Thursday, January 23, 2014


One of the critical tasks preparing for operations has been completing installation of uncoupling magnets.  I am using Kadee 308 under tie magnets for uncoupling in difficult to reach spots.  Permanently mounting these magnets under the ties can lead to undesired uncoupling, so all are mounted on trap door (hinged) hatches.

Preparation for the magnets began with cutting holes in the cork roadbed and plywood subroadbed at the desired locations. 

Uncoupling magnet hole in roadbed.

The holes were then covered with styrene covers.  I used 0.020 inch thick Evergreen black styrene for the hole cover and Evergreen dimensional strip for the cover frame, matching the roadbed height.  I used black (vs. white) styrene to be less noticeable should the eventual ballast cover get disturbed.

Uncoupling magnet hatch covers.  A Kadee 308 magnet and steel field enhancement plate are nestled in the left hatch cover.

The holes were cut and hatch covers were mounted as part of the roadbed preparation before track laying.  The hatches received the same gray latex paint used to prepare all roadbed.  <Note: recent discussion on a Yahoo Group List points out that latex paint “breathes.”  I accept that my roadbed painting is purely cosmetic.  It won’t slow the drying out of the cork.>

With initial operations looming soon, I needed to complete the magnet installation.  As seen in the photo, a typical installation involves mounting a small plywood hatch to the underside of the subroadbed with a hinge.  A corner brace mounted on the side provides a lever arm for actuation.  Airplane control rod (plastic “choke cable”) provides the linkage to a knob mounted in the fascia.  Pulling the knob pulls the magnet hatch up into position.  Pushing the knob back in lowers the hatch, reducing the magnetic field, hopefully preventing unwanted uncoupling.

Typical magnet hatch activation installation.

Two spurs in Springfield are far from the aisle, close to the backdrop.  The team track ramp also might be difficult to reach, so all three get the Kadee 308 magnets.   The Eugene depot tracks are a long reach from the aisle, so many magnets are mounted there.  Further motivation for magnets on the depot tracks comes from providing for some passenger car switching at the depot.  Passenger car diaphragms are notorious for getting in the way of any other uncoupling method.   I’ve added magnets for both switch ladders in the classification yard, even though both sites are within easy reach of the aisle.  The Eugene depot and classification yard complex has sixteen uncoupling magnets mounted.  About half of those were challenging installations.  Still, one learns and develops a set of techniques used for most installations.

Chalk up one more “Must Do” task on the way to bringing the railroad into operation.

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