I have quite a few Kato F7 A&B units and most due fine on my layout that has some small radius turns and inclines, but one A unit is uncharacteristically notorious for derailing especially on the front truck. It does OK backwards and I would use it in an ABA, those Kato front couplers don't hold well so it continually uncouples when used this way. Are there any improvements I could do to the locomotive or more specifically the front truck to cure this, or is this just a bad example from the factory that can't be fixed? Thanks for any help on this.
Kato quality is high. So derailing shows something is wrong. Most likely culprit is wheel gauge. Do you have an NMRA gauge. They are expensive but worth it. You an use it to check wheel gauge and also check the gauge of the track at that spot. Sometimes the problem is a combination of both. The other possibility is that the coupler trip pin is catching on trackwork. And need to be bent upward. Hope you can figure it out.
First there are vastly different mechanisms and runs on those Kato F's, so look here an help identify which flavor you have: http://www.spookshow.net/loco/katof.html But you should be able to do some basic feedback to us on a couple issues: 1) can you feel anything binding or interfering with anything else when you rotate the lead truck around with your fingers? Compare it to one that works OK. More or less stiff in movement? Look at brake shoe clearances, coupler boxes, the front-end ladders hanging on the truck springs, that kind of stuff. On my Kato F's the cab ladders were in very close tolerance with the lead truck springs. If one gets bent in even a hair, there you go. 2) If that shows nothing, check the wheels, particularly the lead pair. Are both wheelsets in alignment with each other? Is one noticeably wider or narrower than the other - and compared to the ones that work? With more information and maybe some photos posted you'll get all the help here you need. Most times it's actually not evil spirits.
Some of my well working Kato F units are the 1995 variety, some are the 1999 variety, while the one in question (the troubled locomotive) is my only FA unit that is the 2003 run. The wheels on all four axles are within gauge (by the NMRA gauge). All wheels seem to move freely and no obvious flaws such as bent ladders, etc exist that I can see.
U18b is a bit ahead of the game. The OP says "Kato front couplers don't hold well," and "It runs fine operating in reverse," Simple solution? replace front Kato coupler with a MT coupler.
I will experiment more with the couplers, but I really did hope to run the A unit in the forward direction since I usually run A&B only. One of my Kato FA units has a MT coupler on the front. I'll see how it does with staying coupled with my existing cars.
Well, it does work in reverse and with the right combination, I can get it to stay coupled, but running forward is a different matter. It does fine by itself, with the B unit and with 3 or 4 cars, but any number of cars more than 3 or 4 and the wheels on the front axle of the front truck want to jump off the rails at the slightest provocation. Would it be a possible fix to change out the front truck? I see Kato doesn't offer trucks for the older models.
There is something wrong with that front truck to constantly derail when going forward and not in a trailing position. It may be as simple as the pickups catching on the frame strips for current or a drooping coupler trip pin. Also it could be the trucks swiveling in the frame is affected by the forward motion and not the backwards motion due to the torque. Could be a bit of flash metal on the frame halves or the plastic on the truck gear tower. Both front and rear trucks should swivel equally. As far as uncoupling I would replace that coupler with an MT or a unimate. Also you may try swapping front and rear trucks.
Thanks very much all. I got it. Even though I was beginning to suspect the evil spirits that Randgust mentioned, I found the slightest interference between the air tanks on the truck and the shell so I filed just the slightest amount (not really visable) off those air tanks (all four) and voila no more derailing. Thanks again for the help.
Sometimes we forget that those trucks rock side to side and front to back and a bit of torque and motion of the body can do it. Glad the problem is resolved and now for the uncoupling issue.
Thanks John, but going in the forward direction, I don't have an uncoupling issue as it was the front coupler and even the front coupler ultimately worked with a few cars. So, no more issues with that locomotive at this time.
I had this same issue with my Kato F3 A unit - there was (and is) something very different about the freedom of movement in its front truck, compared to its rear truck, and compared to both trucks in its matching F3 B unit. The A unit would derail at a certain place on my layout if going forward, but did it not derail if it went through the same place (in the same direction) while going backward. The matching Kato F3 B unit had no problem at this same place, no matter which way it was turned on the track. I examined the freedom of movement for all 4 trucks on the A and B units, and observed that the front truck on the A unit was more constrained than the other 3. The derailment was taking place at a point where I had a had a grade transition - a transition from level track to inclined track - which was also the beginning of a tight curve. I was using sectional track. I took extreme measures to make the start of the curve be almost flat, and to make the transition to inclined track be gradual through that piece of sectional curved track. This cured the derailment problem.
yellow_cad, thank you !!! I've had the same derailment issue with a used custom painted F3. This one ALWAYS derails going from a curve to tangent, but it's fine in reverse. I'll check for the problem you had. The other problem I have with it is the MT coupler box doesn't slip in like all my other F3s and F7s. So far, I've been blaming it all on the fact it's painted for Penn Central !!!
I didn't mention it, but in my filing, I did file the inside edge of the shell right by those little air tanks. I believe that this was the finishing touch and none of my filing shows.
Those trucks can be installed backwards as well, there is an arrow on the front truck, I don’t know if mine is on right or not, it came with the arrow pointing rearwards also. No idea if the clearances are so tight that pointing it forwards would contact the shell.
After reading this thread and if the ideas shared don't fix it. Well...I keep thinking you have the wrong truck on the front end of that unit. You might want to try removing a front truck from one of your better units and see by installing it, if that doesn't solve the problem. I had one like that and that's how I eventually solved the problem. Otherwise there is the round file 13. Or throw it out the window, the window, the seventh story window. With a might heave and a might ho....I think you get my drift. No don't do that. It can be fixed.
