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After recently acquiring a PBL model of D&RGW K-36 #489. I was faced with the task of fitting a front coupler to the snowplow pilot, that would be fully operational for magnetic delayed-action uncoupling. Although it looked to be a somewhat daunting task, Steve Amitrano sent me some pictures of a couple of his locomotives so I knew that it COULD be done! At least by Steve, anyway...!
The following is a brief description of what I did. Steve also sent me a detailed description of what he did, which has yielded similarly pleasant results, and follows at the end of this article
Photo 1. The first think I did was to cut off the centering wedge off of the end of a Kadee coupler. You will note that this is the Kadee #21 underset coupler which is the long shank version. The shank is filed ever so slightly, and then slipped inside a piece of 3/32" square tubing. Put a drop of ACC on the shaft as you slip it in and it will be there forever. Note that the coupler is not quite touching the brass tubing; the shaft is Delrin so this will insulate the coupler from the locomotive frame, as long as you don't cram the coupler up tight against the end of the square tubing!
Photo 2. Here are all the parts. As the pilot beam is quite far back from face of the plow, I wanted to bring the pivot point for the coupler as far forward as I could in order to avoid having to enlarge the coupler opening in the snow plow. I cut a small piece of shim brass out of 1/2" x 0.060" brass bar stock for the the support, and drilled a 5/64" hole in it to accept the screw to mount it to the pilot beam in place of the original coupler pocket. I then fabricated a small U-shaped bracket out of some 0.025" thick shim stock, and soldered it to the support as shown. The opening in the 'U' should be just wide enough for the 3/32" square tubing that is being used for the extended coupler shank.
Now for some drilling! First, clamp your support beam assembly in a vise, and stick a small piece of wood or 3/32" square tubing in the 'U' so that you don't collapse it when you drill the hole for the pivoting point. I used 0.028" brass wire for my pivot shaft, so I used a #69 drill in my Dremel motor tool. Carefully establish a center mark and start your hole. Once started and there is no longer the danger of the drill wandering, put a drop of oil on the drill tip - you'll be amazed how much this helps! Once you break through the top web of the 'U', sight along the end to make sure that you are cutting vertically as you start through the thicker bottom section (it's got the U-bracket plus the base). Once complete, slip the coupler shank in the support beam assembly and mark it where you need to drill for the pivot shaft. Remove it from the support beam assembly and clamp it in your vise - then drill the same #69 hole in it, again taking care to make sure that it is vertically aligned. The last hole we need to drill is towards the coupler head for the 0.006" wire that we will use for a centering spring, as in the standard PBL method.
Picture 3. All the parts have been put together now. The thick wire that is bent over and soldered to the U-shaped bracket is the 0.028" brass wire that is the pivot shaft. You can barely see the 0.006" wire that is the centering spring - it comes up parallel with the shank and is soldered to the inside of the snow plow center reinforcing bracket.
Photo 4. The completed assembly viewed from the side. I found that I had sufficient lateral movement that I didn't have to enlarge the existing opening in the snow plow.
Picture 5. Front view of the snowplow and coupler. The visible portion of the coupler shank has now been painted with Polly Scale Steam Locomotive Black.
Picture 6. It works! The locomotive has just uncoupled from a boxcar, over a permanent magnet as indicated by the LED in the ballast.
Photo 7. D&RGW #489 shoves its charge into the Sapinero team track.
Addendum - Steve's Method!
Gee, if I read my email before I started...Steve sent along the following detailed description of how he did his locomotives, which as follows:
Hi guys,
Jim Brown and I have been talking back and forth concerning mounting operating couplers on K-series snow plows. I have done three (two on PBL locos and one on an OMI) and this is what I did:
First remove the existing coupler and use it as guide for fabricating a new one. I used a rectangular piece of styrene that is the approximate size of the of dummy coupler shank for the new shank. Plastic ensures there are no short circuits when coupled to brass cars. The new shank should be as long as the end of the tip of the plow. Best to leave some extra here, this is important later. Using the dummy coupler as guide, taper and drill the mounting end to fit into the coupler pocket. Don't forget to drill the tiny hole for the centering wire that keeps the coupler centered on the plow. The new shank MUST have some side to side swing (the more the better), mine swings about 2/16 of an inch from center. This has provided derailment-free operations while switching, and while cut in as rear end helper. My minimum radius is 34-inches. To make more side-to-side swing, you may have to file the side coupler hole on the plow (I did, but not much). Test fit and temporarily mount the new shank onto the plow. Then cut a #26 Kadee coupler (any plastic Kadee coupler will work) about 3/16th of an inch back from the coupler head itself. Drill a small hole down the center length of each shank. Cut a scrap piece of wire to fit into these holes. I roughed up the wire so there was more "grip" to bond with the ACC. This wire will provide the strength at the joint where the coupler head and the shank mate. Now test fit to see what the overhang is on the plow and see if there is enough clearance with a car coupled to the plow with the Kadee glad hand/uncoupling pin. The glad hand cannot touch the plow. I try to have about 1/16th to 2/16th of an inch clearance between tip of the plow to the tip of the glad hand. If there is too much space at this test point, cut back the mounting shank as needed. Once you have the desired length, remove the mounting shank from the plow and ACC the wire into the shank and ACC the other end into the coupler head as flush as possible. Fill with putty if necessary, and file/sand smooth so there is no seam. Temporarily mount and test run on your tightest radius. Push the lightest car you have. Then try it with your cars that have the least coupler swing. Be careful not to break the new shank, the weakest area is where the center wire goes through the shank. If there is not enough side-to-side swing, file a bit off the plow hole where the shank goes through. Once satisfied, paint, decal and mount. The most delicate portion of the new shank will be where the centering pin of the plow intersects the shank. To add strength here, ACC this connection. To help break up the extra length profile of the new coupler, I have added a fine chain mounted from the top of plow, where there is a hole to the base of the coupler. On some of the real locomotives a chain was mounted this way too. Lastly, I cut the glad hand off the plow coupler - it just seems to look better - or less busy, so to speak.
Steve Amitrano
Photo 8. #484 takes on water on Steve Amitrano's D&RGW. Note the coupler chain that Steve has added.
Jim Brown - May 2001
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