Self centering, followup


George Hofmann
 

I reported previously that I had replicated the Kadee whisker coupler centering technique for Sergents. That was using some .008 Nitinol super-elastic wire that I had on hand. I ordered some .005 wire because I think that is what Kadee is using. I got it yesterday and converted several narrow shank couplers using that material. They work exactly like the Kadee 158 that I had previous experience with. I got reliable centering with very light resistance to sideways movement. But...there's always a but.

I noticed that the resting position was consistently not quite centered but rather very slightly to the left. If anything the shank should be slightly to the right in my opinion since I believe that will reduce the chance for a clash between an open knuckle and a closed one on the opposite car. I had proposed previously that a thin piece of styrene could be glued to the box wall to provide a little nudge in the opposite direction. However I remembered that I had all of that .008 lying there, now with no future for it. So I reasoned what if I put .008 on the weak side and .005 on the other side. The .008, being slightly stiffer should tend to move the shank away from its side. I tried it. It worked. In the picture below you can see that the shank on the coupler on the right is just slightly moved farther away. It is probably at center or slightly to the right of center. 

So this is one way to precisely manipulate the resting position of the shank. I'm thinking that a little stronger wire could be used here because I think the resting position should not be exactly centered but a little bit to the right. So maybe .010 or .012 wire might work. I don't have either on hand. 

I will make up several couplers with this configuration and see how they play together.

George
Edgewood, WA


UP4096
 

Hi, George
Have you tried adjusting the length of the wires on both sides to center it?


George Hofmann
 

I feel like the wires have to stick out of the box. I don't want them to scrape their ends on the plastic since these wires being incredibly small are sharp. I'm thinking they could dig in to the plastic. Since they stick out their length has no effect. Esthetically it doesn't matter that they stick out as they are nearly invisible.

George


George Hofmann
 

Subsequently I have found that a lateral bias equivalent to substituting .008 wire for .005 can be obtained by installing two .005 wires on one side. Turns out it is just as effective and results in the maximum amount of displacement obtainable using this method. It's probably the maximum amount of displacement that you should strive for as well.

George