Sprung Kato GG1 pantographs

[bbussey]

Has anyone attempted to add a spring mechanism to the Kato GG1 pantographs in order to keep them extended without sagging or listing forward/backward?

[nkalanaga]

The spring would be easy, but the rest would be difficult.  I have built stabilized pans in N scale, and don't recommend it for the faint of heart.  Basically, it requires at least one, and preferably two opposed, stabilizing bars, attached to cranks on the base "hinge rods".  One crank for each bar is above the hinge, one below, and they are connected by the bar.  That way, whenever one end raises or lowers, the other is forced to follow, keeping the contact shoe centered over the base. 

The concept is easy.  Getting everything aligned and the bar exactly the right length is the the hard part.  It CAN be done, but I've only done it on scratchbuilt pans.  Adding stabilizers to a pan that wasn't designed for the could be - interesting? frustrating?

I used the Ncat pans for years, until Overland Models released their Little Joes a few years back, then bought enough spare pans to outfit all of my motors.  Expensive, but they work well, and look good.  They're not designed for pickup, which I didn't need, and are closer to GN/MILW prototypes than to PRR.

[peteski]

They are already sprung. What is missing is the stabilizing links between the bottom arms which woudl keep them upright.  I thought about trying to do something about it (trying to maybe imitate the mechanism used in Arnold, Minitrix or Roco European pantographs) but I never followed through on that.

It really is too bad that Kato designed such a nice looking pantograph which is visually a more accurate rendition than most other N scale ones, just to make it only semi-functional.  They should have gone one step further and made it fully functional.  But looking at Kato's Japanese prototype locos, they seem to be happy with even just plastic posable pantogtaphs. Unlike most European brands  models which usually have fully functional pantographs while visually they lack prototype fidelity.  I guess asking to have best of both worlds is asking too much. 

[bbussey]

I'm going to look into it.  I have a few spare pantos I can play with, and I have a Key GG1 (and Arnold GG1s as well) that I can visually compare it to.  There has to be a way to retrofit etched stabilizers to these otherwise beautiful-looking pantos.  I don't want them to function electrically, I just want them to stay upright and possibly maintain contact against catenary.

[peteski]

I hope that you can come up with a doable solution Bryan!
I have that loco but I haven't looked for quite a while. Actually the problem with pantographs caused me to post my very first message on the Atlas forum (ah, the memories) http://forum.atlasrr.com/forum/topic.asp?TOPIC_ID=48928 > I'm glad that at least for now Atlas forum is still accessible.  On page 2 you can see photos comparing the Arnold and Kato pantographs.

Looking at those photos I recall thinking that it might be difficult to stabilize this panto because the bases of the bottom arms are quite far apart (much more separated than on the Arnold pantos. Also the arms are quite thin and the stabilizing mechansm needs to be firmly attached to the arms. That might be doable but it could destroy the fine look of the Kato units.

Keep us posted on your progress.   As you said, I would also be happy if the pantograph stayed upright and in contact with the catenary.

[Ian MacMillan]

This sounds like a problem for DKS to solve.

[nkalanaga]

Bryan:  Etched stabilizer cranks and a carefully made bending jog should work, if the pan can be taken apart and reassambled easily, and the cranks can be attached solidly.  Solder would be best, but with a tight fit, ACC might hold.  The problem is surviving the occasional wire snag and hand bump.

Peteski:  I agree, on both counts.  If they're already sprung it wouldn't have been hard to go all the way, and Japanese modelers don't seem to care if their pans work or not.  I believe Kato has made working ones for their European models, but wouldn't swear to it.

[VonRyan]

This sounds like a problem for DKS to solve.

I second this motion.

All in favor?...

[Philip H]

we don't have a raised hand smiley, but I'm +1

[Lemosteam]

After reading peteski's AF thread and seeing the pics there, I wonder if four small piano wire torsion springs or bent leaf springs at the four pivots would balance each other and keep the pantograph up and centered.  The idea being that they would each fight each other.  Wire diameter and /or material would be the factors that determine the force to keep them up (and compress them). One would have to either remove/disconnect the springs or add a clip feature to hold the pantographs down if desired.  Just an idea.


Modified Image from Peteski's AF thread (Hope that's OK Peter, I couldn't find the words to describe the idea!).

[nkalanaga]

You'd need something to hold them down in any case.  Even prototypically stabilized pans need a clip.

The Milwaukee used another method, at least on the boxcabs, but it wouldn't work on a model.  Their springs were held tight by air pressure.  When the pressure was released, the springs lost their tension, and the pan dropped.  The drawback was that, if the motor had no air in its tanks, there was no way to raise the pan, so no electricity for the compressor, so no way to start the motor!   The boxcabs came with a "stinger", similar to a trolley pole, but with a flat plate on the end instead of a wheel or shoe.  That could be raised by hand, providing electricity for the compressor, but couldn't carry enough current for the motor itself.  As for the others, I have no idea, but the Little Joes had batteries, so could probably run the compressor on them.

[peteski]

John, no problem with you using my photo to demonstrate your ideal.

I think that since there is nothing keeping the bottom arms in correct relation to each other, the pantograph would still still tilt (from the friction against the overhead wire) in the the direction opposite to the travel direction.   To add the the problem, those springs would need to be soft enough to allow the pantograph to follow the varying height of the overhead wire (which would make the whole thing more prone to tilting).

[rtroop]

 I was also really disappointed with the Kato GG1 pantographs not being sprung or equalized.  I’m afraid that it would be extremely difficult to add springing and equalization.  Both are really needed for proper operation with overhead catenary.  One might be able to add the necessary springing,  but equalization would be another matter.  If you look very closely at the photo below of a GG1 pantograph, you can just make out the two equalization links which are located below the main mounting frame.



The links insure that the front and rear arms rise and fall together which prevent the pantograph from leaning fore or aft due to sliding friction along the contact wire.  The springs which raise the pantograph are installed just inside the mounting frame.  Below is a not to scale mechanical schematic  diagram showing the arrangement of parts on a prototypical pantograph alongside the Kato one.  The dotted line represents the equalization link on the far side of the pantograph.  Not show are the air cylinders used to lower the pantograph, the hold down latch, the air cylinder used to release the latch and the mechanical latch release used to release the pantograph if air pressure was not available in the locomotive.



I looked at pantographs installed on  examples of GG1 locomotives in Z, N, HO, S, O and 1/32 scale.  All of them are sprung except for the Kato N scale.  Most of the locomotives in HO, S, O and 1/32 also feature  equalization.  Some only had one equalization link but worked well.  The Kato does not which unfortunately renders it useful for display purposes only.
Amazingly the tiny but well scaled Z scale Markelin pantographs are both equalized and sprung.  The N scale Key Imports pantographs were sprung but not equalized and suffer from leaning fore and aft.
It’s interesting that if you lift off the Kato pantograph from the locomotive body and inspect the underside you can see that Kato actually molded a shallow relief of the two equalization links.

I don’t think that there is enough structural material on the nicely delicate Kato pantographs to allow the addition of operating springs and equalization links. Perhaps someone such as TrainCat could produce some etched  replacement parts that would render the pantographs fully operational.  It would take someone with good eyes and steady hands to perform any modification on these beautiful but delicate assemblies.

[nkalanaga]

Bob:  It's interesting that the MILW and PRR designed their pans differently.  The MILW's required air to raise them, but lowered by gravity if the air was released, while the PRR's raised automatically, but required air to lower them.  I wonder why the difference?  Just a different designer, or maybe the PRR wanted to make SURE their trains were ready to go on time, while the MILW's freights didn't have to worry about a schedule, so they were trying to reduce stress on the springs?

Years ago I scratchbuilt some N pans with only one equalizer, and elastic thread for springs, and they worked fine.  Two are better, but if everything is adjusted right, one will work.

[bbussey]

Okay, I've dissected a Kato pantograph to see how difficult it will be to equalize it and add the tension spring.  It turns out it may not be that difficult.  It requires a replacement part etched from .30mm blackened stainless steel for the bottom of the panto and some folding thereof.



The diagram on the left is the stock part unfolded.  The diagram on the right is the revised part.  The fold lines are not present so you'll have to envision the finished part at this point.  The tall triangular sides fold up, with the upper holes for where the upper panto parts attach and the lower holes for where the panto attaches to the pivot on the plastic base.  The tab in the center is the stop to prevent the panto from rising too high. 

On the modified design, the long tabs next to the lower holes are for the equalizer wires and fold up opposite the lower pivot holes.  That section of part if viewed from the bottom will have the a "U" shape.  There is not much room to play with to avoid having to modify the body, so hopefully the equalizer holes are offset enough.  The equalizer bars will be formed from .010" diameter steel wire.  The proper length of the bars would be determined after having an actual prototype in hand.  In theory, the equalizer bars could be etched from stainless as well, which would be more than strong enough despite the thinness.

The extended tab on the stop tab is to hold the tension spring.  As with the equalizer tabs, it will fold up and over the stop tab, and the end of the spring will loop around it.

Some plastic on the underside of the panto base may have to be removed to allow clearance of the equalizer bars, but it should not affect the visible detail on top.  Also, a hole must be drilled horizontally lengthwise through the stop tab base on the plastic to provide tension spring clearance.  The tension of the spring will determine how well the extended panto would adjust to variations in the catenary.  I'm thinking a standard Rapido-type coupler box spring should suffice.

The only thing I haven't figured out is how to keep the panto down when it is "unused", as there is no lock mechanism and theoretically the tension spring will always force the panto into the extended position.

I guess only modifying the trailing panto also would "solve" that problem, since Gs and other northeast electrics as a standard ran with the lead panto down.