PRR Catenary

[nstars]

Peteski:  Overhead contact is more reliable than it would seem.  First, most pantograph shoes are flat, giving a wider contact than a round wheel on a rounded rail head.  Second, it's a sliding contact, which tends to keep the wire clean by scraping dirt and oxidation off.  And, the contact is on the bottom of the wire, so dirt can't easily settle there, while there is less oil and grease buildup than on the rails, which means less dirt is attracted.

In general the pantograph is more reliable than a trolley, but the reliability depends on several aspects like f.i. area of the contact wire and the contactforce of the pantograph. The contact wire is normally round, which reduces the contact area with a flat pantograph. In a contact wheel a groove is more or less created by the wear. The contact wire can also be quite small depending on the system. Our DC system has I believe 2x125 mm2 contact wires, while AC systems normally have something of about 50 mm2. In the last case the wire may only be about 8 mm wide.

The biggest advantage of pantographs is the fact that contact between a pantograph and a contact wire is more easy to establish and easier to maintain (minimal chances of junmping of the wire). Most pantographs also have much higher contact pressures. You'll be amazed how far the contact wire can be pushed upwards on HS lines. This could be in the range of 11"

Marc

[peteski]

Marc, Nick and I were discussing the live N scale pantographs and catenary reliability (at least I was).   

[nkalanaga]

The joints in the pans don't usually cause problems, unless it's been painted, or not used regularly.  The spring pressure keeps the joints pressed together, so there's enough rubbing friction to keep the oxidation worn off.  Much of the problem with the Arnold system is that there wasn't enough pressure, and no movement, between the wheel wipers and the vertical piece.  Any oxidation or dirt just sat there.  The system would have worked much better if the truck wipers had been one piece, rubbing on the PC board wiper at the top.

Marc:  The best figure I can find for the MILW is that they considered also 4,000 amps about the maximum for one train, with substations roughly every 30 miles.  Under heavy loads, the 3,300V nominal supply could drop as low as 2,000 at the train, due to resistance losses in the wires.  The system was fine for trains in the teens and 20s, but by the 1940s it was clearly inadequate, and certainly wouldn't be able to handle today's trains.   So, under ideal conditions, they'd have twice the power available that your lines do, but under heavy loads might not do much better than yours.

[nstars]

Marc, Nick and I were discussing the live N scale pantographs and catenary reliability (at least I was).   

U
Oops, next time I have to read the messages much better  . Apologies

Marc

[nkalanaga]

Marc:  I've noticed the wire being pushed up in videos of the MILW.  I assume thats the reason hangers are usually loops rather than solid connections.  Trying to push the entire catenary assembly up would bed the hangers.

For those who've never studied electric systems, the trolley wire isn't just a piece of wire.  It's almost 8 shaped, with a narrow waste, and two round ends.  The top section is connected to the hanger with a clamp, while the pan or pole runs on the bottom portion.  That way the hangers are out of the way, yet can easily be removed when necessary.  I've never heard of anyone, even in O scale, modeling true scale trolley wire, as it would have to be custom drawn.

[Lemosteam]

Keystone Details now has an add on Catenary Pole Extension set in the works:



The extensions interlock where the Caps would be.

[Lemosteam]

Well, I finally got my Catenary designs back from Shapeways.  You can see that as delivered there are some bowing and warping issues buuut:

I think the video below answers the flexibility issues of FXD & FUD as a material.  Now these parts had not been soaked yet, but I don't think the properties will change much:
https://www.facebook.com/john.lemerise/videos/10205757834969755/



This picture shows the mounting magnets I intend to use on my layout.

[Lemosteam]

So it's been a while since my failed Shapeways Catenary pole expreiment, but I did not succumb to this failure, no I redesigned!

I developed an etched pole concept that works as below (and BTW, thanks for the advice on the etch bending tool- it came today) and my confidence has jumped dramatically in the viability of this concept and yes, product.

The pole after fret removal and tab removal:


Removing the tabs with a pair of Fiskars fine tip stainless pruners (my most oft used tool):


Clamped in bending tool:


First bend if "U" section:


Second bend of "U" channel:


Repeat for other end.  After both ends folded:


Openings for Shapeways K baces:


"U" channel folded upon itself to make "H" channel, before solder:


Clamped closed to see the resultant holes for the K Brace:


Short pole after soldering:




Long pole after soldering for pone wire supports:


Completed assembly with Shapeways parts.  Mybases have the ability to accept a 1/8" dia rare earth magnet for locating and easy removal for safe storage.  K Braces will be available in different 2  and 4 track centers (including PRR 13' prototype spacing). 


Thoughts?  Should Keystone Details market and sell this?

[chicken45]

I wonder if there's a need for NTRAK spacing

[Lemosteam]

I wonder if there's a need for NTRAK spacing

Learn to read you must @chicken45 :


  K Braces will be available in different 2  and 4 track centers

[chicken45]

I was expressing curiosity as to if people would be interested in an additional version for NTRAK modules. Yes I saw that, but NTRAK is 3 track, and if you want to do 4 track, it's wider spacing than PRR spacing. I'm just spitballing someone who wants PRR electricity on a module.

[Lemosteam]

I was expressing curiosity as to if people would be interested in an additional version for NTRAK modules. Yes I saw that, but NTRAK is 3 track, and if you want to do 4 track, it's wider spacing than PRR spacing. I'm just spitballing someone who wants PRR electricity on a module.

Basically I can make K brace kits in any span and offer them with the caps and bases and phone wire supports, tall on both sides, short on both, tall/short.  When the kits are ordered the customer can specify what poles they want to go with them and i can send trhe etchings separately.

[Ed Kapuscinski]

These are incredible.

Let me know when I can pull the trigger.

[jmlaboda - RIP]

Now all we need is some closer to scale catenary wire to go with these...

[Lemosteam]

Now all we need is some closer to scale catenary wire to go with these...

I'm gonna use the stretchy telephone wire stuff I think.