Intermountain HO SP cab forward AC12 lead truck derails.

[riogrande]

Now that my DCC is up and running I pulled out my Intermountain 3rd run AC12 SP cab forward and put it on the rails. While it did run very smoothly and could pull 36 ice reefers, ,the lead truck constantly derailed. As anyone had experience with he cab forward and what may be needed to get the lead truck to stay on the rails. I notice there was a small plastic package in the box with springs in it.

[mvlandsw]

I had the same problem. There was a part on the truck installed backwards. I forget exactly what the part was but check the truck. It was obvious when I looked at it.

Mark

[riogrande]

Thanks. I'll take a look at it.

[valenciajim2]

I had a similar problem with a BLI cab forward about 15 years ago.

[edwardsutorik]

Oct 25, 2024 16:47:28 GMT -8 mvlandsw said:

I had the same problem. There was a part on the truck installed backwards. I forget exactly what the part was but check the truck. It was obvious when I looked at it.

Mark

I found this on Trainboard:

"Make sure the lead truck has the curve of its attachment slot curved away from the pilot like this ( if it faces the other way, there is a tendancy to derail. If I remember right, I also removed the spring from the trailing truck as well."

I didn't see the implied picture, however.

I imagine the "curve" is used to position the lead truck while in a curve. So, if it's flipped around, the truck might get jammed into something.

This was after I did a search for:

intermountain cab forward lead truck problem




Ed

[valenciajim2]

I Googled what Edward suggested, except I added BLI.  I found this post in the Model Railroader forum from 2008.  I have no idea whether the BLI and Intermountain cab forwards have similar causes, but perhaps the information contained in this link addressing how to correct a derailment problem with the leading truck will help.


cs.trains.com/mrr/f/88/t/122226.aspx


The relevant text states the following:

"I read your post and was confused for a moment until I realized you're talking about the LEAD truck on the cab-forward (even though it's under the firebox). I've got an AC-5 and I took a look at it. I think you might solve the problem by loosening the screw that holds the truck to the swivel about one or more turns. Also, check the gauge on the front set of lead truck wheels. If they are the slightest bit out of gauge, the smallest bit of uneven trackwork will cause them to ride up the rails and derail. If they are, a slight twist on the insulated wheel should put it back in gauge. But loosening the screw about one or two turns might even the truck up. Try it and see if it works. I've not had any trouble with mine, but your lead truck might have been installed too tight at the factory."

[edwardsutorik]

I think this is an example of the curved attachment slot that was mentioned in my post:





You can see that, if it's installed 180 degrees off, it will be positioning the truck incorrectly.




Ed