i have question? have anyone that has bowser sd40-2 experince derailment on 2% grade curves? on my layout i have 28' radius curve that gose up 2% grade. when engine gose over it the front wheels pop out of the track. the reast of the curves area on my layout the engine wheels stay on track. the rest of my engines have no issues with the curves or grade.
That engine has 3-axle trucks and does not like kinks or abrupt transitions from straight to curve. The center axle wheels still will be wanting to go straight when the front axle wheels are going into the curve......there also could be a dip right there where the center axle wheels are going straight and the front lifts up. To check for that use a small straight edge, even a small block of wood, a little longer than one of the trucks and lay it on top of both rails going into curve, You should not see any daylight between the rails and straight edge.
Good Luck...be meticulous in the above...You may also find that Your engine does not have a lot vertical fore/aft,up/down movement where the truck attaches to the chassis bolster, too stiff.
Take Care!
Frank
Raptorengineer,
I think it would help if we knew what some of your other engines were, as I would, at first, reply much like Frank, that there must be either a kink or sharp transition, that a three-axle truck does not like, but if you had other 6 axle units....
If you have other 6 axle units, then....
I would start by checking the wheelsets on the Bowser unit, making sure they are in gauge, and all sit level. To check that they all sit level, place the unit on a piece of plate glass, or other smooth, known to be perfectly level, surface, and look for daylight beneath any of the wheels. The old "slide a piece of paper under it" trick will also help, as you should not be able to slide a sheet of note paper underneath any of the wheels while it is sitting on said smooth level surface, unless one of the wheelsets is not sitting level.
If every wheel is in gauge and level, then check the bolster is allowing free movement of the truck. It should not bind or catch on anything, but should allow easy movement, both turning and tilting up/down, to the end of it's designed movement anyways.
Once these are checked and answered, we can try to help further.
EDIT: Typo corrected.
Ricky W.
HO scale Proto-freelancer.
My Railroad rules:
1: It's my railroad, my rules.
2: It's for having fun and enjoyment.
3: Any objections, consult above rules.
There is very close clearance between the outer edge of the truck side frame and the inside corner of the steps. A combination of radius and grade may be just enough that the truck hits the backside of the step and prevents it from pivoting enough.
Check with a flashlight right at the point it is derailing and see if that is indeed the problem.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
so for other 6 axle units i have is athearn es44ac and sd70ace, intermountain es44ac and sd40. they run fine. i look under the engine and i see the front side of truck is mm from coupler box. and sometimes it hits it.also it seem to catch the underframe little.
What does it do when You run it with the other truck forward....same thing? Can You sand or file some of the coupler box to give it more room so it don't hit? Still sounds to Me that there is a noticible restriction between that engine and the others with the up/down/pivot movement of the trucks, which leads Me to believe, that there is some sort of dip or rise in the tracks at that point and Your other engines have enough up/down movement to compensate for it and this engine is stiffer in the pivot movement of the trucks.
Could be a pick-up wire that is preventing movement, not enough wire sticking out during assembly. Look at Your other six axle engines for up/down for/aft movement...do they have more than the one derailing? It's hard to give advice without actually seeing it...too many variable's. But the bottom line is 3-axle trucks will find bad spots in trackwork.....period.
Also do the paper test that was mentioned....I did not mention it...cause I believe it still may be in the trackwork at that point...''who know's where evils lurk''.
Good Luck!
so i have fix issue. i added few more layers of tape to level out the track. and how everything for now runs smooth. that woodlandscenics risers set is good but is dose have it challanges and also if your working with double mainline curves one set of risers will be taller then the other when going around curves depending on how many curves there are.