From: ehr@ecsvax.uncecs.edu (Ernest H. Robl)
Subject: Re: Pantograph pickup width Swiss 460
Followup-To: rec.railroad
Summary: zig-zag and model comments
Organization: UNC Educational Computing Service
Date: Wed, 18 Nov 1992 15:03:48 GMT

In article <1992Nov18.040712.38@rcwusr>, stanyermp@rcwusr.bp.com writes:
> In article <1992Nov18.053023.25928@news.uiowa.edu>, jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879) writes:
> 
> -> I've always been impressed with Swiss catenary, because they
> -> seem to make more consistant use of curved catenary than any
> -> other place I've been.  That is, when rounding a curve, the
> -> catenary wire (or top wire, or support wire) is off to one
> -> side, so that it pulls the running wire to the side at every
> -> support point.  This keeps the running wire within a few
> -> (prototype) centimeters of the centerline of the track, so
> -> narrow pickup shoes should pose no problems.
> -> 
> -> By comparison, most catenary I've seen in the US, or France and
> -> Italy, for that matter, has been strung with the support wire
> -> directly above the running wire, so that both hang straignt
> -> from one lineside support pole to the next.  This leads to
> -> deviations of on the order of 10 to 20 cm from the centerline
> -> of the track on a curve, and it clearly needs a wider shoe for
> -> safe running.
> -> 
> -> 				Doug Jones
> -> 				jones@cs.uiowa.edu
>   In the UK British Rail deliberately do not hang their catenary
> wire over the centre of the track... rather they try to zig-zag it
> from support to support. This is in an attempt to minimize wear on the
> pantograph pickups and presumably to prevent grooving taking place
> when travelling at high speeds. This of course does have disadvantages:
> in high winds the maximium speed of pantograph engines has to be reduced
> (sometimes to as low as 70mph) to minimise the risk of de-wiring.
> 
> Moral of the tale... study the prototype and dont extrapolate too far: 
> you might come off the wires.
> 


Actually the Swiss do use a zig-zag pattern.  Because of the tighter
clearances in some of their older tunnels, the zig-zag patterns is
narrower than that used in some other countries.  Therefore, Swiss
pantographs have always been narrower -- as noted in previous
discussions about "Swiss" pantographs on TGVs, etc.

Running with a wider pan on the narrow zig-zag is not a problem --
as long as you have adequate clearance.  This is the case, for
example, for Austrian electrics operating a short distance into
Switzerland.  These lines have the narrow Swiss zig-zag pattern --
but otherwise adequate clearances.


Now, to the 460 -- and its HO model.  The 460's pans are no
smaller than those of other Swiss electrics.  The fact is, however,
that on this new locomotive, when the pan is lowered, it is 
completely surrounded by a streamlining shroud.

Since it's much more difficult to set up a precise zig-zag on
model railroads, particularly on those with unprototypically tight
curves, many model makers have supplied oversized pans on previous
models of Swiss electrics.

With the 460, this would have been a problem for Roco, since an
oversized pan would have conflicted with the with scale streamlined
shroud that covers other roof appliances.  So, Roco chose to make
the pan to scale -- but to supply an accessory clip-on wiper that
you can use on the raised pan -- so that will operate better on 
model catenary.  The lowered pan will still fit inside the 
streamlining -- if it does not have the clip-on wiper attached.

Sources:  (1) Cab ride from Innsbruck, Austria, to Buchs, Switzerland,
on Austrian 1044 electric, during which I discussed such things
as Swiss pantographs with the engineer.  (2) Discussion of 
460 model in Austrian magazine Eisenbahn/Modeleisenbahn.  (3)
Description of 460 model in Roco catalog.

 -- Ernest

-- 
"My other computer is a Nikon N8008." -- Ernest H. Robl
Ernest H. Robl (ehr@ecsvax)  Durham, NC, USA   +1  919   286-3845
                                         FAX:  +1  919   286-1696
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