Chattanooga Modular Modelers

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Installing Kadee Couplers, H.O. Scale Rev.: 11/20/13

          Couplers can keep a train connected if all things are properly seen to, otherwise separations are almost inevitable. Since I have installed upwards of twenty one hundred pairs of couplers I will lay claim to being somewhat of an authority, not for the number, but mainly for the performance. My trains stay coupled, usually. The main reason for my "success" is setting a standard of precision that most modelers do not try to duplicate even though they could "Easily" do so. My "Self Imposed" Tolerance is within 0.005" of "Dead On" by shimming couplers with an eye toward perfection. How can I do it? What is the difference between a 0.010” shim & a 0.015” shim? 0.005”! Or vice versa, you moved the coupler 0.005”, simple huh? 
        Some equipment I use is easy to come by.  The number 1 tool is the # 205 Kadee Height Gauge. Or, the newer #206 insulated height gauge. You may want two of these, one for each end, but make sure they match each others’ height first, especially if you are doing several cars at a time, others are a bright desk-light, a magnifier mirror & a section of track attached to a straight board. The Kadee # 237 Coupler Trip Pin Pliers are a helpful addition. The Kadee # 235 Coupler Spring Pic tool earns its keep also. Having a supply of Kadee # 208 Red 0.015" & # 209 Gray 0.010" shimming washers, a Kadee # 246 2-56 tap & drill set, a goodly supply of varying thickness small metal washers to fit your screws, 2-56 screws in varying lengths primarily 1/4" will get you started. Kadee # 5 couplers will be used most of the time. Wearing a white tee shirt will help with the vision dept., as you will come to see.                
       There is another feature of our # 205 Kadee Height Gauge that is not published anywhere that I have seen. The # 312 & # 321 Permanent Magnet Uncouplers need to be held & centered between the rails while gluing, so Kadee would sell you a # 334 Uncoupler Gluing Jig. Not needed. Two of the # 205s, one on each end back to back, fits the magnet perfectly holding it in alignment until the glue sets.
       There are two primary parts of the Kadee coupler we are interested in: Coupler KNUCKLE, with spring that does the coupling & the SHANK that supports the Coupler Knuckle & holds it in proper position. There are three primary lengths of Kadee couplers 1/4", 9/32", & 25/64". The 1/4" size has its own curved front draft gear box that allows swinging clearance & can fit the longer couplers if needed. The #’s 28, 38, 48 are same as # 5. #58 is scale sized but they are 1/64" longer at 19/64". Each length has three shank positions in relation to its' knuckle: Overset Shank: above center of Knuckle. Centerset Shank: same height as # 5. Underset Shank below center of Coupler.
       Sometimes selecting the correct coupler can be a problem so I would recommend the coupler Sample Test Kits. There are two I recommend: # 13, is the basic kit. And # 92 features the 30 series kit which has the small, fit in tighter spaces, draft gear box that is tedious to assemble, they all have one each, of each size listed. I recommend the 40 series, even though currently there is no test kit, because they’re all metal & won’t bend or flex. It follows size numbers. # 27 is same as 47 etc. 58 & 78 are the only ones in their series, which are similar to # 5. They’re all metal, but scale size, the knuckle being 0.040" shorter & 0.025" narrower, which could cause more frequent separations but would look good on the front of a locomotive or rear of a caboose. #78 is a 58 with assembled narrow, scale size draft gearbox. I have found several #5s that are narrower. The regular size is 0.160”. The scale # 58 is 0.135” & our misfit is in the 0.145” range which is fine if that’s what you want, just be aware. Then there’s a new kid on the block, #148. This guy doesn’t use the brass centering spring because it’s got two steel “whiskers” that keep the coupler centered. I have noticed, however, that a 0.010” spacer washer in draft gear box with the coupler will most likely still be required to control vertical slack. 
Screw installing: turn backwards until it drops in threads, then tighten normally.
      Coupler Mounting: there is only one way to mount a coupler properly, Body Mount. Just for being brutally informative there is a second way called Talgo Mount where the coupler is mounted to the Truck & steers with the wheels. I have found Talgo Mount only works well on the locomotive where there is enough weight to offset torsional forces.  Athern Brand cars use a coupler retainer clip that can be a pain to make it stay on. The best way I have found so far, is grip the part of the clip, with pliers, that snaps over the  wedge on the car, and bend it in slightly by rotating the pliers out, so it slips on easier but holds itself in, gripping the wedge tighter. 
      Body mounting couplers on very long cars. Install long #41 underset, #46 centerset, or #49 overset, couplers in its draft gear box as normal, but tighten only enough to allow the draft gearbox to rotate laterally, no vertical motion allowed. You can put two nuts on mount screw to lock it in place or just glue them. This will allow long cars to negotiate “S” curves without becoming derailed.
       Coupler Height Adjusting: Repeat: Shim coupler inside its draft gear box with a #209 gray 0.010” shim washer if vertical movement is excessive, because if it can move up & down, it won’t stay where you set it.
     First, mount the coupler on the car & reinstall trucks & set on test track with Kadee Height Gauge # 205. Move car close to gauge & look with magnifier mirror at top & bottom alignment of coupler to gauge. You will see three possibilities: Dead On, Too High, or Too low. We'll start with the easiest, if Dead On, coupler installation part is complete. If Too High, coupler needs to go down by shimming between car body & coupler box, go to Overset Shank; or worst, file or grind bolster between Truck & Body. Too Low coupler needs to go up by shimming between Truck & Bolster, or Underset Shank is needed. 
     There are two other height adjusting techniques available: When the coupler is tilted up or down, or just a little bit off, bending as needed can work wonders to finish gauging. It’s really best to stay with the 40 series, # 5 & # 58 couplers that are all metal. Plastic couplers, 20 & 30 series, can flex & won’t stay where set.  The regular size freight car wheels are 33”. If coupler heights are just a bit off try switching around 28” rivarossi & regular 36” passenger car wheels, mixing them with the 33” ones. Coupler height should be re-checked any time wheels, trucks, or couplers are changed, or other maintenance is performed.
      Set Trip Pin Height now, or cut it off.
       PATIENCE, Patience, patience. Coupler Installing can be the most infuriating, monotonous aggravation there is to be encountered, especially by the neophyte railroader. Sometimes l lay everything down right where it is when I feel myself coming to a boil & take a break of some kind to keep me from stomping those annoying critters in to the carpet. Close tolerances require the patience of Job. But is all this aggravation worth it? YES! YES!! YES!!!  When your train runs along perfectly even when you can see the humps & bumps of uneven track but your flanged babies stay coupled like they're tied while our less diligent fellows cannot go one train length without a derailment or separation of some kind. It's called SATISFACTION with a Job Well Done. 
     DERAILMENT???? Did I say the nasty "D" word? l'm afraid so, but there is a fix for this nasty little problem also. Have you heard of the N.M.R.A. Standards Gauge? Well it has PROBLEM SOLVER written all over it.
     [1]Wheel GAUGE i.e. spacing between the flanges, is a specifically predetermined measurement that must be closely adhered to if we expect to attain good operation.
     [2]Wheel WIDTH: there is a go, no-go gauge, that if the wheel fits inside, it's too narrow & may not make it through turnouts & crossovers. Scale wheels are much narrower than normal size model wheels but all track, switches & crossings are scale sized to fit also.
    [3][Truck MOUNTING: N.M.R.A. says: one truck should be fairly rigidly mounted so it can swivel, but not rock. The other truck should be loose enough to rock as well so the car can negotiate rough track & keep all wheels on the rails Or both trucks can be given just a slight looseness to also help resist clothes-lining, preferred by me.  Definition: clothes lining is when a string of cars negotiating a sharp curve might be pulled into a straight line by the head-end power overcoming the drag of the weight of the train. Big train wreck!!!
     [4]Train car weight should be a standard weight for its’ length, which is: 0.5 ounce for up to the first 1 inch of car length + 0.5 oz. For each additional inch of length, so a 6 inch car would be   {0.5 oz. + [(5 x 0.5oz.) =2.5 oz.]} = 3 ounces. 
     [5]Wheels PARALLEL: this one is mine, or at least I haven't heard of it from any where else. Each pair of wheels on an axle must be parallel with the truck frame & the 2nd [and 3rd] set of wheels in the same truck. If not, the truck will be skewed, causing the flanges to dig into the edge of the rail even enough to climb up, & off the rail
      [6]Thin flanges: not in published literature, but thin flanges can become a real bear. Check for thin flanges, they can get sharp enough to shave with, they can pick a switch, ergo, go the wrong way on a turnout. If you always run your train in a circle then reverse direction to equalize flange wear.    
      Addendum: should you wish to place your trains on the track easier than normal: 
There are 2 “rerailer” tools you may wish to use : 1, Kato brand only. Don’t waste your money on anything else or, 2, installing a simulated RR crossing track does well also. Of course you have to take up some track to put it in place.
 Written by Bob Swanner  12/7/01 Pearl Harbor Day 60 years Ago Sun. 8:00 A.M. 12/7/41.