wire but also the Pantograph was to run with the knuckle trailing in direction of travel. hence why the pans change at terminal stations. There is a limtied 25Kv busline between the two pantograph cars but I beleive this is only because there is just one transformer on the unit. Incidentally, IEP requires 2xcoupled short length electric trains running at 125 with both pans raised ! | ||
| 17:33, 27 October 2009: | Report | Quote | ||
| O L Leigh Member
Send a message Joined: Jul 2005 Posts: 752 |
Um, yes I know. What I meant was that the Pendo uses both pans, but only one at a time. Leaving aside OLE sway, running with both pans raised at the same time would not be economical as each pan would be subject to the same wear and tear it would suffer if it was being used singly. However, using one pan on the 'up' and swapping to use the other on the 'down' means that the wear rate is shared between two pans. The benefit is that, as I said before, pan refurbs only come around half as often but there are now two pans to be done so it is double the cost of refurbing just a single pan. This makes them no more costly than having just a single pan for the entire train, as was the case with the LHCS formations. O L Leigh Limited blog archive: Click Some railway pics: Click | ||
| 18:56, 27 October 2009: | Report | Quote | ||
| Paul Scott Member Send a message Joined: Jan 2007 Posts: 2375 |
Um, yes I know. What I meant was that the Pendo uses both pans, but only one at a time. O L Leigh[/quote] Sorry, I read it the wrong way...  Paul | ||
| 07:10, 28 October 2009: | Report | Quote | ||
| Monkey Member Send a message Joined: Mar 2007 Posts: 2659 |
I am probably talking nonsense here but doesn't the pan do less damage to the wires when it is facing a certain direction. ie if the > that the pan creates is point to the direction of travel it is going less damage than if it s going against it. I will have to have a look next time I am on a pendo to see if this is the case, but I am sure I have read somewhere the 91's are more likely to dewire in one direction. The wire bounce sort of makes sense, the class 373 on the ECML used both pans up but were restricted to 110mph on the ECML. I think it was raised to 125mph on some sections later but only after modifications. | ||
| 09:16, 28 October 2009: | Report | Quote | ||
| Skoda Member Send a message Joined: Feb 2009 Posts: 30 |
The reason that pendo has knuckle trailing is for optimal current collect from the wire. If you look at the pan you will notice it has aerofoils and it is aerodynamicially tunned to work best in one direction. I rememebr a few years ago a Class 91 dewirement where the knuckle was leading and the pan was ripped off and hit the adjacent coach and part of it broek a window and entered the saloon. | ||
| 23:33, 29 October 2009: | Report | Quote | ||
| O L Leigh Member
Send a message Joined: Jul 2005 Posts: 752 |
The aerofoils are set up to give more lift in one direction compared to the other in order to equalise the mechanical lift given by the arm. The effect is that the pan head exerts the same pressure on the contact wire irrespective of the way it is facing. In any case, the amount of force applied by the aerofoils alone is small. Additionally, the account of a single dewirement does not illustrate the wider point. Of course a Cl91 pan is going to be more likely to come through a coach window when it is running elbow first. In that configuration the train will be running loco first. If it was the other way round the pan would have gone over the top of the loco and got nowhere near the coaches because the loco would have been the last vehicle in the train. O L Leigh Limited blog archive: Click Some railway pics: Click | ||
| 04:25, 30 October 2009: | Report | Quote | ||
| LM Driver Member Send a message Joined: Nov 2007 Posts: 100 |
The aerofoils on the LM 350's have the words "keep off" on the underside of them. Always struck me as odd thing to write there. This is just my own opinion. | ||
| 21:48, 07 February 2010: | Report | Quote | ||
| TGV Member Send a message Joined: Oct 2004 Posts: 992 |
The reason the sets have 2 pantographs will probably be a reliability issue. Many things on a modern train have redundancy built in, if one part of a system fails, there are others that can either take over, or the train can get by with one failed. Pantographs, however, don't have such a luxury. If you lose one - and only have one to begin with, the whole train fails. So the reason there are two fitted will be to do with that I suspect. However, as to why a specific one is raised depending on direction is probably to make sure that they wear evenly as someone already suggested. If you're going to have 2 fitted, may as well make sure they both get used. The directional thing is probably just a "habit" thing to make sure that it's simple to remember which one was used last etc.. I can't imagine Branson caring much about which pantograph does what - although I don't know that for sure. The direction of travel makes absolutely no difference. Look at a Eurostar - both pans raised on leading and trailing power cars on all (normal) journeys at 186mph, so there's no aero issues at 125mph or 140mph because of the pantograph arm shape - at least none that a small aerofoil can't sort out. Bounce is an issue on some lines - again, anyone who saw the 373's leased to GNER on the ECML would have noted that the front pan made decent contact, but at speed, the rear one looked like a sparkler on bonfire night. This could also be to do with the infamously dodgy OLE on the ECML of course. Number of edits: 2. Last edit: 21:51, 07 February 2010 | ||
| 18:36, 08 February 2010: | Report | Quote | ||
| L E Greys Member Send a message Joined: Oct 2008 Posts: 428 |
TGV pantographs are a bit curious. I know that they have a full-length bus line, but I'm never sure whether it is best to have the front or rear one raised. I know that on 92s, it is always the rear one to prevent the front one from doing any damage to the rear if it falls off (they can both handle multiple voltages, AC and DC). Someone on here once told me that if two TGVs work in multiple, they always use the outer pans to reduce problems with interactions. That is indeed the case (I checked last year). | ||
| 21:30, 11 February 2010: | Report | Quote | ||
| TGV Member Send a message Joined: Oct 2004 Posts: 992 |
Yes, that is true. 373's don't have the 25kV line running the length of the train, but at 400m in length, the 2 pans are far enough apart anyway. They have an extra bit of redundancy built in because if the 25kV pan fails, the 3kV DC pan can be raised under 25kV and used up to a limited speed. The 25kV one can't be used under 3kV DC though because the current is too high - the Faiveley 25kV pan head only has 2 contact strips vs. the Brecknell Willis DC which has 4 strips for the increased current. | ||