Coupler modifications

Coupler and pocket

Figure 2                                                Photo by Bill Summers

The knukle stop (Fig 2-A) has been filed back to allow the knuckle to open completely. File the stop until the tip of the knuckle will open just even with the end of the coupler base. (see Fig 3-A) This extra motion is needed in order to uncouple reliably on curves by just moving one knuckle. Straighten the knuckle actuating pin and then bend it sharply to the knuckle side and at about a 30 degree angle forward. Trim it flush with the outside edge of the knuckle spring mount. Either flatten and drill it for a chain link, or else glue or solder the first link to the end of the arm. Pulling gently on the chain should swing the knuckle all the way open.