toby_farman
Member
Found another Video of 769008 at Hengoed a week or so ago
Anyone know why they've taken the pantograph off and kept the transformer?
Found another Video of 769008 at Hengoed a week or so ago
Anyone know why they've taken the pantograph off and kept the transformer?
Don't need them and easy to take off so why keep them on?Anyone know why they've taken the pantograph off and kept the transformer?
I'd guess there could be multiple factors. Weight retention (affects suspension then tractive effort), option to reinstate 25kV in future, perhaps having the pan in place caused gauging issues?
I don't like to be a know-it-all, but are you sure?That would be my first answer.
I don't like to be a know-it-all, but are you sure?
I would reckon that a pantograph, including its frame and mounting feet, probably has a total mass of around 200kg. This is about 0.6% of the empty mass of a 35 tonne coach. Even if its mass is twice as much this is still only just over 1% of the mass of the coach. Five 80kg passengers weigh as much! Weight saving wouldn't appear to be significant.
If one doesn't need the pantograph then removing it saves maintenance and something else to go wrong. It's easy enough to put it back when its needed.
In which case that is entirely understandable!Apologies, my post was rather ambiguous. My posting was intended as a response to the fact that the Class 319 transformers are retained in all 769s, rather than being removed from the TfW units.
I think that is standard practice on all trains that are designed or delivered with transformers. Electrostars that were delivered as ac/DC but used on DC only for long periods (e.g. some 375s, 377/2s) have their pantographs removed to avoid branches gathering in the well equipment, but the transformers are left in situ. The ac/DC design trains that were delivered as DC only, carry a concrete 'transformer weight'. In both of those cases, there is no need to adjust the suspension dynamics as would be required if a tare weight variation of a ton* or more was involved. The class 707 were also designed to be dual voltage (and the first two were delivered with pantographs fitted). I presume that the whole class carried transformers.In which case that is entirely understandable!
On a 319. It's not.I would imagine the transformer may well be an integral part of the complete electrical system, and would need a redesign if it wasn't there. A ballast weight would also be needed to avoid changing suspension settings etc. Contrariwise, a pantograph is exposed and vulnerable to damage, and is light enough that removing it has little affect on the suspension balance
On a 319. It's not.
For reference. Most pantographs are between 150 and 200kg
I presume that the whole class carried transformers.
That's only two passengers (or a very large one) though?
Weren't the 769s meant to be in service for the May TT? Not surprised that didn't happen though.
It'll end up being May next year the way things are going. And if it is, TfW's 769s will be 3 years late. TfW will be lucky to get 12 months of revenue earning service out of themMay last year not this
OK, well if the first two (707001 & 707002) have had all of the ac kit removed including the transformer, there must have been some adjustment of the bogie dynamics to compensate unless they still have concrete underneath. It says that they were delivered to Wildenrath for ac testing, maybe they went back to the factory for removal of kit so not typical of current new EMU practice.You presume wrong. Analysis of pictures of the underframes of a 707 shows a distinct lack of, well, anything on the pantograph well vehicles.
OK, well if the first two (707001 & 707002) have had all of the ac kit removed including the transformer, there must have been some adjustment of the bogie dynamics to compensate unless they still have concrete underneath. It says that they were delivered to Wildenrath for ac testing, maybe they went back to the factory for removal of kit so not typical of current new EMU practice.
Back to the situation on the 769s, - I've done some calculations to arrive at a rough figures for percentage of the total unit weight available for traction on both 319s and 769s. It's normally expressed as adhesive weight on locos, but as the non-adhesive weight on an MU is defined, it is better defined as a percentage of the total train weight.I would imagine the transformer may well be an integral part of the complete electrical system, and would need a redesign if it wasn't there. A ballast weight would also be needed to avoid changing suspension settings etc. Contrariwise, a pantograph is exposed and vulnerable to damage, and is light enough that removing it has little affect on the suspension balance
class/subclass | tare | full load | crush load |
class 319/0 or 3 | 36.1% | 34.5% | 33.5% |
class 319/4 | 36.1% | 34.7% | 33.8% |
class 769/0 | 32.6% | 31.6% | 31.0% |
class 769/4 | 32.6% | 31.8% | 31.2% |
Can't see a return working in RTT. The 769 paths are still in though. Find it interesting that the 230 runs are happening daily (and boy are they hammering it) but the 769's are not.Colas 37421 is on its way from Rhymney to Cardiff Canton Sidings as 5Z70 this morning. I presume it’s heading back to swap places with 37418 on class 769 thunderbird duties when they restart
Can't see a return working in RTT. The 769 paths are still in though. Find it interesting that the 230 runs are happening daily (and boy are they hammering it) but the 769's are not.
Colas 37421 is on its way from Rhymney to Cardiff Canton Sidings as 5Z70 this morning. I presume it’s heading back to swap places with 37418 on class 769 thunderbird duties when they restart