AF SD70ACe track connectivity and suspension

I suspect there is no difference in the SD70 trucks yet.

The sprung axles are the outside non rubber tired wheelsets and only have .006" of vertical travel. Their tiny springs can get weak with over current and compress too.

 

I have addressed a fix for this and also the late U33s on my web site at:

http://www.tuveson.com/sd70/im...70_power_pickup_.htm 

 

and at:

http://www.tuveson.com/u33-trucks/u33-truck-mod.htm 

 

Heres what happens on insulated frogs.

 

The frogs have to be spaced just right such as a set of ladder track turnouts or a crossover.

 

I have been told manufacturing is aware of the problem and will address it in future designs but have not heard if they have any plans for the locos already with the issue.

 

Carl

 

It will be interesting to see how Lionel responds, this is kind of a big deal. Ben

After everyone ooh'd and aah'd over the nice pictures, I was (regrettably) afraid that posts like this one would start to show up. In a balanced manner, I tried to address similar issues operating on Gilbert trackage for the Y3a.

 

https://ogrforum.com/d...nt/12552510960455502

 

With tweaking and adjustment, the new L-AF can operate well on classic Gilbert track work, but a modular layout that is transported about for years built with Gilbert track is going to be these engines' worse nightmare.

 

I am afraid that the folks at Lionel may not be using a developmental layout with a sufficiently complex track plan with a truly diverse selection of track types to catch the problems associated with operating their new engines. As an example, the test layout that I saw at the Canfield open house last September was truly simple (a loop with a spur) and did not incorporate trackwork configurations likely to reveal , IMHO, potential operational problems. Hopefully, it has been improved and expanded since then. Vintage Gilbert track is one thing, but a modern high(er) numbered high rail turnout is rather another matter. Engines with the lengths of wheel base that these have should be able to traverse turnouts and troublesome bits on a main line without stalling.

 

There is much that I like very much about the new L-AF, but there are some teething problems to work on.

 

Bob

I checked this morning before heading back to the show and my BNSF SD70 does have springs under its outer most axle bearings on both trucks.  Notice I didn't say they have spring suspension because the base plate all but completely compresses those springs.  The four tiny clear washers under the base plate near those axles (see photo) create such little float or travel (Carl's 0.006") that it is perceptibly and operationally immaterial.  Take a look at American Models SD60 for spring suspension equipped trucks. The SD did not return to the  show, but we had similar problems with a U33c - sound cutting out, etc. over less than perfectly level track.  Great engines; I like my U33c and SD70 both very much, but on my layout with issue-free track work.  They should, however, be more robustly designed in terms of the types of track, turnouts, cross-overs, etc., and condition of track on which they can dependably run.  By comparison, we ran lots of other engines - Gilbert Flyer, Lionel Flyer, AM, and SHS on our club layout today without problems. 

It seems part of the problem is the traction tires, which act as an insulator in this case.

 

My scale wheeled SD70 has no traction tires and had no problems on my less than perfect code 100 trackwork.

 

Perhaps a test needs to be done with a scale wheel version on Gilbert track (which should work as long as there are no turnouts) to see if the issue persists.  Unfortunately, I don't have any Gilbert track to test my theory on.

 

Another theory for those who have looked at this issue closely...  Judging by Carl's photo's, it looks possible to relocate the traction tire wheelsets to the middle or outboard location which may change the electrical contact symptoms.

 

Rusty