Body Mounting Kadee 830’s onto: USAT NW-2 & S-4 Switcher Locomotives
Moving beyond factory couplers.
By: Keith Stratton

 This installment is the sixth in a series of ‘How To’ articles on body mounting Kadee 830 or 930 straight shank couplers.
As I have worked my way through converting my locomotive roster over to Kadee couplers, every now and again you have get a little ‘creative’, which is what makes this hobby so enjoyable.  This brings me to the conversion of my two USA Trains switchers, namely a NW-2 in CN livery and a S-4 in CP livery as shown in picture #1.

Picture 1

Picture 2

 In the Kadee catalog on the ‘Conversion’ page it calls for Kadee 787 couplers to convert both locomotives with the option of a Kadee 831 on the NW-2 for use on curves of less than 8’diameter, see picture #2 for examples of both couplers.  I chose not to go this route for a number of reasons:
both are offset couplers, which I dislike the appearance of;
the draft gear box on these types of couplers is tiny and has a non-prototypical pivoting action;
mounts to the ‘U’ shaped brackets that USAT uses which are not mounted to the frame in a very robust manner.
The Kadee 830/930’s are my ‘go to’ couplers for a number of reasons.  They are tough, have straight shanks and have a larger surface area providing numerous mounting options.  So, I had to figure out a way to make these work for me.  Fortunately it turned out to be relatively easy and nearly identical for both locomotives.

Picture 3

Picture 4

 First thing you have to do is remove the existing USAT couplers and ‘U’ shaped mounting posts from each end of the locomotive.  The coupler is removed by removing the single screw holding it in place.  To remove the mounting bracket, as shown in picture #3, remove the two screws that secure it to the underside of the frame.  Now you can start the installation process!
We have to determine if the end sill of the locomotive needs to be modified to accept the 830 coupler’s draft gear box.  Place the locomotive onto some track and then slide a Kadee coupler height gauge up to the engine where the coupler exits the end sill.  Turn the coupler gauge around so the pointed end is toward the sill, as shown in picture #4.  This will show where the top of the draft gear box exits the sill, so make a mark onto the sill for reference.  Do this on both ends of the locomotive.

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Picture 6

 Take the locomotive off of the track and place it upside down on the workbench.  As shown in picture #5, place the draft gear box in position, center it then mark on either side where it sits on the sill.  Cut down these lines down to the height line previously marked to create to opening needed for the draft gear box as shown in picture #6.

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Picture 8

 Picture #7 shows the NW-2 with the opening cut away as well as the two mounting tabs for the USAT coupler mount and picture #8 shows the same thing for the S-4.  Now we can start to mount the coupler.  We will be building up the area under the floor plate with styrene to be flush with the coupler opening in the sill.  First thing we need to do is prep the area for gluing by scraping off the paint from the underside of the floor plate as shown in picture #9.  It is not shown here, but you should also scrape the paint off of the inside of the sill from the top of the coupler opening to the floor plate.  This will ensure a very secure glue up of the styrene shims.

Picture 9

Picture 10

Picture #10 shows the styrene shims in place for the coupler-mounting pad on the NW-2.  Each locomotive needed different amounts of material, but fortunately a combination of off-the-shelf Evergreen Strip Styrene products worked out perfectly (which is a thing of beauty when it happens, because it doesn’t happen very often!).    On both locomotives I decided to run the strips right across from the inside of one step to the other, which yielded the largest gluing surface possible.  Each NW-2 mounting pad required one piece of Item No. 415 that is 0.25” thick x 0.75” wide and cut to 1.75” in length, as well as one piece of Item No. 405 that is 0.188” thick x 0.75” wide and cut to 1.75” in length.  Each S-4 mounting pad required two pieces of Item No. 415 that is 0.25” thick x 0.75” wide and cut to 1.625” in length and one piece of Item No. 405 that is 0.188” thick x 0.75” wide and cut to 1.625” in length.  Once you have cut the shim strips to length, glue each one in place with CA adhesive all the way around for a secure bond.

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Picture 12

 Before mounting the coupler, you will need to shorten the draft gear box by ¼” which corresponds to the end of the coupler shank inside the gear box.  Also, cut off the small half-round tab on the end of the coupler shank.  In addition, you will need to bevel each end with a 45 degree cut.  The completed coupler modification is shown in picture #11.  These modifications do not affect the coupler operation or integrity in any way and are necessary for clearance between the trucks and the back of the coupler draft gear box as the trucks to swing from side to side on curves.
Now mount the coupler by positioning the draft gear box in its final place and then take a scribe and mark the center holes for the mounting screws.  Push and twist the scribe point into the center mark to create an indent for the drill.  A #54 drill bit is used to drill the pilot holes for the mounting screws.  Screw in a #4 pan head screw into the pilot holes and then back it out.  Trim flush the extruded / raised ring of plastic that forms around the hole.  This raised edge must be cut, shaved or chiseled off otherwise the coupler draft gear box will not have a flush fit onto the mounting pad.  Now take two #4 x ¾” pan head Phillips screws and secure the coupler in place.  I usually paint the screw heads brown or black so they blend in but have left them unpainted in the pictures so you can see them better.  The NW-2 mounted coupler is shown in picture #12 and the S-4 mounted coupler is shown in picture #13.  I chose to mount the couplers flush against the sill but they could easily be moved out farther if needed.

Picture 13

Picture 14

Now for the all-important verification!  Place the locomotive back on the track and check the coupler height against a Kadee height gauge, with the NW-2 shown in picture #14 and the S-2 in picture #15.  If you did your initial markings accurately it should line up just right, but have a couple of 1/32” shims handy for final adjustments… just in case.

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Picture 16

Picture #16 shows the ‘business end’ of both converted locomotives.  This coupler mount is very robust, looks prototypical and also works well on small radius curves… it just doesn’t get any better than that!   Now you are ready to do some serious switching!  I hope you have found this information helpful, even if you don’t run Kadee’s!!!  Stay tuned for more articles on how to install these wonderful couplers on our 1/29th scale treasures… *