Lionel SD70ace Jumping Track Thru Switch

in this linked article https://ogrforum.ogaugerr.com/topic/64358525586140096 they show two different dimensions for curves.  One is 042 for the 2005 production and 036 for 2008.  I have a dummy sd70ace which will negotiate 042 curves but have not tried it on 036

Marty

I have run several different Lionel SD-70ACes through O-36 Fastrack switches without issue.  I don't think it's your switches.  Look closely and make sure your uncoupler bar on the pilots is not flipped up hindering the pilots from free movement. 

My SD-70ACes also easily negotiate cross-over switch arrangements like yours but I happen to use O-60s. 

I’ve had the same issue with a new SD70Ace (Santa Fe Legacy #2133322)  Did a previous post on the subject.  Returned the first one. Second one works a little better but only tracks through O36 switches at really slow speeds and still derails from time to time.  Despite having another SD70 and a DASH-9 that track perfectly,  best I can tell that while Lionel has labeled this as tracking O36 curves, it won’t consistently track 036 switches.  Agree with the comment above.  Seems like the trucks (especially the front) are getting caught up keeping them from fully turning.  

Maybe these picture will show it better.  The UP has its uncoupler bar down with the outter handles clear of the grab railings.  The Santa Fe is shown with the handles up which can cause them to catch.  I hope it's that simple.

Yep. same one I have.  So what's the solution without modifying the train?

Just rotate the uncoupled bar in the down direction.  You may need to slightly spread the bar on the ends/handles to get it to rotate down. The bar should be almost touching the coupler itself.  If looks iffy then send a close up pick to share instead of the artist rendering I provided of the Santa Fe.    

Check pick up roller tightness also.

A simple experiment would be to remove one of the switches and extend a straight track from the 036 still in place. That might help show if that short straight is causing issues. I would think that there needs to be enough of a straight section between the switches so that an entire truck length can fit in the space between switch curves.

Just my experience, I tried what the OP  is doing, I gave up wasn't worth the hassle. My SD70 didn't like it and 16" Lionel Box cars didn't like it either(both rated for 036 curves) . I think the distance is too short between the switches.  If you have the room, try what turkey hollow rr suggests and maybe it'll work better.

Thank you for all the advice. I have checked and double checked the uncoupling and in the down position it still jumps the track. I believe the problem is either the distance between the switches (1.375") is too short or the SD70ace does not like the curve length of the switch. I do not have any 048 or O60 switches to try, I will have to get some. I will have to set up another layout to try the longer distance between switches.

I ran some more tests with the SD70ace after I made the previous post. I did not change anything to the layout. The SD70ace went forward thru the switches numerous times and did not jump the track. In reverse the SD70ace forward truck would jump the track for the outer loop switch only about 50% of the time. I do not have access to O48 or O60 switches. I will be getting some to test out to see if that will completely eliminate the jumping.

I had the same problem with 2 Fastrack reverse curves that were too close together.  Most engines were fine, but one or two would derail.  I never figured out why, except that the reverse curves were too close together for some engines.  I added a 5" straight Fastrack piece between the 2 curves and adjusted other tracks, and the problem stopped.

I fasten switches down with screws, and the tracks before and after .  The slightest unevenness of the switch can cause a derailment issue, even the wire coming out the side of  the switch can give it a little elevation making it uneven and cause some trains to derail and not others.  Before I went to wireless remote switches , I drilled a hole underneath the switch and ran the wire that way instead of having it come out the side.                                                                                                  Recently I had Dash9 derailing going backward on a 048 switch , I put an extra screw in and only slightly tightened it down and problem was solved.