EZ Mate II magnetic couplers

[eesnelle]

Bachmann has a selection of long, medium, and short couplers. What is the difference other than length?What is a good length for N Scale Trains? I forgot there is also Center, Upper, and lower couplings. Any particular application for each. Why is it the stock couplers less than it should be?

[Doneldon]

ee-

    All couplers must be in the same location relative to the track to work properly. Do notice that I wrote "track" on purpose. The position of a coupler relative to the car which carries it is secondary and usually unimportant. So where is this magic position? For HO, the center of the knuckle should be .391" above the railhead, +/- .017", and centered between the rails. For N, the numbers are .216" and .010". You can find the standards for other scales at:  
              >>>  http://nmra.com/standards/sandrp/pdf/S-2_2010.07.pdf  <<<

    Okay. But how does one get the knuckle in that obviously precise location? It sure can't be easy to measure thousandths of an inch while floating in thin air above what looks like the center of the track. True. That's exactly why the NMRA produces standards gauges for most commonly modeled scales. The NMRA gauge will show you exactly where in space to put the center of your coupler knuckle. It will do lots more, too (like check the gauge of wheels, track, flange clearances and more), which is why you should purchase one at:  
              >>>  https://www.nmrastores.com/Public_Store/index.php?cPath=27&osCsid=6u8ubrmkt23kbogdohfn3i8371  <<<

      But the position of the coupler relative to its car or locomotive can be important, too. Notice that I wrote "can be", not "is." That's because the position relative to a car or coupler generally isn't important. The two things which make for an exception are very tight curves and long cars or locomotives. Long rolling stock will bump together on the insides of curves if they are too close together. The solution? longer shanks on the couplers so the cars are held farther apart. Tighter curves are more likely to cause this clearance problem so one might have to use longer shanks on normal length cars when curves are very sharp (anything under 22" radius). This is most often seen in the draw bars between steam locos and their tenders. Locos and tenders were pretty close together on 12" to the foot railroads. Such closeness on model railroads would likely cause a clearance problem unless extremely broad curves are used, like 36" or even 48" radius (HO).

      I still haven't mentioned underset and overset knuckles. These products are made for rough or major repositioning of coupler knuckles (seemingly) relative to the car, but (really) to that magic place in space relative to the railhead. Overset knuckles move a too-low coupler up; underset knuckles move a too-high coupler down. Final adjustments are made by shimming the draft gear (coupler box) down below the bottom of a car which is a little too high, or up from the truck bolster of a car which has its floor a little to low. I know that some of this sounds a little counterintuitive but just wait until you are adjusting these things with your car upside down. Then it will really seem like I'm talking through my hat! But I'm not.

      Kadee, who, IMHO, makes the best couplers for the major scales, also makes a coupler gauge. It sits right on the track and you just make sure that your car or loco can couple to it with everything lined up centered vertically and horizontally. It is a very useful tool, and easier to use than the NMRA gauge. It's only downside is that it can't check other critical dimensions and clearances. You can find out a whole lot more about couplers in general and Kadees in particular at:
              >>>  http://www.kadee.com/index.shtml  <<<

      This probably sounds a lot more complicated than it really is. I tried to be painfully detailed with my description to make it as easy as possible for readers to visualize what I'm trying to communicate.

      I don't understand your last question so I'll have to leave that for someone else.
                                                                                                                             -- D