Pantograph & Tilt interaction

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James_D

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Forgive my ignorance on this subject, but I was pondering the interaction between the contact wire on OHLE, pantographs and the use of tilting and non-tilting trains on the same lines.

I assume that the contact wire stays at the same height relative to the position of the rails (with the necessary yaw of 'zig zagging' to allow an even wearing of the Pantograph contact strip), but when a train is tilting, lets say to the left for a right-hand curve, does the pantograph also tilt to the right to maintain connection as the train roof pivots away from the contact wire?

I assume this must be the case as non-tilting trains would require the contact wire to be at the same height and azimuth in relation to its pantograph.

I'm sure I could have found this info somewhere online but the kind users of the forum may be able to enlighten me!
 
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Railsigns

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when a train is tilting, lets say to the left for a right-hand curve, does the pantograph also tilt to the right to maintain connection as the train roof pivots away from the contact wire?

On a right-hand curve the train tilts to the right, not left!
 
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Bald Rick

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Yes the pantograph moves in the opposite direction to the tilt so that it is in the right place for the contact wire.
 

rebmcr

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On Class 390s there is a belt system to maintain the pantograph position relative to the contact wire.
 

Flying_Turtle

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On Pendolinos (at least on some designs) the pantograph is not istalled on the carriage box but on the Bogie. The supports are tied directly to the Bogie and cross the sides of carriage to the roof area where the pantograph is installed. This way, while the carriage tilts, tge pantograph is kept lined with the track/ohl.
 

neilb62

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Heres a couple of pictures of the Class 390 pantograph frame showing the belt drive and curved guides the frame runs on to allow the counter-tilt action. The whole assembly is also heated when needed to prevent freezing.
DSCF0491 by Neil Barker, on Flickr DSCF0490 by Neil Barker, on Flickr
 

cjmillsnun

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On Pendolinos (at least on some designs) the pantograph is not istalled on the carriage box but on the Bogie. The supports are tied directly to the Bogie and cross the sides of carriage to the roof area where the pantograph is installed. This way, while the carriage tilts, tge pantograph is kept lined with the track/ohl.

That's APT technology. ;)
 

Flying_Turtle

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That's APT technology. ;)

I got news for you (you probably know them) ... <D APT technology was sold to FIAT which in turn used it to develop the Pendolinos which were then sold across Europe. So not strange at all before evolving to some additional contraption to add up to train failure chances it was used in earlier pendolino designs
 

edwin_m

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I got news for you (you probably know them) ... <D APT technology was sold to FIAT which in turn used it to develop the Pendolinos which were then sold across Europe. So not strange at all before evolving to some additional contraption to add up to train failure chances it was used in earlier pendolino designs
 

Flying_Turtle

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The mechanism which Neil has kindly shown in #6 shows (disounting the coffee cup!) that the pantograph is moved side to side along a curved guide by a motorised belt drive. This will be controlled by the tilt system so that when the coach tilts one way the pantograph goes the same distance the other way so stays centred over the track. Yes it's another point of failure, but if that happens I imagine the large springs you can see will pull it back to centre, this will no doubt be detected as a tilt failure so the coach in question will be locked in the upright position and the train will continue at non-tilting speeds. It may even be that tilting operation can be resumed by dropping that pantograph and using the other one.

I don't believe the APT had any mechanical linkage to the bogie, though the Hornby APT definitely did! Some earlier tilting trains in other countries (including some known as Pendolinos I think) had a passive tilting arrangement where a frame attached to the bogie reached upwards through channels in the bodywork to pivots near roof level. The bodyshell was hung from these pivots and as the centre of gravity was below the pivot, it would swing outwards on each curve. With this arrangement it wouldn't suprise me if the bogie frame was extended up through the roof and the pantograph fixed to it.

However the APT, UK Pendolino and Voyager all have/had active tilt, where hydraulic or electric actuators rotate the body around an axis which is close to its centre of gravity. If you're designing some actuators to move the entire body then adding another one (controlled by the same tilt signal) to move the pantograph is rather simple by comparison.

I wasn't implying that the system was badly designed or anything of the sort (and I don't know a lot of technical details about APT). For example, the Portuguese pendolinos have that sort of rigid fixing to the bogie.
 
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