Help with a curve

[mike_lawyer]

Hi guys,

I am having difficulty laying half of a curve on my layout.  I have two BLI M1s, and both of them on this curve exhibit slippage, particularly when starting a train.  The curve is 21 inch radius.  It seems that on the curve there are areas where the traction tire driver is not making sufficient contact with the rail.

Interestingly, my two Kato Mikados both run fine over this curve, even when starting a train from a stop.  I am at a loss to figure out why my M1s are having this problem.  They do not show signs of this slippage on my other 21 inch curves on my layout.  I am also not hauling many cars, only 20. 

Any thoughts on what might be causing this problem?  I can't detect any dips in track level by eye, but I also don't know how to test it other than looking at it.

[Maletrain]

Dips in the tracks might be the cause.  Do you have anything that is straight, flat and rather broad, such as a carpenter's level?  Laying that on one rail at a time on the curve and looking to see if it is uneven underneath would help spot dips.

The other possibility is that the curve is slightly out of gauge.  Have you checked that with an NMRA gauge?

One more thing, which seems unlikely, would be that the flanges on one loco are deeper than on the other, so that it lifts the traction tire off the rail in some places where too much ballast got applied.

[mike_lawyer]

Good thought on using a carpenter's level to see if there are any dips in the track.  I will have to purchase a small one so that I can check it out.

[rail_nut]

Shine a light behind the level. Dips/low spots will be very apparent.

[wm3798]

Not fair comparing it with the Kato Mike.  The drivers on those things are equalized and sprung some sort of way.  You can run them on really rough track and never know the difference.

I'm surprised that what you pay for a BLI doesn't get you that sort of design consideration.

Lee