# Modifying PIKO switches



## riderdan (Jan 2, 2014)

Last week, for the first time, I *really* paid attention to why some of my short-wheelbase motive power was struggling through the PIKO switches I have on my layout. Turns out that the depth of the plastic flange way is too shallow for a number of power blocks. This is especially apparent with Heartland and Aristo two-wheeled units.

Looking down into the flangeway, I can see where the metal wheels are scoring the plastic as the wheels ride up on their flanges. This also seems to be the reason that the short-wheelbase guys have trouble making it through--once the wheel flanges are up on the plastic, the wheels are no longer in contact with the brass portion of the switch. I proved this to my own satisfaction by putting a very thin, narrow brass strip down at the bottom of the flangeway, connected the the rail so it was powered. Locos that had hesitated (or outright stopped) on the switch made it through.

I'm looking for a solution to this problem. I have two ideas: one is to remove 1/8" from the top of the plastic so that deeper flanged wheels won't ride up. The other is to put a brass contact strip into the flange way so that contact is maintained. I'm leaning towards cutting down the plastic, as I'm afraid that even a very thin brass strip is likely to increase the chance of derailment.

Has anyone had similar experience with switches? If so, what did you do to resolve it? 

Thanks for any input.


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## Garratt (Sep 15, 2012)

The problem is when you make the flangeway deeper then the wheels that have shallow flanges will drop off the rail head when going through frogs. The frogs on many model railroad switches are designed as flange bearing so wheels don't bump through them. 

Ideally the locomotive and rolling stock flanges should all be a similar height in the first place then this problem could be minimized with the right track set-up. With vastly different wheel flange depths, they will either ride high through the frogs on the flanges or the treads will drop between the rails, perhaps perfectly, somewhere between doing both. There is no avoiding that fact. The electrical conductivity problem is a different one to wheel smoothness through frogs so I would address all the locomotive's flanges and electrical needs first. 

Some switches with long frogs are made with a brass contact strip in the bottom of the frog flangeway so short locomotives don't stall on them. The Piko curved switch is one that does. 

Andrew


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## riderdan (Jan 2, 2014)

Garratt said:


> The problem is when you make the flangeway deeper then the wheels that have shallow flanges will drop off the rail head when going through frogs. The frogs on many model railroad switches are designed as flange bearing so wheels don't bump through them.
> Andrew


Hmmm. So would one good solution be to take the thickness of a brass strip off the flangeway and then install the strip--keeping the current depth while adding the ability to pick up power?


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## Garratt (Sep 15, 2012)

I think that is probably the approach to take but you can't guarantee that the switch has the best frog depth for your wheel requirements. Neatly trenching out the frog flangeways for an electrical strip may be difficult. 
I don't so much offer an overall solution, perhaps those with a lot more track running experience can share what they have done. I'm more just sharing observations. Wheels and track vary between different manufacturers. They all have different specs so I guess 'it just depends' on what you have. The flange bearing frog depth can vary between manufacturers as can the actual wheel flanges so perhaps evaluate what brand switches you intend to use and measure the flange bearing frog depths then evaluate your locomotive flange depths. You will soon see how they range and where things will ride and if adjustments are possible either between frogs or wheels or both. Certain combinations are shockers!
A solution to short locomotives stalling on frogs may be better done with extra electrical pick-ups over greater length, in a tender etc. Then the flangeway electrical strips won't be needed.

P.S. You can get rolls of self adhesive thin copper tape that is made for copper foil glass work. Tiffany lamps etc. This may not last but could be used for experimentation.

Andrew


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## Randy Stone (Jan 2, 2008)

I had the same problem with Aristo Craft's 10ft dia wide switches. Some of my locomotives would literally jump up as they hit the frog. I had to cut the approach down and also deepen the flange way in the frog. I haven't had any problems since. I have LGB, MDC, Aristo Craft and USAT locomotives so I'm sure they don't all have the same flange depth.


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## Greg Elmassian (Jan 3, 2008)

In the case of the Aristo wide radius (10' dia) switches, the frogs work well without having to be "flange bearing", i.e. the frog geometry properly supports the wheels as a prototype does.

If the Piko does not have good geometry, then flange bearing may be the only way to make it work, but as others have pointed out, now you need the flanges on all your equipment to be the same depth. Not easy to do if you do not have all the same brand equipment (and not even that is a guarantee).

Which model piko switches are you using? The ones I looked at did not have any obvious "bad geometry", which would lead me to believe the frog flangeways could be deepened, and perhaps flangeway widths adjusted with shims.

I could do this by observation and measuring, but if you are not comfortable with that level of expertiese, then why not deepen the flangeway on one frog and see if you have issues, although you should also check your rolling stock.

Greg


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## riderdan (Jan 2, 2014)

Thanks Greg.

There are Piko R5's. I do have a "spare" do I could try it out and see what happens.


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## Cougar Rock Rail (Jan 2, 2008)

I recently bought two of the Piko curved switches for a layout revision, and while bench testing them I noticed both of my really short LGB Tm2/2 two-axle locomotives had problems at the frog. When I looked carefully, the sliders were not quite touching the rails when they needed to, causing the hesitation. I then noticed that whenever the loco changed direction, it "side-shifted" ever so slightly before starting off, due to the axle being pushed over as a reaction to the angle of the drive gear against the worm gear. Change directions and it would side shift in the opposite direction. This was causing the slider to move just enough to miss the rail. I put two thin washers on the drive axles to stop the side shift and have never had a problem since. This might not solve your problem, but it's worth a look. 

Keith


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