Hi

Does anyone know whether there is a rule for which pantograph should be raised? I mean, should the front or the rear pantograph be up when travelling in front? Because I think it's never both at the same time!
And what about trains like the ICE? Normally, they have 2 pantographs on, but why only 2 and which 2 of them?

Cheers,

Nuno

I have a manual for the Class 46 Electric Locomotive for a specific line. I will post some points concerning pantographs. I think that rules are different according to the locomotive, the nature and condition of the overhead wires, the load of the train, the required speed, etc.

If you want to check out how the electric locomotives work go to: http://www.trainweb.org/railwaytechnical/tract-02.html.

Some of the points in the manual follow:
<ul>
<li>Raising or lowering of pantographs must never be done whilst any current is being drawn. Current is being drawn when either the throttle is open or any of the four auxiliary high tension machines are running.</li>
<li>During light engine running the rear pantograph only is to be employed.During all train working both pantographs are to be employed. If only one pantograph is employed in train working all of the machines may be adequately fed, but severe sparking would take place if the current draw was heavy. However, between Westmead and points East thereof where two or more locomotives are attached, only one pantograph is to be employed on each locomotive. This exception is due to the lighter nature of the overhead wire.</li>
<li>A Red Stop Board means stop and lower and isolate all pantographs if the 46 class locomotive is required to be hauled beyond that point.</li>
<li>Pantograph Raising and lowering reactions are to be visually inspected by the fireman-observer, with report to the driver.</li>
<li>Before entering a high tension compartment as well as operating the lowering and isolating pantograph mechanism, it is essential to observe that the pantographs have folded down. It is quite possible for the pantograph to remain in contact with the overhead wire
after lowering magnet valves have been operated, due to stiffness of the pantograph details.</li>
<li>To raise a pantograph it is necessary to have a supply of compressed air and to route it to the pantograph cylinder on the roof.</li>
<li>To lower a pantograph it is necessary to prevent air flow to the roof cylinder and to discharge that air already present.</li>
<li>These actions may be made by hand manipulation of the armature plate of the pantograph magnet valve, and this method may be used when a fault exists in the raising or lowering buttons on the cab desk panel.</li>
</ul>

Hi all,
I have also heard that if weather conditions are bad(ice,snow,freezing rain)that both can and should be used,...true?

I have read in an old book (from 1956) about Swedish trains that they did not build streamlined electric locos because it didn't work with the pantographs. On a loco with streamlined front, the air stream pressed the front pantograph upwards and caused it to wear out too quickly. If they used the rear one, the turbulence on the other hand caused bad contact and sparkling. So they decided to use the front pantograph and have square fronts on the locos. Since then, knowledge about aerodynamics have improved a lot, but the aerodynamics of the loco may still play an important role when deciding upon which pantograph to use.

So much for electric locos being safer...

I'd like to add two points to the discussion:

1. Locos with old-style pantographs (single wiper) would normally run with both pantographs up. Locos with modern double-wiper pantographs (introduced 1954) only raise one pantograph.

2. I think there is a misunderstanding about "passenger cars" with respect to pantographs.
German locos use the rear pantograph unless the following car has windshield windows (loco, passenger car with windshield (i.e. cab car), freight car with new cars) or carries flammable substances.
If two locos pull a train, the first loco normally raises the front pantograph, the second loco raises the rear pantograph (to maximize the distance between pantographs to reduce the effects of swinging catenary). If two locos pull a train with new cars or flammable liquids, both will raise the front pantograph - the train may have to reduce speed because of the swinging catenary.

Regards
Thomas