I have an Intercity newest long car 4 unit consist with current conducting couplers. It was tracking just fine last fall. Now being winter, my basement is 7 to 10 degre's cooler. I took the train out of it's storage bin yesterday, and the 43630 cab control car is derailing on the rear bogie on level
R3 C track curves. Not R2's. I checked the wheels and pick-up shoe, and all look ok. Not crooked or bent. The direction of travel makes no difference. Even on the R1 curves and turnouts, it goes through smoothly.
Any thoughts?

Thabk's Dale I checked, and the track is flat through the tunnel.

Hi Märklinist5999
I have the same issue on many of my Märklin Passenger cars.
What happens?: The cars were derailing without apparent cause (derailing never happens on C Track). The coupling and its short coupling mechanic has become very stiff. All of those are equipped with the Märklin contact blade to bring power to the coupler pocket.

On Which cars?: DB passenger cars, Swiss passenger cars

Many of these Trains were not rolling for a while (a few month) in a zone where temperature can drop below 0°C

Fix? I don't know yet I need to open the stiffest car. Note: in the past I have sprayed some contact spray. Did it cause the issue? I am not sure.

So some work for the next train session (less than 2 weeks time I hope)

Cheers

Jean

I applied a teflon spray anywhere plastic parts rubbed against each other in a curve. I needed to remove the bogie to spray the area under it. I wish I could find a lubricant spray, teflon, graphite, or substitute which was more controllable. The large sprays need to be carefully controlled.

Say no more! I mainly use their teflon grease, and for more than just model railroad applications:

https://labelle-lubricants.com/model-train-lubes/

Thank's Dan! I checked that all the buffers are pushed all the way in. They were. I think it's the colder ambient temperature. Yesterday it was 20 degres warmer outside and they didn't derail at least in one direction. Now today it's colder again, and they are derailing on R3's, but not R2's. I applied synthetic lube on tuesday, and it was thicker than in summertime. My basement is 7 to 10 degres coolere than my main floor.