Kadee offers two "scale" sizes to choose from and they represent the standard Type "E" 12 inch high knuckle coupler. Our #1 scale couplers are 1:32 scale and are designed to be mounted at the current NMRA Standards "S-1" coupler height of 1&1/16" (27mm) above the rail, measured from the top of the rail to the "center" of the coupler. Our "G" scale couplers are 1:24 scale and are designed to be mounted at 1&1/8" (1.125") above the rail, just slightly higher than the G scale "narrow gauge" coupler height of 1 & 5/64" above the rail. This is based on narrow gauge being 3/4 of standard gauge, standard G scale coupler height is 1 & 7/16" (1.4375") divided by 3/4 (or x .75) equals 1.078". Both couplers are very close to "actual scale" size. Our #1 scale coupler knuckle is .370" high, measured at the pulling face and our G scale coupler knuckle is .495" high.
Note that the manufacturers of large scale models (due to many reasons) may or may not produce their models entirely to a particular scale size and that their couplers are set at various heights according to the height of ''their'' specific type of uncoupler and not necessarily to the NMRA Standards. Therefore, you will find different styles of couplers mounted at different heights between the various makes of models.
Since "large scale" covers several different "scale proportions" ranging through but not limited to 1:32, 1:29, 1:24, 1:22.6, 1:22.5, and 1:20.3 ratios the particular choice of coupler size is up to the modeler. There are many who like the small #1 scale coupler for the more to scale "appearance" (these are also used mostly on the 1/32 and 1/29 scale models). There are many that use the larger G scale coupler because it has a larger pulling face for use on rougher trackage, like that on outdoor layouts that are exposed to weather and temperature variations (these are used mostly on the 1/24 and larger scale models).
In our large scale coupler conversion list we show the two recommended coupler options of using a #1 or G scale coupler that applies to most models. Many of our #1 and G scale couplers use the same draft gear box so the modeler can follow the same mounting procedures for both scales. The shanks of these couplers are molded to compensate for the difference in the coupler height between the #1 and G scale couplers.
Usually, if the particular model has a truck mounted coupler we also will try to mount our coupler on the truck. Most of the time couplers are truck mounted to help the model negotiate tight radius curves and allow clearance for the wheels to pivot, etc. If the modeler wishes to body mount the coupler instead of truck mount, it usually is a matter of building a level platform to mount a straight or centerset shank coupler on. Then, if needed, shimming down to the correct coupler height. On shorter cars you'll need to make the mounting and coupler as narrow as possible to allow the truck to pivot freely with enough wheel clearance to negotiate the tightest curves on your layout. We have changed truck mounted couplers to body mount on some passenger cars and a few locomotives such as the Bachmann Climax and Shay where we use a coupler in the prototypical shelf pockets. We also mount our couplers for the closest coupling distance between cars (and locos) as possible and still retain the ability to negotiate the tightest curves the model was designed for.
