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Post by modelwarships on Apr 9, 2020 20:59:54 GMT -5
While we all wait for a proper SD40-2 to be released I am trying to MU an AZL SD45 with a U30C on a custom (Gerd) MTL SD40-2 chassis. The photo show the offset on a R220 curve.  I swapped out the broken MTL coupler for an Auto-latch and it works fine on straight track, but derails on virtually every switch and curve. The MTL coupler was more flexible, but is constantly letting go on the grades. I am wondering if something like the P42 body mount couplers would be better. I had to drastically shorten the back half of the standard AZL coupler box to clear the trucks as it is. At this point I'm tempted to open up the rear pilot and attempt to attach a coupler to the truck. |
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Post by Rob Albritton on Apr 9, 2020 22:31:51 GMT -5
I swapped out the broken MTL coupler for an Auto-latch and it works fine on straight track, but derails on virtually every switch and curve. The MTL coupler was more flexible, but is constantly letting go on the grades. I am wondering if something like the P42 body mount couplers would be better. I had to drastically shorten the back half of the standard AZL coupler box to clear the trucks as it is. At this point I'm tempted to open up the rear pilot and attempt to attach a coupler to the truck. Hi Tim, Welcome to my world. The P42 coupler was specifically designed for exactly what you are trying to do. Our original coupler was desinged for short shank truck mounted operation. It has a tight spring, and a tight hold, but that also means it does not rotate, and it's completely unsuitable for body mounted operations. We later softened the spring a bit and added more of a hook to the coupler to try to make it work better with the RDC units (they are body mound) but it did not work as well as we liked, and the softer spring meant that it would not hold as many cars as the tighter spring. When I started working on the P42, we went with a very different design that has a metal leaf spring. It works GREAT. It's only weak point is that when the coupler goes over center, it does not spring back to the middle position - easy to do with your hand, but almost impossible to mess up in Z scale operations. With the upcoming RS3, we are going back to a boxed coupler mounted to the body with a screw. Guess what! That box is the same dimensions as the MTL 905 coupler - and the screw is in the same position, so it should be an easy swap if you want to do prototypical operations. If not, the new coupler has yet ANOTHER design that will allow better rotation. Phew - thats not the entire history of our couplers, but darn close. Is there an immediate solution for you in there? Not exactly, but maybe that gives you some ideas on things you can try. In the meantime, we are VERY aware of the situation and working on it constantly. Best, -Rob(A) AZL |
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Post by modelwarships on Apr 10, 2020 10:24:45 GMT -5
Than you for the insight. Maybe the best solution is the most obvious and that would be to make the AZL Engine a transition one with body mount up front and truck mount on the rear. It kind of limits you on where they can be placed in the consist but hey I like my more detailed engines leading and I like to match up my consists anyway. I have a GP50 (AZL/Gerd) set up that way, but it is more for scale appearance than operation and I don't want to ruin it. I figure doing one end like Domi's Genesee & Wyoming GP38-2 build but with an auto-latch and leaving the other end truck mount should work. If that works out than I get to have fun speed matching my U30C (MTL SD40-2) with a more AZL friendly speed table. Rob, I hope you guys will be adding to the parts section of your website. I'd like to see items like those P42 coupler assy and perhaps the coupler pockets with the screw mount that go on the Lightweight Observation Cars. |
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Post by cwrr on Apr 10, 2020 18:43:59 GMT -5
Nice lookin' U30C, like to see some production versions for the masses! (hint hint AZL)  |
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Post by markm on Apr 11, 2020 8:53:42 GMT -5
I was wondering if people building rolling stock do a minimum radius calculation ? It's a basic trigonometry calculation embodied in the NMRA datasheet d5g. It seems to me that with a couple measurements you can determine what is needed for the coupler/truck swing.
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