To test the locomotive (above), couple it to the yoke car which is attached via a heavy thread and an alligator clip to the postal scale (right). As the engine pulls the yoke car, the pointer on the scale indicates the ounces of force being applied.
For the base, use a scrap of plywood
³/₁₆″ or more thick, and about six to ten inches wide by twenty-four to thirty- six inches long. Optionally, glue down sheet cork to cover it completely. If you use the cork, you may need to put down two or more strips, depending on how wide the cork stock is. If using multiple strips, the slight gap between them is a great place to store some of the gauges described later on. I laid flexible track for the engine test
track. Install it from one end of the base to the other, with a bumper track or ac- cessory bumper at the right end (or both ends), to keep engines from accidentally running off the end. A lighted bumper track is handy for quickly assuring at a glance that you have power to the tracks when performing your engine tests. The track should be inset about an inch or two from the long back edge. An optional re-railer section or two will be handy for placing engines and a “yoke car” on the track. For engines, there’s
a “dynamometer” facility to
measure tractive power and to compare it to the engine’s weight for a power-to- weight ratio. You can measure voltage, and current if you wish, and compare all that to the published reviews. It’s a good idea to measure free- rolling performance for rolling stock, and check wheel gauge, coupler height, weight and other standards for all equipment. The rolling stock test track is a piece of flex track laid about four inches from the long back edge and ter- minating in a Micro-Trains coupler height gauge on the right end. The left end terminates in an acceleration ramp that’s about six to eight inches long, and about one-half to three-quar- ters of an inch higher at its left end than at track level. Experiment with the height to find what’s right for you. The object is to be able to release a car from the top of the ramp and have it roll down the track an acceptable dis-
RAILROAD MODEL CRAFTSMAN
tance so it can be considered “free- rolling.” You can just raise the left end of the track with a wedge of wood or plastic, but it’s better to mount a com- mercial re-railing ramp (e.g., Kato, Model Power, or Rix) on top of the track to make placing the car easier. A stop of some kind at the top of the ramp makes it easy to release cars from the same point each time. Glue a ruler down beside the flat portion of the track with its left edge at the bot- tom of the ramp. A scale ruler is ideal, but anything will do. We are only after a relative measurement with it, but “scale feet” has a nice ring to it. Now for the dynamometer, the key
unit. It consists of a frame that sus- pends a balance-type postal scale, and a yoke car. The frame can be made of plywood, plastic, balsa, foam board, al- most anything about ¹₁₆″ to ¹₈″ thick, but clear plastic would be best to give the best view of the scale.
The two sides should be trapezoids about three and one-half inches at the bottom, one and three-quarters inches at the top, and about six inches high. The top is a rectangle measuring
about 1³₄″×2¹₂″. Glue the top down over the two sides and screw a cup hook in its center. Glue it in place for extra security. The bottom is a piece about three and one-half inches long and wide enough to fit between the sides (about 1¹/₂″). It is glued between the sides high enough to clear the top of the rails when the sides are glued down to the base. This last step should be done next. It goes on the left end of the engine test track and cen- tered over the rails.
Install a screw eye through the bot-
tom and into the base about an inch or two on the left side and centered under the cup hook. Hang the postal scale from the cup hook. For the yoke car, anything will do, but an ore car is good because of its open end frame and short length. It
Bill of materials (Measurements are for N scale test track)
1 Balance postal scale 1 Spring postal scale 4 to 6 feet flexible track 2 Re-railers 2 Lighted bumper track 1 Re-railer ramp 1 Plywood strip (approximately 6″ to 10″×36″) 1 sq. ft. Plywood or foam board 2¹/₂ sq. ft. Sheet cork 1 Micro-Trains coupler height gauge 1 Micro-Trains trip pin height gauge 1 Test meter 1 Power pack 10 Test leads with alligator clips 1 Scale rule 1 Yoke car
Miscellaneous Cup hook, screw eye, thread to the screw eye, wire and glue
should be weighted for best perform- ance. Run a loop of thin wire through the end frame and form a “V” facing away from the car. Now connect the al- ligator clip of the balance scale to the V in the wire loop on the yoke car with a length of heavy thread and run it through the screw eye. When the test car is pulled to the right, it will pull down on the alligator clip on the scale and cause the scale gauge to rise. The scale pointer will then indicate higher readings as the test car is pulled for- ward.
Next, place a spring-type or digital postal scale on the base about an inch back from the near side and an inch from the right edge. You can affix it to the base if you like or leave it free if it’s “borrowed” from your spouse’s supplies. Place an NMRA standards gauge and an NMRA trip pin height gauge in a handy spot on the base. For track power, use an old, cheap power pack if you’ll be testing analog (d.c.) equip- ment, or you can use jumper wires from the test track to a track on your layout, for either d.c. or DCC power.
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