Model railroad scale speed calculator,model railroad team track aastra,greyhound bus new york niagara falls - New On 2016

09.04.2014
ShareThisModel railroaders may know of prototype dynamometer cars, used by railroads to evaluate the effectiveness of newly designed motive power, particularly in the days when railroads designed and built their own. This all started when I read about the details of prototype operating runs with Dynamometer Cars.
This article describes a model laden with instruments that measure: time, speed, distance, drawbar pull, and track voltage (both DC and DCC) all of which are accurate enough to give a layout run meaningful results. Dynamometer cars were sometimes rebuilt cars (like passenger cars) and sometimes built from scratch. Drawbar pull measured the force exerted by the locomotive at the coupler as it traversed its route over the line.
Sometimes, the same kind of run would be made when new appliances like booster engines, feedwater heaters, pumps, and the like were added to an existing locomotive.
I built at least three different spring driven linkages connected to the coupler, and found all of them to do a poor job. Close scrutiny of the brass holding block will show that the block was sloped to allow the length (about 2 inches) of the load cell to fit within the car body, and yet present as much of an angle as possible to the drawbar lever. One of the specific capabilities I wanted in the model dynamometer car was its ability to measure track voltage. This is the first time I have used nearly all available memory space on the little microcontroller. Two axles on the rear truck feed the separate full wave rectifier used to measure track voltage.
Two 0,96 inch OLED display are mounted in the baggage door windows on both sides of the car. All data is recorded in a readable, MS Excel compatible test file on a Mico SD Memory Card. The significant advantage of dropping the file into the spreadsheet is that you can take your mouse and hover over any point on any graph and it will identify the time (horizontal axis) and value (vertical axis).
I have yet to get to filtering, averaging, scaling, adjusting for planetary shifts, gravitational waves, and making things look pretty.
My test loop is exactly that – a double loop of track that I have hacked up a couple of hundred times that still works, and can be taken down and put up at will.
That would qualify as a two part article in some magazines and you managed to make it in one post!
Lots of questions about what the data is saying, but really not appropriate until you have been able to acquire a larger data base. One thing I didn't understand was why the brass angle mount was needed, it looks like there's room to lay the strain sensor down flat? If the strain sensor (load cell) were mounted horizontal, the most efficient transfer of the load pressure would be vertical to the bar.
Does having it measure on the slope require a correction to get a level vector measurement?
They were especially known for their measurement of drawbar pull – the pulling force at the coupler (and hence the ability to move tonnage over the rails).
They were used by many roads, and were manned, in part, by design engineers working for the railroad. Drawbar pull and track voltage are displayed on both sides of a heavily modifies Athearn RPO heavyweight passenger car.
Their front coupler was connected to springs via a mechanical linkage, or to a hydraulic piston assembly, or in modern times, to heavy duty strain gauges, where force could be measured and readings saved on a graphic chart recorder. The locomotive itself would have measurement sensors and gauges added, whose wiring (via cables) would run over the tender and into the chart recorders in the dynamometer car. Live steam railroaders have built working model dynamometer cars to evaluate their own models. In the September 1945 a plan was presented for a recording O scale dynamometer car using a miniature, scratch built chart recorder.
The first one that I am aware was manufactured as a kit by the Devore Company in August, 1952. This car also used a spring mechanism tied to the coupler, which moved a pointer against an unmarked,  vertical scale placed at the side loading door.
Track current is specific to the individual load (loco) and not relevant, but the drop off or droop in the power distribution on a layout is often debated by modelers. The Moteino is a 3.3 Volt device so the DCC voltage needs to be lowered to a safe level for conversion.


It has four tiny rare earth magnets super glued at 90 degree increments around the inside of one wheel. The six wheels in the front truck are all used for power pick up for the on board electronics. I’ve tried successfully using a 32GB card inserted into the top of the chart recorder case.
Knowing the time to can go to the distance graph and find the exact location (distance from start) at that time step. I am fully aware that conversions can be done to scale MPH, scale distance, fast time, slow time, no time, the metric system, and language translation of labels. More pictures, descriptions, schematics, code (sketches), trials, data, and analysis are coming. I have always thought this would be an excellent addition to any railroad, and you have exceeded my expectations !
If you imagine the linkage from the coupler (which is horizontal pulling forward) pivoting the link around its axle, it would be most efficient if the load cell bar were vertical, so the link could press at a 90 degree angle. But dynamometer cars were more than that – they were mobile instrumentation labs on the rails, with a crew to maintain and record their findings over the course of rail operations, not just on a test track.
Data gathered from the on board instruments are sent to a battery powered, handheld receiver, which displays drawbar pull, track voltage, and speed in the form of three graphic charts in real time.
The rotation of the wheels was sometimes coupled to the recorders to synchronize speed and drawbar pull.
Dynamometer cars were sometimes used to characterize the tonnage and motive power requirements over different divisions. To shorten the movement, one would need a shorter, stronger spring that would lose the resolution needed for HO scale.
The load cell will measure the force applied to a fraction of an ounce, and requires very little movement of the coupler shaft.
The RRAmpMeter is a great product often cited in DCC discussions as a great tool – and it is. A full wave rectifier converts the DCC signal to a DC noisy signal that a 5 to 1 voltage divider reduces to a safe level.
As it free spins in transit, a Hall effect sensor (Allegro A1126LUA-T Omnipolar Hall Effect Switch Digikey part # 620-1423-ND) picks up the movement as each magnet switches the device on in turn.
Data packets (telemetry) consisting of the time in milliseconds from the start of the run, a tachometer reading from the last packet sent, the drawbar pull in fractional ounces, and a 5 point average of track voltage with resolution to better than 0.1 volts are sent out about every second of operation. As it free spins in transit, a hall effect sensor picks up the movement as each magnet switches the device on in turn. Based on the data collected already, a 1 GB memory card will hold about 33 minutes of data from a continuous run. Starting out of the Mill Bend yard, we passed through Deschutes Jct, Baynes Valley, Canyon Creek, Tunnels 3 & 2, Oak Hill, and around the big turn! I thought the TV sets in the store window would not be able to be topped, well I was wrong again.
Small scale modelers have been missing the tools to provide the equivalent evaluations on their layouts and club venues …until now. I will number the major sections, when I remember, to aid in directing questions and comments. Measuring pens would move from side to side across a rotating drum of paper to record measurements against speed or time.
The effective use of this power, coupled with fuel and water consumption gave the railroad an understanding of the efficiency of operation and the value of the new loco design.
The key to using the load cell in this fashion is the mechanics needed to apply as much of the force from the drawbar load to the load cell as possible, with no other flexing of the mount, flooring, trucks, or car body as possible.
One should also note that the front of the block has been filed down from the tapped mounting hole of the load cell forward, to expose the underside of the load cell bar, without weakening the mount. Its documentation states that it measures the DCC track voltage with an RMS (Root Mean Squared) measurement technique giving an accurate measurement, and significantly better than an AC or DC meter – also true. A 1.0 uf non polarized capacitor not only filters the high frequency noise but will retain the peak voltage so converted, since there is very little current draw by the analog input of the processor chip. The instantaneous Drawbar pull measured in tenths of an ounce, and the peak track voltage at the car’s location is displayed.
This adventure is described in three parts: short notes on the prototype, and changes in requirements and design I considered for the model railroad environment.


This project evolved to considering what measurements were appropriate to a model railroader on any size layout, irrespective of DC or DCC operation. With no GPS system, a man would be stationed in a cupola towards the front of the car, and note the passing of mile markers by voice, or by pressing a button that would ink mark one of the recordings. Others were used to make efficiency tests regarding fuel consumption, fuel stops, station stops, and helper requirements. The sensor is soldered to a short section of PC board (or PC tie) material screwed to the truck bolster. Next I’ll describe the construction of an operating, recording, HO scale dynamometer car with additional capabilities.
All the data captured and displayed are simultaneously stored in a readable text file on a micro SD Memory Card (like those used in cameras) for later processing on your personal computer or laptop. I may get to present some of the experimental trials (and failures) too, which may be too much for the weak hearted! Another man stationed at the recording desk would annotate mileage, location, and other significant data as they progressed, by writing directly on the charts and in a log book. Firebox and boiler temperatures, operating settings (valve and throttle) , boiler pressure, break line pressure and other readings and were also measured and recorded.
Thin flexible wires are soldered onto the PC material and routed through a hole in the car chassis to the microcontroller. BC&SJ’s Horace Fithers suggested that the chart recorder be equipped with a microphone for adding verbal annotations!
Since that point, I made the mistake of reading another article about Southern Pacific’s dynamometer cars (and the additional measurements they made), and another about track geometry cars (now entering information overload)!
An MS Excel spreadsheet template (provided) can then be loaded directly from the text file, to display the entire run as a multiline graphic set, which the modeler can analyze to their heart’s content. This allowed for a short, brass lever which the coupler shaft would pull to exert force on the lip. A car with a display on one or two sides gives a fleeting view as its train moves past the observer.
This might be particularly useful for maintenance in a large layout or club, where the run might indicate bad trackage or electrical connections. A small strain, or torsional, non-damaging, stress of the metal bar will unbalance the bridge, and this imbalance can be measured. The good news is on many if not most DCC layouts, my experience is that this is a rare event. Even if you could read the information, the prototype showed that a run over the road, under normal operating conditions, is where the real value lay.
Fortunately there is an integrated circuit (and small module) available for a modest price that performs the interface and does the conversion for us – the HX711.
Or maybe you would like to speed match your diesels by knowing at what actual speed they are operating for any given DCC speed step? In the general case, this is not nearly as good a method as the RMS technique, but it can be calibrated to give nearly the same results in many cases at a fraction of the complexity (and cost).
One of the diesels lost power temporarily, and its side effects can be seen in the drop out in speed and drawbar pull in the middle of the third run. Unlike other articles I have written, this one is likely to me more of an exploration, rather than a conclusion, as such, this will be updated over time.
So much that one would need a way to view and manipulate it, to make the whole endeavor worthwhile. Additional data demonstrates changes in drawbar pull as the train goes up and passes a 2.3% grade, later level, and then downhill. That is, there are cases where this method will give incorrect readings (read poorer, faster than the RMS technique).
Nonetheless, looking at a $19 chip to do the RMS reading, I chose to build a peak reading voltmeter for the prototype dynamometer car, and see if it is worth upgrading or not.
Speed jitter is presented in the raw data due to the way the tach interacts with the packet transmission.



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Comments to «Model railroad scale speed calculator»

  1. NEITRINO writes:
    Considering that beginning my basement layout.
  2. Ya_Misis_Seks writes:
    Was the original Thomas the Train shop layout.
  3. EmiLien writes:
    Standard in 1956, and have been.