ESOTERIC TEST FACILITIES


The following equipment is normally limited to satisfying my own curiosity and not put into general use in testing models for sale. However many new products were run through the mill. The information was invaluable in selection of products as well as adding to the overall knowledge of the field, in order to advise customers. Many of the statements and opinions found elsewhere are founded on deeper evaluations with these devices.

Weight, drawbar pull, speed, gear, motor, driver, wheelbase and other data on over 350 locos has been recorded on Superbase 4 Professional database for easy comparison and compilation . On repowered locos both original and modified data are readily compared. Also a complete description of work proposed or done is recorded.

Other files contain data on several thousand cars including weight, length wheel base, couplers, trucks and test results. Having a continuous flow of models from our store, swelled the base to these dimensions. Of course not all models got the full battery of tests, but the odd and troublesome were tested extensively. This data plus customer feedback provided a sound foundation for advice to the buyer. But it also helped satisfy my own curiosity. The order of appearance does not reflect usage of devices.



Very important in starting trains and hauling them up grades, drawbar pull or tractive effort is often bandied about with wild claims. But how often are accurate, comparative measurements made? There are two distinct pulling measurements: the starting tractive effort and the drawbar pull at speed. The Pennsyvania had a very sophisticated loco test plant, but used dynamomter cars for final road testing. In the prototype the starting tractive effort is limited by the weight on drivers, the coefficient of friction between drivers and rail plus the force developed at the track by the prime mover. The same holds true for models, where torque from the prime mover, the motor, produces the force. Accurate measurememts are required to achieve optimum results. MEASURING STARTING TRACTIVE EFFORT _ can be done several ways.


On the prototype, dynamic drawbar pull at speed is limited by the horsepower developed and wheel slippage. This holds true for models where the force is derived from the motor torque through the gear train. Measuring drawbar pull on the road requires a dynamometer car with a calibrated, spring loaded coupler. Through linkage, a needle can indicate pull on a dial. But the problem is in seeing the reading at every point on the layout. Walthers released a working dynamometer car with an indicator dial which is barely visible through small doors on the sides. The scale is numerically unmarked with 1 oz lines to 8 oz. Adjustment is touchy, but it tracks well, when properly set. In their usual disregard for the modeller, the promised infrared remote indicator was cancelled. At best it can reveal relative comparisons.


ELECTRIC METERS are essential to testing and evaluating many items. Each power pack should have an analog ammeter and voltmeter to monitor loco operating conditions. But for more accurate work in testing and calibrating, a good quality digital mutlimeter is hard to beat. Today reasonably priced models have tolerances well within 0.1 % and very high input impedences to avoid loading down test circuit. Automatic range and polarity settings are very convenient and void possible damage. Four digits is more than enough accuracy for almost any testing. Standard inputs are volts, amperes and resistance (ohms). Highly desirable is a continuity buzzer to check for open or short circuits, without watching meter. Some have memories for comparison purposes. If you are into solid state device testing, some have a diode test and hfe test to evaluate transister gain. Size depends on use. A small one is very useful around the layout. A wide variety of pointed, and clip-on tips is useful to free hands. Coiled retractable leads reduce clutter.



Note: Adjust brightness and contrast for optimum viewing.

S: Oscilloscope
D: Data Aquistion Unit
MON: Aniga 2000 monitor
MM: Digital Multimeter



To observe waveforms and other changing values, an oscilloscope is necessary. Basically it shows a plot of magnitude vertiacally and time horizontally. Counting gradicules to determine magnitudes and times is frustrating, so a digital readout is preferred. Cursers are set to the points desired and values are shown on the display. Two input channels provide comparisons. For most modelrailroad applications frequency and bandwidth are not crucial.

Since storage scopes are very expensive, a Data Acquisition Unit was added to an Amiga 2000, where waveforms could be stored on disks for future reference. This is very useful for long time period cases which are difficult to capture on a scope. All parameters are controlled on the display by point and click.

DIGITAL READOUT OSCILLOSCOPE and DATA ACQUISITION UNIT


Other test devices are found under Measuring Indexincluding coupler, clearance and height gauges.

Coming when time permits:

Motor tachometer.
Sloping fixture.

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