At a recent train show I picked up an early ( 1980's ) Sunset brass PRR decapod at a very good price. Unfortunately it has too many "blind" drivers so that when it goes around curves it slips off the rails. I'm thinking of taking the outer flanged drivers off and reinstalling them closer to the center driver and putting the blind drivers at the front and rear of the wheelbase hoping this will curb the tendency of the wheels to slip sideways. I'd welcome comments and suggestions on my "fix" for this problem.
Sounds like the radius of your curves is too tight for the loco... what is the recommended radius for that loco?
You should leave the drivers in the position they are and not change them. The problem is the tight curves on your layout.
Hi Jim:
Logic suggests that moving the flanged drivers towards the center of the locomotive is only going to add to the instability of the engine. The flangeless drivers are simply going to run off the track on the curves, and the flanged drivers won't likely to be able to pull them back onto the track before the engine derails. The flangeless drivers are supporting some of the locomotive's weight so as soon as they run off the track they will drop into the space beside the track. As the old pinball machines used to say: "Tilt"!
I have to agree with the others. You need broader curves. If you can't do that then I'd suggest putting the locomotive back on the market.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
I can like the big steam as much as anyone, and I must agree with the others: I'd consider a smaller locomotive, or rather one with less drivers.
BLI, on their 2-10-2's, tends to bevel the inside part of the blind drivers so that they can more easily slip off the outside rail and then slip back on.
I'm not aware of anyone else actually doing the same.
John
PRR8259 I can like the big steam as much as anyone, and I must agree with the others: I'd consider a smaller locomotive, or rather one with less drivers. BLI, on their 2-10-2's, tends to bevel the inside part of the blind drivers so that they can more easily slip off the outside rail and then slip back on. I'm not aware of anyone else actually doing the same. John
That is prototypical and for the very same reason...physics.
I would advise against fiddling with the flange distribution as well. Figure out how to get more generous curves or...ugh...ditch the engine/make it a shelf queen.
When the wheels "slip sideways" does it cause a bind in the mechanism, or does the model simply continue to run as if nothing happened? What is the radius of the track?
BLI advertises 22" radius operation for 2-10-2's, and even at 26" radius, the middle driver can slip nearly completely off the outside rail for me. In itself, that is ok, as long as the mechanism doesn't bind up (causing hesitant or erratic operation) and as long as the model does not derail.
Is yours derailing? Does the inside wheel stay on a rail?
I had a similar problem with a Sunset PRR 4-8-2. The blind drivers would fall off the inside of any curve, even as wide as 30." My solution was to remove the driver springs and replace them with small styrene shims. The blind drivers would still lose contact in a curve but would not fall below the railhead. This is not an ideal fix, but the loss of springs was less objectionable than the falling drivers.I noticed no loss of electrical contact as the driver journals maintained electrical flow. Give it a try.
I've got two Sunset Model 2-10-0's. Both have excessive sideways play in the axles. My solution would be to add washers behind the wheels. Or make new bearings to take out the slop.
Bernd
New York, Vermont & Northern Rwy. - Route of the Black Diamonds
protolancer(at)kingstonemodelworks(dot)com
Jim this was a common problem with the Sunset I-1's . The drivers will drop off the railhead even on 36'' radius curves. Years ago Sunset offered extra flanged drivers to replace the 2nd and 4th axle. You may want to contact them ( I'm not sure if they still exist ) to see if the drivers are still available. --- Ken
Sorry guys but Sunset Models has been out of business for a number of years now.
Or, you can do what a number of prototype lines with that problem did - lay a full-height guardrail on the inside of the curve, both rails. Actually, 'guard rail' is a misnomer. Its purpose was to support (and gain traction from) blind-tired drivers on the curves that required them.
The tire has to be wider than the flangeway between the running rail and the guardrail, or you will create a bigger problem.
Fortunately, my blind drivers are in no danger of falling off the rails, even on sub-14 inch radius curves. (Mantua 2-6-6-2 mechanism, very short engine wheelbases.)
Chuck (Modeling Central Japan in September, 1964)
I'm not sure what the problem is here. Are the flanged drivers derailing, or is the main driver dropping inside the outer rail on a curve?
PRR I1s locos were built with flanges only on the first and last drivers, but flanges were later added to the no. 2 and no. 4 drivers in some cases. It would therefore be prototypical to add flanges to those drivers. On the prototype, the main driver had a wide tread, but I suspect the model manufacturer used a standard-width tread. It may be difficult to find wider tires for your engine, but it might be possible to add an inside guard rail for the tire to ride on, as Chuck suggests. Maybe the main driver could be rigidized so that the outside driver on a curve will remain at the same level as the inside driver, and not drop off the rail.
The real solution, which may not be practical for you, is to use broader curves.
Tom
Thanks for all your suggestions, guys. I'm afraid that my 28" radius curves are there to stay as everything else I have does fine on them. As to flanges, I once had a Bowser Dec that did the same thing as the Sunset model. I put extra flanged drivers on it and the problem went away. That was when Bowser parts were plentiful and easy to get. I'm going to try moving the flanged drivers to the center of the wheel base because that just might prevent the drivers from sliding off the railhead. As per suggestions, I might also alter the spring rigging. My ultimate goal for this engine is to install sound and DCC but not until it tracks properly, if ever! As I said it was a cheap buy for brass and I sort of knew I was gambling on making it run properly.
Moving the flanged drivers from the #1 and #5 position to the #2 and #4 position MIGHT work, but I'm not sure I'd count on it. Maybe put the flanges in the #2 and #5 position, and add some type of centering spring to the lead truck to pull the lead driver into a curve. It might be necessary to reduce spring tension on the lead driver --- maybe rigidize it.
Andrew Dodge built his narrow gauge On3 2-8-0's so that they would work in a somewhat similar fashion. If he had built the engines in the normal way, the swing of the lead truck would have been excessive. Instead, he built the 2-8-0's so that their suspension is actually an 0-10-0, with the lead axle being the nonpowered lead truck.
This is just brainstorming. No guarantees here.