I just purchased an Intermountain FP-7 in HO. I’m having problems with the lead axle derailing every time it enters a curve. These are curves that are 24 inch radius with easements and don’t cause problems for the other F-7s I have (including another Intermountain FP-7) so I don’t think it’s the track. The front axle is in gauge. From looking at it while running, it seems that the weight on the front truck is backloaded so that the front-right wheel rides high. What should I do here? Should I return it to the manufacturer or are there basic tweaks I should try first?
Sounds like a warped truck frame - definitely a warranty repair. If your track is level, all four wheels should be planted on the rails.
For a positive check, turn the loco on its back (on a soft cloth or in a cradle) and press a piece of flat glass against it. All four wheels should be in contact with the glass.
You could check to see if there is something in the front axle “housing” that is keeping the front wheels from riding down. But since it is new, I agree with others. Return it. ALL wheels (as you know) should contact.
If the wheels are out of gauge, this would cause it to, the flange’s could be tight in the rails, this would cause the wheel to push its self out of the rail once it enters the curve section of track.
Are you using sectional track? Does it do it in the same spot on the track? Does it do it if you run the loco backwards?
If it keeps derailing at the same spot on the layout double check the track. Take a 12" or 18" ruler on edge and check each rail for any small dips (especially at joiner locations) or deviations over the length and 12" either side. Also take a small level and check the level across the two rails and move the level over the same distance and see if the level changes and adjust accordingly. If the level is off the wheel will climb out of the track regardless if gauging is on. This will happen more often when on a corner! Sounds exactly like my intermountain FP7 problems I had, but know longer!
I had the same problem. The truck was warped, and after determining which wheei was riding high I just gave the truck frame a twist in the other direction (not enough to break it). No problem since
It sound as if experienced members have narrowed it down nicely.
Invert the engine and, with some weight bearing down on the pivot of that truck, does it turn freely left and right through a wide enough arc? No grittyness, no slight binding? It is not a swiveling problem.
The wheels are really close to gauge…as in within 1/64"? They are probably wide if it derails in a curve. Or, the track itself is just a bit tight in gauge, even if all other items have no problems.
Sight down the inverted truck and look for non-parallel axles. Check, with all axles pressed snugly to the same truck sideframe, that all flanges are line-astern. If one is not lined up, it could be the problem.
You’ve stated in your post that the gauge is good on the wheel sets and that none of your other engines by the same manufacturer have a problem in this location (do you have any cars derail at this location? If so then you might check track but it sounds like the front truck of the engine.) so you can illiminate the track and look to the front truck to see if it’s tweeked out causing the right front wheel to ride high.
I fixed a fellow modelers SD40-2 at a train show, had the same problem. Tweeked the whole truck in the opposite direction slightly and it set everything straight. You could try this but don’t break it, the mfg. won’t take care of that.
To be on the safe side I’d just send it back to the mfg. and tell them their other products do not have this problem so it seems this engine needs repaired or replaced. Let them take care of the problem. You paid good money for it and they should fix it for you.