Based on layout limitations, and spur locations, need to have forward going counterclockwise. Have an Atlas SD35 that on the 9.75 radius curves, derails in reverse when moving clockwise however when in reverse moving counterclockwise derailment never occurs. While most of the time forward will be counterclockwise... Also, and after 100s of hrs and a perfect record of non-derailment pass thru, this is a Kato double crossover derailment first for me, the SD35 derails about 1/5 times when forward is clockwise entering the double crossover's upper inner leg. Any idea's Thank you
You and I have shared some agony over our Atlas CNJ SD-35s. Wheels are in gauge and trucks rotate freely, right? I think one of my wheelsets was slightly narrow in its gauge and after I fixed it, things improved. Knocking on wood, my pair has been excellent of late. BTW, I love the sound in yours as heard on your video elsewhere. Neat stuff.
Me Too!! The ESU and speaker combination in terms of fidelity is awesome and materially better than the Broadway Limited Paragon F3. Quite honestly, haven't checked gauge and wheels since after service trip 2. They appeared ok but have less than 5 checks lifetime experience so my analysis is questionable. Going to bring SD35 to hobby shop and have 3rd party confirmation. Unsure whether Atlas service checked but presumably they would considering the loco has been back 4 times and is so troublesome??
I don't have an SD35 but, from experience in other locos, a common culprit in derailments such as this is a truck sideframe snagging on something when running in one direction and also turning in a certain direction. A common snag point is with a stepwell.
I assume it is the rear truck that derails? Can you swap trucks? Does the problem persist, and follow the truck or not? The latter indicates some interference between the frame or shell and the truck. A burr (mold flash, etc.) in the pivot socket or on the pivot tower, or something like tehachapifan noted. Assuming it derails to the outside of the curve? I'm sure you are aware, but 9.75" radius is at the very lower limit of what a lot of N scale locos can negotiate reliably, and some can't. Sometimes easing a curve transition with a section of slightly longer radius at the beginning and ending of a tighter curve helps a lot. About the dbl crossover derailments, is the loco on a curve adjacent to the crossover (making an S-curve), or is it on straight track, as it enters the crossover?
"Truck pivots freely" doesn't mean it pivots enough. We have a small loop of track on a club module, and there is no way to predict what will work. I've had 2 identical locos (purchased from the same run) and one will negotiate the curves and one will derail......always to the outside, meaning the truck isn't pivoting enough. No obvious clearance issues, so I'm assuming there is something (or several somethings) like extra flashing on the truck tower or in the socket it snaps into, possibly in the gear/worm interface, who knows what. A fact of model RRing is "not all locos are created equal" even if they should be.
An additional point with what I and others mentioned regarding sideframe snagging, is that a snag can sometimes be hard to identify when pivoting a truck by hand. First, it's hard to keep the truck aligned horizontally, or parallel with the underframe, when checking for this. If it's not horizontal, as it would be when on the track, the angle that it is on may cause the snag to actually swing clear. Second, when checking clearances by hand, it is easy to not account for what I think is called "gear lash", where the truck will shift forward or back slightly depending on direction and when under power. This can be accounted for when checking by hand by gently pushing the truck forward and then back before checking swing clearances. Hope this makes sense.
One of the discoveries on the Atlas SD-35s that @Mark Ricci and I made was that the trucks are now hard-wired .... with something near 0 Gauge wire. Well, perhaps not that bad, but the gauge they used seems overly stiff for an N Scale locomotive application and is an odd "improvement" over the expected sliding contacts which have been successfully used in past releases of this locomotive.
I don't feel comfortable swapping trucks. The soldering is the easy part but my lack of mechanical knowledge makes me a bit apprehensive in attempting. Yes, on both counts, it is the rear truck and derails to the outside of the curve. Took a gamble with a 6 axle loco ..since using unitrack. The F3 and GP7 have 4 axles and "love" the layout. Guess what I'd like to know and asked Atlas, as they consistently claimed loco ran fine on their track and yet the prior 3 times back from service, as well as saying no problems in reverse, the SD35 bombs on my layout. My thoughts its probably a combination of things;?? 1-the vertical truck movement is stiffer than the other 2 locos 2-The loco always had issues in the path, almost as if a wheel flange or something is catching on one of the broken rail paths of the dxover. 3-There seems to be mixed feelings overall on the SD35 new truck design. 4-Different wheel flange sizes among the 3 loco's?? 5-Maybe a track imperfection exists that does not adversely impact the 4 axles locos.. And the more flexible vertical truck movement they have?? 6-All the handling and shipping back and forth This is my first layout and a number of track areas would be different if done again. Going to take a close up look tomorrow am to look at what you, @MRLdave and @tehachapifan have suggested. Atlas has no SD35 trucks in stock -- on waiting list - I'll give a few months. Thanks everyone!
This magazine review finally convinced me to buy. Believe part of the truck wires can be seen in the chassis view. My review would be a little different. https://www.trains.com/mrr/news-rev.../atlas-master-series-n-scale-emd-sd35-diesel/
Its kinda of funny, I guess... I bought the SD35 solely because it was CNJ green and would have preferred a shorter SW7 (my favorite model) or VO1000..There is something about the round roof.... if the BLI Paragon 4 with new truck and pickup design is an improvement, I'd try one and die to turn something from this; into this
OK, can't easily swap trucks... Hadn't seen wired trucks in N-scale before, but I don't have that much variety in my locomotives either. And the only places I've ever used 9.75R curves were not adjacent to straight track. That transition from straight (tangent) track to curved track is the biggest problem area. Lots of locos and coupled railcars can handle a complete circle of tighter radius than they can in and oval, adjacent to the straight track. Very often, the transition between differing radii (straight having infinite radius) is the bugger. Or it could be a problem piece of track. Does the loco derail in the opposite (diagonally) "corner" too, when travelling in the same direction around the track? If not, try swapping those two sections of track, and see if the problem follows the track piece. If it does not follow the track piece, try swapping the adjacent straight pieces instead. Hope your track is not too securely glued down...
What are you comfortable doing? Can you remove the shell? Also, do you have any idea what vintage your locos are? I've never seen ANY Atlas loco with wired trucks.......doesn't mean it didn't happen, but I'm not sure why Atlas would suddenly switch designs. They continue to plug along with all their DCC unfriendly RS1's, RS3's and RS 4/5's even though they now have access to the LL RS2 chassis which uses a drop in decoder. Another thing I didn't mention, is that it IS possible to overtighten the frame screws. If you are comfortable taking the shell off, try loosening the 2 frame screws (or at least the one on the "bad" end) just 1/8 turn at a time and try running it. Taking the shell off will also eliminate any possible clearance problems between the chassis and shell. To swap the trucks, you just need to loosen those screws a little more and the trucks will come right out of the frame.........no parts should fall out, just the complete truck. Be sure to pay attention to how they come out........some trucks have the towers offset and they need to go back in the same way. You can swap them end for end, but if the tower is offset (for example towards the end of the loco) they need to stay that way. Which brings up another possibility.......you didn't mention if these were new or used, but the trucks could have gotten reversed before you got them, although I would have hoped the repair shop would have caught that.
They are the new DCC/sound chassis. You can see them on Spookshows encyclopedia here: http://www.spookshow.net/loco/sd35ln.html
The track is secured with adhesive latex caulk at each segment junction and white ceiling paint which is adheres the ground cover (snow) to the roadbed. As you know, ceiling paint has adhesive to minimize drip. It actually works quite well?? So to answer your question, yep.. It's down. -There are some imperfect joints but no other piece of rolling stock or the other 2 locos have issues-- forward or backward. -Going to test some additional rolling stock and order in reverse but have had not reverse derailments with a 60' passenger. In a few I'm going to test the 2 new 60's I just got assuming the longer cars would be more likely to derail or behave like the 60' SD35 ??? -For a few $ buy some Atlas 9.75 radii track, lay it out on a perfectly flat hardwood surface ensuring perfect junctions, and test the loco totally eliminating anything to do with the layout. The people at Atlas "test only on Atlas track" If I'm going to wait for whenever ...trucks are in stock and send this thing back for the 5th time..... Plus, a little reluctant to start ripping things up after the Kato Double Crossover thing.
Is this 9.75" curve adjacent to a switch? In other words, as the engine comes out of the curve does it enter the front of the switch (by the points). Had a six axle unit always derail when doing this. Solved it by installing a section of straight track between the curve and the switch. Only happened with 9.75" curves. The switch was an Atlas #6. Just one of the reasons I don't like tight curves except on my trolley line. Come to think of it, the engine involved was an Atlas SD35 but it was from the initial issue without the hard wired trucks. Engine was one of four I have. Never had any issues with the others and no problems since. Got two Atlas FM H24-66 Trainmasters at about same time. No problems with these either.
Recognizing my weakness in mechanical side of things bought all 3 locos brand new. To the best of my knowledge, the Broadway Limited F3, The Atlas SD35 and Bachmann GP7 are the newest and only n scale CNJ green locomotives available from a US retailer since I started hobby. The F3 in 11/20 (released in 2017 or 18), the SD35 (approximately same vintage) in April of 21 and the Bachmann GP7 in Aug 21( think 2013 manufacture)? The trucks on the F3 are easily removable. As a added plus, it facilitates periodic cleaning and checking wiper strike angle of the pickup contacts at every 3-4 wheel cleanings. This may better explain... If you gave me a decoder that needed to be soldered into a green CNJ locomotive, would have no problem assuming not under warranty, the locomotive's shell is easily removable (like F3) or has been removed and mechanically disassembled to the point of wiring and soldering. The big, self imposed problem, how to replace or repair the CNJ green shell if broken. If you gave me any other locomotive, where road name was not an absolute priority, and not under warranty, I'd probably attempt.
Only 1 9.75 radii goes into a #4 RT, the remaining 7 connect to another 9.75 or straight track. Derailment occurs at about all of the 9.75 junctions and not just the 1 that attaches to the #4
