ADD- what does it mean?

[jnjkerbin]

What is an ADD? I notice according to this: http://www.opentraintimes.com/stats/rtppm that EC were affected by one today.

Joe

 

[Smudger105e]

What is an ADD? I notice according to this: http://www.opentraintimes.com/stats/rtppm that EC were affected by one today.

Joe

ADDitional stop?

 

[driver_m]

Auto drop device. Drops the pan if it gets damaged.

 

[swt_passenger]

'Automatic Dropping Device' is probably referring to the failsafe thing on a pantograph system.

Idea is that if the pantograph thinks it is going wrong it gets dropped before the OHLE is damaged?

 

[Smudger105e]

Auto drop device. Drops the pan if it gets damaged.

Oh yeah, was told that when I did my 319 course! Air pressure under the pan carbon is released if the carbon is damaged, and the pan crashes down.

 

[Dave1987]

ADD ("Automatic Dropping Device") is to drop the pan if the arm over extents (i.e run out of overhead wires) or one of the carbons which is the bit in contact with the overheads has come off. It essentially protects the pantograph and the OHLE (Overhead Line Equipment)

 

[jnjkerbin]

Wow, that was quick! Thanks

 

[455driver]

ADD, the opposite of MINUS.

It means many different things in different contexts.
As stated by Loco Fitter, in this case it means additional stop.

 

[Anvil1984]

ADD, the opposite of MINUS.

It means many different things in different contexts.
As stated by Loco Fitter, in this case it means additional stop.

Highly doubt it was an additional stop, itll have been a pantograph problem. I think this was the service which delayed the other EC services in another thread

 

[455driver]

You are right in that case it is a pan drop.

Note to self never assume the poster in front has replied correctly and look myself!

 

[transmanche]

And there was me thinking we had a train suffering from Attention Deficit Disorder...

 

[455driver]

1A02 is the 0530 Leeds to Kings Cross and lost 29 minutes at Welwyn, now about that double pan idea that they are trying out!

 

[millemille]

ADD ("Automatic Dropping Device") is to drop the pan if the arm over extents (i.e run out of overhead wires) or one of the carbons which is the bit in contact with the overheads has come off. It essentially protects the pantograph and the OHLE (Overhead Line Equipment)

Auto Drop Device drops the pan if the pan carbons (the contact strips that contact the contact wire of the OHL) are missing/damaged (and leaking air from a pressurised gallery under the carbons) to prevent OHL damage/dewiring.

Overheight drops the pan if it goes too high, normally as a result of the OHL already being damaged, through a plunger mechanism operated when the pantograph arm reaches a certain angle.

 

[TGV]

It also functions if the carbons are too badly worn. Some designs of pan have the ADD pipe as part of the carbon itself, others have a copper pipe underneath the carbon at a set height above the carrier to prevent it running on the wire. The copper pipe will be breached by the contact with the wire and down it goes.

The air supply to the pan is first routed up to the pan head, then back down to the raising cylinder (or "air motor" if you prefer), so if the air is vented from the head, then the cylinder is starved of the required pressure to keep the pan up. You can often see the ADD pipe as a small (usually 6mm diameter) plastic pipe routed up the arms of the pantograph.

Some pantographs require purely air pressure to raise and drop under gravity, others use the air pressure to overcome "lowering" springs and are aided by "raising" springs, but the interaction with the ADD in both cases is essentially the same.

Strictly speaking, ADD is poorly named as it's not a "device" but a system of interacting assemblies and components, but the ADD acronym has stuck over the years.